Exhibit 10.13.1

[*] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE
COMMISSION PURSUANT TO RULE 24B-2 OF THE SECURITIES ACT OF 1934, AS AMENDED.

SECOND AMENDMENT TO
LICENSE AGREEMENT

        This SECOND AMENDMENT TO LICENSE AGREEMENT (this "Second Amendment"),
dated as of November 6 2007, is entered into between SRI INTERNATIONAL, a
California not-for-profit corporation ("SRI"), SLOAN-KETTERING INSTITUTE FOR
CANCER RESEARCH, a New York not-for-profit corporation ("SKI"), SOUTHERN
RESEARCH INSTITUTE, an Alabama not-for-profit corporation ("SoRI" and, together
with SRI and SKI, the "Licensor"), and ALLOS THERAPEUTICS, INC., a Delaware
corporation ("Allos"). Allos and Licensor are each sometimes individually
referred to herein as a "Party" and collectively as the "Parties."

WITNESSETH

        WHEREAS, the Parties entered into that certain License Agreement dated
as of December 23, 2002 (the "Original Agreement"), pursuant to which Allos
obtained from Licensor an exclusive license to certain patent rights and
know-how relating to a proprietary compound known as PDX in exchange for certain
rights and consideration provided to Licensor;

        WHEREAS, the Parties entered into a First Amendment to the Original
Agreement dated as of May 9, 2006 (the "First Amendment") (the Original
Agreement and First Amendment are sometimes collectively referred to herein as
the "License Agreement");

        WHEREAS, the Parties now desire to further amend the License Agreement
to modify the terms and conditions relating to certain payments payable to
Licensor thereunder;

        NOW, THEREFORE, in consideration of the foregoing premises and for other
good and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the Parties hereby agree as follows:

AGREEMENT

        1.     All capitalized terms used but not defined herein shall have the
meanings assigned to them in the License Agreement.

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        2.     Section 3.3 of the License Agreement is hereby deleted in its
entirety and replaced with the following:

        3.3    Milestone Payments.    Allos shall pay Licensor the following
one-time milestone payments within [*] of the date of achieving each milestone:

Milestone
  Amount  

1. The earlier of: (a) enrollment of the first patient in a multi-center,
Allos-sponsored Phase II Trial; or (b) eighteen (18) months from the Effective
Date. 

  $ 1,000,000 (Paid)  

2. The earlier of: (a) enrollment of the first patient in an Allos-sponsored
Registration Trial (as defined below); or (b) four (4) years from the Effective
Date, payable at the rate of $500,000 per year until enrollment of the first
patient in an Allos-sponsored Registration Trial, at which time the balance
shall be paid in full. 

 
$
2,000,000 ($500,000 Paid)  

3. FDA acceptance of NDA for review. 

 
$
1,500,000  

4. US FDA approval for sale of Product. 

 
$
5,300,000  

5. EU Approval for sale of Product. 

 
$
3,500,000  

Licensor acknowledges and agrees that, as of the date of this Second Amendment,
Allos has fully paid Milestone 1 above and has paid $500,000 of Milestone 2
above.

For purposes of this Section 3.3, a "Registration Trial" shall mean any clinical
trial that is reasonably expected to form the primary basis of an efficacy claim
in support of the submission of an NDA (whether it is a Phase II, Phase III or
Phase II/III Trial) for an indication with an estimated U.S. prevalence over
250,000.

Each milestone payment set forth in this Section 3.3 shall be payable by Allos
only once; provided, however, in the event that any Product receives U.S. FDA
Approval for sale triggering Milestone 4 without having previously triggered
payment of Milestones 2 and 3, each of the amounts for Milestones 2 and 3 shall
be due and payable with and in addition to Milestone 4.

        3.     Licensor hereby represents and warrants to Allos that: (a) it has
taken all necessary corporate action to authorize the execution and delivery of
this Second Amendment; and (b) this Second Amendment has been duly executed and
delivered on behalf of Licensor, and constitutes a legal, valid, binding
obligation, enforceable against Licensor in accordance with its terms.

        4.     This Second Amendment shall be made part of the Agreement and be
governed by all its terms.

        5.     This Second Amendment may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

        6.     This Second Amendment shall be effective upon its execution by
each of SRI, SKI, SoRl and Allos.

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        IN WITNESS WHEREOF, the parties have caused this Second Amendment to be
executed by their duly authorized representatives as of the date first set forth
above.

SRI INTERNATIONAL
 
ALLOS THERAPEUTICS, INC.
By:
 
/s/ JOHN MCINTIRE

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By:
 
/s/ MARC H. GRABOYES

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Name:   John McIntire   Name:   Marc H. Graboyes Title:   Deputy General Counsel
  Title:   Vice President, General Counsel
SLOAN-KETTERING INSTITUTE FOR CANCER RESEARCH
 
SOUTHERN RESEARCH INSTITUTE
By:
 
/s/ GUSTAVE BERNHARDT

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By:
 
/s/ DAVID W. MASON

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    Gustave J. Bernhardt   Name:   David W. Mason Title:   Director, Research
Resources Management   Title:   Director CIP

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