The primary catalyst for the stock’s strong upward movement today is a major regulatory victory. The U.S. Food and Drug Administration (FDA) approved Keytruda and Keytruda Qlex, in combination with Gilead Sciences’ antibody-drug conjugate Trodelvy, for the first-line treatment of adult patients with advanced or metastatic triple-negative breast cancer (TNBC) whose tumors express PD-L1. This landmark decision marks the first time a PD-1 inhibitor has been approved in combination with a Trop-2-directed antibody-drug conjugate for this aggressive and hard-to-treat cancer. Given that Keytruda is the cornerstone of the company’s oncology franchise, this expanded indication significantly boosts its long-term revenue pipeline and reinforces…