Exhibit 10.18.1  
 [
* ] = 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.  2.Section 3.3 of the License Agreement
is hereby deleted in its entirety and replaced with the following:  3.3Milestone Payments. 
Allos shall pay Licensor the following one-time milestone payments
within [ * ] of the date of achieving each milestone:  1


Milestone
  
  Amount[ * ]
  
  [ * ]  Licensor
acknowledges and agrees that, as of the date of this Second Amendment, Allos
has fully paid [ * ].  For
purposes of this Section 3.3, a [ * ] shall mean [ * ].  Each
milestone payment set forth in this Section 3.3 shall be payable by Allos
only once; provided, however, in
the event that [ * ].  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.  2


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
  
  By:
  /s/ Marc H. GraboyesName:
  John McIntire
  
  Name:
  Marc H. GraboyesTitle:
  Deputy General Counsel
  
  Title:
  Vice President, General CounselSLOAN-KETTERING INSTITUTE FOR
  CANCER RESEARCH
  SOUTHERN RESEARCH INSTITUTEBy:
  /s/ Gustave Bernhardt
  
  By:
  /s/ David W. MasonName:
  Gustave J. Bernhardt
  
  Name:
  David W. MasonTitle:
  Director, Research Resources Management
  
  Title:
  Director CIP  3