What happened

TG Therapeutics (NASDAQ:TGTX) ended Friday up 17% in anticipation of presentations at the American Society of Clinical Oncology (ASCO) meeting tomorrow and Monday. A blog post by Richard Pazdur, the director of the Food and Drug Administration's (FDA) Oncology Center of Excellence, about the use of surrogate endpoints for measuring clinical benefit, also may have helped boost the share price today.

So what

The most important data will come tomorrow when TG Therapeutics presents the results of the phase 3 GENUINE trial testing ublituximab in combination with Imbruvica, sold by Johnson & Johnson (NYSE:JNJ) and AbbVie (NYSE:ABBV). The top-line data for the trial, which was released back in March, showed an 80% overall response rate for high-risk chronic lymphocytic leukemia patients who received ublituximab plus Imbruvica compared to a 47% overall response rate in patients who only received Imbruvica.

But the devil is often in the details, which will be presented at ASCO. The meeting will also give investors a sense of how the drug will be received by the doctors who will prescribe the medication if ublituximab is approved by the Food and Drug Administration.

Doctor with a patient in a hospital bed.

Image source: Getty Images.

TG Therapeutics also has a pair of presentations on Monday testing a second drug, TGR-1202, either in combination with ublituximab and Imbruvica, or on its own. The results aren't as important for TG Therapeutics' near-term valuation because they were earlier-stage trials.

Now what

Pazdur's blog post pointing to the use of surrogate endpoints, such as TG Therapeutics' overall response rate, supports the approval of TG Therapeutics, but this idea isn't all that new for the oncology division of the FDA. TG Therapeutics' data is so strong, it would be kind of a shock if the FDA didn't approve it based on overall response rate.

A 17% jump ahead of the presentation seems a bit overdone, but the price is still lower than where it was when it peaked in March after the top-line data was released, so today's move may be caused by investors buying back in after taking profits a few months ago.

Brian Orelli has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Johnson & Johnson. The Motley Fool has a disclosure policy.