ALLOS THERAPEUTICS, INC. REGISTRATION RIGHTS AGREEMENT

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Exhibit 10.42

ALLOS THERAPEUTICS, INC.
REGISTRATION RIGHTS AGREEMENT

        REGISTRATION RIGHTS AGREEMENT, dated as of March 4, 2005, among the investors listed on Schedule I hereto (the "Investors") and Allos Therapeutics, Inc., a Delaware corporation (the "Company").

R E C I T A L S

        WHEREAS, the Investors have, pursuant to the terms of the Securities Purchase Agreement, dated as of March 2, 2005, by and among the Company and the Investors (the "Purchase Agreement"), agreed to purchase shares of Series A Exchangeable Preferred Stock, par value $0.001 per share, of the Company (the "Exchangeable Preferred Stock"); and

        WHEREAS, the shares of Exchangeable Preferred Stock are, under certain conditions, exchangeable into shares of common stock, par value $0.001 per share of the Company (the "Common Stock"); and

        WHEREAS, the Company has agreed, as a condition precedent to the Investors' obligations under the Purchase Agreement, to grant the Investors certain registration rights; and

        WHEREAS, the Company and the Investors desire to define the registration rights of the Investors on the terms and subject to the conditions herein set forth.

        NOW, THEREFORE, in consideration of the foregoing premises and for other good and valuable consideration, the parties hereby agree as follows:

SECTION 1. DEFINITIONS

        As used in this Agreement, the following terms have the respective meanings set forth below:

        Agreement:    shall mean this Registration Rights Agreement among the Investors and the Company;

        Commission:    shall mean the Securities and Exchange Commission or any other federal agency at the time administering the Securities Act;

        Exchange Act:    shall mean the Securities Exchange Act of 1934, as amended;

        Holder:    shall mean any Investor who is a holder of Registrable Securities or any assignee of record of such Registrable Securities in accordance with the terms hereof;

        Initiating Holder:    shall mean Warburg Pincus Private Equity VIII, L.P.;

        Person:    shall mean an individual, partnership, joint-stock company, corporation, trust or unincorporated organization, and a government or agency or political subdivision thereof;

        Register, Registered and Registration:    shall mean a registration effected by preparing and filing a registration statement in compliance with the Securities Act (and any post-effective amendments filed or required to be filed) and the declaration or ordering of effectiveness of such registration statement;

        Registrable Securities:    shall mean (A) shares of Common Stock issuable upon exchange of the shares of Exchangeable Preferred Stock purchased by the Investors pursuant to the Securities Purchase Agreement, (B) any other shares of Common Stock acquired by the Investors and (C) any stock of the Company issued as a dividend or other distribution with respect to, or in exchange for or in replacement of, the shares of Exchangeable Preferred Stock or Common Stock referred to in clause (A) or (B); provided, however, that notwithstanding the foregoing, Registrable Securities shall not include any securities (i) sold by a Holder to the public either pursuant to a registration statement or Rule 144, or (ii) sold in a private transaction in which the transferor's rights under Section 2 hereof are not assigned in accordance with the terms of this Agreement.

        Registration Expenses:    shall mean all expenses incurred by the Company in compliance with Section 2(a), (b) and (c) hereof, including, without limitation, all registration and filing fees, printing expenses, fees and disbursements of counsel for the Company, fees and expenses of one counsel for all the Holders in an amount not to exceed $15,000, blue sky fees and expenses and the expense of any special audits incident to or required by any such registration (but excluding the compensation of regular employees of the Company, which shall be paid in any event by the Company);

        security, securities:    shall have the meaning set forth in Section 2(1) of the Securities Act;

        Securities Act:    shall mean the Securities Act of 1933, as amended; and

        Selling Expenses:    shall mean all underwriting discounts and selling commissions applicable to the sale of Registrable Securities and all fees and disbursements of counsel for each of the Holders other than fees and expenses of one counsel for all the Holders in an amount not to exceed $15,000.

SECTION 2. REGISTRATION RIGHTS

        (a)   Requested Registration.

