SpringWorks Gets CHMP Nod for Mirdametinib in Rare Disease

SpringWorks Therapeutics (SWTX) received a positive CHMP opinion for mirdametinib, recommending conditional marketing authorization in the EU for symptomatic, inoperable plexiform neurofibromas in patients with neurofibromatosis type 1, mirroring its FDA approval as Gomekli in the U.S. earlier this year where it generated $4.9 million in Q1 sales. The positive news comes as Merck KGaA is set to acquire SpringWorks for $3.9 billion, gaining access to Ogsiveo, a desmoid tumor treatment with $44.1 million in Q1 U.S. sales, and potentially expanding its market reach pending EMA review.

Analysis

SpringWorks Therapeutics (SWTX) has received a significant regulatory endorsement with the European Medicines Agency's CHMP issuing a positive opinion for conditional marketing authorization of mirdametinib for NF1-PN, a rare genetic disorder. This development, targeting both pediatric and adult patients, positions mirdametinib to potentially become the first and only approved therapy for this condition in the EU, with a European Commission decision anticipated in Q3 2025. This mirrors the drug's recent FDA approval in February 2025 under the brand name Gomekli, which has already begun contributing to revenue with $4.9 million in U.S. sales in Q1 2025. Concurrently, SpringWorks is advancing Ogsiveo, its FDA-approved treatment for desmoid tumors that generated $172 million in 2024 and $44.1 million in Q1 2025, towards potential EU approval with a CHMP opinion expected in Q2 2025. These positive pipeline developments occur alongside the pending acquisition of SpringWorks by Merck KGaA for $47 per share in cash, a deal valued at approximately $3.9 billion and expected to close in the second half of 2025. This acquisition is poised to leverage Merck KGaA's resources for global market expansion of SpringWorks' rare tumor treatments. The company's stock has reflected this positive trajectory, rising 28.6% year-to-date, in stark contrast to the industry's 5.5% decline.

Key Decisions for Investors

• Investors should primarily focus on the progression and successful completion of the pending acquisition by Merck KGaA at $47 per share, as this largely defines the expected return for SWTX shares in the near term.
• The positive CHMP opinion for mirdametinib and anticipated EU regulatory milestones for Ogsiveo de-risk SpringWorks' asset portfolio, supporting the strategic rationale for the Merck KGaA acquisition and increasing the likelihood of deal completion.
• Given that SpringWorks' shares have already appreciated 28.6% year-to-date, largely factoring in these positive developments and the acquisition premium, existing shareholders might view the $47 per share acquisition price as a cap on further significant upside.