Why TG Therapeutics Inc. Shares Temporarily Plunged

Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of TG Therapeutics , a clinical-stage biopharmaceutical company focused on developing therapies to treat cancer, temporarily plunged as much as 15% this morning after reporting preliminary clinical results of a phase 2 study in combination with Pharmacyclics' Imbruvica (formerly ibrutinib). Shares have since rebounded and are now higher by 3% on the day as of this writing.

So what: According to TG Therapeutics' press release, TG-1101 in combination with Imbruvica led to an impressive 90% overall response rate (out of 10 evaluable patients) at the first efficacy assessment in patients with previously treated chronic lymphocytic leukemia and mantle cell lymphoma. As noted in its press release, "The addition of TG-1101 appears to abrogate ibrutinib related lymphocytosis in patients with CLL, with patients experiencing a median ~80% reduction in their absolute lymphocyte count (ALC) by month 4 following initiation of combination therapy." In addition, the combo appeared to be generally safe and well-tolerated in the initial 28 patients, though one grade 3/4 adverse event was reported that led to study discontinuation.

Now what: Today's sharp, but temporary move lower merely looks like a combination of emotional trading and profit taking following TG Therapeutics' 92% surge higher over the past month. Although the data, while preliminary, would certainly appear to indicate that Imbruvica could have legs as a combination therapy, and that a combination with TG-1101 might be one of those therapies that eventually reaches the market. Admittedly, with just 10 evaluable patients I'm not reading to declare this a wholly effective combo just yet, but I believe the case has been made that this combo should be followed closely going forward.

One final thing to consider, however, is that as a purely clinical-stage company TG Therapeutics may choose to offer shares for sale in order to raise cash for future research studies - a somewhat common practice in the biotech sector. Investors may want to consider the potential for dilution following TG's large run higher.