5,250,000 Shares CEMPRA, INC. COMMON STOCK, PAR VALUE $0.001 PER SHARE UNDERWRITING AGREEMENT

Exhibit 1.1

5,250,000 Shares

CEMPRA, INC.

COMMON STOCK, PAR VALUE $0.001 PER SHARE

UNDERWRITING AGREEMENT

January 7, 2015

To the Managers named in Schedule I hereto

for the Underwriters named in Schedule II hereto

Ladies and Gentlemen:

Cempra, Inc., a Delaware corporation (the “Company”), proposes to issue and sell to the several underwriters named in Schedule II hereto (the “Underwriters”), for whom you are acting as managers (the “Managers”), the number of shares of its common stock, par value $0.001 per share, set forth in Schedule I hereto (the “Firm Shares”). The Company also proposes to issue and sell to the several Underwriters not more than the number of additional shares of its common stock, par value $0.001 per share (the “Additional Shares”) if and to the extent that you, as Managers of the offering, shall have determined to exercise, on behalf of the Underwriters, the right to purchase such shares of common stock granted to the Underwriters in Section 2 hereof. The Firm Shares and the Additional Shares are hereinafter collectively referred to as the “Shares.” The shares of common stock, par value $0.001 per share, of the Company to be outstanding after giving effect to the sales contemplated hereby are hereinafter referred to as the “Common Stock.” If the firm or firms listed in Schedule II hereto include only the Managers listed in Schedule I hereto, then the terms “Underwriters” and “Managers” as used herein shall each be deemed to refer to such firm or firms.

The Company has filed with the Securities and Exchange Commission (the “Commission”) a registration statement, including a prospectus (the file number of which is set forth in Schedule I hereto) on Form S-3, relating to the securities (the “Shelf Securities”), including the Shares, to be issued from time to time by the Company. The registration statement as amended to the date of this Agreement, including the information (if any) deemed to be part of the registration statement at the time of effectiveness pursuant to Rule 430A or Rule 430B under the Securities Act of 1933, as amended (the “Securities Act”), is hereinafter referred to as the “Registration Statement”, and the related prospectus covering the Shelf Securities dated December 29, 2014 in the form first used to confirm sales of the Shares (or in the form first made available to the Underwriters by the Company to meet requests of purchasers pursuant to Rule 173 under the Securities Act) is hereinafter referred to as the “Basic Prospectus.” The Basic Prospectus, as supplemented by the prospectus supplement specifically relating to the Shares in the form first used to confirm sales of the Shares (or in the form first made available to the Underwriters by the Company to meet requests of purchasers pursuant to Rule 173 under the Securities Act) is hereinafter referred to as the “Prospectus,” and the term “preliminary prospectus” means any preliminary form of the Prospectus. For purposes of this Agreement, “free writing prospectus” has the meaning set forth in Rule 405 under the Securities Act, “Time of Sale Prospectus”

means the documents and pricing information set forth opposite the caption “Time of Sale Prospectus” in Schedule I hereto, and “broadly available road show” means a “bona fide electronic road show” as defined in Rule 433(h)(5) under the Securities Act that has been made available without restriction to any person. As used herein, the terms “Registration Statement,” “Basic Prospectus,” “preliminary prospectus,” “Time of Sale Prospectus” and “Prospectus” shall include the documents, if any, incorporated by reference therein as of the date hereof. The terms “supplement,” “amendment,” and “amend” as used herein with respect to the Registration Statement, the Basic Prospectus, the Time of Sale Prospectus, any preliminary prospectus or the Prospectus shall include all documents subsequently filed by the Company with the Commission pursuant to the Securities Exchange Act of 1934, as amended (the “Exchange Act”), that are deemed to be incorporated by reference therein.

1. Representations and Warranties. The Company represents and warrants to and agrees with each of the Underwriters that:

(a) The Registration Statement has become effective; no stop order suspending the effectiveness of the Registration Statement is in effect, and no proceedings for such purpose are pending before or threatened by the Commission. If the Registration Statement is an automatic shelf registration statement as defined in Rule 405 under the Securities Act, the Company is a well-known seasoned issuer (as defined in Rule 405 under the Securities Act) eligible to use the Registration Statement as an automatic shelf registration statement and the Company has not received notice that the Commission objects to the use of the Registration Statement as an automatic shelf registration statement.

(b) (i) Each document, if any, filed or to be filed pursuant to the Exchange Act and incorporated by reference in the Time of Sale Prospectus or the Prospectus complied or will comply when so filed in all material respects with the Exchange Act and the applicable rules and regulations of the Commission thereunder, (ii) each part of the Registration Statement, when such part became effective, did not contain, and each such part, as amended or supplemented, if applicable, will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading, (iii) the Registration Statement as of the date hereof does not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading, (iv) the Registration Statement and the Prospectus comply, and as amended or supplemented, if applicable, will comply in all material respects with the Securities Act and the applicable rules and regulations of the Commission thereunder, (v) the Time of Sale Prospectus does not, and at the time of each sale of the Shares in connection with the offering when the Prospectus is not yet available to prospective purchasers and at the Closing Date (as defined in Section 4), the Time of Sale Prospectus, as then amended or supplemented by the Company, if applicable, will not, contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, (vi) each broadly available road show, if any, when considered together with the Time of Sale

Prospectus, does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading and (vii) the Prospectus does not contain and, as amended or supplemented, if applicable, will not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, except that the representations and warranties set forth in this paragraph do not apply to statements or omissions in the Registration Statement, the Time of Sale Prospectus or the Prospectus based upon information relating to any Underwriter furnished to the Company in writing by such Underwriter through the Managers expressly for use therein.

(c) The Company is not an “ineligible issuer” in connection with the offering pursuant to Rules 164, 405 and 433 under the Securities Act. Any free writing prospectus that the Company is required to file pursuant to Rule 433(d) under the Securities Act has been, or will be, filed with the Commission in accordance with the requirements of the Securities Act and the applicable rules and regulations of the Commission thereunder. Each free writing prospectus that the Company has filed, or is required to file, pursuant to Rule 433(d) under the Securities Act or that was prepared by or behalf of or used or referred to by the Company complies or will comply in all material respects with the requirements of the Securities Act and the applicable rules and regulations of the Commission thereunder. Except for the free writing prospectuses, if any, identified in Schedule I hereto forming part of the Time of Sale Prospectus, and electronic road shows, if any, each furnished to you before first use, the Company has not prepared, used or referred to, and will not, without your prior consent, prepare, use or refer to, any free writing prospectus.

(d) The Company has been duly incorporated and is validly existing as a corporation in good standing under the laws of the State of Delaware, with full corporate power and authority to own, lease and operate its properties and conduct its business as described in the Time of Sale Prospectus and to enter into and perform its obligations under this Agreement, and has been duly qualified as a foreign corporation for the transaction of business and is in good standing under the laws of each other jurisdiction in which it owns or leases properties or conducts any business so as to require such qualification, except where the failure so to qualify or be in good standing would not have a material adverse effect on the Company and its subsidiaries, taken as a whole.

(e) Each subsidiary of the Company has been duly incorporated and is validly existing as a corporation in good standing under the laws of the jurisdiction of its incorporation, with full corporate power and authority to own, lease and operate its properties and conduct its business as described in the Time of Sale Prospectus, and has been duly qualified as a foreign corporation for the transaction of business and is in good standing under the laws of each other jurisdiction in which its owns or leases properties or conducts any business so as to require such qualification, except where the failure so to qualify or be in good standing would not have a material adverse effect on the Company and its subsidiaries, taken as a whole; all of the issued and

outstanding capital stock of each subsidiary has been duly and validly authorized and issued, is fully paid and non-assessable and is owned by the Company, directly or through subsidiaries, free and clear of any security interest, mortgage, pledge, lien, encumbrance, claim or equity.

(f) This Agreement has been duly authorized, executed and delivered by the Company.

(g) The Company’s capitalization is as set forth under the captions “Capitalization” and “Description of Common Stock” in the Time of Sale Prospectus, and all of the issued and outstanding shares of capital stock of the Company have been duly and validly authorized and issued, are fully paid and non-assessable and conform to the descriptions thereof contained in the Time of Sale Prospectus; and none of the issued and outstanding shares of capital stock of the Company are subject to any preemptive or similar rights. The form of certificates for the Shares conforms to the corporate law of the jurisdiction of the Company’s incorporation and to any requirements of the Company’s organizational documents. Subsequent to the respective dates as of which information is given in the Registration Statement, the Time of Sale Prospectus and the Prospectus, except as otherwise specifically stated therein, the Company has not: (a) issued any securities, (b) incurred any liability or obligation, direct or contingent, for borrowed money or (c) declared or paid any dividend or made any other distribution on or in respect to its capital stock.

(h) The Shares have been duly and validly authorized and, when issued and delivered to and paid for by the Underwriters in accordance with the terms of this Agreement, will be duly and validly issued and fully paid and non-assessable and will conform to the descriptions thereof contained in each of the Time of Sale Prospectus and the Prospectus; and the issuance of such Shares is not subject to any preemptive or similar rights.

