What happened

After reporting positive data from one cohort of a trial evaluating its lymphoma drug umbralisib, TG Therapeutics (NASDAQ:TGTX) shares soared 30.5% as of 3:35 p.m. EST.

So what

Marginal zone lymphoma (MZL) is typically diagnosed in elderly patients. It's a slow-glowing type of non-Hodgkin lymphoma, and there are 7,500 new patients diagnosed in the U.S. with MZL annually. In the first-line setting, Rituxan is typically used. However, there remains a need for additional treatment options for relapsing patients. 

A man listens through a wall using a plastic cup.


Today, TG Therapeutics reported that it met its primary endpoint of an overall response rate of between 40% to 50% in 69 MZL patients enrolled in its study. The study was designed to support a possible accelerated Food and Drug Administration (FDA) approval, and if the full primary data anticipated later this year remains solid, the company plans to file for FDA approval before year-end. By comparison, Imbruvica won accelerated approval in this indication following a midstage study in which it achieved a 46% overall response rate.

Management also updated investors on the timing for results from a cohort evaluating umbralisib in follicular lymphoma (FL) and small lymphocytic lymphoma (SLL). That cohort is fully enrolled, and results are expected later this year. Similar to the MZL cohort, the company's targeting a 40% to 50% overall response rate. If it hits that target, then TG Therapeutics hopes it can win an accelerated OK there, too. 

Additionally, the company's still awaiting maturing progression-free survival data from its phase 3 trial evaluating ublituximab and umbralisib as combination therapy in chronic lymphocytic leukemia. Management expects to have results available from that study later this year or early in 2020. 

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Now what

Lymphoma is a multibillion dollar per year commercial opportunity. Although there have been advances in recent years, there's still an opportunity to address patients who fail to respond or see their disease progress following initial treatment. The umbrasilib data in MZL is encouraging because management says the overall response rate can't weaken between now and the primary data readout, suggesting it's only a matter of time before the company can present this drug to regulators.

It remains to be seen, though, if the company can deliver in FL and SLL or in CLL. There's also no guarantee that the FDA will approve umbralisib in MZL prior to another trial, so there's still some risk here to consider. For this reason, only risk-tolerant investors should be considering TG Therapeutics for their portfolios.