A 7-year-old alliance between Celgene and Acceleron is paying off with more promising PhIII data for luspatercept

Jay Backstrom

Just days after hitting its first set of marks in a critically important Phase III study, Acceleron $XLRN and its partners at Celgene $CELG say that their prospective blockbuster luspatercept has rung all the right bells in a pivotal study for beta thalassemia.

Their drug has succeeded in the closely watched BELIEVE study, say investigators, with a “highly statistically significant improvement in the primary endpoint of erythroid response, which was defined as at least a 33% reduction from baseline in red blood cell (RBC) transfusion burden with a reduction of at least 2 units during the protocol-defined period of 12 consecutive weeks, from week 13 to week 24, compared to placebo.”

The researchers added that the drug also hit on statistical significance for all the key secondary endpoint, further building the case they plan to take regulators in the US and Europe.

Acceleron’s stock price jumped 11% in after-market trading.

The drug is designed to spur the production of red blood cells by targeting transforming growth factor-beta proteins. In the first Phase III the biotechs says that the drug also significantly helped patients with myelodysplastic syndromes and anemia.

The alliance between Acceleron and Celgene on this anemia drug (initially dubbed ACE-536) dates back 7 years, when Celgene paid $25 million to opt in. Milestones amounted to a modest $217 million.

The positive data have been boosting Celgene at a time the company has struggled to overcome a series of setbacks on their top pipeline prospects. Leerink’s Geoffrey Porges has been leery about the lack of details, holding back any glee until he sees the actual data — perhaps at ASH. Still, he was willing to give the partners a high percentage chance of winning an approval and set sales at 2023 at a likely $1.5 billion on the MEDALIST success. The analyst put out a new note giving the partners a thumbs up on the second Phase III win, noting some big gains for Celgene’s battered stock price in the wake of their success here.

After the positive result for MEDALIST shares of Acceleron have gained ~40% and we believe another 5-10% boost could come now that the second phase III is clearly positive. Celgene’s shares have gained ~9% since the MEDALIST disclosure and we believe this second positive set of news could further improve sentiment in this stock ahead of the Q2 earnings release later this month.

“For decades, the management of beta-thalassemia in adults has been limited to transfusions and iron chelation. Reduction of transfusion burden represents an important step forward for patients with this rare and debilitating blood disease,” said Jay Backstrom, chief medical officer for Celgene.

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