Big biotech Amgen and its partner Cytokinetics had an intriguing drug candidate -- omecamtiv mecarbill, which treats shortness of breath in patients with acute heart failure -- fail a mid-stage trial. Amgen wasn't affected, but shares of Cytokinetics plunged 25% on the news.

There is a caveat to this failure: It was at the lower dosing, and most analysts didn't expect the trial to succeed. The higher dosing did show efficacy, but when the data was pooled, the results became muddled.

In this video, health-care analyst David Williamson discusses whether the heart-failure drug will reach phase 3 testing and looks at whether Cytokinetics or Amgen is the better play for investors.

David Williamson has no position in any stocks mentioned. Follow David on Twitter: @MotleyDavid.

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