What happened

Shares of Clovis Oncology Inc. (NASDAQ:CLVS), an oncology-focused biotech company, fell after investigators presented interim results from a clinical trial with its lead drug, Rubraca. Investors less than thrilled with comments from management on the results pushed the stock 12% lower as of 3:55 p.m. EDT on Friday.

So what

This April, Rubraca earned full approval for the maintenance treatment of ovarian cancer. Clovis's lead drug competes with Zejula from Tesaro and Lynparza from AstraZeneca for this patient group, which is why investors were looking forward to today's presentation of prostate cancer data.

Tired-looking person holding a downward-sloping arrow

Image source: Getty Images.

Around 13% of prostate cancer patients harbor a genetic mutation called an ATM alteration, and investors had hoped Rubraca would outperform for this group. Today's loss is largely due to disappointing comments made by Clovis CEO Patrick Mahaffy in an interview with Vantage during the European Society for Medical Oncology meeting. In a nutshell, it doesn't look like the drug produced a meaningful difference for ATM-positive patients.

Now what

Although the stock has fallen, the 44% tumor response rate observed among 25 prostate cancer patients who harbor a BRCA mutation is impressive. Clovis previously stated it would seek accelerated approval for treatment of prostate cancer if Rubraca shrank tumors for just 25% of this group, so we can probably expect the company to send an application to the Food and Drug Administration sooner rather than later.

If you're thinking about picking up shares of Clovis Oncology on the dip, you might want to look a little closer. The company lost $179 million in the first half of the year despite selling $42 million worth of Rubraca. If Rubraca sales don't start rocketing higher soon, the company's recent enterprise value of $1.5 billion could fall much further.