As Acceleron Pharma Inc.’s phase II trial of sotatercept hit its primary endpoint and some key secondary endpoints in significantly reducing pulmonary vascular resistance, the stock (NASDAQ:XLRN) reacted accordingly, gaining 50% on Jan. 28. The stock ended the day at $79.39, up $26.52.
The Cambridge, Mass.-based company’s candidate is a fusion protein aimed at pulmonary arterial hypertension (PAH). The phase II PULSAR trial’s top-line data, taken from patients who were also on PAH-specific therapies, showed sotatercept achieving a statically significant reduction in pulmonary vascular resistance, which was the study’s primary endpoint, at week 24 vs. placebo. More than half the patients were on three or more therapies during the study.
There’s a chance of it becoming a monotherapy for treating PAH, according to Jay T. Backstrom, Acceleron’s executive vice president and head of R&D.
“I think what's critical is to move it up as early as we can in the treatment paradigm,” Backstrom said in Monday evening’s investor call. “And as we do that and gain more data, whether it's monotherapy or combination remains to be seen.”
The double-blind trial also achieved statistically significant improvements in the key secondary endpoints of the six-minute walk distance, amino-terminal brain natriuretic propeptide (NT-proBNP), and World Health Organization functional class.
In the study, 106 patients were randomized to get the placebo, 0.3 mg/kg of sotatercept or 0.7 mg/kg of sotatercept subcutaneously every 21 days in combination with stable background PAH-specific therapies over a 24-week treatment period.
PAH is a rare disease in which constricted pulmonary arteries and high blood pressure strain the heart, reducing physical activity, leading to heart failure and a reduced life expectancy. Although fewer than 200 people in the U.S. are diagnosed with it annually, there’s a market to be had.
“The typical successful PAH medicine will become a $1B drug” within five to 10 years, wrote SVB Leerink’s Geoffrey Porges, “and given the information provided so far, we would expect sotatercept to perform at least in line with the top quartile of such products, if not better, which means that its more realistic revenue potential” is likely to be in the $1.5 billion to $2 billion range by year five and $3 billion in the long term.
Acceleron withheld much of the data, saying more would be revealed later this year at a conference.
Three years ago, Acceleron began evaluating sotatercept PAH patients in a collaboration with Celgene Corp. The drug received orphan drug status for treating PAH patients on Sept. 5, 2019.
Acceleron also has another phase II trial underway using sotatercept, the SPECTRA trial for adults with WHO functional class III PAH. Patients are being enrolled now and the study is expected to conclude in May. Depending upon the results, H.C. Wainwright’s Edward White, writing about the newly released top-line data Monday, noted that sotatercept “could become part of the [standard of care] for patients with WHO functional class II and III PAH.”
In November, Iconovo AB and Crystecpharma Ltd. launched a collaboration to develop dry powder inhaler products for pulmonary fibrosis, cystic fibrosis and pulmonary arterial hypertension. No financial details were released.
In January 2017, Campbell, Calif.-based Vivus Inc. entered an agreement with Selten Pharma Inc., of San Carlos, Calif., for exclusive, worldwide rights to develop and commercialize tacrolimus and ascomycin for treating PAH and related vascular diseases. Vivus has tacrolimus at the phase II stage for PAH. Vivus assumed all development and commercialization responsibilities. Selten assigned Vivus its license to a family of patents owned by the board of trustees of the Leland Stanford Junior University and all rights under a collection of patent applications owned by Selten.
Acceleron, along with Celgene Corp., scored a big win in November when the FDA approved Reblozyl (luspatercept-aamt), an erythroid maturation agent for treating anemia in beta-thalassemia. The FDA gave it priority review approval for patients requiring regular red blood cell transfusions.