ALLOS THERAPEUTICS INC
EX-10.1
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<p align="right" style="margin:0pt 0pt 12.0pt;text-align:right;text-indent:0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Exhibit
10.1</font></b></p>

<p align="center" style="margin:0pt 0pt .0001pt;text-align:center;text-indent:0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">BAKER BROS. INVESTMENTS, L.P.</font></b></p>

<p align="center" style="margin:0pt 0pt .0001pt;text-align:center;text-indent:0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">BAKER BROS. INVESTMENTS II, L.P.</font></b></p>

<p align="center" style="margin:0pt 0pt .0001pt;text-align:center;text-indent:0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">BAKER/TISCH INVESTMENTS, L.P.</font></b></p>

<p align="center" style="margin:0pt 0pt .0001pt;text-align:center;text-indent:0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">BAKER BIOTECH FUND I, L.P.</font></b></p>

<p align="center" style="margin:0pt 0pt .0001pt;text-align:center;text-indent:0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">14159, L.P.</font></b></p>

<p align="center" style="margin:0pt 0pt .0001pt;text-align:center;text-indent:0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">BAKER BROTHERS LIFE SCIENCES, L.P.</font></b></p>

<p align="center" style="margin:0pt 0pt .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">667 Madison Avenue, 17th Floor</font></b></p>

<p align="center" style="margin:0pt 0pt 12.0pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">New York,
New York 10021</font></b></p>

<p style="margin:0pt 0pt 12.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">January 28, 2007</font></p>

<p style="margin:0pt 0pt .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Allos Therapeutics, Inc.</font></p>

<p style="margin:0pt 0pt .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">11080 CirclePoint Road</font></p>

<p style="margin:0pt 0pt .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Westminster, CO 80020</font></p>

<p style="margin:0pt 0pt 12.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Attention: Chief
Executive Officer</font></p>

<p style="margin:0pt 0pt 12.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Gentlemen:</font></p>

<p style="margin:0pt 0pt 12.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">In connection with the
proposed acquisition of shares of Common Stock, par value $0.001 per share (the
&#147;<b><i style="font-weight:bold;">Common Stock</i></b>&#148;), of Allos
Therapeutics, Inc., a Delaware corporation (the &#147;<b><i style="font-weight:bold;">Company</i></b>&#148;),
in connection with the registered offering of Common Stock pursuant to a
Registration Statement on Form S-3 (File No. 333-134965) (the &#147;<b><i style="font-weight:bold;">Offering</i></b>&#148;) by each of Baker Brothers
Life Sciences, L.P., Baker/Tisch Investments, L.P., Baker Biotech Fund I, L.P.,
and 14159, L.P. (collectively, the &#147;<b><i style="font-weight:bold;">Purchaser Group</i></b>&#148;),
the Company and the Purchaser Group agree as follows:</font></p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:36.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">1.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Definitions.</font></b>&#160; For purposes of this letter
agreement, the following terms have the respective meanings set forth below:</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:72.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(a)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>&#147;<b><i style="font-weight:bold;">Affiliates</i></b>&#148; shall mean any fund,
whether existing now or in the future, that (i) directly, or indirectly through
one or more intermediaries, controls or is controlled by, or is under common
control with, any member of the Purchaser Group, or (ii) is otherwise an
affiliate (as defined in Rule 405 under the Securities Act of 1933, as amended)
of any member of the Purchaser Group.</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:72.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(b)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>&#147;<b><i style="font-weight:bold;">Beneficially Owns</i></b>&#148; (including the
terms &#147;<b><i style="font-weight:bold;">Beneficial Ownership</i></b>&#148;, &#147;<b><i style="font-weight:bold;">Beneficially Owned</i></b>&#148; or &#147;<b><i style="font-weight:bold;">Beneficially Owning</i></b>&#148;) shall mean
beneficial ownership within the meaning of Rule 13d-3 under the Exchange Act.</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:72.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(c)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>&#147;<b><i style="font-weight:bold;">Board</i></b>&#148; shall mean the Board of
Directors of the Company.</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:72.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(d)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>&#147;<b><i style="font-weight:bold;">Effective Time</i></b>&#148; shall mean the time
and date of sale and delivery of the shares of Common Stock by the Company
pursuant to Section 2(b) of the Purchase Agreement.</p>