(i) The issuance and sale of the Shares to be sold by the Company hereunder, the execution of this Agreement by the Company and the compliance by the Company with all of the provisions of this Agreement and the consummation of the transactions herein contemplated will not conflict with or result in a breach or violation of any of the material terms or provisions of, or constitute a material default under, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company or any of its subsidiaries is a party or by which the Company or any of its subsidiaries is bound or to which any of the property or assets of the Company or any of its subsidiaries is subject, nor will such action result in any violation (a) of the provisions of the certificate or articles of incorporation or bylaws of the Company or any of its subsidiaries or (b) any statute or any order, rule or regulation of any court or governmental agency or body having jurisdiction over the Company or any of its subsidiaries or any of their properties; and no consent, approval, authorization, order, registration or qualification of or with any such court or governmental agency or body is required for the issuance and sale of the Shares or the consummation by the Company of the transactions contemplated by this Agreement, except the registration under the Securities Act of the Shares and such consents,

approvals, authorizations, registrations or qualifications as may be required under state securities or Blue Sky laws or the rules and regulations of the Financial Industry Regulatory Authority, Inc. (“FINRA”) or the NASDAQ Global Market in connection with the purchase and distribution of the Shares by the Underwriters.

(j) There has not been any material adverse change, or any development involving a prospective material adverse change, in or affecting the general affairs, business, prospects, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole, from that set forth in the Time of Sale Prospectus.

(k) Other than as set forth in the Time of Sale Prospectus, there are no legal or governmental proceedings, other than review by patent offices of pending applications for patents in the ordinary course, pending to which the Company or any of its subsidiaries is a party or of which any property of the Company or any of its subsidiaries is the subject which, if determined adversely to the Company or its subsidiaries, individually or in the aggregate, would have or would reasonably be expected to have a material adverse effect on the general affairs, business, prospects, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole, or would prevent or impair the consummation of the transactions contemplated by this Agreement, or which are required to be described in the Registration Statement or the Time of Sale Prospectus; and, to the best of the Company’s knowledge, no such proceedings are threatened or contemplated by governmental authorities or others.

(l) Each preliminary prospectus filed as part of the registration statement as originally filed or as part of any amendment thereto, or filed pursuant to Rule 424 under the Securities Act, complied when so filed in all material respects with the Securities Act and the applicable rules and regulations of the Commission thereunder.

(m) The Company is not, and after giving effect to the offering and sale of the Shares and the application of the proceeds thereof as described in the Prospectus will not be, required to register as an “investment company” as such term is defined in the Investment Company Act of 1940, as amended.

(n) Neither the Company nor any of its subsidiaries is in violation of any statute or any rule, regulation, decision or order of any governmental agency or body or any court, domestic or foreign, relating to the use, production, disposal or release of hazardous or toxic substances or relating to the protection or restoration of the environment or human exposure to hazardous or toxic substances (collectively, “environmental laws”), owns or, to the knowledge of the Company with respect to real property that it leases, operates any real property contaminated with any substance that is subject to any environmental laws, is liable for any off-site disposal or contamination pursuant to any environmental laws, or is subject to any claim relating to any environmental laws, which violation, contamination, liability or claim, individually or in the aggregate, would have a material adverse effect on the general affairs, business, prospects, management, financial position, shareholders’ equity or

results of operations of the Company and its subsidiaries, taken as a whole; and the Company is not aware of any pending investigation which would reasonably be expected to lead to such a claim.

(o) There are no contracts, agreements or understandings between the Company and any person granting such person the right to require the Company to file a registration statement under the Securities Act with respect to any securities of the Company or to require the Company to include such securities with the Shares registered pursuant to the Registration Statement, except rights which have been waived.

(p) Neither the Company nor any of its subsidiaries or affiliates, nor any director, officer, or employee, nor, to the Company’s knowledge, any agent or representative of the Company or of any of its subsidiaries or affiliates, has taken or will take any action in furtherance of an offer, payment, promise to pay, or authorization or approval of the payment or giving of money, property, gifts or anything else of value, directly or indirectly, to any “government official” (including any officer or employee of a government or government-owned or controlled entity or of a public international organization, or any person acting in an official capacity for or on behalf of any of the foregoing, or any political party or party official or candidate for political office) to influence official action or secure an improper advantage; and the Company and its subsidiaries and affiliates have conducted their businesses in compliance with applicable anti-corruption laws and have instituted and maintain and will continue to maintain policies and procedures designed to promote and achieve compliance with such laws and with the representation and warranty contained herein.

(q) The operations of the Company and its subsidiaries are and have been conducted at all times in material compliance with all applicable financial recordkeeping and reporting requirements, including those of the Bank Secrecy Act, as amended by Title III of the Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act of 2001 (USA PATRIOT Act), and the applicable anti-money laundering statutes of jurisdictions where the Company and its subsidiaries conduct business, the rules and regulations thereunder and any related or similar rules, regulations or guidelines, issued, administered or enforced by any governmental agency (collectively, the “Anti-Money Laundering Laws”), and no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company or any of its subsidiaries with respect to the Anti-Money Laundering Laws is pending or, to the best knowledge of the Company, threatened.

(r) (i) Neither the Company nor any of its subsidiaries, nor any director, officer, or employee thereof, nor, to the Company’s knowledge, any agent, affiliate or representative of the Company or any of its subsidiaries, is an individual or entity (“Person”) that is, or is owned or controlled by a Person that is:

(A) the subject of any sanctions administered or enforced by the U.S. Department of Treasury’s Office of Foreign Assets Control

(“OFAC”), the United Nations Security Council (“UNSC”), the European Union (“EU”), Her Majesty’s Treasury (“HMT”), or other relevant sanctions authority (collectively, “Sanctions”), nor

(B) located, organized or resident in a country or territory that is the subject of Sanctions (including, without limitation, Cuba, Iran, North Korea, Sudan and Syria).

(ii) The Company will not, directly or indirectly, use the proceeds of the offering, or lend, contribute or otherwise make available such proceeds to any subsidiary, joint venture partner or other Person:

(A) to fund or facilitate any activities or business of or with any Person or in any country or territory that, at the time of such funding or facilitation, is the subject of Sanctions; or

(B) in any other manner that will result in a violation of Sanctions by any Person (including any Person participating in the offering, whether as underwriter, advisor, investor or otherwise).

(iii) For the past 5 years, the Company and its subsidiaries have not knowingly engaged in, are not now knowingly engaged in, and will not engage in, any dealings or transactions with any Person, or in any country or territory, that at the time of the dealing or transaction is or was the subject of Sanctions.

(s) All United States federal income tax returns of the Company and its subsidiaries required by law to be filed have been filed and all taxes shown by such returns or otherwise assessed, which are due and payable, have been paid, except assessments against which appeals have been or will be promptly taken and as to which adequate reserves have been provided. The Company and each of its subsidiaries have filed all other tax returns that are required to have been filed by them pursuant to applicable foreign, state, local or other law, except insofar as the failure to file such returns, individually or in the aggregate, would not result in a material adverse effect on the general affairs, business, prospects, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole, and have paid all taxes due pursuant to such returns or pursuant to any assessment received by the Company or any subsidiary except for such taxes, if any, as are being contested in good faith and as to which adequate reserves have been provided. The charges, accruals and reserves on the books of the Company and its subsidiaries in respect of any income and corporation tax liability for any years not finally determined are adequate to meet any assessments or re-assessments for additional income tax for any years not finally determined.

(t) The Company and each of its subsidiaries have made and keep books, records and accounts, which, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the Company and its subsidiaries. The Company maintains a system of internal accounting controls sufficient to provide

reasonable assurance that (1) transactions are executed in accordance with management’s general or specific authorizations, (2) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles and to maintain accountability for assets, (3) access to assets is permitted only in accordance with management’s general or specific authorization, and (4) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences; and (v) the interactive data in eXtensible Business Reporting Language included or incorporated by reference in the Registration Statement is accurate.

(u) Since the date of the latest audited financial statements included in the Time of Sale Prospectus, (a) the Company has not been advised of (1) any significant deficiencies in the design or operation of internal controls that could adversely affect the ability of the Company and each of its subsidiaries to record, process, summarize and report financial data, or any material weaknesses in internal controls and (2) any fraud, whether or not material, that involves management or other employees who have a significant role in the internal controls of the Company and each of its subsidiaries, and (b) since that date, there has been no change in the Company’s internal control over financial reporting that has materially affected, or is reasonably likely to materially affect, the Company’s internal control over financial reporting.

(v) The Company maintains disclosure controls and procedures (as such term is defined in Rule 13a-15(e) of the Exchange Act) that comply with the requirements of the Exchange Act, and such disclosure controls and procedures are effective.

(w) The interactive data in eXtensible Business Reporting Language included or incorporated by reference in the Registration Statement fairly presents the information called for in all material respects and has been prepared in accordance with the Commission’s rules and guidelines applicable thereto.

(x) From the time of the initial filing of the Registration Statement with the Commission (or, if earlier, the first date on which the Company engaged directly or through any person authorized to act on its behalf in any Testing-the-Waters Communication) through the date hereof, the Company has been and is an “emerging growth company,” as defined in Section 2(a) of the Securities Act. The Company (i) has not alone engaged in any Testing-the-Waters Communication other than Testing-the-Waters Communications with the consent of the Managers with entities that are qualified institutional buyers within the meaning of Rule 144A under the Act or institutions that are accredited investors within the meaning of Rule 501 under the Act and (ii) has not authorized anyone other than its officers and the Managers to engage in Testing-the-Waters Communications. “Testing-the-Waters” means any oral or written communication with potential investors undertaken in reliance on Section 5(f) of the Securities Act.

