GSK came out of the collaboration with one candidate, which is in Phase I.

GlaxoSmithKline (GSK) says that because of a change in its portfolio focus, it will not exercise its option to license two cancer drug candidates, ispinesib or SB-743921, from Cytokinetics. Under the terms of the agreement between the companies, rights to these compounds will return to Cytokinetics, and the collaboration will proceed with a compound called GSK-923295 for advanced cancers.

In September, Cytokinetics went through a restructuring where they decided to continue one internal program and two partnered development-stage programs: Amgen’s heart failure treatment until Phase IIb and GSK’s anticancer agents until completion of the Phase I part of Phase I/II trials.

Now that GSK has decided not to proceed with ispinesib or SB-743921, Robert I. Blum, Cytokinetics’ president and CEO, informs that they “are committed to advancing these two drug candidates through to the end of Phase I and will then evaluate the next steps for ispinesib and SB-743921 in context of the results, required funding, and other partnering possibilities.”

The GSK-Cytokinetics collaboration inked in 2001 to discover, develop, and commercialize mitotic kinesins for cancer and diseases resulted in three candidates. Ispinesib and SB-743921, each inhibitors of kinesin spindle protein (KSP), are both in Phase I testing, while GSK-923295 is an inhibitor of centromere-associated protein E (CENP-E) that has completed Phase I studies.

The companies revised the arrangement in November 2006, such that Cytokinetics assumed responsibility for the costs and activities associated with the continued development of ispinesib and SB-743921, subject to GSK’s option to resume responsibility for some or all development and commercialization

Each company will receive royalties from the sale of any products arising from the strategic alliance that the other company progresses to commercialization. For GSK-923295, Cytokinetics retains the option to cofund certain later-stage development activities, thereby providing Cytokinetics an opportunity to increase its potential royalties and obtain copromotion rights in North America.

In June, Cytokinetics announced a further one-year extension of the strategic alliance’s research term to continue activities focused toward translational research directed to CENP-E, which was likely affected by the restructuring, which nixed oncology research activities.

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