KEYTRUDA Combination Therapy Gains FDA Approval for Advanced Triple-Negative Breast Cancer

The FDA has approved KEYTRUDA combination therapy with Trodelvy as first-line treatment for adults with unresectable locally advanced or metastatic triple-negative breast cancer whose tumors express PD-L1 at a Combined Positive Score of 10 or greater. This marks the first regulatory nod for a PD-1 inhibitor paired with a Trop-2–directed antibody-drug conjugate in this setting and offers a meaningful delay in disease progression for patients who often never reach later lines of therapy.

Regulatory Milestone Reshapes TNBC Care

KEYTRUDA combination therapy now stands as an evidence-based option that outperformed PD-1 inhibition plus chemotherapy, addressing a critical gap where rapid progression has limited subsequent treatment opportunities.

Trial Evidence Drives Confidence

The approval rests on the KEYNOTE-D19/ASCENT-04 Phase 3 trial, which randomized 443 previously untreated patients with PD-L1–positive advanced disease. Blinded independent central review showed a 35 percent reduction in the risk of progression or death, extending median progression-free survival to 11.2 months versus 7.8 months, with objective response rates of 61 percent versus 55 percent and complete responses in 12 percent versus 8 percent of patients.

Safety Profile Matches Expected Patterns

Serious adverse reactions occurred in 38 percent of patients and fatal events in 3.2 percent, consistent with the known toxicities of each agent. High rates of neutropenia, diarrhea, and fatigue led to dose interruptions in 67 percent of patients and permanent discontinuation of pembrolizumab in 9 percent, allowing clinicians to anticipate and manage supportive-care needs.

Reimbursement and Access Implications

As announced by Merck, these data plus the National Comprehensive Cancer Network category 1 recommendation strengthen the case for value-based reimbursement of KEYTRUDA combination therapy. Health technology assessors and payers will now weigh the incremental benefit of delayed progression and higher response rates against the cost of the antibody-drug conjugate and predictable resource utilization, particularly for younger patients and communities disproportionately affected by triple-negative breast cancer.