Cytokinetics Announces Selection of Heart Failure Drug Development Candidate

Second Program Leveraging Cytoskeletal Pharmacology Platform Progresses to Development Stage

South San Francisco, CA - March 3, 2005

Cytokinetics, Inc. (Nasdaq: CYTK) announced today that it has recently selected a compound arising from its heart failure drug discovery program for development. The selected compound is currently in preclinical studies. Based on the successful completion of the preclinical program, Cytokinetics intends to submit a regulatory filing for the initiation of first-time-in-human clinical studies in 2005.

Cytokinetics’ heart failure program focuses on the discovery and development of small molecules that directly activate cardiac myosin, a cytoskeletal protein that drives cardiac muscle contractility. This mechanism of action results in increased cardiac contractility without increasing intracellular calcium or inhibiting phosphodiesterase activity, which are properties of existing pharmaceuticals that may be associated with adverse clinical effects in heart failure patients. Cardiac myosin activators represent a potential next-generation approach to the treatment of acute and chronic congestive heart failure.

This newly advanced compound replaces another cardiac myosin activator identified in 2004 as the lead drug candidate arising from this program. Cytokinetics had nominated that particular compound for development while continuing to further optimize other compounds in this series. Through this process, the company identified this newer compound that additional research has demonstrated to be a more attractive drug candidate for pharmaceutical development due to properties that include improved potency, tolerability, pharmacokinetics and pharmaceutics. These properties increase the possibility of developing a novel, next-generation pharmaceutical for the treatment of acute heart failure, while still providing opportunity for exploration of this class of compounds in the treatment of chronic heart failure.

“We are excited about the potential for this compound,” stated James H. Sabry, M.D., Ph.D., Cytokinetics’ President and Chief Executive Officer. “Cytokinetics’ expertise in cytoskeletal pharmacology has now generated a development compound with potential application as a next-generation treatment for both acute and chronic heart failure patients. This achievement provides further validation of our cytoskeletal pharmacology platform which has generated development stage compounds in two distinct therapeutic areas, heart failure and cancer." “The selection of this compound represents an important step forward for the development of activators of cardiac myosin as novel therapeutics in the treatment of heart failure,” said David J. Morgans, Jr., Ph.D., Cytokinetics’ Senior Vice President of Drug Discovery and Development. “Through an extensive optimization process, we identified and characterized a broad array of compounds in order to inform our decision to advance this particular drug candidate. As a result, we now have a greater knowledge base of multiple compounds that act by this novel mechanism and have generated an extensive data set on our selected drug candidate which may improve our ability to conduct clinical trials in this area. In addition, we can now explore the potential for this class of compounds in the treatment of chronic heart failure.”

Background on the Heart Failure Market

Congestive heart failure is a widespread disease affecting approximately five million people in the United States alone. The high and rapidly growing prevalence of congestive heart failure translates into significant hospitalization rates and associated societal costs. The number of hospital discharges in the United States identified with a primary diagnosis of congestive heart failure rose from 550,000 in 1989 to 970,000 in 2002. Congestive heart failure is one of the most common primary discharge diagnoses identified in hospitalized patients over the age 65 in the United States. The annual costs of congestive heart failure in the United States are estimated to be $27.9 billion, including $18.3 billion for inpatient care. The market for congestive heart failure drugs was approximately $2.7 billion in 2001, according to industry reports. Despite currently available therapies, readmission rates for patients over the age of 65 remain high at 30 to 40 percent within six months of hospital discharge and mortality rates over a eight year period range from 70% to 80% for patients under the age of 65. The limited effectiveness of current therapies points to the need for next-generation agents with improved efficacy without increased adverse events.

