ARIAD Receives Patent on Selective Cell Elimination Technology.

CAMBRIDGE, MA--(BW HealthWire)--Nov. 11, 1998--

Initial Therapeutic Applications in Graft versus Host Disease 

ARIAD Pharmaceuticals, Inc. (Nasdaq: ARIA) today announced the issuance of its second major patent on ARGENT, the Company's proprietary technology for

controlling cellular activities through the administration of small molecule drugs. U.S. Patent No. 5,834,266 covers materials and methods for inducing cellular self-elimination (apoptosis) using a "dimerizer" drug.

ARGENT, a breakthrough technology conceived by Stuart Schreiber, Ph.D. of Harvard University, Gerald Crabtree, M.D. and David Spencer, Ph.D. of Stanford University and their colleagues, is based on the principle that many cellular events are initiated by dimerization, the process of bringing two proteins together within the cell. By selecting protein interactions that produce a desired cellular response, and engineering those proteins to interact only in the presence of a dimerizer drug, it is possible to bring complex biological processes under direct pharmacological control.

ARIAD is developing an ARGENT inducible apoptosis product to treat graft vs. host disease (GvHD) in patients undergoing allogeneic bone marrow transplantation (BMT). In this product, a proprietary dimerizer drug is used to bring together signaling proteins called Fas. Crosslinking Fas in vivo initiates apoptosis, the natural cell death program present in all cells. Each year, approximately 40,000 patients worldwide undergo BMT. The procedure is required in patients who receive high doses of chemotherapy for certain types of cancer, such as leukemia. GvHD, the most common complication of BMT, results from an imperfect match between the T cells contained in the donated bone marrow (graft) and the cells of the patient (host). GvHD affects over 11,000 transplant patients each year and severely limits the number of BMT's that can be performed. Patients who develop moderate to severe GvHD have a 70% chance of death.

Using the ARGENT GvHD product, donated T cells can be genetically engineered so that they can be eliminated in vivo by administering a proprietary dimerizer drug in the event of GvHD. Such a product would allow physicians to treat certain cancers aggressively with the assurance that they can selectively eliminate donor T cells that attack normal host tissue. ARIAD has demonstrated that its GvHD product eliminates engineered T cells in animal models. The Company expects to begin human clinical testing of its proprietary dimerizer drug, AP1903, later this year. AP1903 is a proprietary synthetic molecule specifically designed to crosslink engineered Fas proteins in vivo. The structural analysis, design, synthesis and initial animal testing of AP1903 were described in the September 1998 issue of the Proceedings of the National Academy of Sciences (vol. 95, pp. 10437-10442).

"The concept of treating GvHD by selective cell elimination has been validated by our collaborator, Dr. Claudio Bordignon, M.D. of the Istituto Scientifico H.S. Raffaele in Milan," said Michael Gilman, Ph.D., chief scientific officer of ARIAD. "We look forward to working with him and other leaders in the field as we develop and test this exciting new approach to cancer therapy."

"The patent covering dimerization and inducible apoptosis is an important step in the commercialization of ARGENT," said Harvey J. Berger, M.D., chairman and chief executive officer of ARIAD. "It is part of an integrated strategy to protect the commercialization benefits of this versatile and powerful technology."

A copy of the ARIAD patent (U.S. Patent No. 5,834,266) will be posted on the world wide web at www.patents.ibm.com.

ARIAD Pharmaceuticals is a leader in the discovery and development of orally administered therapeutics based on signal transduction technology. ARIAD's integrated drug discovery platform includes extensive efforts in functional genomics research, small-molecule drug design and regulated gene therapy.

Some of the matters discussed in this news release are forward-looking statements that involve risks and uncertainties. Other risks and uncertainties include, but are not limited to risks and uncertainties regarding the Company's preclinical studies, the ability of the Company to commence clinical trials of the ARGENT GvGH system and the success of such trials, as well as risks and uncertainties relating to economic conditions, markets, products, services and prices, and other factors under the heading "Cautionary Statement Regarding Forward-Looking Statements" in ARIAD's Annual Report on Form 10-K for the fiscal year ended December 31, 1997 filed with Securities and Exchange Commission.