March 13, 1995

Immunomedics, Inc.
300 American Road
Morris Plains, New Jersey 07950

Gentlemen:

        Reference is hereby made to a certain Amended and Restated
License Agreement dated December 11, 1990 (the "Agreement")
by and between the Center for Molecular Medicine and
Immunology, Inc. (the "Center") and Immunomedics, Inc.
("Immunomedics"), made to amend and restate in its entirety
a certain agreement by and among the Center, Immunomedics
and David M. Goldenberg, Sc.D., M.D., dated May 1983. Terms
defined in the Agreement, but not defined herein, shall,
when used herein, have the meanings ascribed to them in the
Agreement.

     l. This will confirm our understanding that the
Agreement is hereby amended to provide that Immunomedics
will not use or exploit any technology or rights obtained
under the Agreement for any fee other than a fee which (1)
represents a fair market price for the use of such
technology or rights and (2) is determined at the time the
license of such technology or rights is entered into.
Subject to the foregoing: (a) the first sentence of
paragraph 2.1 of the Agreement is hereby amended to provide
that, except for products developed under a third-party
proposal as set out in paragraph 2.8 of the Agreement,
whenever the Center has developed a Product, the Center
promptly thereafter shall submit a Proposal (as defined in
the Agreement as a "Research and Development Proposal")
regarding said Product to the Immunomedics Liaison; and (b)
paragraphs 3 and 4 of the Agreement are hereby amended to
provide that all Patents and Know-How shall be the property
of the Center, subject to the rights granted to Immunomedics
under the Agreement (as amended by this letter agreement),
and that the Center grants to Immunomedics, for a period of
one-hundred eighty (180) days after submission by the Center
of a Proposal, the first right and option to negotiate, in
good faith, the terms of an exclusive or non-exclusive (as
shall be determined by Immunomedics) worldwide
commercialization license (with the right to sublicense)
with respect to the Patents and Know-How covered by the
Proposal, commercially reasonable under the circumstances
and fairly reflecting the risks incurred by Immunomedics and
the costs of subsequent research and development needed to
bring the Product to the marketplace. The license will
specify the licensed fields of use, breadth of exclusivity,
and royalties payable by the licensee. Royalty rates will
also be based on Product sales and the prevailing rates
conventionally granted in the field identified in the
Proposal for Products with reasonably similar commercial


potential, based primarily on the royalties payable by
unrelated third parties and Immunomedics for the same (or
comparable) rights to and licenses of the same (or
comparable) technology to independent third parties under
similar circumstances considering all relevant facts,
adjusted to account for material differences in contractual
terms and economic conditions in which transactions
occurred. Royalty rates will be negotiated at the time the
license is entered into. Royalty rates for exclusive
commercialization licenses for Patents and Know-How
generally will not exceed a rate within the following
ranges: for Products resulting from technology developed by
the Center after May 1983 and prior to December 11, 1990 -
1.1-2.3 percent; and for Products resulting from technology
developed by the Center on or after December 11, 1990,
including new Products emerging from a new technology
developed and submitted as a Proposal by the Center
subsequent to the date of this letter agreement - 2.2-4.6
percent. Contingent royalty schemes based on, e.g. patent
issuance or nonissuance, and provisions treating the
stacking of royalties or packaging of other licensed Patents
and Know-How developed under the Proposal or licensed from
the Center may be provided. Any such license will reserve
unto the Center the royalty-free right to use such licensed
Patents and Know-How for research and academic purposes on a
non-commercial basis. In the event a license is not entered
into by the Center and Immunomedics within such 180-day
period, or Immunomedics earlier notifies the Center in
writing that it does not desire to obtain a license, the
Center may thereafter, if it shall have complied with the
provisions of the Agreement, offer to and grant one or more
licenses or other rights in the Patents and Know-How covered
by the Proposal to others without any further obligation to
Immunomedics; provided that the Center shall not offer
substantially the same submission to a third party on terms,
considered as a whole, more favorable than those terms last
offered to Immunomedics without first offering such other
terms to Immunomedics for sixty (60) days.

