Late-stage trial results for Global Blood Therapeutics’ sickle cell disease therapy, released on Wednesday, were mostly positive.
Patients on the therapy, called voxelotor, showed a statistically significant improvement on the trial’s primary endpoint, measuring an increase in the oxygen-transporting protein hemoglobin, compared with the placebo.
And a majority of patients — 58% — on the higher dose of voxelotor demonstrated an increase in hemoglobin after 12 weeks of treatment, relative to 9% of patients on the placebo. That’s also better than a 35% response rate that the company had discussed with the Food and Drug Administration.
Those results came from Part A of the of the phase 3 HOPE study, which stands for Hemoglobin Oxygen Affinity Modulation to Inhibit HbS PolymErization.
And hope is the right word here. Though the trial was intended to continue, Global Blood Therapeutics GBT, +23.51% is betting that results so far are enough to get the drug an accelerated approval from the FDA. What’s more, though the company will continue to dose some patients, it won’t be enrolling any more individuals until it’s done speaking with the FDA.
“We know that the outcomes for sickle cell patients are terrible. They will ultimately lose their organs and they will ultimately die, about three decades earlier than they should,” said Chief Executive Ted Love on a Wednesday conference call. The company’s results so far should be enough for an initial approval, and would be followed up by additional studies regarding clinical benefit, he said.
The gamble has sent company shares swinging wildly on Wednesday, first down 5% in the morning and now up nearly 10% in heavy afternoon trade.
If the FDA doesn’t approve voxelotor, pausing enrollment could set Global Blood Therapeutics’ timeline back, perhaps significantly so. And even if it does, not enough data could cause problems down the road.
haodongvli@haodongvli
Sickle cell anemia is an inherited condition that causes patients’ red blood cells to become shaped like sickles, preventing blood flow and causing painful attacks, fatigue, organ damage, stroke and more. The rare disease affects predominantly African-Americans in the U.S., and there are few treatment options.
Lately, though, there’s been a surge of development. Other companies working to develop a sickle cell disease drug include pharmaceutical giants PfizerPFE, -0.33% and Novartis NVS, -1.26% . Gene therapy/editing approaches are in the works from bluebird bio Inc. BLUE, -1.73% and Vertex PharmaceuticalsVRTX, -2.21% /CRISPR Therapeutics CRSP, -4.12% .
Love told MarketWatch earlier this year that the company planned to enroll about 400 patients total in the pivotal trial, and expected to complete drug development in the first half of 2019. By contrast, under the company’s latest plan, about 270 patients will have been dosed with voxelotor, Love said on Wednesday.
The decision to pause enrollment was also the company’s own, Love emphasized on the call, due to a “technical issue” regarding the trial’s protocol and the amount of patients that could be enrolled in Part B.
The company plans to give more information about discussions with regulators “as soon as possible, but no later than year-end,” Love said.
The early phase 3 results also weren’t wholly positive.
Painful attacks that can last hours or weeks, called vaso-occlusive crises, are a major symptom of sickle cell anemia. With few treatment options available, these crises can make patients’ lives miserable.
But Global Blood Therapeutics couldn’t report that there were statistically fewer such episodes “due to limited patient follow-up” in the trial. But there were “numerically fewer” ones in both groups of patients on the drug, the company said, as compared with the placebo.
Andy Biotech@AndyBiotech$GBT Hemoglobin response and hemolysis markers hit largely expectedVOC: numerically fewer episodes but no numbers or p-value provided (presumably no strong trend?)PRO: total bustSafety: no detailsOverall believe below street expectation…
Global Blood Therapeutics’ Love has sought to minimize this by saying that vaso-occlusive crises are less important than the disease itself, specifically the possibility of preventing organ failure and patients’ early deaths.
“We’re more concerned with the transformative outcomes that we believe voxelotor can produce,” Love said. The company does believe the drug can reduce the crises, he added, though there isn’t data for it.
Meanwhile, patient-reported outcomes — a secondary endpoint for the clinical trial — “were difficult to interpret due to low baseline symptom scores and high inter-subject and intra-subject variability,” the company said, so now it doesn’t plan to use the result as a key secondary endpoint.
Global Blood Therapeutics shares have dropped nearly 11% over the last three months, compared with a 4% rise in the S&P 500 SPX, -0.34% and a 1.8% rise in the Dow Jones Industrial Average DJIA, -0.20%
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