Exhibit 10.16

                                     [LOGO]

SCRIPTGEN

                                                                   June 19, 1997

Mr. Mark T. Weedon
23 Boulters Gardens
Maidenhead Berkshire
United Kingdom SL6 8TR
1628-33230

Dear Mark:

On behalf of the Board of Directors of Scriptgen Pharmaceuticals, I am pleased
to extend the following offer of employment to you:

Position:         President and CEO reporting to Board of Directors; a member of
                  the Board of Directors.

Start Date:       Promptly after your receipt of H1B Visa from U.S. Immigration.
                  Anticipate that you will receive U.S. Visa between July 14 to
                  July 21, 1997, and that you will commence to perform your
                  duties as President and CEO promptly after receipt of U.S.
                  Visa.

Term:             Employment may be terminated by either party upon thirty (30)
                  days notice.

Initial Stock:    Options to purchase 5% (approximately 1,044,000 shares of
                  common stock) of the Company's fully diluted capitalization at
                  a price of $.05 per share, The options will vest over a four
                  (4) year period at a rate of 1/48 of the total each month,
                  Each option will be exercisable at any time from and after
                  date of vesting. Eligible for additional option grants in the
                  future as determined by the Board of directors. All options
                  vest if Company is sold for a price of at least $5.00 per
                  share based on the Company's current capitalization. All
                  vested stock options will remain


                  exercisable by you during a period of one (1) year
                  following termination.

Salary:           $230,000 annually, to be reviewed at end of first year.

Bonus:            Guaranteed $25,000 payable no later than first anniversary.
                  Additional $25,000 if Company completes an IP0 before first
                  anniversary.

Expenses:         All expenses incurred on behalf of the Company, including
                  expenses for business travel, as well as a house hunting trip
                  for your spouse, up to ninety (90) days of reasonable
                  temporary living expenses, and relocation, will be reimbursed
                  by the Company. In addition, the Company will reimburse you
                  for up to a maximum of $5,000 for costs and expenses
                  (including legal fees and disbursements) incurred by you in
                  connection with your efforts to effectuate and complete this
                  employment agreement and all related employment arrangements
                  with the Company.

Benefits:         Current Scriptgen benefits package. The Board would be willing
                  to consider recommended changes to current package.

Severance:        Nine (9) months of salary and benefits while remaining
                  unemployed if terminated without cause in the first year of
                  employment, six months if terminated thus in the second year,
                  and four months thereafter.

Other:            You will sign Scriptgen's standard employee invention and
                  non-disclosure agreement. You will also enter into a one (1)
                  year non-competition agreement. upon the terms contained in
                  the Company's Agreement for Science Employees.


Public
Announcement      We and you agree that no public announcements concerning this
                  Letter of Agreement or the employment arrangements
                  contemplated hereby will be made, and that every reasonable
                  effort will be made by us and by you to preserve the privacy
                  and confidentiality of this Letter of Agreement and the
                  related employment arrangements, until you have received your
                  U.S. H1B Visa or until such earlier date as may be mutually
                  agreed by us and you.

We acknowledge that, promptly upon your acceptance of this Letter of Agreement
and in reliance upon our offer of employment, you will take immediate steps to
terminate your employment with your present employer, Glaxo Wellcome.

If you are in agreement with the forgoing Letter of Agreement, please sign the
form of acceptance and return a signed counterpart of this Letter of Agreement
to us, whereupon this Letter of Agreement and all provisions thereof shall,
effective as of the date hereof, become a legally binding agreement of
employment between Scriptgen Pharmaceuticals, Inc. and you.

Sincerely yours,


      /s/ Barry Weinberg

By:   Barry Weinberg
      Chairman of the Board

The foregoing Letter of Agreement is hereby accepted and agreed to by the
undersigned, and the undersigned agrees to be bound, effective as of the date of
the foregoing Letter of Agreement, by all of the terms thereof.


/s/ Mark T. Weedon                  Date: June 24, 1997
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Mark T. Weedon