Background on Cardiac Myosin Activators and Cardiac Contractility

Cardiac myosin is the cytoskeletal motor protein in the cardiac muscle cell that is directly responsible for converting chemical energy into the mechanical force resulting in cardiac contraction. Cardiac contractility is driven by the cardiac sarcomere, the fundamental unit of muscle contraction in the heart that is a highly ordered cytoskeletal structure composed of cardiac myosin, actin and a set of regulatory proteins. The sarcomere represents one of the most thoroughly characterized protein machines in human biology.

Cytokinetics’ heart failure program is focused towards the discovery and development of small molecule cardiac myosin activators in order to create next-generation treatments to manage acute and chronic congestive heart failure. Cytokinetics’ program is based on the hypothesis that activators of cardiac myosin may address certain mechanistic liabilities of existing pharmaceuticals by increasing cardiac contractility without increasing intracellular calcium or inhibiting phosphodiesterase activity, each of which may be associated with adverse clinical effects in heart failure patients. Existing drugs that seek to improve cardiac cell contractility increase the concentration of intracellular calcium, which indirectly activates cardiac myosin, but this effect on calcium levels also has been linked to potentially life-threatening side effects. In contrast, cardiac myosin activators have been shown to work by a novel mechanism that directly stimulates the activity of the cardiac myosin motor protein by accelerating the rate-limiting step of the myosin enzymatic cycle and thereby shifting the enzymatic cycle in favor of the force producing state.

About Cytokinetics

Cytokinetics is a leading biopharmaceutical company focused on the discovery, development and commercialization of novel small molecule drugs that specifically target the cytoskeleton. The cytoskeleton is a complex biological infrastructure that plays a fundamental role within every human cell. Cytokinetics’ focus on the cytoskeleton enables it to develop novel and potentially safer and more effective classes of drugs directed at treatments for cancer, cardiovascular disease and other diseases. Cytokinetics has developed a cell biology driven approach and proprietary technologies to evaluate the function of many interacting proteins in the complex environment of the intact human cell. Cytokinetics employs the PUMA™ system and Cytometrix™ technologies to enable early identification and automated prioritization of compounds that are highly selective for their intended protein targets without other cellular effects, and are thereby less likely to give rise to clinical side effects. Cytokinetics and GlaxoSmithKline have entered into a strategic alliance to discover, develop and commercialize small molecule therapeutics targeting human mitotic kinesins for applications in the treatment of cancer and other diseases. GlaxoSmithKline is conducting Phase II and Phase Ib clinical trials for SB-715992 and a Phase I clinical trial for SB-743921, each a drug candidate that has emerged from the strategic alliance. Cytokinetics’ heart failure program is the second program to leverage the company’s expertise in cytoskeletal pharmacology. Cytokinetics expects to enter human clinical trials in 2005 with a novel small molecule cardiac myosin activator for the treatment of heart failure. Additional information about Cytokinetics can be obtained at www.cytokinetics.com.

This press release contains forward-looking statements for purposes of the Private Securities Litigation Reform Act of 1995 (the “Act”). Cytokinetics disclaims any intent or obligation to update these forward-looking statements, and claims the protection of the Safe Harbor for forward-looking statements contained in the Act. Examples of such statements include, but are not limited to, statements relating to the expected timing, scope and results of our clinical development and research program, including Company milestones for 2005, initiation of clinical trials, and statements regarding the potential benefits of our drug candidates and potential drug candidates and the enabling capabilities of our proprietary technologies. Such statements are based on management’s current expectations, but actual results may differ materially due to various factors. Such statements involve risks and uncertainties, including, but not limited to, those risks and uncertainties relating to difficulties or delays in development, testing, regulatory approval, production and marketing of Cytokinetics’ drug candidates that could slow or prevent clinical development, product approval or market acceptance (including the risks relating to uncertainty of patent protection for Cytokinetics’ intellectual property or trade secrets, Cytokinetics’ ability to obtain additional financing if necessary and unanticipated research and development and other costs). For further information regarding these and other risks related to Cytokinetics’ business, investors should consult Cytokinetics’ filings with the Securities and Exchange Commission.