What happened

Shares of Corcept Therapeutics (NASDAQ:CORT) were up 18.6% in November, according to data provided by S&P Global Market Intelligence, after the biotech released promising third-quarter earnings results and made progress on its second-generation Cushing's syndrome drug candidate relacorilant.

So what

Revenue jumped 51% year over year as doctors increased their use of Corcept Therapeutics' Korlym, which also treats Cushing's syndrome. While the increase is large, it comes off a small user base, so revenue in the third quarter only came in at $64.4 million.

Management stuck with its guidance for 2018 revenue in the $250 million to $270 million range. After subtracting out sales from the first three quarters of the year, that puts fourth-quarter guidance at $65.6 million to $85.6 million. Presumably it can hit the bottom of the guidance, which would be a pretty small quarter-over-quarter increase, but the top of the guidance might be a bit of a stretch.

Korlym works well, but it has some off-target effects that can cause endometrial thickening and vaginal bleeding in women, as well as lower potassium levels. There are about 10,000 Cushing's syndrome patients in the U.S. potentially eligible for treatment, but only a fraction of them use Korlym because of the side effects.

For Corcept Therapeutics to grow sales beyond the few hundred million dollars that Korlym brings in, the company needs to have success with its next-generation Cushing's syndrome drug, relacorilant, which doesn't seem to have the same side effects.

Based on solid phase 2 data for relacorilant, Corcept treated the first patient in its phase 3 Grace study last month, moving it one step closer to gaining regulatory approval for the follow-on drug.

Doctor with her hand on a patient's shoulder

Image source: Getty Images.

Now what

Corcept is planning on enrolling 130 patients in the Grace study, which will test the drug for 22 weeks, followed by a 12-week withdraw period in which half of the patients who responded in the initial 22 weeks will get relacorilant and half will get placebo. Add in a couple of months to crunch the numbers, and investors can expect data from the trial within a year after enrollment completes.

Until then, investors should focus on sales of Korlym and an impending patent fight with Teva Pharmaceutical (NYSE:TEVA) as the company tries to launch a generic version of Korlym.