        (i)    Request for Registration. Subject to the conditions of this Section 2(a), if the Company shall receive from the Initiating Holder, at any time on or after the second anniversary of the date hereof, a written request that the Company effect any registration with respect to all or a part of the Registrable Securities, the Company will:

        (1)   promptly give written notice of the proposed registration, qualification or compliance to all other Holders; and

        (2)   subject to the limitations of this Section 2(a), as soon as practicable, use its commercially reasonable efforts to effect such registration (including, without limitation, the execution of an undertaking to file post-effective amendments, appropriate qualification under applicable blue sky or other state securities laws and appropriate compliance with applicable regulations issued under the Securities Act) as may be so requested and as would permit or facilitate the sale and distribution of all or such portion of such Registrable Securities as are specified in such request, together with all or such portion of the Registrable Securities of any Holder or Holders joining in such request as are specified in a written request received by the Company within ten (10) business days after written notice from the Company is given under Section 2(a)(i)(1) above; provided that the Company shall not be obligated to effect, or take any action to effect, any such registration pursuant to this Section 2(a):

        (A)  In any particular jurisdiction in which the Company would be required to qualify to do business or execute a general consent to service of process in effecting such registration, qualification or compliance, unless the Company is already subject to service in such jurisdiction and except as may be required by the Securities Act or applicable rules or regulations thereunder;

        (B)  After the Company has effected one (1) such registration pursuant to this Section 2(a) and such registration has been declared or ordered effective;

        (C)  If the Registrable Securities requested by all Holders to be registered pursuant to such request do not have an anticipated aggregate public offering price (before any underwriting discounts and commissions) of not less than $7,500,000;

        (D)  if within thirty (30) days of receipt of a written request from the Initiating Holder pursuant to Section 2(a), the Company gives notice to the Holders of the Company's intention to file a registration statement for a public offering within sixty (60) days, other than pursuant to (i) a registration statement relating to any employee benefit plan or (ii) with respect to any corporate reorganization or transaction under Rule 145 of the Securities Act, including any registration statements related to the issuance or resale of securities issued in such a transaction or (iii) a registration related to stock issued upon conversion of debt securities (each a "Special Registration Statement");

        (E)  if the Initiating Holders propose to dispose of shares of Registrable Securities that may be immediately registered on Form S-3 pursuant to a request made pursuant to Section 2(c) below; or

        (F)  If the Board of Directors, in its good faith judgment, determines that any registration of Registrable Securities requested pursuant to this Section 2(a) (a "Requested Registration") should not be made or continued because it would interfere with any material financing, acquisition, corporate reorganization or merger or other material transaction involving the Company (a "Valid Business Reason"), the Company may (x) postpone filing a registration statement relating to a Requested Registration until such Valid Business Reason no longer exists, but in no event for more than ninety (90) days, and (y) in case a registration statement has been filed relating to a Request Registration, if the Valid Business Reason has not resulted from actions taken by the Company, the Company may cause such registration statement to be withdrawn and its effectiveness terminated or may postpone amending or supplementing such registration statement (so long as the Initiating Holders shall have the rights set forth in this Section 2(a) within ninety (90) days of any such event). The Company shall give written notice of its determination to postpone or withdraw a registration statement (provided that the Company shall not disclose any information that could be deemed material non-public information to any holder of Registrable Securities that are included in a registration statement that is subject to such postponement or withdrawal) and of the fact that the Valid Business Reason for such postponement or withdrawal no longer exists, in each case, promptly after the occurrence thereof. Notwithstanding anything to the contrary contained herein, the Company may not postpone or withdraw a filing due to a Valid Business Reason more than once in any twelve (12) month period. In addition, the Company shall not be required to effect any registration pursuant to Section 2(a), within ninety (90) days after the effective date of any other Registration Statement of the Company if the Registration Statement was not for the account of the Initiating Holders but the Initiating Holders had the opportunity to include at least two-thirds of the Registrable Securities they requested to include in such registration pursuant to Section 2(b).

        The registration statement filed pursuant to the request of the Initiating Holders may, subject to the provisions of Section 2(a)(ii) below, include other securities of the Company which are held by Persons who, by virtue of agreements with the Company, are entitled to include their securities in any such registration ("Other Stockholders"). In the event any Holder requests a registration pursuant to this Section 2(a) in connection with a distribution of Registrable Securities to its partners, the registration shall provide for the resale by such partners, if requested by such Holder.

        The registration rights set forth in this Section 2 may be assigned, in whole or in part, to any transferee of Registrable Securities (who shall be bound by all obligations of this Agreement) that (a) is a subsidiary, parent, general partner, limited partner, retired partner, member or retired member, of a Holder that is a corporation, partnership or limited liability company, (b) is a Holder's family member or trust for the benefit of an individual Holder, or (c) acquires at least five hundred thousand (500,000) shares of Registrable Securities (as adjusted for stock splits and combinations); or (d) is an entity affiliated by common control with such Holder; provided, however, (i) the transferor shall, within ten (10) days after such transfer, furnish to the Company written notice of the name and address of such transferee or assignee and the securities with respect to which such registration rights are being assigned and (ii) such transferee shall agree to be subject to all restrictions set forth in this Agreement.

        (ii)   Underwriting. If the Initiating Holders intend to distribute the Registrable Securities covered by their request by means of an underwriting, they shall so advise the Company as a part of their request made pursuant to Section 2(a)(i).

