Rigel scores green light in AML just 4 months after buying asset from Forma

Four months ago, Rigel Pharmaceuticals spent just $2 million—plus ponying up another $233 million in potential milestones—to acquire Forma Therapeutics’ leukemia drug Rezlidhia.

On Thursday, Rigel got Rezlidhia across the finish line, more than two months ahead of its FDA target date of Feb. 15. The endorsement is for adults with relapsed or refractory acute myeloid leukemia (AML) with a specific genetic mutation—isocitrate dehydrogenase-1 (IDH1)—as detected by Abbott’s Real Time IDH1 diagnostic tool. Rezlidhia is an oral treatment that binds and inhibits mIDH1 to reduce hydroxygutarate levels and restore normal differentiation of myeloid cells.

Rigel’s shares had dropped 74% this year, but had rebounded 40% by late Friday morning. Just 10 days ago, the company received a letter from Nasdaq notifying the company that it did not meet its listing requirement as its share price had dipped below the $1.00 standard for 30 straight days.

The nod was based on a phase 2 study that showed Rezlidhia produced a 35% complete remission rate, with a median duration of 26 months, which “appears to be longer than currently available treatment options,” Jorge Cortes, M.D., the director of the Georgia Cancer Center and trial investigator, said in a release.

“Rezlidhia provides a new and important, oral therapy option for patients who typically have a poor clinical outcome,” Rigel’s CEO Raul Rodriguez, said in the release. “Additionally, this approval greatly strengthens and expands Rigel's commercial hematology-oncology portfolio.”

Rigel’s other product on the market, Tavalisse, for the rare bleeding disorder immune thrombocytopenic purpura, was approved in 2018. It generated sales of $63 million in 2021, for a 2% increase from the prior year.

The green light for Rezlidhia sets Rigel up to compete with Servier’s Tibsovo, which the FDA blessed as a monotherapy in 2018, when Agios owned the asset. Last year, Servier acquired the company in a $1.8 billion purchase. Then this May, Sevier scored an FDA go-ahead for Tibsovo as a combo agent along with Bristol Myers Squibb’s chemotherapy Vidaza as a first-line treatment.

Sevier did not report a 2021 sales figure for Tibsovo but said when it gained the drug that it expected to make $170 million after Agios collected $120 million in 2020.

Another IDH inhibitor, BMS’ Idhifa—which also Agios developed—won FDA's endorsement in 2017 for R/R AML with the IDH2 mutation.