Therapy Focus - TG Could Benefit From Zydelig Setback

Gilead’s (NASDAQ:GILD) recent decision to terminate a number of clinical trials with Zydelig as a front-line therapy for chronic lymphocytic leukaemia because of serious adverse events raises the question of whether any of its competitors in the PI3K inhibitor space could receive a boost.

And, assuming that the Zydelig safety issues are not a class effect, the answer is that TG Therapeutics (NASDAQ:TGTX) might do (see table below). TG’s PI3K inhibitor TGR-1202 is in a phase III study for CLL and squarely targets the malignancy where both of the abandoned Gilead phase III studies were pitched.

However, TG's benefit could be short-lived due to the recent approval of J&J/AbbVie’ (JNJ, ABBV) BTK inhibitor Imbruvica in front-line CLL.

Zydelig suspension

Earlier this month, Gilead disclosed that six Zydelig trials – including two of four ongoing phase IIIs – had been stopped after serious adverse events including deaths had emerged. Both of the now closed phase III studies were in previously untreated CLL, one in which the drug was added to bendamustine/Rituxan, and another in which it was being tested against chlorambucil, on top of Roche's (OTCQX:RHHBY) Gazyva.

Four phase II studies have also been closed, and an investigator-sponsored trial in Waldenström's macroglobulinaemia is listed as suspended pending a safety review.