        If Other Stockholders request inclusion of their securities in the underwriting, the Holders shall offer to include the securities of such Other Stockholders in the underwriting and may condition such offer on their acceptance of the further applicable provisions of this Section 2. The Holders whose shares are to be included in such registration and the Company shall (together with all Other Stockholders proposing to distribute their securities through such underwriting) enter into an underwriting agreement in customary form with the representative of the underwriter or underwriters selected for such underwriting by the Initiating Holders and reasonably acceptable to the Company; provided, however, that such underwriting agreement shall not provide for indemnification or contribution obligations on the part of the Holders materially greater than the obligations of the Holders under Section (f)(ii). Notwithstanding any other provision of this Section 2(a), if the representative advises the Holders in writing that marketing factors require a limitation on the number of shares to be underwritten, the securities of the Company held by Other Stockholders shall be excluded from such registration to the extent so required by such limitation. If, after the exclusion of such shares, further reductions are still required, the number of shares included in the registration by each Holder shall be reduced on a pro rata basis (based on the number of shares held by such Holder), by such minimum number of shares as is necessary to comply with such request. No Registrable Securities or any other securities excluded from the underwriting by reason of the underwriter's marketing limitation shall be included in such registration. If any Other Stockholder who has requested inclusion in such registration as provided above disapproves of the terms of the underwriting, such Person may elect to withdraw therefrom by written notice to the Company, the underwriter and the Initiating Holders. The securities so withdrawn shall also be withdrawn from registration. If the underwriter has not limited the number of Registrable Securities or other securities to be underwritten, the Company and officers and directors of the Company may include its or their securities for its or their own account in such registration if the representative so agrees and if the number of Registrable Securities and other securities which would otherwise have been included in such registration and underwriting will not thereby be limited.

        (b)   Company Registration.

        (i)    If at any time on or after the second anniversary of the date hereof, the Company shall determine to register any of its equity securities either for its own account or for the account of Other Stockholders, other than a registration relating solely to employee benefit plans, or a registration relating solely to a Rule 145 transaction under the Securities Act, or a registration on any registration form which does not permit secondary sales or does not include substantially the same information as would be required to be included in a registration statement covering the sale of Registrable Securities, the Company will:

        (1)   promptly give to each of the Holders a written notice thereof (which shall include a list of the jurisdictions in which the Company intends to attempt to qualify such securities under the applicable blue sky or other state securities laws); and

        (2)   include in such registration (and any related qualification under blue sky laws or other compliance), and in any underwriting involved therein, all the Registrable Securities specified in a written request or requests, made by the Holders within fifteen (15) days after receipt of the written notice from the Company described in clause (1) above, except as set forth in Section 2(b)(ii) below. Such written request may specify all or a part of the Holders' Registrable Securities and shall describe the intended method of disposition of the Registrable Securities by such Holders. In the event any Holder requests inclusion in a registration pursuant to this Section 2(b) in connection with a distribution of Registrable Securities to its partners, the registration shall provide for the resale by such partners, if requested by such Holder.

        (ii)   Underwriting. If the registration of which the Company gives notice is for a registered public offering involving an underwriting, the Company shall so advise each of the Holders as a part of the written notice given pursuant to Section 2(b)(i)(1) above. In such event, the right of each of the Holders to registration pursuant to this Section 2(b) shall be conditioned upon such Holders' participation in such underwriting and the inclusion of such Holders' Registrable Securities in the underwriting to the extent provided herein. The Holders whose shares are to be included in such registration shall (together with the Company and the Other Stockholders distributing their securities through such underwriting) enter into an underwriting agreement in customary form with the representative of the underwriter or underwriters selected for underwriting by the Company; provided, however, that such underwriting agreement shall not provide for indemnification or contribution obligations on the part of the Holders materially greater than the obligations of the Holders under Section f(ii). Notwithstanding any other provision of this Section 2(b), if the representative determines that marketing factors require a limitation on the number of shares to be underwritten, the representative may (subject to the allocation priority set forth below) limit the number of Registrable Securities to be included in the registration and underwriting to not less than twenty five percent (25%) of the shares included therein (based on the number of shares). The Company shall so advise all holders of securities requesting registration, and the number of shares of securities that are entitled to be included in the registration and underwriting shall be allocated in the following manner: the securities of the Company held by officers, directors and Other Stockholders of the Company (other than Registrable Securities and other than securities held by holders who by contractual right demanded such registration ("Demanding Holders")) shall be excluded from such registration and underwriting to the extent required by such limitation, and, if a limitation on the number of shares is still required, the number of shares that may be included in the registration and underwriting by each of the Holders and Demanding Holders shall be reduced, on a pro rata basis (based on the number of shares held by such holder), by such minimum number of shares as is necessary to comply with such limitation. If any of the Holders or any officer, director or Other Stockholder disapproves of the terms of any such underwriting, he may elect to withdraw therefrom by written notice to the Company and the underwriter, delivered at least five (5) business days prior to the effective date of the registration statement. Any Registrable Securities or other securities excluded or withdrawn from such underwriting shall be withdrawn from such registration.

