SpringWorks Therapeutics' Gomekli (mirdametinib) has received FDA approval for treating adult and pediatric patients (2 years and older) with neurofibromatosis type 1 (NF1) who have symptomatic plexiform neurofibromas (PN) not amenable to complete resection. This marks a significant milestone as Gomekli becomes the first and only medicine approved for both adults and children with this condition.
The FDA's decision was supported by data from the Phase 2b ReNeu trial, a multi-center study that enrolled 114 patients (58 adults and 56 pediatric patients). The trial demonstrated a confirmed objective response rate (ORR) of 41% in adults and 52% in children, as assessed by blinded independent central review. These results highlight the drug's potential to provide meaningful clinical benefit to a patient population with limited treatment options.
Clinical Efficacy and Safety
The ReNeu trial showcased deep and durable tumor volume reductions with a median best percentage change in target PN volume of -41% in adults and -42% in children. Moreover, 88% of adults and 90% of children with a confirmed response experienced a response duration of at least 12 months. The safety profile of Gomekli was deemed manageable, with common adverse events including rash, diarrhea, nausea, and musculoskeletal pain.
Christopher Moertel, M.D., Medical Director Pediatric Neuro-Oncology and Neurofibromatosis Programs at the University of Minnesota, emphasized the importance of this approval, stating, "It was very encouraging in the ReNeu trial to see that GOMEKLI provided deep and durable responses, with a manageable safety profile that enabled patients to stay on therapy. This approval represents an important advance, especially for adults who previously did not have an approved treatment."
Addressing an Unmet Need
NF1 is a genetic disorder affecting approximately 100,000 individuals in the United States. Patients with NF1 face a 30-50% lifetime risk of developing plexiform neurofibromas, tumors that can cause severe disfigurement, pain, and functional impairment. Surgical removal of these tumors is often challenging, with up to 85% considered not amenable to complete resection.
Prior to Gomekli's approval, treatment options for adults with NF1-PN were limited. This new therapy offers a targeted approach to manage the disease, potentially improving the quality of life for a significant number of patients.
Regulatory and Commercial Aspects
Gomekli received Priority Review, Orphan Drug, and Fast Track designations from the FDA, highlighting the urgency and unmet need in this patient population. With the approval, SpringWorks was granted a rare pediatric disease priority review voucher (PRV), which can be used to expedite the review of a future drug application.
SpringWorks anticipates making Gomekli available in the United States within two weeks through a specialty pharmacy and specialty distributor network. The Marketing Authorization Application for mirdametinib is also under review by the European Medicines Agency (EMA), with a decision expected in 2025.
Ongoing Development
SpringWorks is also evaluating mirdametinib in pediatric and young adult patients with low-grade gliomas in a Phase 2 study. Additionally, the company is exploring the potential of brimarafenib, a RAF dimer inhibitor, in combination with Amgen's EGFR inhibitor, panitumumab, in colorectal and pancreatic cancer patients with MAPK pathway mutations.
