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                                                                    Exhibit 10.1
                                                                    ------------
                                AMENDMENT NO. 2


                       License and Development Agreement

                                    Between

                          Aronex Pharmaceuticals, Inc.

                                      and

                              Genzyme Corporation


 This is Amendment No. 2 to the License and Development Agreement between Aronex
Pharmaceuticals, Inc., as successor to Argus Pharmaceuticals, Inc., and Genzyme
Corporation dated September 10, 1993 (the "Development Agreement").

 WHEREAS, the parties have been operating under the Development Agreement and
have discovered in the course of their collaboration that it would be desirable
to make several changes to the Development Agreement to improve efficiency and
clarity; and

 WHEREAS, Aronex desires to transfer responsibility for manufacturing and
quality control of AR-623 to Genzyme and Genzyme wishes to assume such
responsibility; and

 WHEREAS, the parties wish to make certain additional amendments to the Stock
Purchase Agreement between the parties dated September 10, 1993.

 NOW THEREFORE, in consideration of the foregoing, the parties agree to the
following amendments to the Development Agreement:

1.  Section 3.2(c) is hereby modified by adding the following to the end of the
section:

          The Work Plan and Budget for 1997 will include the transfer of
responsibility for the manufacturing, process development, quality control and
stability of AR-623 from Aronex to Genzyme by the end of 1997.

2.  Section 4.2(a) is hereby replaced in its entirety with the following:

          (a)  Myelogenous Leukemia Indications.  Aronex shall be responsible
for funding all commercially reasonable Development Costs in the United States
for Myelogenous Leukemia indications of the Product, except that Genzyme will be
responsible for funding: (x) all such costs incurred after January 1, 1996 and
(y) all expenses incurred by Aronex pursuant to Section 4.2(b)(i) after January
1, 1996, which together exceed $5,350,000, subject to compliance to Section
3.2(c);
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3.  Section 4.2(b)(ii) is hereby replaced in its entirety with the following:

          (ii)  Pivotal/Regulatory.  If the Project Representatives agree to the
filing of a protocol for a Pivotal Clinical Trial of the Product for a non-
hematologic indication, Genzyme shall fund all commercially reasonable
Development Costs relating to Pivotal Clinical Trials and NDA filing for that
indication.  If the Project Representatives agree that such a filing should not
be made, Genzyme will reimburse Aronex for all Development Costs in connection
with the non-hematologic indication incurred by Aronex after June 1, 1996
pursuant to Section 4.2(b)(i) above.


 IN WITNESS WHEREOF, the parties hereto have caused this Amendment No. 2 to be
duly executed and delivered a of the last date below.

                                 ARONEX PHARMACEUTICALS, INC.



                                 /s/ James Chubb                    9/10/96
                                 -----------------------------   -----------  
                                 By: James M. Chubb, Ph.D.            Date
                                 Title: President

                                 GENZYME CORPORATION



                                 /s/ Richard Douglas                 9/10/96
                                 ------------------------------  ------------
                                 By:  Richard H. Douglas, Ph.D.        Date
                                 Title: Vice-President,
                                           Corporate Development