(y) The Company has not distributed and, prior to the later to occur of the Closing Date (as defined in Section 4 hereof) and completion of distribution of the

Shares, will not distribute any offering materials in connection with the offering and sale of the Shares, other than the Time of Sale Prospectus, the Prospectus and, subject to compliance with Section 6 hereof, any free writing prospectus; and the Company and its affiliates have not taken and will not take, directly or indirectly, any action designed to cause or result in, or which constitutes or would reasonably be expected to constitute, the stabilization or manipulation of the price of any security of the Company to facilitate the sale of the Shares.

(z) PricewaterhouseCoopers LLC, who have expressed their opinion with respect to the audited consolidated financial statements of the Company and its subsidiaries which are incorporated by reference into the Registration Statement, are an independent registered public accounting firm as required by the Securities Act, and the rules and regulations promulgated thereunder, and the Public Company Accounting Oversight Board (United States). The financial statements, together with related notes, incorporated by reference in the Registration Statement and the Time of Sale Prospectus comply in all material respects with the requirements of the Securities Act and present fairly the consolidated financial position, results of operations and cash flows of the Company and its subsidiaries at the respective dates or for the respective periods to which they apply; such statements and related notes have been prepared in accordance with generally accepted accounting principles consistently applied throughout the periods involved; and the selected financial data and the summary financial data included or incorporated by reference in the Registration Statement, the Time of Sale Prospectus and the Prospectus present fairly the information shown therein and have been compiled on a basis consistent with that of the financial statements incorporated by reference in the Registration Statement.

(aa) Neither the Company nor any subsidiary has sustained since the date of the latest audited financial statements included in the Time of Sale Prospectus any material loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree, otherwise than as set forth or contemplated in the Time of Sale Prospectus; and, except as disclosed in the Time of Sale Prospectus, since the respective dates as of which information is given in the Registration Statement and the Time of Sale Prospectus, except as otherwise specifically stated therein, (1) there has not been any change in the capital stock or long-term debt of the Company or any of its subsidiaries, (2) there have been no transactions entered into by, and no obligations or liabilities, contingent or otherwise, incurred by the Company or any of its subsidiaries, whether or not in the ordinary course of business, which are material to the Company and its subsidiaries, taken as a whole or (3) there has been no dividend or distribution of any kind declared, paid or made by the Company on any class of its capital stock, in each case, otherwise than as set forth or contemplated in the Time of Sale Prospectus.

(bb) The section entitled “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Critical Accounting Policies and Estimates” set forth or incorporated by reference in the Registration Statement, the Time of Sale Prospectus and the Prospectus accurately and fully describes in all material respects (i)

the accounting policies that the Company believes are the most important in the portrayal of the Company’s financial condition and results of operations and that require management’s most difficult, subjective or complex judgments (“Critical Accounting Policies”) and (ii) the judgments and uncertainties affecting the application of Critical Accounting Policies.

(cc) Neither the Company nor any of its subsidiaries is (1) in violation of its certificate of incorporation or bylaws, or (2) in violation of any law, ordinance, administrative or governmental rule or regulation applicable to the Company or any of its subsidiaries, or (3) in violation of any decree of any court or governmental agency or body having jurisdiction over the Company or any of its subsidiaries, or (4) in default in the performance of any obligation, agreement or condition contained in any bond, debenture, note or any other evidence of indebtedness or in any agreement, indenture, lease or other instrument to which the Company or any of its subsidiaries is a party or by which any of them or any of their respective properties may be bound, except, in the case of clauses (2), (3) and (4), where any such violation or default, individually or in the aggregate, would not have a material adverse effect on the general affairs, business, prospects, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole.

(dd) Each of the Company and each subsidiary has good and marketable title to all real and personal property owned by it, in each case free and clear of all liens, encumbrances and defects except such as are described in the Time of Sale Prospectus or such as do not materially affect the value of such property and do not interfere with the use made and proposed to be made of such property by the Company or any subsidiary; and any real property and buildings held under lease by the Company or any subsidiary are held under valid, subsisting and enforceable leases with such exceptions as are not material and do not interfere with the use made and proposed to be made of such property and buildings by the Company or any subsidiary.

(ee) The Company and its subsidiaries possess all permits, licenses, approvals, consents and other authorizations (collectively, “Permits”) issued by the appropriate federal, state, local or foreign regulatory agencies or bodies necessary to conduct the businesses now operated by them, and the Company and its subsidiaries are in compliance with the terms and conditions of all such Permits and all of the Permits are valid and in full force and effect, except, in each case, where the failure so to comply or where the invalidity of such Permits or the failure of such Permits to be in full force and effect, individually or in the aggregate, would not have a material adverse effect on the general affairs, business, prospects, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole; and neither the Company nor any subsidiary has received any notice of proceedings relating to the revocation or material modification of any such Permits.

(ff) The Company and its subsidiaries solely own, or, to the knowledge of the Company, possess valid and enforceable licenses to use or sublicense all inventions, copyrights, know-how (including trade secrets and other unpatented and/or unpatentable proprietary or confidential information, systems or procedures),

trademarks, service marks and trade names, patents and patent rights and other intellectual property (collectively “Intellectual Property”) material to carrying on their businesses as described in the Time of Sale Prospectus (collectively, “Company Intellectual Property”), such ownership and, to the knowledge of the Company, such licenses, being free and clear of all liens, encumbrances and defects, except such as are described in the Time of Sale Prospectus, and the Company has taken reasonable steps to secure its interests in the Company Intellectual Property, including obtaining assignments of Company owned Company Intellectual Property from its employees and contractors. Neither the Company nor any subsidiary has received any written correspondence relating to or asserting rights in any Company Intellectual Property, or written notice of infringement, misappropriation or violation of asserted rights of others in any Company Intellectual Property, which, in either case, would render any Company Intellectual Property invalid or unenforceable. To the knowledge of the Company, the conduct and the proposed conduct of the businesses of the Company and its subsidiaries, including the research, development, manufacture, sale and use of its current products and its products in development, as described in the Time of Sale Prospectus, has not infringed or misappropriated, and is not reasonably expected to infringe or misappropriate, the valid Intellectual Property rights of any third party. The Company is not aware of any facts or circumstances that would reasonably be expected to render any Company Intellectual Property invalid or unenforceable, and the Company is not aware of any infringement or misappropriation by any third party of any Company Intellectual Property, which would reasonably be expected to have a material adverse effect on the general affairs, business, prospects, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole. None of the Company Intellectual Property is or has been involved in any opposition, cancellation, interference, reissue or reexamination proceeding and no Company Intellectual Property is the subject of any judicial, administrative or arbitral order, award, decree, injunction, lawsuit, proceeding or stipulation, which, in either case, has had or would reasonably be expected to have a material adverse effect on the general affairs, business, prospects, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole, other than review by patent offices of pending applications for patents in the ordinary course. There are no outstanding options, licenses or agreements of any kind that have been entered into by the Company, and to the knowledge of the Company, by any third party, that relate to the Company Intellectual Property that are required by applicable law to be described in the Registration Statement, the Time of Sale Prospectus or the Prospectus that are not described therein in all material respects. None of the Intellectual Property used by the Company or any of its subsidiaries has been obtained or is being used by the Company or its subsidiaries in violation of any contractual obligation binding on the Company, any of its subsidiaries or, to the knowledge of the Company, any of the officers, directors or employees of the Company or any of its subsidiaries, other than such violations as would not individually or in the aggregate if the subject of an unfavorable decision, ruling or finding, reasonably be expected to have a material adverse effect on the general affairs, business, prospects, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole.

(gg) The Company and its subsidiaries have duly and properly filed or caused to be filed with the United States Patent and Trademark Office (the “PTO”) and applicable foreign and international patent authorities all pending or issued patent applications owned by the Company or its subsidiaries (the “Owned Patent Applications”), and, to the Company’s knowledge, those third parties that have exclusively licensed to the Company or its subsidiaries rights in Company Intellectual Property not owned by the Company (such third parties, “Company Licensors”) have duly and properly filed or caused to be duly and properly filed with the PTO and applicable foreign and international patent authorities all pending or issued patent applications exclusively licensed to the Company or its subsidiaries (the “Licensed Patent Applications”; collectively, with Owned Patent Applications, “Company Patent Applications”). To the knowledge of the Company, the Company, its subsidiaries, and Company Licensors, as applicable, have complied with the PTO’s duty of candor, good faith and disclosure and best mode requirement for the Company Patent Applications, and all other requirements for patentability and enforceability of any resultant patents, and have made no material misrepresentation in the Company Patent Applications with an intent to deceive the PTO. To the knowledge of the Company, the Company, its subsidiaries, and Company Licensors, as applicable, have complied with the relevant foreign filing requirements underlying patentability and enforceability of any resultant patents for the Company Patent Applications pending in countries outside of the United States. The Company is not aware of any information material to a determination of patentability regarding the Company Patent Applications not submitted to the PTO or, if required, similar foreign authority by the Company, its subsidiaries, or Company Licensors, with respect to the prosecution of any Company Patent Applications. The Company has no knowledge of any information which would preclude the Company or its subsidiaries from having clear title to any Owned Patent Applications, or would preclude the patentability, validity or enforceability of any patents or patent applications included in the Company Intellectual Property.

