The Food and Drug Administration (FDA) has granted Breakthrough Therapy designation for nirogacestat (SpringWorks Therapeutics) for the treatment of adult patients with progressive, unresectable, recurrent or refractory desmoid tumors or deep fibromatosis.

Desmoid tumors, also known as aggressive fibromatosis or desmoid-type fibromatosis, are rare, generally nonmalignant, soft tissue tumors that are abnormal growths of connective tissue. The tumors are often debilitating and disfiguring with symptoms that vary greatly depending on size and location. The cause of desmoid tumors is unknown and there are no FDA-approved treatments currently available.

Nirogacestat is an oral, selective, small molecule gamma-secretase inhibitor that works by blocking proteolytic activation of Notch receptors. The Company believes Notch signaling plays a vital role in desmoid tumor growth.

The designation was based on data from phase 1 and phase 2 clinical trials that evaluated nirogacestat as monotherapy in 24 patients with desmoid tumors. Results demonstrated a 100% disease control rate as measured by RECIST criteria. Median progression free survival was not reached by the time of publication due to lack of patients progressing on therapy.

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Regarding safety, nirogacestat was generally well-tolerated with the most common adverse events being diarrhea, skin disorders and hypophosphatemia.

The phase 3 DeFi trial is currently investigating nirogacestat in adult patients with desmoid tumors.

“We are committed to pursuing the rapid development of nirogacestat given the important need for new therapies for patients with desmoid tumors and are pleased to receive this Breakthrough Therapy Designation,” said Saqib Islam, CEO of SpringWorks. “We […] will continue to work closely with the FDA with the goal of bringing nirogacestat to patients as quickly as possible.”

The FDA granted nirogacestat Orphan Drug and Fast Track designations in June 2018 and November 2018, respectively.

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