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<p style="margin:0pt 0pt 12.0pt;text-indent:36.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-indent:72.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(e)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>&#147;<b><i style="font-weight:bold;">Independent Directors</i></b>&#148;
shall mean those directors that the Board has determined to be independent
within the meaning of NASD Marketplace Rule 4200(15) (or any successor rule).</p>

<p style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-indent:72.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(f)</font></b>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; &#147;<b><i style="font-weight:bold;">Purchase Agreement</i></b>&#148; shall mean that
certain Purchase Agreement to be entered into on or about the date hereof by
and between the Company and Merrill Lynch &amp; Co., Merrill Lynch, Pierce,
Fenner &amp; Smith Incorporated and each of the Underwriters named in Schedule
A thereto, with respect to the issue and sale by the Company and the purchase
by the Underwriters, acting severally and not jointly, of the respective
principal amounts set forth in Schedule A thereto of an aggregate of 9,000,000
shares of the Company&#146;s Common Stock.</p>

<p align="left" style="margin:0pt 0pt 12.0pt;text-align:left;text-indent:36.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">2.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Standstill.</font></b></p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:72.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(a)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>For
a period of four years from the Effective Time (the &#147;<b><i style="font-weight:bold;">Standstill
Period</i></b>&#148;), no member of the Purchaser Group or any of their
respective Affiliates shall, without the prior written consent of a majority of
the Independent Directors who are not affiliated with the Purchaser Group, in
any manner acquire, agree or seek to acquire, or make any proposal or offer
(other than to a member of the Board or senior management of the Company by
means that would not cause public dissemination thereof) to acquire, whether
directly or indirectly:</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:108.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(i)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>any
material assets of the Company; or</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:108.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(ii)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>Beneficial
Ownership of any shares of Common Stock, voting equity securities of the
Company or any securities convertible or exchangeable into or exercisable for
any such shares of Common Stock or other securities (including derivatives), in
excess of twenty (20)% of the outstanding Common Stock (the &#147;<b><i style="font-weight:bold;">Permitted Shares</i></b>&#148;).</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:72.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(b)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>For
so long as the Purchaser Group and their Affiliates Beneficially Own more than
ten percent (10%) of the Company&#146;s outstanding Common Stock, no member of the
Purchaser Group or any of their respective Affiliates shall, without the prior
written consent of a majority of the Independent Directors who are not
affiliated with the Purchaser Group:</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:108.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(i)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>propose
to any person (other than to a member of the Board or senior management of the
Company by means that would not cause public dissemination thereof) or effect,
seek to effect or enter into, whether alone or in concert with others, any
merger, tender offer, consolidation, acquisition, scheme, business combination
or other extraordinary transaction in which the Company or any of its
subsidiaries is a constituent corporation or party (a &#147;<b><i style="font-weight:bold;">Business
Combination</i></b>&#148;);</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:108.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(ii)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>solicit
proxies or stockholder consents or participate in any such solicitation for any
purpose relating to the election or removal of directors of the Company;</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:108.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(iii)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>support,
solicit proxies or stockholder consents or participate in any such solicitation
or vote in favor of any Business Combination, or propose to any person or
effect, seek to effect or enter into, whether alone or in concert with others,
any Business Combination, in which the Purchaser Group receives or would be
entitled to receive consideration on a per share basis which is greater than
the consideration to be received on a per share basis by the other holders of
Common Stock;</p>