        (iii)  Right to Terminate Registration. The Company shall have the right to terminate or withdraw any registration initiated by it under this Section 2(b) whether or not any Holder has elected to include securities in such registration, and shall promptly notify any Holder that has elected to include shares in such registration of such termination or withdrawal. The Registration Expenses of such withdrawn registration shall be borne by the Company in accordance with Section 2(d) hereof.

        (c)   Form S-3. The Company shall use commercially reasonable efforts to maintain its qualification for registration on Form S-3 for secondary sales. The Initiating Holder shall, at any time on or after the second anniversary of the date hereof, have the right to collectively request two (2) registrations on Form S-3 (such requests shall be in writing and shall state the number of shares of Registrable Securities to be disposed of and the intended method of disposition of shares by such holders), provided that the Company shall not be obligated to effect, or take any action to effect, any such registration pursuant to this Section 2(c):

        (i)    Unless the Initiating Holder or Holders requesting registration propose to dispose of shares of Registrable Securities having an aggregate price to the public (before deduction of Selling Expenses) of more than $2,000,000;

        (ii)   In any particular jurisdiction in which the Company would be required to qualify to do business or execute a general consent to service of process in effecting such registration, qualification or compliance, unless the Company is already subject to service in such jurisdiction and except as may be required by the Securities Act or applicable rules or regulations thereunder;

        (iii)  if within thirty (30) days of receipt of a written request from any Holder or Holders pursuant to this Section 2(c), the Company gives notice to such Holder or Holders of the Company's intention to make a public offering within sixty (60) days, other than pursuant to a Special Registration Statement;

        (iv)  If the Board of Directors, in its good faith judgment, determines that any registration of Registrable Securities pursuant to this Section 2(c) (an "S-3 Registration") should not be made or continued because of a Valid Business Reason, the Company may (x) postpone filing a registration statement relating to a S-3 Registration until such Valid Business Reason no longer exists, but in no event for more than ninety (90) days, and (y) in case a registration statement has been filed relating to a S-3 Registration, if the Company reasonably believes that there is or may be in existence material nonpublic information or events involving the Company, the failure of which to be disclosed in the prospectus included in the registration statement could result in a Violation (as defined below), the Company may cause such registration statement to be withdrawn and its effectiveness terminated or may postpone amending or supplementing such registration statement (so long as the Holders shall have the rights set forth in this Section 2(c) within ninety (90) days of any such event). The Company shall give written notice of its determination to postpone or withdraw a registration statement (provided that the Company shall not disclose any information that could be deemed material non-public information to any holder of Registrable Securities that are included in a registration statement that is subject to such postponement or withdrawal) and of the fact that the Valid Business Reason for such postponement or withdrawal no longer exists, in each case, promptly after the occurrence thereof. Notwithstanding anything to the contrary contained herein, the Company may not postpone or withdraw a filing due to a Valid Business Reason more than once in any twelve (12) month period. In addition, the Company shall not be required to effect any registration pursuant to Section 2(c), (i) within ninety (90) days after the effective date of any other Registration Statement of the Company if the Registration Statement was not for the account of the Holders but the Holders had the opportunity to include at least two-thirds of the Registrable Securities they requested to include in such registration or (ii) if Form S-3 (or any successor form then in effect) is not available for such offering by the Holders.

        The Company shall give written notice to all Holders of the receipt of a request for registration pursuant to this Section 2(c) and shall provide a reasonable opportunity for other Holders to participate in the registration, provided that if the registration is for an underwritten offering, the terms of Section 2(a)(ii) above shall apply to all participants in such offering. Subject to the foregoing, the Company will use commercially reasonable efforts to effect promptly the registration of all shares of Registrable Securities on Form S-3 to the extent requested by the Holder or Holders thereof for purposes of disposition. In the event any Holder requests a registration pursuant to this Section 2(c) in connection with a distribution of Registrable Securities to its partners, the registration shall provide for the resale by such partners, if requested by such Holder.

