Cytokinetics Announces Clinical Trials Data to Be Presented at the 2007 Annual Meeting of the American Society of Clinical Oncology

Market Wire, May, 2007

Cytokinetics, Incorporated (NASDAQ: CYTK) announced today that three abstracts summarizing data from clinical trials relating to its oncology program will be presented at the 2007 Annual Meeting of the American Society of Clinical Oncology (ASCO) in Chicago, IL, June 1-5, 2007. Two of these abstracts relate to clinical trials evaluating ispinesib that were sponsored by GlaxoSmithKline (GSK) or the National Cancer Institute (NCI). The third abstract relates to a clinical trial sponsored by Cytokinetics evaluating SB-743921.

Ispinesib and SB-743921 are both novel, chemically distinct, small molecule inhibitors of kinesin spindle protein (KSP), a mitotic kinesin essential for proper cell division. Both drug candidates have arisen from a broad strategic collaboration between Cytokinetics and GSK to discover, develop and commercialize novel small molecule therapeutics targeting human mitotic kinesins for applications in the treatment of cancer and other diseases.

Poster Presentations and Publications of Abstracts at ASCO

The following abstracts will be presented at ASCO or published in the ASCO 2007 Annual Meeting Proceedings and will be available through the ASCO website ( www.asco.org ):

Poster Presentation:

Abstract #5562: A Phase II, Open-Label Study of Ispinesib (SB-715992) in Patients with Platinum/Taxane Refractory or Resistant Relapsed Ovarian Cancer. (Oral presentation by Mark S Shahin, Abington Memorial Hospital, Abington, PA, on Saturday, June 2, 2007, Gynecologic Cancer; S Hall A2, Board #S5, 2:00 PM - 6:00 PM).

Publication of Abstract: (Abstract will be published in the ASCO 2007 Annual Meeting Proceedings)

Abstract #15573: University of Chicago Consortium Phase II Study of Ispinesib (SB-715992) in Patients with Advanced Renal Cell Carcinoma. K. W. Beekman, University of Michigan, Ann Arbor, MI.

Abstract #18516: A Phase I-II Study to Assess the Safety, Pharmacokinetics, and Potential Efficacy of Intravenous SB-743921 on Days 1 and 15 of a 28-day Cycle in Patients with Non-Hodgkin Lymphoma. A. Goy, Hackensack University Medical Center, Hackensack, NJ.

Clinical Trials of Ispinesib

Ispinesib has been the subject of a broad Phase II clinical trials program under the sponsorship of GlaxoSmithKline (GSK) and is also being developed in collaboration with the National Cancer Institute (NCI). GSK has sponsored three Phase II clinical trials, one evaluating ispinesib as second- or third-line treatment for patients with locally advanced or metastatic breast cancer, one evaluating ispinesib as second-line treatment for patients with non-small cell lung cancer, and one evaluating ispinesib as second-line treatment for patients with advanced ovarian cancer. Enrollment in all of these studies has been closed. To date, clinical activity with ispinesib has been observed in breast cancer and in non-small cell lung cancer, with the more robust clinical activity observed in a Phase II clinical trial evaluating ispinesib in the treatment of metastatic breast cancer patients that have failed treatment with taxanes and anthracyclines. GSK has informed Cytokinetics that final data are expected from the breast cancer clinical trial in the first half of 2007.

In addition, GSK has sponsored three dose-escalating Phase Ib clinical trials. Each of these clinical trials was designed to evaluate the safety, tolerability and pharmacokinetics of ispinesib in combination with a leading anti-cancer therapeutic, one in combination with carboplatin, the second in combination with capecitabine, and the third in combination with docetaxel. The clinical trial evaluating ispinesib in combination with capecitabine is ongoing. Final data from this trial are expected in 2007.

Under a November 2006 amendment to its collaboration and license agreement with GSK, Cytokinetics assumed responsibility for the costs and activities associated with the continued development of the KSP inhibitors, ispinesib and SB-743921, subject to GSK's option to resume responsibility for some or all development and commercialization activities associated with each of these novel drug candidates. Cytokinetics plans to conduct, at its expense, a focused development program for ispinesib in breast cancer specifically designed to supplement the broad series of Phase I and Phase II clinical trials sponsored by GSK that have demonstrated clinical activity in the treatment of patients with metastatic breast cancer and that have shown an acceptable tolerability profile for ispinesib in combination with standard chemotherapeutics.

The NCI has sponsored six additional Phase II clinical trials, one evaluating the potential efficacy of ispinesib in the second-line treatment of patients with colorectal cancer, one in the first-line treatment of patients with hepatocellular cancer, one in the first-line treatment of patients with melanoma, one in the first- or second-line treatment of patients with head and neck cancers, one in the second-line treatment of patients with hormone-refractory prostate cancer, and one in the second-line treatment of patients with renal cell cancer. Enrollment has been closed for all of these trials; patients remain on treatment in the renal cell cancer trial. Data are expected from the hepatocellular cancer, the prostate cancer, the melanoma, and the renal cell cancer trials in 2007. Data from the other ispinesib clinical trials have already been reported.