     2. Immunomedics and the Center acknowledge that any
such licensed Patents and Know-How or a portion thereof is
likely to have been or to be developed with financial or
other assistance from the United States of America, and that
applicable statutes, regulations and Executive Orders of the
United States of America, as well as published guidelines
and considerations for recipients of grants and contracts
from the National Institutes of Health and other federal
departments and agencies, may control, apply or affect the
right of Immunomedics to receive any Proposal, any license
granted under such license agreement or any sublicense
thereof, and notwithstanding anything contained herein to
the contrary, the rights and obligations of the parties
under the Agreement are subject to compliance therewith to
the extent controlling, applicable or affecting the rights


and obligations of the parties. This paragraph shall not be
deemed to be a waiver by Immunomedics of any right it may
have to contest with the appropriate governmental authority
the validity of any statutes, regulations, Executive Orders,
guidelines and considerations or their applicability to all
or any part of the Agreement as amended by this letter
agreement.

     3. In addition, paragraph 8.1 of the Agreement is
hereby amended in its entirety to provide that the Agreement
shall continue in full force and effect until December 31,
1999, unless sooner terminated as provided in the Agreement;
provided, that if during the five-year term ending December
31, 1999 (I) the Center shall file a patent application or
(ii) a written invention disclosure or notice of invention
shall be filed by or with the Center or a principal
investigator of the Center, with respect to technology
covered by the Agreement (except for technology developed
under a third-party proposal as set out in paragraph 2.8 of
the Agreement), then subject to the submission by the Center
of a Proposal, during the five years commencing upon the
date of such filing, the rights of Immunomedics under the
Agreement with respect to such technology shall be as
follows:

     (a) The Center shall promptly after such filing submit
a licensing proposal to Immunomedics with respect to such
technology (which shall be deemed to be a "Proposal" under
the Agreement) and thereupon Immunomedics shall have the
first right and option, for a period of one-hundred eighty
(180) days after submission by the Center, to negotiate a
license of such technology, upon the terms and conditions
set forth in paragraph 1 above; and

     (b) In the event a license is not entered into by the
Center and Immunomedics within such 180-day period, or
Immunomedics earlier notifies the Center in writing that it
does not desire to obtain a license, the Center may
thereafter offer to and grant one or more licenses or other
rights in the technology covered by such (deemed) Proposal
to others without any further obligation to Immunomedics;
provided that, until the expiration of five years after such
filing, the Center shall not offer substantially the same
submission to a third party on terms, considered as a whole,
more favorable than those terms last offered to Immunomedics
without first offering such other terms to Immunomedics for
sixty (60) days.

At least ninety days and not more than one hundred eighty
days prior to the expiration of the initial term of the
Agreement (without considering any rights set forth in
clauses (a) and (b) above), Immunomedics may give to the
Center written notice of its desire to renew the Agreement
for an additional five-year period. In such event, the


Center and Immunomedics will, during the sixty days after
receipt of such notice, attempt to agree in good faith upon
the terms and conditions of the Agreement to be in effect
during such additional five-year period. In the event that
the Center and Immunomedics shall be unable to agree upon
all of such terms and conditions prior to the expiration of
the term of the Agreement, the Agreement shall terminate in
accordance with its terms.

Except as set forth in this letter agreement, all of the
terms of the Agreement shall continue in full force and
effect. This letter agreement is the legal, valid, binding
and enforceable obligation of the parties. Each of the
parties represents to the other that the execution and
delivery of this letter agreement has been duly authorized
by all necessary corporate action of such party.

It is further acknowledged that the modifications to the
Agreement contained in this letter agreement are being
requested by the Center in order to better conform the
Agreement to the provisions of a certain tax certificate to
be delivered by the Center to the Essex County Improvement
Authority, McCarter & English and others, regarding the
Essex County Improvement Authority $3,600,000 County of
Essex Guaranteed Revenue Bonds, Series 1994 Garden State
Cancer Center Project. This letter agreement shall become
effective upon the closing of the sale of such Bonds, and
shall automatically terminate if such closing shall not
occur on or before May 15, 1995.

                         Very truly yours,

                         CENTER FOR MOLECULAR MEDICINE
                         AND IMMUNOLOGY, INC.
                         BY:  /s/ Raymond Menard, Ph.D.

                         Agreed:

IMMUNOMEDICS, INC.

By:  /s/ Amy Factor