ArQule, Inc. (NASDAQ: ARQL) today announced the presentation of Phase 1 results of a clinical trial among patients with metastatic colorectal cancer (CRC) treated with ARQ 197, a selective small molecule inhibitor of the c-MET receptor tyrosine kinase, in combination with irinotecan and cetuximab. ARQ 197 is under development by Daiichi Sankyo Co., Ltd. and ArQule.

Data presented at the ASCO 2011 Gastrointestinal Cancers Symposium showed that this combination was well tolerated and demonstrated encouraging anti-tumor activity in patients with relapsed metastatic CRC. Among nine patients treated, one had a complete response, two had partial responses and five had stable disease. The systemic exposure of ARQ 197 with this combination regimen was consistent with previous observations, and no dose-limiting toxicities were observed.

?These results provide important support for the ongoing Phase 2 randomized study of this combination,? said Dr. Brian Schwartz, chief medical officer of ArQule. ?We believe they strengthen the rationale for this study, which includes the previous demonstration of anti-cancer activity by ARQ 197 in a human colorectal cancer xenograft model, as well as the link shown between an increase in c-MET signaling and the development of resistance to therapy with epidermal growth factor receptor (EGFR) inhibitors.?

The ongoing Phase 2 study of ARQ 197 in CRC is enrolling patients with the wild-type form of the KRAS gene who have received front-line systemic therapy. The primary objective of the trial is progression-free survival. Secondary objectives include overall survival and objective response rate. Approximately 150 patients will be enrolled at clinical trial sites in the U.S. and Europe. The trial is being conducted by Daiichi Sankyo Pharma Development, the global development arm of Daiichi Sankyo, the co-developer with ArQule of ARQ 197 outside of certain countries in Asia.

Additional cancers currently being evaluated in randomized trials of ARQ 197 as a single agent or in combination therapy include non-small cell lung cancer (Phase 3) and hepatocellular carcinoma (Phase 2). Patients, physicians and other healthcare professionals seeking additional information regarding these and other trials involving ARQ 197 may call 1-800-373-7827.

About ARQ 197 and c-MET

ARQ 197 is an orally available, selective inhibitor of c-Met, a receptor tyrosine kinase that is currently in Phase 2 and Phase 3 clinical trials and is not yet approved for commercial sale. In healthy adult cells, c-Met is present in normal levels to support natural cellular function, but in cancer cells, c-Met is inappropriately and continuously activated for unknown reasons. When abnormally activated, c-Met plays multiple roles in aspects of human cancer, including cancer cell growth, survival, angiogenesis, invasion and metastasis.

Pre-clinical data have demonstrated that ARQ 197 inhibits c-Met activation in a range of human tumor cell lines and shows anti-tumor activity against several human tumor xenografts. In clinical trials to date, treatment with ARQ 197 has been well-tolerated and has resulted in tumor responses and prolonged stable disease across a broad range of tumors.

In December 2008, ArQule and Daiichi Sankyo Co., Ltd. signed a license, co-development and co-commercialization agreement to co-develop ARQ 197 in the U.S., Europe, South America and the rest of the world, excluding Japan, China (including Hong Kong), South Korea and Taiwan, where Kyowa Hakko Kirin Co., Ltd. has exclusive rights for development and commercialization.

About ArQule

ArQule is a biotechnology company engaged in the research and development of next-generation, small-molecule cancer therapeutics. The Company's targeted, broad-spectrum products and research programs are focused on key biological processes that are central to human cancers. ArQule's lead product, in Phase 2 and Phase 3 clinical development, is ARQ 197, an inhibitor of the c-Met receptor tyrosine kinase. The Company has also initiated Phase 1 clinical testing with ARQ 621, designed to inhibit the Eg5 kinesin motor protein, and with ARQ 736, designed to inhibit the RAF kinases. ArQule's current discovery efforts, which are based on the ArQule Kinase Inhibitor Platform (AKIP?), are focused on the identification of novel kinase inhibitors that are potent, selective and do not compete with ATP (adenosine triphosphate) for binding to the kinase.

This press release contains forward-looking statements regarding the progress of the Company's clinical trials, including its Phase 2 trial with ARQ 197 in colorectal cancer and trials that may be conducted by Daiichi Sankyo and/or Kyowa Hakko Kirin under their agreements with the Company. These statements are based on the Company's current beliefs and expectations, and are subject to risks and uncertainties that could cause actual results to differ materially. Positive information about early stage clinical trial results is not necessarily indicative of clinical efficacy and does not ensure that later stage or larger scale clinical trials will be successful. For example, ARQ 197 may not demonstrate promising therapeutic effect; in addition, this compound may not demonstrate an appropriate safety profile in further pre-clinical testing and in current, later stage or larger scale clinical trials as a result of known or as yet unanticipated side effects. The results achieved in later stage trials may not be sufficient to meet applicable regulatory standards. Problems or delays may arise during clinical trials or in the course of developing, testing or manufacturing these compounds that could lead the Company or its partner to discontinue development. Even if later stage clinical trials are successful, the risk exists that unexpected concerns may arise from analysis of data or from additional data or that obstacles may arise or issues be identified in connection with review of clinical data with regulatory authorities or that regulatory authorities may disagree with the Company's view of the data or require additional data, information or studies. In addition, the planned timing of initiation and completion of clinical trials for ARQ 197 are subject to the ability of the Company or Daiichi Sankyo, its partner, and Kyowa Hakko Kirin, a licensee of ARQ 197, to enroll patients, enter into agreements with clinical trial sites and investigators, and other technical hurdles and issues that may not be resolved. Moreover, Daiichi Sankyo has certain rights to unilaterally terminate the ARQ 197 license, co-development and co-commercialization agreement. Drug development involves a high degree of risk. Only a small number of research and development programs result in the commercialization of a product. Furthermore, ArQule may not have the financial or human resources to pursue drug discovery successfully in the future. For more detailed information on the risks and uncertainties associated with the Company's drug development and other activities see the Company's periodic reports filed with the Securities and Exchange Commission. The Company does not undertake any obligation to publicly update any forward-looking statements.

ArQule, Inc.
William B. Boni, 781-994-0300
VP, Investor Relations/
Corp. Communications
www.ArQule.com