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                                                                    Exhibit 99.1


MORPHOSYS ENTERS CANCER COLLABORATION WITH IMMUNOGEN

    CAMBRIDGE, Mass. and MUNICH, Germany, Oct. 2 /PRNewswire/ -- MorphoSys AG
(Neuer Markt: MOR), the German biotechnology company based in
Munich/Martinsried, today announced a collaboration with ImmunoGen, Inc.
(Nasdaq: IMGN), a Cambridge, Massachusetts-based biotechnology company. The two
companies will collaborate on the development of human antibodies for the
treatment of cancer. Under the agreement, MorphoSys will receive a technology
access payment, as well as development-related milestone payments and royalties
on marketed products. Financial details were not disclosed.

    In the collaboration, MorphoSys will apply its HuCAL-Fab technology to
discover and optimize fully human antibodies against an unspecified ImmunoGen
cell surface target associated with a number of forms of cancer. ImmunoGen will
be responsible for developing one or more antibodies generated by MorphoSys into
a marketable product.

    "We are delighted to be collaborating with ImmunoGen, a company with great
experience in the development of antibody-based cancer therapeutics," commented
Daniel L. Menichella, President, MorphoSys USA and Senior Vice President of
Corporate Development. "This deal, our sixth this year, is another example of
our ability to form partnerships based on our HuCAL technology with companies
committed to developing fully human antibodies."

    "We look forward to working with MorphoSys in this program. We believe their
antibody library is the best technology available for rapid generation of human
antibodies to our target," said Walter A. Blattler, Ph.D., Executive Vice
President, Science and Technology, ImmunoGen." This program is a part of our
strategy of developing antibody-based products from targets generated by our
Apoptosis Technology, Inc. subsidiary, and is an example of our efforts to fill
our pipeline of internally-developed products."

    MorphoSys develops and applies innovative technologies for the production of
synthetic antibodies which accelerate drug discovery and target
characterisation. Founded in 1992, the Company's proprietary Human Combinatorial
Antibody Library (HuCAL) technology is used by researchers world-wide for human
antibody generation. The Company currently has licensing and research
collaborations with Bayer (Berkeley, California/USA), Roche AG
(Basel/Switzerland), DuPont Pharmaceuticals (Wilmington, Delaware/USA),
Millennium (Cambridge, Mass/USA), Chiron (Emeryville, California/USA), GPC
Biotech AG (Munich/Germany) ProChon Biotech (Revohot/Israel) and Eos
Biotechnology (South San Francisco/California/USA).

    ImmunoGen, Inc. develops innovative biopharmaceuticals, primarily for
cancer treatment. The Company creates potent tumor-activated prodrugs (TAPs),
consisting of small molecular, cytotoxic drugs coupled to monoclonal antibodies
for delivery to and destruction of cancer cells. The most advanced TAP,
huC242-DM1/SB-408075, designed to treat colorectal and pancreatic cancer, is in
two Phase I/II human clinical studies. The Company's subsidiary, Apoptosis
Technology, Inc. (ATI), identifies defects in apoptosis - also known as cell
suicide -- pathways. Besides MorphoSys, the company has collaborations with
SmithKline Beecham, Genentech, Abgenix and British Biotech.

    Statements included in this press release which are not historical in nature
are intended to be, and are hereby identified as, "forward-looking
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statements" for purposes of the safe harbour provided by Section 21E of the
Securities Exchange Act of 1934, as amended by the Private Securities Litigation
Reform Act of 1995. Forward-looking statements may be identified by words
including "anticipates", "believes", "intends", "estimates", "expects" and
similar expressions. The companies caution readers that forward-looking
statements, including without limitation those relating to the companies' future
operations and business prospects, are subject to certain risks and
uncertainties that could cause actual results to differ materially from those
indicated in the forward-looking statements. Factors that may affect future
operations and business prospects include, but are not limited to, clinical and
scientific results and developments concerning corporate collaborations and the
companies' proprietary rights, uncertainties related to operations and other
factors described in the Offering Circular of MorphoSys dated March 5,1999
relating to the company's public offering. The companies are not undertaking any
obligation to release publicly any updates to any forward-looking statements to
reflect events or circumstances after the date of this release or to reflect the
occurrence of unanticipated events.

    This press release includes forward-looking statements based on
management's current expectations. Factors that could cause future results to
differ materially from such expectations include, but are not limited to: the
ability to secure future funding; the success of ImmunoGen's research strategy;
the applicability of the discoveries made therein; the difficulties inherent in
the development of pharmaceuticals, including uncertainties as to the timing and
results of preclinical studies; delayed achievements of milestones; reliance on
collaborators; uncertainty as to whether ImmunoGen's potential products will
succeed in entering human clinical trials and uncertainty as to the results of
such trials; uncertainty as to whether adequate reimbursement for these products
will exist from the government, private healthcare insurers and third-party
payors; and the uncertainties as to the extent of future government regulation
of the pharmaceutical business.