FDA Approves Gomekli as First Adult Neurofibromatosis Drug

The US Food and Drug Administration (FDA) has granted approval to Gomekli (mirdametinib), a treatment developed by SpringWorks Therapeutics, for neurofibromatosis type 1 (NF1). This rare genetic condition affects both children and adults. Gomekli is specifically designed for patients with symptomatic plexiform neurofibromas (PN) that are inoperable.

NF1 is a genetic disorder impacting around 100,000 individuals in the United States. The disorder results in alterations to the NF1 gene, which is responsible for coding the protein neurofibromin, a tumor suppressor. People with NF1 have a significant risk, between 30% and 50%, of developing plexiform neurofibromas. These are challenging tumors that grow along the peripheral nerve sheath, often leading to disfigurement, pain, and impaired bodily functions.

In 2020, AstraZeneca's Koselugo (selumetinib) became the first drug approved in the US for NF1-PN, but its use is restricted to children two years of age and older. SpringWorks estimates that about 40,000 people in the US, both adults and children, are affected by NF1-PN.

Both Gomekli and Koselugo function as kinase inhibitors, targeting mitogen-activated protein kinase kinases 1 and 2. These enzymes facilitate cell growth and are particularly active in those with NF1. In the Phase 2b ReNeu trial (NCT03962543), SpringWorks’ Gomekli showed promising results with objective response rates of tumor volume reduction at 41% in adults and 52% in children. Among those who responded to the treatment, 88% of adults and 90% of children experienced positive effects that lasted beyond a year. The drug's safety and tolerability are considered manageable, with common side effects including vomiting, rash, and diarrhea.

Dr. Christopher Moertel, the lead investigator of the trial, highlighted the significant responses seen in both adults and children during the ReNeu trial. He emphasized the importance of this approval, particularly for adults who previously lacked an approved therapeutic option. The safety profile of Gomekli was conducive to continued therapy, providing a new hope for affected individuals.

Gomekli will be available in both capsule and oral suspension forms, and SpringWorks, based in Connecticut, plans to begin its distribution in the US within the next two weeks. Additionally, the drug is under regulatory scrutiny in Europe, with a decision anticipated by the end of the year.

The approval came with a rare pediatric designation, allowing SpringWorks to receive a priority review voucher from the FDA. This voucher enables the company to expedite the review process for another drug candidate, potentially bringing it to market four months earlier than usual. Such vouchers have been sold for over $100 million recently, providing a potential financial boost for the company.

The FDA's approval comes during a period when Merck KGgA, a German pharmaceutical giant, is considering acquiring SpringWorks. According to reports, Merck is in advanced talks with the developer of Gomekli, although no binding agreement has been finalized. If an acquisition deal is reached, it could materialize in a few weeks. Following the news, SpringWorks’ share price surged by 34%, elevating its market value to over $4 billion.