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<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:108.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(iv)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>form,
join, encourage, influence, advise or participate in a &#147;group&#148; (as defined in
Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the &#147;<b><i style="font-weight:bold;">Exchange Act</i></b>&#148;)) in connection with
any of the foregoing;</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:108.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(v)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font></b>make,
or take any action (including a request to waive or amend any provision of this
agreement) that would cause the Company to make, a public announcement regarding
any intention of the Purchaser Group or any of their respective Affiliates to
take an action which would be prohibited by any of the foregoing.</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:36.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">3.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Waiver of Section 203.</font></b>&#160; The
Company represents and warrants to the Purchaser Group that the Board has taken
all action necessary to approve the acquisition by the Purchaser Group of the
Common Stock in the Offering for the purposes of the provisions of Section 203
of the General Corporation Law of the State of Delaware (&#147;<b><i style="font-weight:bold;">Section
203</i></b>&#148;) solely as it relates to the acquisition by the Purchaser
Group of beneficial ownership of the Common Stock (the &#147;<b><i style="font-weight:bold;">Waiver</i></b>&#148;);
<i>provided</i>, <i>however</i>,
such Waiver provides that, to the fullest extent permitted by law, it shall no
longer be applicable if, subsequent to becoming an &#147;interested stockholder&#148; (as
defined in Section 203), the Purchaser Group no longer has Beneficial Ownership
of fifteen percent (15%) or more of the Common Stock as a result of any sale or
disposition of Beneficial Ownership of Common Stock by the Purchaser Group.</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:36.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">4.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Amendments to Rights Agreement.</font></b>&#160; The
Company represents and warrants to the Purchaser Group that the Rights
Agreement, dated May 6, 2003, amended March 4, 2005, by and between the Company
and Mellon Investor Services LLC, as rights agent (the &#147;<b><i style="font-weight:bold;">Rights
Agreement</i></b>&#148;), shall be duly amended, effective immediately prior
to the Effective Time, to exclude the Purchaser Group from the definition of
the term &#147;Acquiring Person&#148; as such term may relate to the acquisition by the
Purchaser Group (including by &#147;affiliates&#148; and &#147;associates&#148;, as such terms are
defined in Rule 12b-2 under the Exchange Act, of the Purchaser Group) of
Beneficial Ownership of the Permitted Shares described in Section 2(a)(ii)
hereof.&#160; During the Standstill Period, so
long as the Purchaser Group is not in material breach of its obligations under
this Agreement, the Company shall not amend or modify the definition of &#147;Acquiring
Person&#148; in the Rights Agreement, if, as a result of such amendment or
modification, the Purchaser Group would be deemed to be an &#147;Acquiring Person&#148;
thereunder.&#160; During the Standstill
Period, so long as the Purchaser Group is not in material breach of its
obligations under this Agreement, the Company shall not adopt a new rights
agreement or an agreement having substantially the same effect of the Rights
Agreement if the Purchaser Group would be considered an &#147;Acquiring Person&#148; (or
would have the same or substantially similar effect of an &#147;Acquiring Person&#148;
under the Rights Agreement).</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:36.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">5.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Representations.</font></b>&#160; Each
party represents to the other that: (a) this letter agreement has been duly
authorized by all necessary corporate or partnership action, as the case may
be; and (b) this letter agreement is a valid and binding agreement of such
party, enforceable against it in accordance with its terms.</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:36.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">6.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Specific Enforcement; Legal Effect.</font></b>&#160; The
parties hereto agree that any breach of this letter agreement would result in
irreparable injury to other party and that money damages would not be an
adequate remedy for such breach.&#160; Accordingly,
without prejudice to the rights and remedies otherwise available under
applicable law, either party shall be entitled to specific performance and
equitable relief by way of injunction or otherwise if the other party breaches
or threatens to breach any of the provisions of this letter agreement.&#160; It is further understood and agreed that no
failure or delay by</p>


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<p align="left" style="margin:0pt 0pt 12.0pt;text-align:left;text-indent:36.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="left" style="margin:0pt 0pt 12.0pt;text-align:left;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">either party in exercising any right, power or privilege hereunder
shall operate as a waiver thereof, nor shall any single or partial exercise
thereof preclude any other or further exercise thereof or the exercise of any
right, power or privilege hereunder.&#160; If
any term, provision, covenant or restriction in this letter agreement is held
by a court of competent jurisdiction to be invalid, void or unenforceable, the
remainder of the terms, provisions, covenants and restrictions of this letter
agreement shall remain in full force and effect and shall in no way be
affected, impaired or invalidated, provided that the parties hereto shall
negotiate in good faith to attempt to place the parties in the same position as
they would have been in had such provision not been held to be invalid, void or
unenforceable.&#160; This letter agreement
contains the entire agreement between the parties hereto concerning the matters
addressed herein.&#160; No modification of
this letter agreement or waiver of the terms and conditions hereof shall be
binding upon either party hereto, unless approved in writing by each such
party; <i>provided</i>, <i>however</i>,
that no waiver or amendment shall be effective as against the Company unless
such waiver or amendment is approved in writing by the vote a majority of the
independent members of the Board who are not affiliated with the Purchaser
Group.&#160; This Agreement shall be governed
by and construed in accordance with the law of the State of Delaware without
regard to principles of conflicts of law that would cause the application of
the laws of any jurisdiction other than the State of Delaware.</font></p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:36.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">7.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Termination</font></b>.&#160; This agreement shall continue
in full force and effect from the Effective Time until such time as the
Purchaser Group and their Affiliates Beneficially Own less than ten percent
(10%) of the Company&#146;s outstanding Common Stock; <i>provided,
however, that</i> if (i) the Purchase Agreement is not executed
within thirty (30) days from the date of this agreement, or (ii) the Purchase
Agreement terminates or is terminated prior to the payment for and delivery of
the shares for sale thereunder, this agreement shall terminate immediately upon
such date and be of no further force and effect.</p>

