Merck's Calderasib Gets FDA's Breakthrough Therapy Tag for NSCLC
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Merck's experimental oral KRAS G12C inhibitor, calderasib, has secured its first FDA Breakthrough Therapy tag. When combined with Keytruda, it targets newly diagnosed metastatic non-small cell lung cancer (NSCLC) harboring KRAS G12C mutations.
Merck announced that the FDA has granted Breakthrough Therapy designation to its investigational oral specific KRAS G12C inhibitor, calderasib (MK-1084), for treating certain patients with newly diagnosed metastatic KRAS G12C-mutant non-small cell lung cancer (NSCLC).
The regulatory body granted Breakthrough Therapy designation to calderasib in combination with Merck’s blockbuster PD-L1 inhibitor Keytruda for the first-line treatment of patients with advanced or metastatic NSCLC with a KRAS G12C mutation and expressing PD-L1. This marks the first Breakthrough Therapy designation for calderasib. The FDA’s Breakthrough Therapy designation is intended to facilitate drug development and expedite the review of therapies for serious diseases with unmet medical needs.
Year to date, shares of Merck have risen 13.6% compared with the industry’s 3.9% increase.
More on MRK’s Calderasib Development Program
The FDA’s Breakthrough Therapy tag for calderasib was based on positive data from the phase I KANDLELIT-001 study. The Breakthrough Therapy designation underscores the potential of calderasib to address a significant unmet need in patients with KRAS G12C-mutated NSCLC.
Merck is developing calderasib in collaboration with Taiho Pharmaceutical and Astex Pharmaceuticals (UK), a wholly owned subsidiary of Otsuka Pharmaceutical. KRAS mutations are among the most common genetic alterations in cancer, occurring frequently in NSCLC, pancreatic, urogenital and colorectal cancers.
Merck’s biggest revenue driver, Keytruda, alone accounts for around 55% of the company’s pharmaceutical sales. The drug recorded sales of $8.0 billion in the first quarter of 2026, increasing 8% year over year. Keytruda sales are rising from continued strong momentum in metastatic indications and rapid uptake across earlier-stage indications. Management expects Keytruda to continue to grow through label expansion into new indications and global markets, while maintaining a strong market share.
