Novartis has backed away from its pursuit of Cytokinetics, putting a damper on the prospects of a deal for the promising heart-drug developer. 

The Swiss drug giant had been closing in on a purchase of South San Francisco-based Cytokinetics, with an agreement expected as soon as this week, The Wall Street Journal reported Monday. But Novartis, which had been pursuing the biotech for several months, backed away sometime in the past day or two, according to the people.