Second time's a charm for PharmaEssentia as FDA approves Besremi to treat rare blood cancer

FDA Building 2
After a March rejection for PharmaEssentia's Besremi, the Taiwan-based company has alleviated the regulator's concerns and won approval for the drug used to treat a rare blood cancer called polycythemia vera. (FDA)

Eight months after losing its bid for FDA approval of a treatment for a rare blood cancer, PharmaEssentia has alleviated the agency's concerns and gained a green light for Besremi.

The injected drug scored clearance to treat adults with polycythemia vera, which causes a thickening of the blood and affects roughly 6,200 people each year in the United States. The disorder causes overproduction of red blood cells, slowing blood flow and increasing the chance for blood clots, stroke and heart attack.

In March, the FDA sent the Taiwan-based company a complete response letter requesting more information on the instructions for the prefilled syringes used to administer the drug. As a promising sign at the time, the regulator requested no additional data on its clinical profile.

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In addition, PharmaEssentia attributed the FDA's prior rejection to a delay of a preapproval inspection of its manufacturing plant in Taiwan because of COVID-19 pandemic travel restrictions.

Besremi, which won approval in Europe in 2019, becomes the first FDA-approved medicine for polycythemia vera that patients can take regardless of their treatment history. It also is the first interferon drug approved for the disorder. The therapy binds to interferon receptors, triggering processes that reduce red blood cell production in the bone marrow.  

Patients take Besremi every two weeks. If successful in lowering the production of red blood cells after a year, patients can reduce dosing to once per month.

The orphan drug carries a boxed warning detailing the risk of serious effects including aggravation of neuropsychiatric, autoimmune, ischemic and infection disorders. Once starting on the medicine, patients must be monitored closely for signs of these conditions.

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“The reality of living with a rare and chronic cancer like polycythemia vera is that it is often underrecognized and the limited treatments available cannot properly address the disease beyond the symptoms,” Ann Brazeau, the CEO of MPN Advocacy and Education International, said in a release.

Incyte’s Jakafi is approved as a second-line treatment for polycythemia vera, while Besremi is a first-line therapy.