Merck and Gilead Halt Keytruda-Trodelvy Combo Study in Lung Cancer

What happened

Merck and Gilead announced the discontinuation of the Phase 3 KEYNOTE-D46/EVOKE-03 trial evaluating Trodelvy plus Keytruda versus Keytruda alone in previously untreated metastatic non-small cell lung cancer. The decision likely reflects a lack of efficacy benefit or an unfavorable risk-benefit profile for the combination, though no specific data were disclosed. For Merck, this removes one potential avenue to extend Keytruda's franchise via combination therapy, but the impact is muted given Keytruda's already strong monotherapy position. The setback does not alter the fundamental timeline for Keytruda's 2028-2029 patent cliffs or the urgent need to build post-Keytruda revenue pillars through internal launches and acquisitions. Investors should view this as a minor negative that marginally reduces pipeline optionality but does not change the WAIT rating or the need for visible progress on Gardasil-China and new launches.

Implication

Over the long term, this discontinuation removes a potential incremental revenue stream from combination therapy, slightly increasing the burden on other pipeline assets and acquisitions to close the post-2028 revenue gap. However, Keytruda's standalone efficacy remains intact, and the overarching investment case still hinges on execution of restructuring, new launches, and BD clarity. The thesis remains WAIT until we see China Gardasil restart signals and stable 2026 headwind containment.

Thesis delta

The discontinuation of the Keytruda-Trodelvy combo study is a minor negative that trims pipeline optionality but does not change the core investment thesis. The key drivers—Gardasil-China restart, 2026 headwind containment, and post-Keytruda diversification—remain unchanged. This event reinforces the need for Merck to demonstrate organic launch traction and successful BD integration, without altering the WAIT rating or entry/exit levels.