FDA Approves Gomekli as First NF1 Treatment for Adults & Children

The FDA has granted approval to SpringWorks Therapeutics’ Gomekli (mirdametinib) for the treatment of adult and pediatric patients aged two years and older with neurofibromatosis type 1 (NF1).

NF1 is a rare genetic disorder characterized by the development of tumors along nerves in the skin, brain and other parts of the body.

According to SpringWorks, in the US, the disease affects approximately 100,000 children and adults.

Gomekli is specifically indicated for patients who have symptomatic plexiform neurofibromas (PN) not conducive to complete surgical resection.

PNs are a type of tumor associated with NF1 that grow in an infiltrative pattern along the peripheral nerve sheath that can cause significant disfigurement, pain and functional impairment due to their size, location and invasiveness, making complete surgical removal a challenge.

NF1 patients have approximately a 30% to 50% lifetime risk of developing PNs, which can transform into malignant peripheral nerve sheath tumors, an aggressive and potentially deadly disease. An estimated 40,000 people in the US have NF1-PN, the majority of whom are adults who, until now, have not had an approved treatment option.

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Gomekli is the first treatment approved for both adults and children with the disorder. In 2020, AstraZeneca and Merck won FDA approval for Koselugo (selumetinib) to treat NF1-PNs, but its approval was limited to pediatric patients.

Mirdametinib is an oral MEK inhibitor that targets the MEK1 and MEK2 proteins, which are part of the RAS/MAPK pathway implicated in the development of NF1-associated tumors.

The approval of mirdametinib provides a new therapeutic option for patients with NF1-PN, addressing a significant unmet medical need in this population.

“The NF1-PN patient community has a great need for more treatment options,” SpringWorks’ CEO Saqib Islam said in the approval announcement. “With today’s approval, we are honored to serve both adults and children with NF1-PN and provide them with a therapy that has the potential to shrink their tumors and offer meaningful symptomatic relief.”

Related: Neurocrine Biosciences’ Crenessity Approved as First New Treatment in Decades for Rare Genetic Disorder CAH

The FDA’s approval was based on results from the Phase IIb ReNeu trial, a multicenter, single-arm study involving 114 patients (58 adults and 56 pediatric patients) with symptomatic, inoperable NF1-associated PN.

The trial demonstrated that mirdametinib achieved a confirmed overall response rate (ORR) of 41% in adults and 52% in pediatric patients, as assessed by blinded independent central review using volumetric MRI analysis.

Among the participants, 88% of adults and 90% of children with a confirmed response had a response that lasted at least 12 months; and 50% and 48%, respectively, had a response of at least 24 months duration.

SpringWorks said that via multiple patient-reported outcome tools, patients in both cohorts reported early and sustained significant improvements from baseline in pain and quality of life,

The FDA approval further boosts SpringWorks’ value as Merck KGaA moves toward acquiring the Connecticut-based rare disease biotech, recently confirming it is in “advanced discussions” regarding the deal.

Gomekli is SpringWorks’ second FDA approval in the past 15 months. The company, a Pfizer spinout founded in 2017, specializes in developing treatments for rare diseases. In December 2023, it was awarded approval for Ogsiveo (nirogacestat) for the treatment of desmoid tumors, an ultra-rare subtype of non-cancerous soft tissue carcinomas.

SpringWorks has set a wholesale price of $206.25 per mg for Gomekli, and estimates that the monthly treatment cost will average around $22,000 for pediatric patients and $30,000 for adults.

Gomekli received FDA approval under Priority Review, and SpringWorks was awarded a Rare Pediatric Disease Priority Review voucher. Previously, it was granted Orphan Drug and Fast Track designations for the treatment of NF1-PN.

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