<p align="left" style="font-family:Times New Roman;font-size:10.0pt;margin:0pt 0pt 12.0pt;text-align:left;text-indent:36.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">8.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Counterparts.</font></b>&#160; This letter agreement may be
executed in counterpart (including by facsimile), each of which shall be deemed
an original.</p>

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<p style="margin:0pt 0pt 12.0pt;text-indent:72.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">If you are in
agreement with the terms set forth above, please sign this letter agreement in
the space provided below and return an executed copy to the undersigned.</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Very truly yours,</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">BAKER
BROS. INVESTMENTS, L.P.</font></b></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; Baker Bros. Capital, L.P.,</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; Baker Bros. Capital (GP), LLC,</font></p>

<p style="margin:0pt 0pt 12.0pt 144.0pt;text-indent:72.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:<u>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; /s/ Julian Baker&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </u></font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Name:
Julian Baker</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Title:&#160;&#160; Managing Member</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">BAKER
BROS. INVESTMENTS II, L.P.</font></b></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; Baker Bros. Capital, L.P.,</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; Baker Bros. Capital (GP), LLC,</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:<u>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; /s/ Julian Baker&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </u></font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Name:
Julian Baker</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Title:&#160;&#160; Managing Member</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">BAKER /
TISCH INVESTMENTS, L.P.</font></b></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; Baker / Tisch Capital, L.P.,</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; Baker / Tisch Capital (GP), LLC,</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:<u>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; /s/ Julian Baker&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </u></font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Name:
Julian Baker</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Title:&#160; Managing Member</font></p>


 <p style="font-size:10.0pt;margin:24.0pt 0pt .0001pt;text-align:center;"><font face="Times New Roman">5</font></p> <br><hr size="3" width="100%" noshade color="#010101" align="center">

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<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="3" face="Times New Roman">&nbsp;</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">BAKER
BIOTECH FUND I, L.P.</font></b></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; Baker Biotech Capital, L.P.,</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; Baker Biotech Capital (GP), LLC,</font></p>

<p style="margin:0pt 0pt 12.0pt 144.0pt;text-indent:72.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:<u>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; /s/ Julian Baker&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </u></font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Name:
Julian Baker</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Title:&#160;&#160; Managing Member</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">14159,
L.P.</font></b></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; 14159 Capital, L.P.,</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; 14159 Capital (GP), LLC,</font></p>

<p style="margin:0pt 0pt 12.0pt 144.0pt;text-indent:72.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:<u>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; /s/ Julian Baker&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </u></font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Name:&#160; Julian Baker</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Title:&#160;&#160; Managing Member</font></p>

<p style="margin:0pt 0pt 12.0pt 144.0pt;text-indent:72.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">BAKER
BROTHERS LIFE SCIENCES, L.P.</font></b></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; Baker Brothers Life Sciences Capital, L.P.,</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160; Baker Brothers Life Sciences Capital (GP),</font></p>

<p style="margin:0pt 0pt 12.0pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">LLC, its general partner</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:<u>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; /s/ Julian Baker&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </u></font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Name:&#160; Julian Baker</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Title:&#160;&#160; Managing Member</font></p>

<p style="margin:0pt 0pt .0001pt;text-indent:216.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0pt 0pt 12.0pt;page-break-after:avoid;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Confirmed and Agreed:</font></p>

<p style="margin:0pt 0pt 12.0pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">ALLOS THERAPEUTICS, INC.</font></b></p>

<p style="margin:0pt 0pt .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:&#160;&#160; <u>/s/
Marc H. Graboyes&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </u></font></p>

<p style="margin:0pt 0pt .0001pt;page-break-after:avoid;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Name:&#160;&#160;&#160;&#160; Marc H.
Graboyes</font></p>

<p style="margin:0pt 0pt 12.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Title: &#160;&#160;&#160;&#160;&#160; Vice President, General Counsel</font></p>

<p style="margin:0pt 0pt 12.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>


 <p style="font-size:10.0pt;margin:24.0pt 0pt .0001pt;text-align:center;"><font face="Times New Roman">6</font></p>
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