        (d)   Expenses of Registration. All Registration Expenses incurred in connection with any registration, qualification or compliance pursuant to this Section 2 shall be borne by the Company, and all Selling Expenses shall be borne by the Holders of the securities so registered pro rata on the basis of the number of their shares so registered. The Company shall not, however, be required to pay for expenses of any registration proceeding begun pursuant to Section 2(a) or 2(c), the request of which has been subsequently withdrawn by the Initiating Holder unless (a) the withdrawal is based upon material adverse information concerning the Company of which the Initiating Holder was not aware at the time of such request or (b) the Holders of a majority of Registrable Securities agree to deem such registration to have been effected as of the date of such withdrawal for purposes of determining whether the Company shall be obligated pursuant to Section 2(a) or 2(c), as applicable, to undertake any subsequent registration, in which event such right shall be forfeited by all Holders). If the Holders are required to pay the Registration Expenses, such expenses shall be borne by the holders of securities (including Registrable Securities) requesting such registration in proportion to the number of shares for which registration was requested. If the Company is required to pay the Registration Expenses of a withdrawn offering pursuant to clause (a) above, then such registration shall not be deemed to have been effected for purposes of determining whether the Company shall be obligated pursuant to Section 2(a) or 2(c), as applicable, to undertake any subsequent registration.

        (e)   Registration Procedures. In the case of each registration effected by the Company pursuant to this Section 2, the Company will keep the Holders, as applicable, advised in writing as to the initiation of each registration and as to the completion thereof. At its expense, the Company will:

        (i)    keep such registration effective for a period of sixty (60) days or until the Holders (or in the case of a distribution to the partners of such Holder, such partners), as applicable, have completed the distribution described in the registration statement relating thereto, whichever first occurs; provided, however, that (1) such sixty (60)-day period shall be extended for a period of time equal to the period during which the Holders or partners, as applicable, prohibited from selling any securities included in such registration due to any suspension of effectiveness provided for in accordance with the provisions in Sections 2(a)(i)(2)(F) or 2(c)(iv) hereof; and (2) in the case of any registration of Registrable Securities on Form S-3 which are intended to be offered on a continuous or delayed basis, such sixty (60)-day period shall be extended until all such Registrable Securities are sold, not to exceed two (2) years or the period ending on the date on which all of the Registrable Securities may be sold pursuant to Rule 144 (without giving effect to Rule 144(k) thereof) of the Securities Act within ninety (90) days after such date, provided that Rule 415, or any successor rule under the Securities Act, permits an offering on a continuous or delayed basis, and provided further that applicable rules under the Securities Act governing the obligation to file a post-effective amendment permit, in lieu of filing a post-effective amendment which (y) includes any prospectus required by Section 10(a) of the Securities Act or (z) reflects facts or events representing a material or fundamental change in the information set forth in the registration statement, the incorporation by reference of information required to be included in (y) and (z) above to be contained in periodic reports filed pursuant to Section 12 or 15(d) of the Exchange Act in the registration statement;

        (ii)   furnish such number of prospectuses and other documents incident thereto as each of the Holders, as applicable, from time to time may reasonably request;

        (iii)  notify each Holder of Registrable Securities covered by such registration at any time when a prospectus relating thereto is required to be delivered under the Securities Act of the happening of any event as a result of which the prospectus included in such registration statement, as then in effect, includes an untrue statement of a material fact or omits to state a material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances then existing; and

        (iv)  furnish, on the date that such Registrable Securities are delivered to the underwriters for sale, if such securities are being sold through underwriters or, if such securities are not being sold through underwriters, on the date that the registration statement with respect to such securities becomes effective, (1) an opinion, dated as of such date, of the counsel representing the Company for the purposes of such registration, in form and substance as is customarily given to underwriters in an underwritten public offering and reasonably satisfactory to a majority in interest of the Holders participating in such registration, addressed to the underwriters, if any, and to the Holders participating in such registration and (2) a letter, dated as of such date, from the independent certified public accountants of the Company, in form and substance as is customarily given by independent certified public accountants to underwriters in an underwritten public offering and reasonably satisfactory to a majority in interest of the Holders participating in such registration, addressed to the underwriters, if any, and if permitted by applicable accounting standards, to the Holders participating in such registration.

        (f)    Indemnification.

        (i)    The Company will indemnify each of the Holders, as applicable, each of its officers, directors and partners, and each Person controlling each of the Holders, with respect to each registration which has been effected pursuant to this Section 2, and each underwriter, if any, and each person who controls any underwriter, against all claims, losses, damages and liabilities (or actions in respect thereof) arising out of or based on any untrue statement (or alleged untrue statement) of a material fact contained in any prospectus, offering circular or other document (including any related registration statement, notification or the like) incident to any such registration, qualification or compliance, or based on 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, or any violation by the Company of the Securities Act or the Exchange Act or any rule or regulation thereunder applicable to the Company and relating to action or inaction required of the Company in connection with any such registration, qualification or compliance (collectively a "Violation"), and will reimburse each of the Holders, each of its officers, directors and partners, and each Person controlling each of the Holders, each such underwriter and each Person who controls any such underwriter, for any legal and any other expenses reasonably incurred in connection with investigating and defending any such claim, loss, damage, liability or action; provided that the Company will not be liable in any such case to the extent that any such claim, loss, damage, liability or expense arises out of or is based on any untrue statement or omission based upon written information furnished to the Company by the Holders or underwriter and stated to be specifically for use therein; provided, further, that the indemnity agreement contained in this Section 2(f)(i) shall not apply to amounts paid in settlement of any such loss, claim, damage, liability or action if such settlement is effected without the consent of the Company, which consent shall not be unreasonably withheld.