(hh) No material labor dispute with the employees of the Company or its subsidiaries exists, or, to the knowledge of the Company, is imminent. The Company is not aware of any existing or imminent labor disturbance by the employees of any of its or any subsidiary’s principal suppliers, manufacturers, customers or contractors, which, individually or in the aggregate, would reasonably be expected to result in a material adverse effect on the general affairs, business, prospects, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole.

(ii) The Company and its subsidiaries are insured by insurers of recognized financial responsibility against such losses and risks (including risks related to clinical trials and product liability) and in such amounts as are prudent and customary in the businesses in which they are engaged; neither the Company nor any subsidiary has been refused any insurance coverage sought or applied for; and the Company has no reason to believe that either it or any subsidiary will not be able to renew its existing insurance coverage as and when such coverage expires or to obtain similar coverage from similar insurers as may be necessary to continue its business at a cost that would not have a material adverse effect on the Company and its subsidiaries, taken as a whole.

(jj) There are no statutes, regulations, documents or contracts of a character required to be described in the Registration Statement or the Time of Sale Prospectus or to be filed as an exhibit to the Registration Statement which are not described or filed as required.

(kk) Each employee benefit plan, within the meaning of Section 3(3) of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”), that is maintained, administered or contributed to by the Company or any subsidiary for employees or former employees of the Company and its affiliates has been maintained in compliance with its terms and the requirements of any applicable statutes, orders, rules and regulations, including but not limited to ERISA and the Internal Revenue Code of 1986, as amended (the “Code”), except to the extent that failure to so comply, individually or in the aggregate, would not have a material adverse effect on the general affairs, business, prospects, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole. No prohibited transaction, within the meaning of Section 406 of ERISA or Section 4975 of the Code has occurred with respect to any such plan excluding transactions effected pursuant to a statutory or administrative exemption.

(ll) The statistical and market and industry-related data included or incorporated by reference in the Registration Statement, the Time of Sale Prospectus and the Prospectus are based on or derived from sources which the Company believes to be reliable and accurate or represent the Company’s good faith estimates that are made on the basis of data derived from such sources, and the Company has obtained the written consent to the use of such data from sources to the extent required.

(mm) Any certificate signed by any officer of the Company delivered to the Underwriters or to counsel for the Underwriters shall be deemed a representation and warranty by the Company to the Underwriters as to the matters covered thereby.

(nn) Solely to the extent that the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act of 2002, as amended, and the rules and regulations promulgated by the Commission and the Nasdaq Global Market thereunder (the “▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act”) have been applicable to the Company, there is and has been no failure on the part of the Company to comply in all material respects with any provisions of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act. The Company has taken all actions necessary to ensure that it is in compliance with all provisions of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act that are in effect and with which the Company is required to comply.

(oo) To the Company’s knowledge, there are no affiliations or associations between any member of FINRA and any of the Company’s officers, directors or 5% or greater securityholders.

(pp) Upon issuance, the Shares will be listed on The NASDAQ Global Market.

(qq) There are no relationships or related-party transactions involving the Company or any of its subsidiaries or any other person required to be described in the Registration Statement, the Time of Sale Prospectus and the Prospectus which have not been described as required.

(rr) The Company has not sold or issued any securities that would be integrated with the offering of the Shares contemplated by this Agreement pursuant to the Securities Act, the rules and regulations thereunder or the interpretations thereof by the Commission.

(ss) Except as described in the Time of Sale Prospectus, and except as would not, individually or in the aggregate, have or would reasonably be expected to have a material adverse effect on the general affairs, business, prospects, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole (i) neither the Company nor any of its subsidiaries has received any unresolved FDA Form 483, warning letter or untitled letter from the U.S. Food and Drug Administration (“FDA”), or any other court or arbitrator or federal, state, local or foreign governmental or regulatory authority, alleging or asserting noncompliance with the Federal Food, Drug and Cosmetic Act (21 U.S.C. § 301 et seq.) (the “FFDCA”) or similar law, (ii) the Company and each of its subsidiaries is and has been in compliance with applicable health care laws, including without limitation, the FFDCA, the federal Anti-Kickback Statute (42 U.S.C. § 1320a-7b(b)(2)), the civil False Claims Act (31 U.S.C. §§ 3729(a) et seq.), the administrative False Claims Law (42U.S.C. § 1320a -7b(a)), the Anti-Inducement Law (42 U.S.C. § 1320a-7a(a)(5)), the Health Insurance Portability and Accountability Act of 1996 (42 U.S.C. § 1320d et seq.), and the Patient Protection and Affordable Care Act of 2010 (Public Law 111-148), as amended by the Health Care and Education Affordability Reconciliation Act of 2010 (Public Law 111-152), and the regulations promulgated pursuant to such laws, and comparable state laws, and all other local, state, federal, national, supranational and foreign laws, manual provisions and written administrative guidance relating to the regulation of the Company (collectively, “Health Care Laws”), (iii) the Company and each of its subsidiaries possesses all licenses, certificates, approvals, clearances, authorizations and permits required by any such Health Care Laws and/or to carry on its businesses as now conducted (“Authorizations”) and such Authorizations are valid and in full force and effect and the Company is not in violation of any term of any such Authorizations, (iv) neither the Company nor any of its subsidiaries has received written notice of any ongoing claim, action, suit, proceeding, hearing, enforcement action, investigation or arbitration from any U.S. or non-U.S. federal, state, local or other governmental or regulatory authority, governmental or regulatory agency or body, court or arbitrator (each, a “Governmental Authority”) or third party alleging that any product operation or activity is in violation of any Health Care Laws or Authorizations or has any knowledge that any such Governmental Authority or third party is considering any such claim, litigation, arbitration, action, suit, investigation or proceeding, (v) neither the Company nor any of its subsidiaries has received written notice that any Governmental Authority has taken, is taking or intends to take action to limit, suspend, modify or revoke any Authorizations or has any knowledge that any such

Governmental Authority is considering such action, (vi) the Company and each of its subsidiaries has filed, obtained, maintained or submitted all reports, documents, forms, notices, applications, records, claims, submissions and supplements or amendments as required by any Health Care Laws or Authorizations and that all such reports, documents, forms, notices, applications, records, claims, submissions and supplements or amendments were complete, correct and not misleading on the date filed (or were corrected or supplemented by a subsequent submission), and (vii) neither the Company nor any of its subsidiaries has, either voluntarily or involuntarily, initiated, conducted, or issued or caused to be initiated, conducted or issued, any recall, market withdrawal or replacement, safety alert (but excluding adverse event reports in clinical trials), post sale warning, “dear doctor” letter, or other notice or action relating to the alleged lack of safety or efficacy of any product or any alleged product defect or violation and, to the Company’s knowledge, no third party has initiated or conducted any such notice or action.

(tt) To the knowledge of the Company, the research, studies and tests conducted by or on behalf of the Company and its subsidiaries have been and, if still pending, are being conducted with reasonable care and in accordance with those experimental protocols, procedures and controls required by any applicable Health Care Laws and Authorizations; the descriptions of the results of such research, studies and tests contained in the Registration Statement, the Time of Sale Prospectus and the Prospectus are accurate and complete and fairly present the data derived from such research, studies, and tests; the Company is not aware of any research, studies or tests, the results of which the Company believes reasonably call into question the research, study or test results concerning the Company’s current or proposed products described or referred to in the Registration Statement, the Time of Sale Prospectus and the Prospectus when viewed in the context in which such results are described; and neither the Company nor any of its subsidiaries has received any notices or correspondence from any Governmental Authority requiring the termination, suspension or material modification of any research, study or test conducted by or on behalf of the Company or its subsidiaries, as applicable. Except as disclosed in the Time of Sale Prospectus, to the knowledge of the Company, there have been no adverse episodes or complications resulting from any research, study or test conducted by or on behalf of the Company or its subsidiaries.

(uu) The Company (i) does not have any material lending or other relationship with any bank or lending affiliate of any Underwriter and (ii) does not intend to use any of the proceeds from the sale of the Shares to repay the principal of any outstanding debt owed to any affiliate of any Underwriter.

(vv) Except as disclosed in the Time of Sale Prospectus, the Company has not sold, issued or distributed any shares of Common Stock during the six-month period preceding the date hereof, including any sales pursuant to Rule 144A, Regulation D or Regulation S under the Securities Act, other than shares issued pursuant to employee benefit plans, qualified stock option plans or other employee compensation plans or pursuant to outstanding options, rights or warrants.

2. Agreements to Sell and Purchase. The Company hereby agrees to sell to the several Underwriters, and each Underwriter, upon the basis of the representations and warranties herein contained, but subject to the conditions hereinafter stated, agrees, severally and not jointly, to purchase from the Company the respective numbers of Firm Shares set forth in Schedule II hereto opposite its name at the purchase price set forth in Schedule I hereto (the “Purchase Price”).

