Merck is set to present more than 100 oncology studies at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, with the centrepiece data focusing on pembrolizumab — marketed as Keytruda — in combination regimens for gastrointestinal cancers, the company confirmed ahead of Friday's presentation schedule.

Among the most closely watched abstracts is a Phase 3 trial evaluating Keytruda plus chemotherapy in previously untreated metastatic gastric and gastroesophageal junction adenocarcinoma, where investigators reported a median overall survival improvement of approximately 3.2 months over the chemotherapy-alone arm. A second dataset examines a Keytruda-based combination in microsatellite-instability-high colorectal cancer patients who had progressed on prior therapy, with response rates exceeding 40 percent.

Merck's oncology franchise has relied heavily on label expansions to sustain Keytruda's dominance ahead of its key US patent expiry in 2028. The ASCO presentations are widely seen as groundwork for supplemental Biologics License Applications to the FDA, which analysts at Bernstein estimate could be filed within six to nine months of the data readout. The gastric indication in particular would compete directly with Bristol-Myers Squibb's Opdivo, approved in a comparable setting in 2021.

Beyond Keytruda, Merck's ASCO portfolio includes early-stage data on its TIGIT inhibitor co-formulated with pembrolizumab, as well as antibody-drug conjugate programme results from its collaboration with Daiichi Sankyo. Oncologists attending the conference noted that the breadth of Merck's data package reflects a strategy to defend market share on multiple fronts as rivals including AstraZeneca and Roche accelerate their own immuno-oncology combinations.

The ASCO Annual Meeting, running through Sunday in Chicago's McCormick Place convention centre, draws more than 40,000 oncology professionals and is the year's single most consequential forum for cancer drug approvals pipeline visibility. Investor attention will focus on whether Merck's survival data in GI cancers meets the threshold regulators have signalled is necessary for priority review designation, a question the company's chief medical officer is expected to address in a Friday afternoon press briefing.