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                                                                    EXHIBIT 10.4


March 12, 1997


FAX #:  609/683-8916

David S. Gordon, M.D.
22 Florence Lane
Princeton, NJ  08540

Dear David:

I am extremely pleased that you have agreed to join Aronex.  The Company is at a
very exciting period in its evolution and your involvement will surely add
significant value.

As agreed, I am pleased to offer you the position of Senior Vice President of
Medical Affairs and Chief Medical Officer. In this position, you will report
directly to me.  Your primary responsibility will be to develop and validate the
Company's clinical Development strategy, as well as assure that the strategic
plans and time lines are effectively executed.  You will be responsible for
assuring the clinical data are published in a timely manner and you will be
responsible for securing expert clinical advocates for the company's products.
You will also assist in identifying and will be responsible for evaluating and
recommending a clinical course of action for potential development candidates.
You will be the chief medical spokesman for the Company and be responsible for
presenting the Company's clinical strategy and direction to the pharmaceutical,
financial and regulatory communities.  The Company, its Board of Directors, and
its consultants will provide total support to you in fulfilling this role.  You
will be responsible for the departments and personnel in Regulatory, Clinical
Research, and Statistical Services/Data Management.  The organization and
necessary hiring to build a cohesive, competent team with capabilities of
progressing at least three products through clinical development simultaneously
will be your responsibility.

You will be an officer of the Company and a member of the Company's Executive
Committee consisting of the following department heads:  Preclinical Research,
Pharmaceutical Development, Clinical Research, Regulatory, Finance and Business
Development.  This Committee is responsible for developing the Company's short
and long term strategy, and defining the Company's budget.  An official starting
date of March 24 is acceptable.  However, since you will be out of the country
through the first three weeks of April, payment of your salary and benefits will
not commence until April 28, 1997.

Compensation for this position includes the following:

     Base Salary:  $213,000 annually.  Annual salary adjustments as determined
                   by the Compensation Committee based upon performance.

     Stock
     Options:      One hundred twenty-five (125,000) options at fair market
                   value. Twenty-five thousand (25,000) will vest upon joining
                   Aronex on April 28, 1997. The balance will vest over four
                   years at a rate of 1/48 per month. You will have a two year
                   period from the time you leave the Company to exercise vested
                   options.

     Bonus:        A target annual bonus of up to 20% set by the Compensation
                   Committee of the Board of Directors will be paid annually.
                   The bonus will be paid as a percentage of salary in cash,
                   stock grants/or stock options, dependent upon meeting Company
                   and department goals.

     Benefits:     Benefits include medical, dental, disability, 401K Plan,
                   Stock Purchase Plan, Medical Benefits Cafeteria Plan, term
                   life insurance equal to one times your annual salary, three
                   weeks vacation, and all the other Company benefits defined in
                   the Company's Benefit Manual. These documents have been sent
                   under separate cover.
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David S. Gordon, M.D.
March 12, 1997
Page 2


                   In addition, the Company will provide a full membership to
                   The Woodlands Country Club. You will be personally
                   responsible for the monthly Country Club fees and any charges
                   you incur.

     Relocation:   Up to a maximum of $1,750/month for 12 months from the date
                   of joining Aronex to cover rental cost for housing in Houston
                   or for mortgage payments on a house purchased in Houston.
                   Costs related to real estate commissions and closing costs of
                   your current house, closing costs on your new home, and
                   moving costs of personal property, including up to two
                   automobiles will be covered. Personal property may be moved
                   in partial shipments, if necessary, to furnish your Houston
                   home or provide transportation.

                   We recognize the issues you have concerning the relocation to
                   Houston. To ameliorate those issues to a major extent, we are
                   willing to pay, as indicated, above $1,750/month of your
                   rental or mortgage costs for the first 12 months after you
                   join Aronex. We would hope that within one year, you would
                   make Houston your primary residence. If circumstances are
                   such that this cannot be done in one year, Company bonuses
                   and annual increases should attenuate the housing expense
                   post 12 months. We are also willing for you to manage your
                   time so that you can be in New Jersey to conduct business as
                   is appropriate. At the same time, we expect you to devote
                   whatever time is required in Houston to manage the Clinical
                   Affairs program, provide strategic direction and represent
                   the Company as needed. The need to balance your requirements
                   with Aronex and your personal obligations will, undoubtedly,
                   be a challenge. I believe we should strive for this balance
                   to appear seamless by the Company and the team that will be
                   reporting to you.

                   We are also prepared for your continued Board involvement on
                   the Hycor Board and, if appropriate, joining one other Board.
                   We also would encourage you to obtain a clinical appointment
                   at M.D. Anderson Cancer Center. We believe the interaction
                   you will have in such an association will be valuable to
                   Aronex.

     Employment
     Agreement:    A one year severance package of base salary and benefits if
                   you are terminated not for cause.

We are delighted you will be joining us and look forward to an exciting and
rewarding venture.  For our administrative records, please sign and return the
attached copy by mail marked "Confidential."

Best regards,

/s/  James M. Chubb

James M. Chubb, Ph.D.
President

JMC/cc

Accepted and agreed upon this 28th day of March, 1997.



                                    /s/ David S. Gordon, M.D.
                                    -------------------------
                                    David S. Gordon, M.D.