FDA Approves PharmaEssentia’s Besremi for Rare Blood Cancer

Rare Daily Staff

The U.S. Food and Drug Administration has approved PharmaEssentia’s Besremi for adults with essential thrombocythemia, a rare chronic blood cancer in which the bone marrow produces too many platelets.

The approval makes Besremi the first new FDA-approved treatment for the condition in nearly 30 years, according to the company.

Essential thrombocythemia, or ET, is a type of myeloproliferative neoplasm, a group of blood cancers in which the bone marrow produces too many blood cells. In ET, excess platelets can increase the risk of potentially serious blood clots, including strokes, heart attacks, and pulmonary embolisms. Some patients may also experience abnormal bleeding or an enlarged spleen.

Besremi is a long-acting interferon therapy designed to provide sustained disease control. The drug was previously approved for adults with polycythemia vera, another myeloproliferative neoplasm characterized by overproduction of red blood cells.

The expanded approval allows use of Besremi in adults with ET regardless of disease status or genetic subtype, including newly diagnosed people who have not previously received cytoreductive therapy, which is intended to reduce elevated blood-cell counts.

PharmaEssentia said the decision was based on results from the global phase 3 SURPASS-ET study, which compared Besremi with anagrelide in people with ET who had not responded adequately to hydroxyurea or could not tolerate it. The company said Besremi produced higher rates of durable response according to modified European LeukemiaNet criteria, sustained control of blood counts, and fewer thromboembolic events over 12 months of treatment.

Unlike treatments that focus primarily on lowering platelet counts or managing symptoms, PharmaEssentia said Besremi is designed to act on disease-driving cells in the bone marrow. The therapy uses monopegylation technology, which extends the time the drug remains active in the body.

Besremi is expected to be available immediately in the United States. The therapy was also recently approved for ET in Japan and Taiwan.

Like other interferon alfa therapies, Besremi carries a boxed warning for the risk of serious or potentially life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders. It is contraindicated in people with severe depression or a history of suicidal ideation or suicide attempt; hypersensitivity to interferons or any inactive ingredients in the drug; moderate to severe liver impairment; active serious or untreated autoimmune disease; or a history of transplantation while taking immunosuppressive drugs. Patients taking Besremi require regular clinical and laboratory monitoring.

“For nearly 30 years, people living with ET and the physicians treating them have had limited treatment innovation,” said Ruben Mesa, principal investigator of the SURPASS-ET trial and president of Advocate Health’s Cancer National Service Line. “The approval of Besremi provides an important new treatment option that is supported by strong clinical evidence and that also works at the source of the disease rather than solely managing symptoms.”