ARIAD Announces Update on Preclinical Molecularly Targeted Oncology Programs at American Association for Cancer Research Annual Meeting.

CAMBRIDGE, Mass. -- ARIAD Pharmaceuticals, Inc. (Nasdaq: ARIA) today announced that several preclinical studies being presented at the American Association for Cancer Research (AACR) annual meeting demonstrate broad anti-cancer activity of ARIAD's oncogenic kinase inhibitors and bone-targeted mTOR inhibitors - new molecularly targeted oncology therapies.

"These data provide solid confirmation of the pharmacologic activity of ARIAD's preclinical compounds and validate their potential to advance further in the development process," said Harvey J. Berger, M.D., chairman and chief executive officer of ARIAD. "Later this year, we expect to select a compound from these promising programs to advance to clinical development."

Oncogenic Kinase Inhibitor Program

ARIAD's preclinical kinase inhibitors fall into two classes: inhibitors of key mutant kinases that confer resistance to current therapies and compounds that inhibit multiple pathways associated with cancer progression, such as metastasis, angiogenesis and survival.

"The compounds described in the AACR presentations represent early compounds that we have been sharing with academic collaborators to illuminate their potential applications and corresponding biology," said Timothy P. Clackson, Ph.D., chief scientific officer of ARIAD. "The data from these studies have provided the necessary insights for lead optimization and extensive preclinical investigations. We are currently characterizing select and markedly more potent compounds from which we expect to move forward with our next development candidate."

Abstract 4852: Targeted inhibition of gatekeeper variant "T315I" of Bcr-Abl by a purine-based ATP competitive inhibitor

The Bcr-Abl oncoprotein is responsible for a wide range of human leukemias, including most cases of chronic myeloid leukemia (CML). CML is a slowly progressing cancer in which too many white blood cells are made in the bone marrow. The disease is most commonly treated with bone marrow transplantation, drug therapy, or a combination of the two - all of which have limitations. The molecularly targeted drug, imatinib, inhibits Bcr-Abl and is an effective therapy in treating CML. However, treatment with imatinib is prone to the emergence of mutations that create drug resistance over time, as is treatment with second-generation compounds currently in clinical development.

Data presented at AACR demonstrate that compounds from ARIAD's kinase inhibitor program potently inhibit a particular Bcr-Abl mutant called T315I. This is particularly important as CML harboring the T315I mutant is refractory to currently available therapies. Agents that are able to inhibit T315I may address a definite unmet medical need in CML. Imatinib resistance due to T315I appears to represent approximately 25% of total drug resistance in CML and is not treated effectively by any of the Bcr-Abl inhibitors in clinical development - providing a significant opportunity for new treatment options.

Abstract Number 962: Src as a novel therapeutic target in ovarian carcinoma

Abstract Number 2294: Lyn activation is necessary for Ewing's sarcoma tumor growth in a mouse model

Src, a non-receptor tyrosine kinase, is a central convergence point for signals from a variety of extracellular sources and is a target for inhibiting cell invasion (metastasis), and potentially angiogenesis and survival - all processes key to tumor growth. ARIAD is investigating the effects of inhibiting Src family kinases in preclinical models of various tumor types.

Data presented at AACR describe the activities of ARIAD's compound, AP23994, which inhibits the protein Src and related enzymes, in mouse models of ovarian cancer and Ewing's sarcoma (a form of bone cancer). According to these studies, the compound was able to reduce tumor size, reduce expression of a marker of angiogenesis, and prolong survival. Combination with docetaxel (a taxane) significantly enhanced the antitumor effect and the survival benefit. This illustrates the potential of Src-targeted compounds for the multi-mechanism attack of cancer progression.

Bone-targeted mTOR Inhibitor Program

Bone metastases, frequently the consequence of common malignancies such as breast, lung and prostate cancer, involve complex molecular processes and are extremely difficult to treat.

"ARIAD's bone-targeted mTOR inhibitor program is examining a novel set of compounds that have demonstrated a dual-mechanism of action in multiple animal models, both slowing tumor growth and reducing bone breakdown," said Dr. Clackson. "This class of compounds represents a potentially promising and unique approach to the treatment of cancers that have either spread to bone or originate in bone."

Abstract Number 1116: Bone-targeted rapamycin analogs inhibit osteolysis and tumor growth in a PC-3-GFP intratibial bone cancer model in nude mice

Abstract Number 4857:A tissue selective rapamycin analog inhibits MDA-MB-231 breast cancer cell-induced osteolytic bone metastases in nude mice

These in-vivo efficacy studies describe a new set of lead compounds with a range of bone-targeting properties. Compounds were tested using mouse models of prostate and breast cancer that have metastasized to bone. One compound in particular, AP24170, demonstrated significant inhibition both of tumor growth and of bone breakdown in the prostate model and a reduction of destructive lesions in the breast cancer model, consistent with the predicted dual-action profile of such compounds. Further preclinical studies of AP24170 and its analogs are planned.

About ARIAD

ARIAD is engaged in the discovery and development of breakthrough medicines to treat disease by regulating cell signaling with small molecules. The Company is developing a comprehensive approach to patients with cancer that addresses the greatest medical need - aggressive and advanced-stage cancers for which current treatments are inadequate. Medinol Ltd. also is developing stents and other medical devices that deliver ARIAD's lead cancer product candidate to prevent reblockage at sites of vascular injury following stent-assisted angioplasty. ARIAD has an exclusive license to pioneering technology and patents related to certain NF-(kappa)B treatment methods, and the discovery and development of drugs to regulate NF-(kappa)B cell-signaling activity, which may be useful in treating certain diseases. Additional information about ARIAD can be found on the web at www.ariad.com.

Some of the matters discussed herein are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements are identified by the use of words such as "anticipate," "estimate," "expect," "project," "intend," "plan," "believe," and other words and terms of similar meaning. Such statements are based on management's current expectations and are subject to certain factors, risks and uncertainties that may cause actual results, outcome of events, timing and performance to differ materially from those expressed or implied by such forward-looking statements. These risks include, but are not limited to, risks and uncertainties regarding our ability to advance compounds such as those discussed in this press release from preclinical development to clinical development, and the timing thereof, and that the results of preclinical studies such as those described in this press release may not be predictive of future results, risks and uncertainties regarding our ability to accurately estimate the timing and actual R&D expenses and other costs associated with the preclinical and clinical development and manufacture of our product candidates, the adequacy of our capital resources and the availability of additional funding, risks and uncertainties regarding our ability to manufacture or have manufactured our product candidates on a commercial scale, risks and uncertainties regarding our ability to successfully enroll and conduct clinical studies of product candidates, risks and uncertainties that clinical trial results at any phase of development may be adverse or may not be predictive of future results or lead to regulatory approval of any of our or any partner's product candidates, risks and uncertainties of third-party intellectual property claims relating to our and any partner's product candidates, and risks and uncertainties relating to regulatory oversight, the timing, scope, cost and outcome of legal proceedings, including litigation concerning our NF-(kappa)B patent portfolio, future capital needs, key employees, dependence on collaborators and manufacturers, markets, economic conditions, products, services, prices, reimbursement rates, competition and other factors detailed in the Company's public filings with the Securities and Exchange Commission, including ARIAD's Annual Report on Form 10-K for the fiscal year ended December 31, 2005. The information contained in this document is believed to be current as of the date of original issue. The Company does not intend to update any of the forward-looking statements after the date of this document to conform these statements to actual results or to changes in the Company's expectations, except as required by law.