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                                                                   EXHIBIT 10.40


June 30, 2000



Seenu V.Srinivasan, Ph.D.
5806 Trailridge
Parkville, MO  64152-6065


Dear Seenu:

I am pleased to present for your consideration the following proposal to join
Aronex Pharmaceuticals, Inc. as Vice President, Pharmaceutical Development and
Operations. In this position, you will report directly to me and you will be a
member of the Executive Committee. A starting date of August 7, 2000 is
anticipated.

Compensation for the position would include the following:

         Base Salary:      $170,000 annually, paid in accordance with normal
                           payroll practices.

         Stock Options:    You will be granted an option to purchase 60,000
                           shares of Aronex Pharmaceuticals, Inc. Common Stock
                           under Aronex Pharmaceuticals, Inc. 1998 Stock Option
                           Plan, subject to formal approval of the Board of
                           Directors. The exercise price of the options will be
                           equal to the fair market value of Aronex
                           Pharmaceuticals, Inc. Common Stock on the date of
                           grant. The options shall vest at the rate of 25% per
                           year on your anniversary date.

         Bonus:            The final amount of each annual bonus shall be
                           discretionary. To the extent a bonus is payable, the
                           target annual bonus of 20% of base salary, may be
                           paid in cash, stock grants and/or stock options,
                           dependent upon you meeting both personal and Company
                           goals and Board approval. This bonus will be prorated
                           and guaranteed for the year ending December 31, 2000.

         Benefits:         Benefits will include medical, dental, life, long and
                           short term disability, and AD&D. Insurance on the
                           same basis as is made available to other similar
                           Aronex Pharmaceuticals, Inc. employees. You will


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                           also be entitled to four (4) weeks paid vacation per
                           year. (See attached benefits summary)

         Relocation:       You will be reimbursed for reasonable expenses
                           incurred in one house hunting trip for you and your
                           family to select new housing. You will also be
                           reimbursed for reasonable moving costs of personal
                           property and closing costs associated with the
                           purchase of a new home in the Houston area and cost
                           associated with selling your home in Kansas City. Six
                           months of interim housing will be provided if needed
                           and will be re-evaluated at the end of six months
                           should this become necessary. Aronex will also pay up
                           to $5,000. for storage of personal property if
                           needed. Aronex will provide for grossing up
                           relocation costs for tax purposes.

         Term/Severance:   Subject to the severance payments provided herein,
                           your employment is "at-will," which means either you
                           or Aronex Pharmaceuticals, Inc. may terminate the
                           employment relationship at any time, with or without
                           "Cause" (as herein defined).

                           If your employment is terminated by Aronex
                           Pharmaceuticals, Inc. without Cause or in connection
                           with a "Change of Control" (as herein defined), you
                           will be entitled to a salary continuation benefit
                           equal to your then base salary and benefits for a
                           period of 12 months following the date of
                           termination. Such payments will be made in accordance
                           with Aronex Pharmaceuticals, Inc. normal payroll
                           practices.

                           For purposes hereof, "Cause" shall mean (i) repeated
                           failure, neglect or refusal to perform your duties,
                           (ii) gross negligence or willful or intentional
                           wrongdoing or misconduct, (iii) a breach of the
                           Proprietary Information and Inventions and
                           Non-Competition Agreement or other confidentiality
                           agreement with Aronex Pharmaceuticals, Inc., or (iv)
                           the conviction of a felony or any crime involving
                           moral turpitude.

                           For purposes hereof, a "Change of Control" shall
                           include:

                           (i)      the acquisition by any third party or group
                                    of 50% or more of Aronex Pharmaceuticals,
                                    Inc.


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                                    Common Stock or combined voting securities
                                    provided that an acquisition directly from
                                    Aronex Pharmaceuticals, Inc., an acquisition
                                    by Aronex Pharmaceuticals, Inc. or an
                                    acquisition by an employee benefit plan of
                                    Aronex Pharmaceuticals, Inc. shall not cause
                                    a Change in Control; or

                                    (ii) The consummation of a merger,
                                    consolidation, reorganization or sale of all
                                    or substantially all of Aronex
                                    Pharmaceuticals, Inc. assets unless
                                    following such transaction (a) the holders
                                    of Aronex Pharmaceuticals, Inc. Common Stock
                                    and other voting securities continue to own
                                    more than 50% of common stock and other
                                    voting securities of the entity surviving
                                    such transaction (including, without
                                    limitation, a corporation which owns all or
                                    substantially all of Aronex Pharmaceuticals,
                                    Inc. assets) in substantially the same
                                    proportion of their prior ownership, and (b)
                                    at least a majority of the directors of the
                                    surviving corporation were directors of
                                    Aronex Pharmaceuticals, Inc. at the time the
                                    transaction was originally approved.


I believe this package is very reasonable and reflects the importance of the
position and the value we perceive you will bring to Aronex Pharmaceuticals,
Inc.

I hope you find this proposal acceptable, and if the terms are acceptable,
please sign this letter agreement in the space provided below and return it to
me. I look forward to you joining Aronex Pharmaceuticals, Inc. as early as
possible.

Best regards,



Geoffrey F. Cox, Ph.D.
Chairman and CEO

Accepted and agreed upon this  day of August 16th,
2000 by

/s/ Seenu V. Srinivasan.
Seenu V. Srinivasan