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                                                                EXHIBIT 10.27







                         [ALANEX CORPORATION LETTERHEAD]


July 17, 1996


Marvin R. Brown, M.D.
Alanex Corporation
3550 General Atomics Court
San Diego, California  92121

Dear Dr. Brown:

This letter will serve to memorialize our agreement regarding the payment of
severance benefits in the event of termination without cause at any time during
the period of your employment with Alanex Corporation (the "Company").

The Company agrees that if your employment with the Company is terminated
without cause, you shall be entitled to continuation of your base salary for a
period of three hundred and sixty-five (365) days from the date of your
termination, with such base salary continuation to be at the rate of your
current base salary in effect as of the date of termination. In the event,
however, that your employment with the Company is terminated for cause, you
shall be entitled to receive only your accrued base salary and other accrued
benefits required by law to be paid to you, prorated to the date of termination.
For purposes of this letter, "for cause" termination shall be limited to the
following: (1) engaging in or in any way participating in any activity which is
competitive with or intentionally injurious to the Company or which violates any
provisions of the Proprietary Information and Inventions Agreement signed by you
and the Company; (2) the commission of any fraud against the Company or use or
appropriation for your personal use or benefit any funds or properties of the
Company not so authorized by the Board of Directors; (3) the conviction of a
crime involving dishonesty or moral turpitude; or (4) conduct which in good
faith and reasonable determination of the Board of Directors demonstrates gross
unfitness to serve in your position.

Notwithstanding the above agreement, the employment relationship between you and
the Company continues to be at-will. As such, you may terminate your employment
with the Company at any time and for any reason whatsoever simply by notifying
the Company of your intent to do so. In the event that you terminate the
employment relationship with the Company for any reasons whatsoever, you will
not be entitled to any severance payment provided for hereunder. Likewise, the
Company may terminate your employment at any 
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Marvin R. Brown, M.D.
July 17, 1996
Page Two

time and for any reason whatsoever, with or without cause or advance notice.
This at-will employment relationship cannot be changed except in a writing
signed by an authorized officer of the Company.

Very truly yours,

ALANEX CORPORATION


By:      /s/ Michelle A. Youngers
- --------------------------------------
Name:      Michelle A. Youngers
Title:     Director of Finance



ACCEPTED BY:



/s/ Marvin R. Brown
- --------------------------------------
Marvin R. Brown, M.D.

Dated:     July 17, 1996