On the basis of the representations and warranties contained in this Agreement, and subject to its terms and conditions, the Company agrees to sell to the Underwriters the Additional Shares, and the Underwriters shall have the right to purchase, severally and not jointly, up to the number of Additional Shares set forth in Schedule I hereto at the Purchase Price, provided, however, that the amount paid by the Underwriters for any Additional Shares shall be reduced by an amount per share equal to any dividends declared by the Company and payable on the Firm Shares but not payable on such Additional Shares. You may exercise this right on behalf of the Underwriters in whole or from time to time in part by giving written notice not later than 30 days after the date of the Prospectus. Any exercise notice shall specify the number of Additional Shares to be purchased by the Underwriters and the date on which such shares are to be purchased. Each purchase date must be at least one business day after the written notice is given and may not be earlier than the closing date for the Firm Shares nor later than ten business days after the date of such notice. Additional Shares may be purchased as provided in Section 4 hereof solely for the purpose of covering sales of shares in excess of the number of the Firm Shares. On each day, if any, that Additional Shares are to be purchased (an “Option Closing Date”), each Underwriter agrees, severally and not jointly, to purchase the number of Additional Shares (subject to such adjustments to eliminate fractional shares as you may determine) that bears the same proportion to the total number of Additional Shares to be purchased on such Option Closing Date as the number of Firm Shares set forth in Schedule II hereto opposite the name of such Underwriter bears to the total number of Firm Shares.

3. Public Offering. The Company is advised by you that the Underwriters propose to make a public offering of their respective portions of the Shares as soon after the Registration Statement and this Agreement have become effective as in your judgment is advisable. The Company is further advised by you that the Shares are to be offered to the public upon the terms set forth in the Prospectus.

4. Payment and Delivery. Payment for the Firm Shares shall be made to the Company in Federal or other funds immediately available in New York City on the closing date and time set forth in Schedule I hereto, or at such other time on the same or such other date, not later than the fifth business day thereafter, as may be designated in writing by you. The time and date of such payment are hereinafter referred to as the “Closing Date.”

Payment for any Additional Shares shall be made to the Company in Federal or other funds immediately available in New York City on the date specified in the corresponding notice described in Section 2 or at such other time on the same or on such other date, in any event not later than the tenth business day thereafter, as may be designated in writing by you.

The Firm Shares and the Additional Shares shall be registered in such names and in such denominations as you shall request in writing not later than one full business day prior to the Closing Date or the applicable Option Closing Date, as the case may be, for the respective accounts of the several Underwriters, with any transfer taxes payable in connection with the transfer of the Shares to the Underwriters duly paid, against payment of the Purchase Price therefor.

5. Conditions to the Underwriters’ Obligations. The several obligations of the Underwriters are subject to the following conditions:

(a) Subsequent to the execution and delivery of this Agreement and prior to the Closing Date:

(i) there shall not have occurred any downgrading, nor shall any notice have been given of any intended or potential downgrading or of any review for a possible change that does not indicate the direction of the possible change, in the rating accorded any of the securities of the Company or any of its subsidiaries by any “nationally recognized statistical rating organization,” as such term is defined in Section 3(a)(62) of the Exchange Act; and

(ii) there shall not have occurred any change, or any development involving a prospective change, in the condition, financial or otherwise, or in the earnings, business or operations of the Company and its subsidiaries, taken as a whole, from that set forth in the Time of Sale Prospectus that, in your judgment, is material and adverse and that makes it, in your judgment, impracticable to market the Shares on the terms and in the manner contemplated in the Time of Sale Prospectus.

(b) The Underwriters shall have received on the Closing Date a certificate, dated the Closing Date and signed by an executive officer of the Company, to the effect set forth in Section 5(a)(i) above and to the effect that the representations and warranties of the Company contained in this Agreement are true and correct as of the Closing Date and that the Company has complied with all of the agreements and satisfied all of the conditions on its part to be performed or satisfied hereunder on or before the Closing Date.

The officer signing and delivering such certificate may rely upon the best of his or her knowledge as to proceedings threatened.

(c) The Underwriters shall have received on the Closing Date an opinion of ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇ & ▇▇▇▇▇▇ LLP, outside counsel for the Company, dated the Closing Date, substantially in the form of Exhibit B-1 hereto.

(d) The Underwriters shall have received on the Closing Date an opinion of ▇▇▇▇▇▇▇▇▇ & ▇▇▇▇▇▇▇ LLP, as regulatory counsel to the Company, addressed to the Underwriters and dated the Closing Date, substantially in the form attached hereto as Exhibit B-2 hereto.

(e) The Underwriters shall have received on the Closing Date an opinion of each of ▇▇▇▇▇▇▇ ▇▇▇▇▇▇ & ▇▇▇▇▇▇▇▇ PC and Royalance, ▇▇▇▇▇▇ Berdo & ▇▇▇▇▇▇▇, L.L.P., as intellectual property counsel to the Company, addressed to the Underwriters and dated the Closing Date, substantially in the forms attached hereto as Exhibits B-3 and B-4 hereto.

(f) The Underwriters shall have received on the Closing Date an opinion of ▇▇▇▇▇ ▇▇▇▇ & ▇▇▇▇▇▇▇▇ LLP, counsel for the Underwriters, dated the Closing Date, with respect to such matters as the Managers may reasonably require, and the Company shall have furnished to such counsel such documents as they reasonably request for the purpose of enabling them to pass upon such matters.

(g) The Underwriters shall have received, on each of the date hereof and the Closing Date, a letter dated the date hereof or the Closing Date, as the case may be, in form and substance satisfactory to the Underwriters, from PricewaterhouseCoopers LLC, independent public accountants, containing statements and information of the type ordinarily included in accountants’ “comfort letters” to underwriters with respect to the financial statements and certain financial information contained in the Registration Statement, the Time of Sale Prospectus and the Prospectus; provided that the letter delivered on the Closing Date shall use a “cut-off date” not earlier than the date hereof.

(h) The “lock-up” agreements, each substantially in the form of Exhibit A hereto, between you and certain shareholders, officers and directors of the Company, relating to sales and certain other dispositions of shares of Common Stock or certain other securities, shall have been delivered to you on or before the date hereof, and shall be in full force and effect on, the Closing Date.

(i) The Underwriters shall have received, on each of the date hereof and the Closing Date, a certificate dated the date hereof or the Closing Date and signed by the chief financial officer of the Company, substantially in the form of Exhibit C hereto.

(j) The several obligations of the Underwriters to purchase Additional Shares hereunder are subject to the delivery to you on the applicable Option Closing Date of the following:

(i) a certificate, dated the Option Closing Date and signed by an executive officer of the Company, confirming that the certificate delivered on the Closing Date pursuant to Section 5(b) hereof remains true and correct as of such Option Closing Date;

(ii) a certificate, dated the Option Closing Date and signed by the chief financial officer of the Company, confirming that the certificate delivered on the Closing Date pursuant to Section 5(i) hereof remains true and correct as of such Option Closing Date;

(iii) an opinion of ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇ & ▇▇▇▇▇▇ LLP, outside counsel for the Company, dated the Option Closing Date, relating to the Additional Shares to be purchased on such Option Closing Date and otherwise to the same effect as the opinion required by Section 5(c) hereof;

(iv) an opinion of ▇▇▇▇▇▇▇▇▇ & ▇▇▇▇▇▇▇ LLP, as regulatory counsel to the Company, dated the Option Closing Date, relating to the Additional Shares to be purchased on such Option Closing Date and otherwise to the same effect as the opinion required by Section 5(d) hereof.

(v) an opinion of each of ▇▇▇▇▇▇▇ ▇▇▇▇▇▇ & ▇▇▇▇▇▇▇▇ PC and Royalance, ▇▇▇▇▇▇ Berdo & ▇▇▇▇▇▇▇, L.L.P., as intellectual property counsel to the Company, dated the Option Closing Date, relating to the Additional Shares to be purchased on such Option Closing Date and otherwise to the same effect as the opinion required by Section 5(e) hereof.

(vi) an opinion of ▇▇▇▇▇ ▇▇▇▇ & ▇▇▇▇▇▇▇▇ LLP, counsel for the Underwriters, dated the Option Closing Date, relating to the Additional Shares to be purchased on such Option Closing Date and otherwise to the same effect as the opinion required by Section 5(f) hereof;

(vii) a letter dated the Option Closing Date, in form and substance satisfactory to the Underwriters, from PricewaterhouseCoopers LLC, independent public accountants, substantially in the same form and substance as the letter furnished to the Underwriters pursuant to Section 5(e) hereof; provided that the letter delivered on the Option Closing Date shall use a “cut-off date” not earlier than three business days prior to such Option Closing Date; and

(viii) such other documents as you may reasonably request with respect to the good standing of the Company, the due authorization and issuance of the Additional Shares to be sold on such Option Closing Date and other matters related to the issuance of such Additional Shares.

6. Covenants of the Company. The Company covenants with each Underwriter as follows:

(a) To furnish to you, without charge, a signed copy of the Registration Statement (including exhibits thereto and documents incorporated by reference therein) and to deliver to each of the Underwriters during the period mentioned in Section 6(e) or 6(f) below, as many copies of the Time of Sale Prospectus, the Prospectus, any documents incorporated by reference therein and any supplements and amendments thereto or to the Registration Statement as you may reasonably request.

(b) Before amending or supplementing the Registration Statement, the Time of Sale Prospectus or the Prospectus, to furnish to you a copy of each such proposed amendment or supplement and not to file any such proposed amendment or supplement to which you reasonably object.

(c) To furnish to you a copy of each proposed free writing prospectus to be prepared by or on behalf of, used by, or referred to by the Company and not to use or refer to any proposed free writing prospectus to which you reasonably object.

(d) Not to take any action that would result in an Underwriter or the Company being required to file with the Commission pursuant to Rule 433(d) under the Securities Act a free writing prospectus prepared by or on behalf of the Underwriter that the Underwriter otherwise would not have been required to file thereunder.