        (ii)   Each of the Holders will, if Registrable Securities held by it are included in the securities as to which such registration, qualification or compliance is being effected, indemnify the Company, each of its directors and officers and each underwriter, if any, of the Company's securities covered by such a registration statement, each person who controls the Company or such underwriter, each Other Stockholder and each of their officers, directors, and partners, and each person controlling such Other Stockholder against all claims, losses, damages and liabilities (or actions in respect thereof) arising out of or based on any untrue statement (or alleged untrue statement) of a material fact contained in any such registration statement, prospectus, offering circular or other document made by such Holder, any omission (or alleged omission) to state therein a material fact required to be stated therein or necessary to make the statements by such Holder therein not misleading, and will reimburse the Company and such Other Stockholders, directors, officers, partners, persons, underwriters or control persons for any legal or any other expenses reasonably incurred in connection with investigating and defending any such claim, loss, damage, liability or action, in each case to the extent, but only to the extent, that such untrue statement (or alleged untrue statement) or omission (or alleged omission) is made in such registration statement, prospectus, offering circular or other document, or such violation is made, in reliance upon and in conformity with written information furnished to the Company by such Holder and stated to be specifically for use therein; provided, however, that the obligations of each of the Holders hereunder shall be limited to an amount equal to the proceeds to such Holder of securities sold as contemplated herein; provided further, that the indemnity agreement contained in this Section 2(f)(ii) shall not apply to amounts paid in settlement of any such loss, claim, damage, liability or action if such settlement is effected without the consent of the Holder, which consent shall not be unreasonably withheld.

        (iii)  Each party entitled to indemnification under this Section 2(f) (the "Indemnified Party") shall give notice to the party required to provide indemnification (the "Indemnifying Party") promptly after such Indemnified Party has actual knowledge of any claim as to which indemnity may be sought, and shall permit the Indemnifying Party to assume the defense of any such claim or any litigation resulting therefrom; provided that counsel for the Indemnifying Party, who shall conduct the defense of such claim or any litigation resulting therefrom, shall be approved by the Indemnified Party (whose approval shall not unreasonably be withheld) and the Indemnified Party may participate in such defense at such party's expense (unless the Indemnified Party shall have reasonably concluded that there may be a conflict of interest between the Indemnifying Party and the Indemnified Party in such action, in which case the fees and expenses of counsel shall be at the expense of the Indemnifying Party), and provided further that the failure of any Indemnified Party to give notice as provided herein shall not relieve the Indemnifying Party of its obligations under this Section 2(f) unless the Indemnifying Party is materially prejudiced thereby. No Indemnifying Party, in the defense of any such claim or litigation shall, except with the consent of each Indemnified Party, consent to entry of any judgment or enter into any settlement which does not include as an unconditional term thereof the giving by the claimant or plaintiff to such Indemnified Party of a release from all liability in respect to such claim or litigation. Each Indemnified Party shall furnish such information regarding itself or the claim in question as an Indemnifying Party may reasonably request in writing and as shall be reasonably required in connection with the defense of such claim and litigation resulting therefrom.

        (iv)  If the indemnification provided for in this Section 2(f) is held by a court of competent jurisdiction to be unavailable to an Indemnified Party with respect to any loss, liability, claim, damage or expense referred to herein, then the Indemnifying Party, in lieu of indemnifying such Indemnified Party hereunder, shall contribute to the amount paid or payable by such Indemnified Party as a result of such loss, liability, claim, damage or expense in such proportion as is appropriate to reflect the relative fault of the Indemnifying Party on the one hand and of the Indemnified Party on the other in connection with the statements or omissions which resulted in such loss, liability, claim, damage or expense, as well as any other relevant equitable considerations. The relative fault of the Indemnifying Party and of the Indemnified Party 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 Indemnifying Party or by the Indemnified Party and the parties' relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission.

        (v)   Notwithstanding the foregoing, to the extent that the provisions on indemnification and contribution contained in the underwriting agreement entered into in connection with any underwritten public offering contemplated by this Agreement are in conflict with the foregoing provisions, the provisions in such underwriting agreement shall be controlling.

