Merck Shares Rise on Positive Phase 3 Keytruda Trial Data

Shares of Merck (NYSE: MRK) rose 2.8% in pre-market trading Monday after the pharmaceutical giant announced positive results from two separate late-stage clinical trials involving its blockbuster cancer immunotherapy, Keytruda.

Key Clinical Trial Successes

Merck reported that its Phase 3 KEYNOTE-C93 trial met its primary endpoint of progression-free survival (PFS). The study evaluated Keytruda as a standalone treatment (monotherapy) for patients with mismatch repair deficient (dMMR) advanced or recurrent endometrial cancer, demonstrating superiority over standard chemotherapy.

The company also noted a positive trend toward improvement in overall survival, a critical secondary endpoint, at a pre-specified interim analysis. This result adds significant clinical weight to the drug's profile in this indication.

Separately, a Phase 3 study conducted with partner Kelun-Biotech, the OptiTROP-Lung06 trial, also met its primary PFS endpoint. This trial evaluated Keytruda in combination with sacituzumab tirumotecan, a TROP2-targeting antibody-drug conjugate, in patients with a difficult-to-treat form of non-small cell lung cancer. According to the announcement, this is the first global Phase 3 success in this specific patient population, reinforcing Keytruda's foundational role in combination therapies.

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Analyst Outlook and Market Context

The positive clinical data builds investor confidence ahead of Merck's second-quarter 2026 earnings report, scheduled for August 4. The news also follows recent positive commentary from Wall Street analysts.

BMO Capital recently maintained its Outperform rating on the stock and raised its price target to $142. The firm cited the anticipated strong uptake of the subcutaneous formulation of Keytruda, known as Qlex, following its receipt of a permanent J-code for reimbursement.

While a modestly positive broader market provided a supportive backdrop, Monday's move was primarily driven by these company-specific clinical catalysts, which investors see as extending the growth trajectory of the crucial Keytruda franchise.