(e) If the Time of Sale Prospectus is being used to solicit offers to buy the Shares at a time when the Prospectus is not yet available to prospective purchasers and any event shall occur or condition exist as a result of which it is necessary to amend or supplement the Time of Sale Prospectus in order to make the statements therein, in the light of the circumstances, not misleading, or if any event shall occur or condition exist as a result of which the Time of Sale Prospectus conflicts with the information contained in the Registration Statement then on file, or if, in the opinion of counsel for the Underwriters, it is necessary to amend or supplement the Time of Sale Prospectus to comply with applicable law, forthwith to prepare, file with the Commission and furnish, at its own expense, to the Underwriters and to any dealer upon request, either amendments or supplements to the Time of Sale Prospectus so that the statements in the Time of Sale Prospectus as so amended or supplemented will not, in the light of the circumstances when the Time of Sale Prospectus is delivered to a prospective purchaser, be misleading or so that the Time of Sale Prospectus, as amended or supplemented, will no longer conflict with the Registration Statement, or so that the Time of Sale Prospectus, as amended or supplemented, will comply with applicable law.

(f) If, during such period after the first date of the public offering of the Shares as in the opinion of counsel for the Underwriters the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) of the Securities Act) is required by law to be delivered in connection with sales by an Underwriter or dealer, any event shall occur or condition exist as a result of which it is necessary to amend or supplement the Prospectus in order to make the statements therein, in the light of the circumstances when the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) of the Securities Act) is delivered to a purchaser, not misleading, or if, in the opinion of counsel for the Underwriters, it is necessary to amend or supplement the Prospectus to comply with applicable law, forthwith to prepare, file with the Commission and furnish, at its own expense, to the Underwriters and to the dealers (whose names and addresses you will furnish to the Company) to which Shares may have been sold by

you on behalf of the Underwriters and to any other dealers upon request, either amendments or supplements to the Prospectus so that the statements in the Prospectus as so amended or supplemented will not, in the light of the circumstances when the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) of the Securities Act) is delivered to a purchaser, be misleading or so that the Prospectus, as amended or supplemented, will comply with applicable law.

(g) To endeavor to qualify the Shares for offer and sale under the securities or Blue Sky laws of such jurisdictions as you shall reasonably request.

(h) To make generally available to the Company’s security holders and to you as soon as practicable an earning statement covering a period of at least twelve months beginning with the first fiscal quarter of the Company occurring after the date of this Agreement which shall satisfy the provisions of Section 11(a) of the Securities Act and the rules and regulations of the Commission thereunder.

(i) Whether or not the transactions contemplated in this Agreement are consummated or this Agreement is terminated, to pay or cause to be paid all expenses incident to the performance of its obligations under this Agreement, including: (i) the fees, disbursements and expenses of the Company’s counsel and the Company’s accountants in connection with the registration and delivery of the Shares under the Securities Act and all other fees or expenses in connection with the preparation and filing of the Registration Statement, any preliminary prospectus, the Time of Sale Prospectus, the Prospectus, any free writing prospectus prepared by or on behalf of, used by, or referred to by the Company and amendments and supplements to any of the foregoing, including the filing fees payable to the Commission relating to the Shares (within the time required by Rule 456 (b)(1), if applicable), all printing costs associated therewith, and the mailing and delivering of copies thereof to the Underwriters and dealers, in the quantities hereinabove specified, (ii) all costs and expenses related to the transfer and delivery of the Shares to the Underwriters, including any transfer or other taxes payable thereon, (iii) the cost of printing or producing any Blue Sky or Legal Investment memorandum in connection with the offer and sale of the Shares under state securities laws and all expenses in connection with the qualification of the Shares for offer and sale under state securities laws as provided in Section 6(g) hereof, including filing fees and the reasonable fees and disbursements of counsel for the Underwriters in connection with such qualification and in connection with the Blue Sky or Legal Investment memorandum, (iv) all filing fees and the reasonable fees and disbursements of counsel to the Underwriters incurred in connection with the review and qualification of the offering of the Shares by the FINRA, (v) all costs and expenses incident to listing the Shares on the NASDAQ Global Market, (vi) the cost of printing certificates representing the Shares, (vii) the costs and charges of any transfer agent, registrar or depositary, (viii) the costs and expenses of the Company relating to investor presentations on any “road show” undertaken in connection with the marketing of the offering of the Shares, including, without limitation, expenses associated with the preparation or dissemination of any electronic road show, expenses associated with the production of road show slides and graphics, fees and expenses of any consultants engaged in connection with the road

show presentations with the prior approval of the Company, travel and lodging expenses of the representatives and officers of the Company and any such consultants, and the cost of any aircraft chartered in connection with the road show, (ix) the document production charges and expenses associated with printing this Agreement and (x) all other costs and expenses incident to the performance of the obligations of the Company hereunder for which provision is not otherwise made in this Section. It is understood, however, that except as provided in this Section, Section 8 entitled “Indemnity and Contribution” and the last paragraph of Section 10 below, the Underwriters will pay all of their costs and expenses, including fees and disbursements of their counsel, stock transfer taxes payable on resale of any of the Shares by them and any advertising expenses connected with any offers they may make.

(j) If the third anniversary of the initial effective date of the Registration Statement occurs before all the Shares have been sold by the Underwriters, prior to the third anniversary to file a new shelf registration statement and to take any other action necessary to permit the public offering of the Shares to continue without interruption; references herein to the Registration Statement shall include the new registration statement declared effective by the Commission.

(k) If requested by the Managers, to prepare a final term sheet relating to the offering of the Shares, containing only information that describes the final terms of the offering in a form consented to by the Managers, and to file such final term sheet within the period required by Rule 433(d)(5)(ii) under the Securities Act following the date the final terms have been established for the offering of the Shares.

The Company also covenants with each Underwriter that, without the prior written consent of the Managers identified in Schedule I with the authorization to release this lock-up on behalf of the Underwriters, it will not, during the restricted period set forth in Schedule I hereto (the “Restricted Period”), (1) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock, or (2) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Common Stock, whether any such transaction described in clause 1 or 2 above is to be settled by delivery of Common Stock or such other securities, in cash or otherwise or (3) file any registration statement with the Commission relating to the offering of any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock, except for the filing of a registration statement on Form S-3 registering shares of common stock and preferred stock, debt securities, warrants to purchase common stock, preferred stock or debt securities, and units, provided that (x) such registration statement replaces and supersedes the Registration Statement, (y) no sales of any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock shall be made under such registration statement during the Restricted Period and (z) no prospectus supplement to such registration statement shall be filed nor any other filing or public announcement of an intent to sell under such registration statement shall be made during the Restricted Period

with respect to the offering or proposed offering of any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock. The foregoing sentence shall not apply to (a) the Shares to be sold hereunder, (b) the issuance by the Company of shares of Common Stock upon the exercise of an option or warrant or the conversion of a security outstanding on the date hereof and which are disclosed in the Registration Statement, the Time of Sale Prospectus and the Prospectus, or (c) the establishment of a trading plan pursuant to Rule 10b5-1 under the Exchange Act, for the transfer of shares of Common Stock, provided that (i) such plan does not provide for the transfer of Common Stock during the Restricted Period and (ii) to the extent a public announcement or filing under the Exchange Act, if any, is required of or voluntarily made by the Company regarding the establishment of such plan, such announcement or filing shall include a statement to the effect that no transfer of Common Stock may be made under such plan during the Restricted Period.

7. Covenants of the Underwriters. Each Underwriter severally covenants with the Company not to take any action that would result in the Company being required to file with the Commission under Rule 433(d) a free writing prospectus prepared by or on behalf of such Underwriter that otherwise would not be required to be filed by the Company thereunder, but for the action of the Underwriter.

8. Indemnity and Contribution. (a) The Company agrees to indemnify and hold harmless each Underwriter, each person, if any, who controls any Underwriter within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act and each affiliate of any Underwriter within the meaning of Rule 405 under the Securities Act from and against any and all losses, claims, damages and liabilities (including, without limitation, any legal or other expenses reasonably incurred in connection with defending or investigating any such action or claim) caused by any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement or any amendment thereof, any preliminary prospectus, the Time of Sale Prospectus or any amendment or supplement thereto, any issuer free writing prospectus as defined in Rule 433(h) under the Securities Act, any Company information that the Company has filed, or is required to file, pursuant to Rule 433(d) under the Securities Act, any “road show” as defined in Rule 433(h) under the Securities Act (a “road show”), or the Prospectus or any amendment or supplement thereto, or caused by any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, except insofar as such losses, claims, damages or liabilities are caused by any such untrue statement or omission or alleged untrue statement or omission based upon information relating to any Underwriter furnished to the Company in writing by such Underwriter through you expressly for use therein.

(b) Each Underwriter agrees, severally and not jointly, to indemnify and hold harmless the Company, its directors, its officers who sign the Registration Statement and each person, if any, who controls the Company within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act to the same extent as the foregoing indemnity from the Company to such Underwriter, but only with reference to information relating to such Underwriter furnished to the Company in

writing by such Underwriter through you expressly for use in the Registration Statement, any preliminary prospectus, the Time of Sale Prospectus, any issuer free writing prospectus, road show, or the Prospectus or any amendment or supplement thereto.

