GBT touts positive sickle cell trial, but shares yo-yo as investors mull data

red blood cells
More detailed data for the blood disorder will be posed later this year. (Pixabay/Geralt)

Global Blood Therapeutics saw its shares dip and climb this morning as those plugging the positive fought it out with those questioning how good its data really are, and whether it can achieve its new goal of a swift approval.

GBT, said to be in the M&A crosshairs of Novo Nordisk, posted the long-anticipated phase 3 data early this morning, showing in part A of the so-called "Hope" study that its experimental sickle cell disease (SCD) drug voxelotor (a.k.a GBT440) hit its primary endpoint after achieving statistically significant increases at both the higher 1,500 mg dose and lower 900 mg doses after 12 weeks of treatment, when pitted against a dummy treatment.

Drilling into the numbers, GBT’s drug showed that just over half (58%) of patients on the higher dose and 38% of patients on the lower dose achieved a greater-than 1 g/dL increase in hemoglobin at 12 weeks: This was against just 9% of patients taking placebo.

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“This compares favorably to the hemoglobin increase assumption agreed to with the FDA in the Hope study protocol of a 35% response,” the company said in a statement.

But there were some weak notes too. Patient reported outcomes (PRO) data were “difficult to interpret due to low baseline symptom scores and high inter-subject and intra-subject variability,” so GBT says it will ditch PRO as a secondary endpoint.

It also said on VOC (vaso-occlusive crisis, a common painful complication of sickle cell anemia) that it saw fewer VOC episodes in both voxelotor groups than in the placebo group, but the company said this was, “as anticipated,” not enough to hit statistical significance. Its reasoning: limited patient follow-up.

Details on safety were scant, but the company said: “The independent DSMB completed its most recent clinical safety review in May 2018 and did not identify safety concerns with voxelotor.” More detailed data are set to be rolled out later this year.

The company also said it now wants a faster FDA review, saying the second part of the study won’t go ahead as planned, but rather used its current data to try and get to market sooner in a gamble it will hope to win.

“Based on the positive part A results and ongoing regulatory discussions, GBT continues to dose part A patients, plus approximately 100 additional patients across all three treatment arms, to gather more data. At this time, GBT does not plan additional enrollment until it completes discussions with the FDA,” it said.

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“Given the well-established association between chronic hemolytic anemia and SCD-related morbidity and mortality, we believe the clinically meaningful increase in hemoglobin and improvement in hemolysis together with the safety profile demonstrated in part A are highly encouraging,” said Ted Love, M.D., president and CEO of GBT.

“Based upon voxelotor’s robust impact on hemolytic anemia, we believe it meets the standard for accelerated approval, and we look forward to providing further updates on our regulatory discussions as soon as possible, but no later than year-end. We are grateful to the patients and families who have participated in our clinical studies, allowing us to potentially deliver this transformative therapy to the SCD community.”

Its shares dropped around 12% in premarket trading before levelling out after a very brief surge when the data first hit. When the markets opened, it was trading down 8% on the news.