        (vi)  The foregoing indemnity agreement of the Company and Holders is subject to the condition that, insofar as they relate to any loss, claim, liability or damage arising out of a statement made in or omitted from a preliminary prospectus but eliminated or remedied in the amended prospectus on file with the Commission at the time the registration statement in question becomes effective or the amended prospectus filed with the Commission pursuant to Rule 424(b) under the Securities Act (the "Final Prospectus"), such indemnity or contribution agreement shall not inure to the benefit of any underwriter or Holder if a copy of the Final Prospectus was furnished to the underwriter and was not furnished to the Person asserting the loss, liability, claim or damage at or prior to the time such action is required by the Securities Act.

        (g)   Information by the Holders.

        (i)    Each of the Holders holding securities included in any registration shall furnish to the Company such information regarding such Holder and the distribution proposed by such Holder as the Company may reasonably request in writing and as shall be reasonably required in connection with any registration, qualification or compliance referred to in this Section 2.

        (ii)   In the event that, either immediately prior to or subsequent to the effectiveness of any registration statement, any Holder shall distribute Registrable Securities to its partners, such Holder shall so advise the Company and provide such information as shall be necessary to permit an amendment to such registration statement to provide information with respect to such partners, as selling security holders. Promptly following receipt of such information, the Company shall file an appropriate amendment to such registration statement reflecting the information so provided. Any incremental expense to the Company resulting from such amendment shall be borne by such Holder.

        (h) Rule 144 Reporting.

        With a view to making available the benefits of certain rules and regulations of the Commission which may permit the sale of restricted securities to the public without registration, the Company agrees to:

        (i)    make and keep public information available as those terms are understood and defined in Rule 144 under the Securities Act ("Rule 144");

        (ii)   use its best efforts to file with the Commission in a timely manner all reports and other documents required of the Company under the Securities Act and the Exchange Act at any time after it has become subject to such reporting requirements; and

        (iii)  so long as a Holder owns any Registrable Securities, furnish to such Holder upon request, a written statement by the Company as to its compliance with the reporting requirements of Rule 144 and of the Securities Act and the Exchange Act, a copy of the most recent annual or quarterly report of the Company, and such other reports and documents so filed as such Holder may reasonably request in availing itself of any rule or regulation of the Commission allowing such Holder to sell any such securities without registration.

        (i)    Termination. The registration rights set forth in this Section 2 shall not be available to any Holder if, (i) in the opinion of counsel to the Company, all of the Registrable Securities then owned by such Holder could be sold in any ninety (90)-day period pursuant to Rule 144 (without giving effect to the provisions of Rule 144(k)), or (ii) all of the Registrable Securities held by such Holder have been sold in a registration pursuant to the Securities Act or pursuant to Rule 144.

SECTION 3. MISCELLANEOUS

        (a)   Directly or Indirectly. Where any provision in this Agreement refers to action to be taken by any Person, or which such Person is prohibited from taking, such provision shall be applicable whether such action is taken directly or indirectly by such Person.

        (b)   Governing Law. This Agreement shall be governed by and construed in accordance with the laws of the State of Delaware applicable to contracts made and to be performed entirely within such State.

        (c)   Section Headings. The headings of the sections and subsections of this Agreement are inserted for convenience only and shall not be deemed to constitute a part thereof.

        (d)   Notices.

        (i)    All communications under this Agreement shall be in writing and shall be delivered by hand or facsimile or mailed by overnight courier or by registered or certified mail, postage prepaid:

        (1)   if to the Company, to ▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇▇, ▇▇▇▇▇▇▇▇, ▇▇▇▇▇, Attention: President ▇▇▇▇▇▇▇ ▇. ▇▇▇▇ (facsimile: (▇▇▇) ▇▇▇-▇▇▇▇), or at such other address as it may have furnished in writing to the Holders, with a copy to Cooley Godward LLP (facsimile: (▇▇▇) ▇▇▇-▇▇▇▇), Attention: ▇▇▇▇▇ ▇▇▇▇▇▇▇, Esq.

        (2)   if to the Holders, at the address or facsimile number listed on Schedule I hereto, or at such other address or facsimile number as may have been furnished the Company in writing, with a copy to ▇▇▇▇▇▇▇ ▇▇▇▇ & ▇▇▇▇▇▇▇▇▇ LLP, ▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇ (facsimile: (▇▇▇) ▇▇▇-▇▇▇▇), Attention: ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇, Esq.

        (ii)   Any notice so addressed shall be deemed to be given: if delivered by hand or facsimile, on the date of such delivery; if mailed by overnight courier, on the first business day following the date of such mailing; and if mailed by registered or certified mail, on the third business day after the date of such mailing.