(c) In case any proceeding (including any governmental investigation) shall be instituted involving any person in respect of which indemnity may be sought pursuant to Section 8(a) or 8(b), such person (the “indemnified party”) shall promptly notify the person against whom such indemnity may be sought (the “indemnifying party”) in writing and the indemnifying party, upon request of the indemnified party, shall retain counsel reasonably satisfactory to the indemnified party to represent the indemnified party and any others the indemnifying party may designate in such proceeding and shall pay the fees and disbursements of such counsel related to such proceeding. In any such proceeding, any indemnified party shall have the right to retain its own counsel, but the fees and expenses of such counsel shall be at the expense of such indemnified party unless (i) the indemnifying party and the indemnified party shall have mutually agreed to the retention of such counsel or (ii) the named parties to any such proceeding (including any impleaded parties) include both the indemnifying party and the indemnified party and representation of both parties by the same counsel would be inappropriate due to actual or potential differing interests between them. It is understood that the indemnifying party shall not, in respect of the legal expenses of any indemnified party in connection with any proceeding or related proceedings in the same jurisdiction, be liable for the fees and expenses of more than one separate firm (in addition to any local counsel) for all such indemnified parties and that all such fees and expenses shall be reimbursed as they are incurred. Such firm shall be designated in writing by the Manager authorized to appoint counsel under this Section set forth in Schedule I hereto, in the case of parties indemnified pursuant to Section 8(a), and by the Company, in the case of parties indemnified pursuant to Section 8(b). The indemnifying party shall not be liable for any settlement of any proceeding effected without its written consent, but if settled with such consent or if there be a final judgment for the plaintiff, the indemnifying party agrees to indemnify the indemnified party from and against any loss or liability by reason of such settlement or judgment. Notwithstanding the foregoing sentence, if at any time an indemnified party shall have requested an indemnifying party to reimburse the indemnified party for fees and expenses of counsel as contemplated by the second and third sentences of this paragraph, the indemnifying party agrees that it shall be liable for any settlement of any proceeding effected without its written consent if (i) such settlement is entered into more than 30 days after receipt by such indemnifying party of the aforesaid request and (ii) such indemnifying party shall not have reimbursed the indemnified party in accordance with such request prior to the date of such settlement. No indemnifying party shall, without the prior written consent of the indemnified party, effect any settlement of any pending or threatened proceeding in respect of which any indemnified party is or could have been a party and indemnity could have been sought hereunder by such indemnified party, unless such settlement includes an unconditional release of such indemnified party from all liability on claims that are the subject matter of such proceeding.

(d) To the extent the indemnification provided for in Section 8(a) or 8(b) is unavailable to an indemnified party or insufficient in respect of any losses, claims, damages or liabilities referred to therein, then each indemnifying party under such paragraph, in lieu of indemnifying such indemnified party thereunder, shall contribute to the amount paid or payable by such indemnified party as a result of such losses, claims, damages or liabilities (i) in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and the Underwriters on the other hand from the offering of the Shares or (ii) if the allocation provided by clause 8(d)(i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause 8(d)(i) above but also the relative fault of the Company on the one hand and of the Underwriters on the other hand in connection with the statements or omissions that resulted in such losses, claims, damages or liabilities, as well as any other relevant equitable considerations. The relative benefits received by the Company on the one hand and the Underwriters on the other hand in connection with the offering of the Shares shall be deemed to be in the same respective proportions as the net proceeds from the offering of the Shares (before deducting expenses) received by the Company and the total underwriting discounts and commissions received by the Underwriters bear to the aggregate initial public offering price of the Shares set forth in the Prospectus. The relative fault of the Company on the one hand and the Underwriters on the other hand shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company or by the Underwriters and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. The Underwriters’ respective obligations to contribute pursuant to this Section 8 are several in proportion to the respective number of Shares they have purchased hereunder, and not joint.

(e) The Company and the Underwriters agree that it would not be just or equitable if contribution pursuant to this Section 8 were determined by pro rata allocation (even if the Underwriters were treated as one entity for such purpose) or by any other method of allocation that does not take account of the equitable considerations referred to in Section 8(d). The amount paid or payable by an indemnified party as a result of the losses, claims, damages and liabilities referred to in Section 8(d) shall be deemed to include, subject to the limitations set forth above, any legal or other expenses reasonably incurred by such indemnified party in connection with investigating or defending any such action or claim. Notwithstanding the provisions of this Section 8, no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Shares underwritten by it and distributed to the public were offered to the public exceeds the amount of any damages that such Underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The remedies provided for in this Section 8 are not exclusive and shall not limit any rights or remedies which may otherwise be available to any indemnified party at law or in equity.

(f) The indemnity and contribution provisions contained in this Section 8 and the representations, warranties and other statements of the Company contained in this Agreement shall remain operative and in full force and effect regardless of (i) any termination of this Agreement, (ii) any investigation made by or on behalf of any Underwriter, any person controlling any Underwriter or any affiliate of any Underwriter or by or on behalf of the Company, its officers or directors or any person controlling the Company and (iii) acceptance of and payment for any of the Shares.

9. Termination. The Underwriters may terminate this Agreement by notice given by you to the Company, if after the execution and delivery of this Agreement and prior to the Closing Date (i) trading generally shall have been suspended or materially limited on, or by, as the case may be, any of the New York Stock Exchange, the NYSE MKT, the NASDAQ Global Market, the Chicago Board of Options Exchange, the Chicago Mercantile Exchange or the Chicago Board of Trade, (ii) trading of any securities of the Company shall have been suspended on any exchange or in any over-the-counter market, (iii) a material disruption in securities settlement, payment or clearance services in the United States shall have occurred, (iv) any moratorium on commercial banking activities shall have been declared by Federal or New York State authorities or (v) there shall have occurred any outbreak or escalation of hostilities, or any change in financial markets or any calamity or crisis that, in your judgment, is material and adverse and which, singly or together with any other event specified in this clause (v), makes it, in your judgment, impracticable or inadvisable to proceed with the offer, sale or delivery of the Shares on the terms and in the manner contemplated in the Time of Sale Prospectus or the Prospectus.

10. Effectiveness; Defaulting Underwriters. This Agreement shall become effective upon the execution and delivery hereof by the parties hereto.

If, on the Closing Date or an Option Closing Date, as the case may be, any one or more of the Underwriters shall fail or refuse to purchase Shares that it has or they have agreed to purchase hereunder on such date, and the aggregate number of Shares which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase is not more than one-tenth of the aggregate number of the Shares to be purchased on such date, the other Underwriters shall be obligated severally in the proportions that the number of Firm Shares set forth opposite their respective names in Schedule II bears to the aggregate number of Firm Shares set forth opposite the names of all such non-defaulting Underwriters, or in such other proportions as you may specify, to purchase the Shares which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase on such date; provided that in no event shall the number of Shares that any Underwriter has agreed to purchase pursuant to this Agreement be increased pursuant to this Section 10 by an amount in excess of one-ninth of such number of Shares without the written consent of such Underwriter. If, on the Closing Date, any Underwriter or Underwriters shall fail or refuse to purchase Firm Shares and the aggregate number of Firm Shares with respect to which such default occurs is more than one-tenth of the aggregate number of Firm Shares to be purchased on such date, and arrangements satisfactory to you and the Company for the purchase of such Firm Shares are not made within 36 hours after such default, this Agreement shall terminate without

liability on the part of any non-defaulting Underwriter or the Company. In any such case either you or the Company shall have the right to postpone the Closing Date, but in no event for longer than seven days, in order that the required changes, if any, in the Registration Statement, in the Time of Sale Prospectus, in the Prospectus or in any other documents or arrangements may be effected. If, on an Option Closing Date, any Underwriter or Underwriters shall fail or refuse to purchase Additional Shares and the aggregate number of Additional Shares with respect to which such default occurs is more than one-tenth of the aggregate number of Additional Shares to be purchased on such Option Closing Date, the non-defaulting Underwriters shall have the option to (i) terminate their obligation hereunder to purchase the Additional Shares to be sold on such Option Closing Date or (ii) purchase not less than the number of Additional Shares that such non-defaulting Underwriters would have been obligated to purchase in the absence of such default. Any action taken under this paragraph shall not relieve any defaulting Underwriter from liability in respect of any default of such Underwriter under this Agreement.

If this Agreement shall be terminated by the Underwriters, or any of them, because of any failure or refusal on the part of the Company to comply with the terms or to fulfill any of the conditions of this Agreement, or if for any reason the Company shall be unable to perform its obligations under this Agreement, the Company will reimburse the Underwriters or such Underwriters as have so terminated this Agreement with respect to themselves, severally, for all out-of-pocket expenses (including the fees and disbursements of their counsel) reasonably incurred by such Underwriters in connection with this Agreement or the offering contemplated hereunder.

11. Entire Agreement. (a) This Agreement, together with any contemporaneous written agreements and any prior written agreements (to the extent not superseded by this Agreement) that relate to the offering of the Shares, represents the entire agreement between the Company and the Underwriters with respect to the preparation of any preliminary prospectus, the Time of Sale Prospectus, the Prospectus, the conduct of the offering, and the purchase and sale of the Shares.

(b) The Company acknowledges that in connection with the offering of the Shares: (i) the Underwriters have acted at arms length, are not agents of, and owe no fiduciary duties to, the Company or any other person, (ii) the Underwriters owe the Company only those duties and obligations set forth in this Agreement and prior written agreements (to the extent not superseded by this Agreement), if any, and (iii) the Underwriters may have interests that differ from those of the Company. The Company waives to the full extent permitted by applicable law any claims it may have against the Underwriters arising from an alleged breach of fiduciary duty in connection with the offering of the Shares.

