Cytokinetics Announces Interim Clinical Trial Data Relating to CK-1827452 Presented at the European Society of Cardiology Congress 2008

Market Wire, September, 2008

Cytokinetics, Incorporated (NASDAQ: CYTK) announced today that additional interim results from an ongoing Phase IIa clinical trial of CK-1827452 were presented as a poster presentation at the European Society of Cardiology (ESC) Congress 2008, at the Messe München GmbH in Munich, Germany. The trial is evaluating an intravenous formulation of CK-1827452, a novel cardiac myosin activator being developed for the potential treatment of patients with either acutely decompensated or chronic heart failure. CK-1827452 is the subject of a collaboration and option agreement between Cytokinetics and Amgen Inc.

A poster entitled, "First Clinical Trial of the Selective Cardiac Myosin Activator, CK-1827452, in Heart Failure: Effect of Dose and Plasma Concentration on Systolic Function" was presented by John Cleland, MD, FACC, FRCP, FESC, Professor of Cardiology, Castle Hill Hospital, University of Hull, United Kingdom on September 1, 2008.

The interim analysis included eight patients from each of Cohorts 1 and 2 and six patients from Cohort 3. There were statistically significant correlations between CK-1827452 concentration and increases in systolic ejection time and stroke volume (each p < 0.0001), and between CK-1827452 concentration and increases in fractional shortening and cardiac output (each p < 0.01). Changes in ejection fraction, left ventricular end-diastolic volume and left ventricular end-systolic volume were not statistically significant. Heart rate declined slightly at the higher concentrations and there were no dose-related changes in blood pressure. Treatments were well tolerated at pre-specified dosages. The authors concluded that CK-1827452 appears to be well-tolerated in stable heart failure patients over a broad range of plasma concentrations during continuous intravenous administration. The authors also concluded that CK-1827452 increases stroke volume, cardiac output, fractional shortening and systolic ejection time in a concentration-dependent manner. In addition, the authors concluded that the observed improvements in systolic function support further study in a larger patient population, and translation of this novel and unique mechanism into populations with more severe and acute heart failure.

"These additional echocardiographic data assist in the interpretation of results previously presented from this ongoing clinical trial and augment our understanding of the novel pharmacodynamic mechanism and encouraging tolerability of CK-1827452," stated Andrew A. Wolff, MD, FACC, Cytokinetics' Senior Vice President of Clinical Research and Development and Chief Medical Officer. "We believe that the absence of an increase in left ventricular end-diastolic volume further supports our view that Doppler-derived stroke volume is an accurate and sensitive measure of the effect of CK-1827452 to increase left ventricular systolic function. We look forward to continuing this trial and plan to present additional data at upcoming conferences."

Cytokinetics plans to present interim data from additional patients who have completed treatment in this ongoing trial as part of the Late Breaking Clinical Trials Session at the Annual Meeting of the Heart Failure Society of America in Toronto, Ontario, Canada on September 24, 2008 at 8:30 am ET.

Phase IIa Clinical Trial Design

This Phase IIa clinical trial is a multi-center, double-blind, randomized, placebo-controlled, dose-escalation, pharmacokinetic and pharmacodynamic trial of CK-1827452 in patients with stable heart failure. The primary objective of this trial is to evaluate the safety and tolerability of CK-1827452 administered as an intravenous infusion to stable heart failure patients. The secondary objectives of this trial are to establish a relationship between the plasma concentration and pharmacodynamic effects of CK-1827452 and to determine the pharmacokinetics of CK-1827452 in stable heart failure patients. In addition to routine assessments of vital signs, blood sampling for CK-1827452 levels, and electrocardiographic monitoring, echocardiograms are performed to evaluate cardiac function at various pre-defined time points before, during and after the infusion of CK-1827452.

In this trial, CK-1827452 is administered as an intravenous infusion to cohorts of eight patients each. In each cohort, patients undergo four treatment periods, receiving three escalating active doses of CK-1827452 and one placebo treatment randomized into the dose escalation sequence to maintain blinding. Patients receive a loading infusion to rapidly achieve a target plasma concentration of CK-1827452 during the first hour, followed by a slower one-hour infusion intended to maintain that plasma concentration during the remainder of the infusion. The first two of these cohorts are designed to study a range of target CK-1827452 plasma concentrations, from 90 ng/ml in the lowest dose regimen in Cohort 1 to 650 ng/ml in the highest dose regimen in Cohort 2; Cohort 3 was designed to gain experience across the same range plasma of concentrations, but with infusions of a longer duration. In the first two cohorts, the second, slower, maintenance infusion was continued for one hour; in the third cohort, the maintenance infusion was continued for 23 hours. Following review of safety data from this interim analysis, Cytokinetics opened enrollment in a fourth cohort in this trial. This cohort will also evaluate a one-hour loading infusion followed by 23 hours of maintenance infusions over the same range of target CK-1827452 plasma concentrations evaluated in Cohort 3.