Clovis Oncology's (NASDAQ:CLVS) lung cancer drug CO-1686 was in the spotlight at ASCO today, and, while the drug seemed to be potentially more effective than AstraZeneca's (NYSE:AZN) competitor AZD9291, the stock still dropped.

In a phase 1/2 trial, CO-1686 caused high blood sugar in 22% of patients, according to Clovis, and CEO Pat Mahaffay reportedly commented that a few patients had to receive insulin injections to handle their hyperglycemia.

In this video, from Monday's Market Checkup, the Motley Fool's health care-focused investing show, analysts Michael Douglass and David Williamson discuss the side effects and what this could mean for Clovis moving forward.

Even if the next batch of data is much better, Clovis could have serious trouble keeping up with this top stock.
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David Williamson has no position in any stocks mentioned. Michael Douglass has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.