        (e)   Reproduction of Documents. This Agreement and all documents relating thereto, including, without limitation, any consents, waivers and modifications which may hereafter be executed may be reproduced by the Holders by any photographic, photostatic, microfilm, microcard, miniature photographic or other similar process and the Holders may destroy any original document so reproduced. The parties hereto agree and stipulate that any such reproduction shall be admissible in evidence as the original itself in any judicial or administrative proceeding (whether or not the original is in existence and whether or not such reproduction was made by the Holders in the regular course of business) and that any enlargement, facsimile or further reproduction of such reproduction shall likewise be admissible in evidence.

        (f)    Successors and Assigns. This Agreement shall inure to the benefit of and be binding upon the successors and assigns of each of the parties.

        (g)   Entire Agreement; Amendment and Waiver. This Agreement constitutes the entire understanding of the parties hereto relating to the subject matter hereof and supersedes all prior understandings among such parties. This Agreement may be amended, and the observance of any term of this Agreement may be waived, with (and only with) the written consent of the Company and the Holders holding a majority of the then outstanding Registrable Securities. Any amendment or waiver effected in accordance with this Section 3(g) shall be binding upon each Holder and the Company.

        (h)   Severability. In the event that any part or parts of this Agreement shall be held illegal or unenforceable by any court or administrative body of competent jurisdiction, such determination shall not affect the remaining provisions of this Agreement which shall remain in full force and effect.

        (i)    Counterparts. This Agreement may be executed in two or more counterparts (including by facsimile), each of which shall be deemed an original and all of which together shall be considered one and the same agreement.

        (j)    Additional Investors. Notwithstanding anything to the contrary contained herein, if the Company shall issue additional shares of its Common Stock or Exchangeable Preferred Stock pursuant to the Purchase Agreement, any purchaser of such securities shall become a party to this Agreement by executing and delivering an additional counterpart signature page to this Agreement and shall be deemed an "Investor," a "Holder" and a party hereunder.

[Remainder of Page Intentionally Left Blank]

        IN WITNESS WHEREOF, the undersigned have executed this Agreement as of the date first set forth above.

		ALLOS THERAPEUTICS, INC.
		By:		/s/  ▇▇▇▇▇▇▇ ▇. ▇▇▇▇       Name: ▇▇▇▇▇▇▇ ▇. ▇▇▇▇ Title: President and Chief Executive Officer

WARBURG PINCUS PRIVATE EQUITY VIII, L.P.
By:		WARBURG PINCUS & CO., General Partner
By:		/s/  ▇▇▇▇▇▇▇▇ ▇▇▇▇       Name: ▇▇▇▇▇▇▇▇ ▇▇▇▇ Title: Partner

Counterpart Signature Page to Registration Rights Agreement
(pursuant to Section 3(j))

        IN WITNESS WHEREOF, the undersigned Investors have executed this Registration Rights Agreement as of March 8, 2005.

		INVESTOR:
		FrontPoint Healthcare Fund, L.P.
		By:		FrontPoint Healthcare Fund GP, LLC, its General Partner
		By:		/s/  ▇▇▇▇▇▇ ▇. ▇▇▇
		Name:		▇▇▇▇▇▇ ▇. ▇▇▇
		Title:		Authorized Signatory
		INVESTOR:
		FrontPoint Healthcare Horizons Fund, L.P.
		By:		FrontPoint Healthcare Horizons Fund GP, LLC, its General Partner
		By:		/s/  ▇▇▇▇▇▇ ▇. ▇▇▇
		Name:		▇▇▇▇▇▇ ▇. ▇▇▇
		Title:		Authorized Signatory

Schedule I
Investors

Investor Name and Address

Warburg Pincus Private Equity VIII, L.P.
▇▇▇ ▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇
▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇
Facsimile: (▇▇▇) ▇▇▇-▇▇▇▇
Attention: ▇▇. ▇▇▇▇▇▇▇▇ ▇. ▇▇▇▇

FrontPoint Healthcare Fund, L.P.
▇▇ ▇▇▇▇▇ ▇▇▇▇▇ ▇▇▇▇
▇▇▇▇▇▇▇▇▇, ▇▇ ▇▇▇▇▇
Facsimile: ▇▇▇-▇▇▇-▇▇▇▇
Attention: ▇▇▇▇▇▇ ▇. ▇▇▇

FrontPoint Healthcare Horizons Fund, L.P.
▇▇ ▇▇▇▇▇ ▇▇▇▇▇ ▇▇▇▇
▇▇▇▇▇▇▇▇▇, ▇▇ ▇▇▇▇▇
Facsimile: ▇▇▇-▇▇▇-▇▇▇▇
Attention: ▇▇▇▇▇▇ ▇. ▇▇▇

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ALLOS THERAPEUTICS, INC. REGISTRATION RIGHTS AGREEMENT