rld’s largest biotechnology company, paid $50 million for rights to Cytokinetics’ experimental heart-failure drug. Cytokinetics, based in San Francisco, saw its shares rise 33 percent in Nasdaq trading May 26 after the deal was announced.

Amgen exercised an option that makes it responsible to develop and sell the drug, CK-1827452, the companies said in a statement. The heart failure drug is Cytokinetics’ leading product candidate. The drug is the first in a new family of medicines designed to treat heart failure by increasing the duration of each contraction of the muscle. That helps pump more blood through the body without increasing the heart rate — a side effect of older medicines, according to Bloomberg News.

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