12. Counterparts. This Agreement may be signed in two or more counterparts, each of which shall be an original, with the same effect as if the signatures thereto and hereto were upon the same instrument.

13. Applicable Law. This Agreement shall be governed by and construed in accordance with the internal laws of the State of New York.

14. Headings. The headings of the sections of this Agreement have been inserted for convenience of reference only and shall not be deemed a part of this Agreement.

15. Notices. All communications hereunder shall be in writing and effective only upon receipt and if to the Underwriters shall be delivered, mailed or sent to you at the address set forth in Schedule I hereto; and if to the Company shall be delivered, mailed or sent to the address set forth in Schedule I hereto.


Very truly yours,

CEMPRA, INC.

By:		/s/ ▇▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇, Ph.D.
		Name: ▇▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇, Ph.D.
		Title: President and Chief Executive Officer


Accepted as of the date hereof

▇▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co. LLC ▇▇▇▇▇ and Company, LLC

Acting severally on behalf of themselves and the several Underwriters named in Schedule II hereto.

By:		▇▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co. LLC

By:		/s/ ▇▇▇ ▇▇▇▇▇▇▇▇▇
		Name: ▇▇▇ ▇▇▇▇▇▇▇▇▇
		Title: Vice President


By:		▇▇▇▇▇ and Company, LLC

By:		/s/ ▇▇▇▇▇ ▇▇▇▇▇▇
		Name: ▇▇▇▇▇ ▇▇▇▇▇▇
		Title: Managing Director

SCHEDULE I


Managers:	▇▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co. LLC ▇▇▇▇▇ and Company, LLC

Manager authorized to release lock-up under Section 6:	▇▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co. LLC ▇▇▇▇▇ and Company, LLC

Manager authorized to appoint counsel under Section 8(c):	▇▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co. LLC

Registration Statement File No.:	333-200360

Time of Sale Prospectus	1.	Prospectus dated December 29, 2014 relating to the Shelf Shares

	2.	The preliminary prospectus supplement dated January 5, 2015 relating to the Shares

	3.	Number of Firm Shares: 5,250,000

	4.	Number of Additional Shares: 787,500

	5.	Initial Public Offering Price: $24.50 a share

Lock-up Restricted Period:	The period ending 90 days after the date of the Prospectus

Title of Shares to be purchased:	Common Stock, par value $0.001 per share

Number of Firm Shares:	5,250,000

Number of Additional Shares	787,500

Purchase Price:	$23.03 a share

Initial Public Offering Price	$24.50 a share

Selling Concession:	$0.882 a share

Closing Date and Time:	January 13, 2015 10:00 a.m.

Closing Location:	▇▇▇▇▇ ▇▇▇▇ & ▇▇▇▇▇▇▇▇ LLP ▇▇▇ ▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇ ▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇

Address for Notices to Underwriters:	c/o Morgan ▇▇▇▇▇▇▇ & Co. LLC ▇▇▇▇ ▇▇▇▇▇▇▇▇ ▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇ Attention: Equity Syndicate Desk, with a copy to the Legal Department

I-1


		c/o Cowen and Company, LLC ▇▇▇ ▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇ ▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇ Attention: Head of Equity Capital Markets

Address for Notices to the Company:		Cempra, Inc. ▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇ ▇▇▇ ▇▇▇▇▇▇ ▇▇▇▇, ▇▇▇▇▇ ▇▇▇▇▇▇▇▇ ▇▇▇▇▇-▇▇▇▇ Attention: ▇▇▇▇ ▇▇▇▇

I-2

SCHEDULE II


Underwriter	Number of Firm Shares To Be Purchased

▇▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co. LLC		2,100,000

▇▇▇▇▇ and Company, LLC		1,575,000

▇▇▇▇▇▇, ▇▇▇▇▇▇▇▇ & Company, Incorporated		1,050,000

▇▇▇▇▇▇▇▇▇▇▇ & Co. Inc.		315,000

Ladenburg ▇▇▇▇▇▇▇▇ & Co. Inc.		210,000


Total:		5,250,000

II-1

EXHIBIT A

FORM OF LOCK-UP LETTER

January , 2015

▇▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co. LLC

▇▇▇▇ ▇▇▇▇▇▇▇▇

▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇

▇▇▇▇▇ and Company, LLC

▇▇▇ ▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇

▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇

Ladies and Gentlemen:

The undersigned understands that ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co. LLC and Cowen and Company, LLC (the “Managers”) propose to enter into an Underwriting Agreement (the “Underwriting Agreement”) with Cempra, Inc., a Delaware corporation (the “Company”), providing for the public offering (the “Public Offering”) by the several Underwriters, including the Managers (the “Underwriters”), of 5,250,000 shares of the Common Stock, par value $0.001 per share of the Company (the “Common Stock”).

To induce the Underwriters that may participate in the Public Offering to continue their efforts in connection with the Public Offering, the undersigned hereby agrees that, without the prior written consent of each of the Managers on behalf of the Underwriters, it will not, during the period commencing on the date hereof and ending [90][60]¹ days after the date of the final prospectus (the “Restricted Period”) relating to the Public Offering (the “Prospectus”), (1) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock beneficially owned (as such term is used in Rule 13d-3 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”)), by the undersigned or any other securities so owned convertible into or exercisable or exchangeable for Common Stock or (2) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Common Stock, whether any such transaction described in clause (1) or (2) above is to be settled by delivery of Common Stock or such other securities, in cash or otherwise. The foregoing sentence shall not apply to (a) transactions relating to shares of Common Stock or other securities acquired in open market transactions after the completion of the Public

¹	90 days in the case of officers of the Company and 60 days in the case of directors and certain stockholders of the Company.

Offering, provided that no filing under Section 16(a) of the Exchange Act shall be required or shall be voluntarily made in connection with subsequent sales of Common Stock or other securities acquired in such open market transactions, (b) transfers of shares of Common Stock or any security convertible into Common Stock as a bona fide gift, by will or intestate succession, or by sales or other dispositions of shares of Common Stock, in each case that are made exclusively between and among the undersigned or members of the undersigned’s family, (c) shares transferred to a trust for the benefit of the undersigned’s family or, if the undersigned is a trust, shares transferred to its grantor or beneficiaries pursuant to its terms, (d) shares of Common Stock transferred to any corporation, partnership, limited liability company, or other entity all of the beneficial ownership interests of which are held by the undersigned, the undersigned’s family or affiliates of the undersigned, (e) distributions of shares of Common Stock or any security convertible into Common Stock to limited partners, stockholders or equity holders of the undersigned, (f) the transfer of shares of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock pursuant to a bona fide third party tender offer, merger, consolidation or other similar transaction made to all holders of the Common Stock involving a change of control of the Company approved by the board of directors of the Company and occurring after the consummation of the Public Offering; provided that in the event that the tender offer, merger, consolidation or other such transaction is not completed, the Common Stock owned by the undersigned shall remain subject to the restrictions contained in this agreement; provided that in the case of any transfer or distribution pursuant to clauses (b) through (e), (i) each donee, transferee or distributee shall sign and deliver a lock-up letter substantially in the form of this letter and (ii) no filing under Section 16(a) of the Exchange Act, reporting a reduction in beneficial ownership of shares of Common Stock, shall be required or shall be voluntarily made during the Restricted Period, or (h) the establishment of a trading plan pursuant to Rule 10b5-1 under the Exchange Act for the transfer of shares of Common Stock, provided that (i) such plan does not provide for the transfer of Common Stock during the Restricted Period and (ii) to the extent a public announcement or filing under the Exchange Act, if any, is required of or voluntarily made by or on behalf of the undersigned or the Company regarding the establishment of such plan, such announcement or filing shall include a statement to the effect that no transfer of Common Stock may be made under such plan during the Restricted Period. In addition, the undersigned agrees that, without the prior written consent of each of the Managers on behalf of the Underwriters, it will not, during the Restricted Period, make any demand for or exercise any right with respect to, the registration of any shares of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock. The undersigned also agrees and consents to the entry of stop transfer instructions with the Company’s transfer agent and registrar against the transfer of the undersigned’s shares of Common Stock except in compliance with the foregoing restrictions.

It is understood that, (i) if the Company notifies the Underwriters, prior to the execution of the Underwriting Agreement, that it does not intend to proceed with the Public Offering, (ii) if the Underwriting Agreement (other than the provisions thereof which survive termination) shall terminate or be terminated prior to payment for and delivery of the Common Stock, or (iii) if the Underwriting Agreement has not been executed on or before January 30, 2015, then the undersigned will be released from its obligations under this lock-up letter agreement.

The undersigned understands that the Company and the Underwriters are relying upon this agreement in proceeding toward consummation of the Public Offering. The undersigned further understands that this agreement is irrevocable and shall be binding upon the undersigned’s heirs, legal representatives, successors and assigns.

Whether or not the Public Offering actually occurs depends on a number of factors, including market conditions. Any Public Offering will only be made pursuant to an Underwriting Agreement, the terms of which are subject to negotiation between the Company and the Underwriters.


Very truly yours,

By:
		Name:
		Title

5,250,000 Shares CEMPRA, INC. COMMON STOCK, PAR VALUE $0.001 PER SHARE UNDERWRITING AGREEMENT

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