Labcorp Launches FDA-Approved PD-L1 Test for Keytruda in Ovarian Cancer
Labcorp has begun nationwide testing with the FDA-approved PD-L1 IHC 22C3 pharmDx companion diagnostic to identify platinum-resistant ovarian cancer patients with PD-L1 CPS ≥1 eligible for Merck’s KEYTRUDA and KEYTRUDA QLEX regimens. The rollout leverages Labcorp’s early validation program to ensure immediate clinical access.
1. Launch of Companion Diagnostic
Labcorp is now offering Agilent’s PD-L1 IHC 22C3 pharmDx test nationwide, the only FDA-approved companion diagnostic to detect PD-L1 expression in epithelial ovarian, fallopian tube and primary peritoneal carcinoma. The assay identifies patients with PD-L1 CPS ≥1 who may benefit from pembrolizumab-based regimens.
2. Clinical Impact and Patient Population
Approximately 80% of ovarian cancer cases recur after platinum-based chemotherapy, leading to platinum-resistant disease with limited options. KEYTRUDA and KEYTRUDA QLEX regimens have shown statistically significant improvements in progression-free and overall survival for patients expressing PD-L1 CPS ≥1.
3. Nationwide Rollout and Readiness
Labcorp joined Agilent’s Early Validation Program and completed standardized training to ensure immediate testing readiness following FDA clearance in February 2026. Its network of over 190 central laboratories can now process PD-L1 IHC 22C3 pharmDx tests with rapid turnaround.
4. Potential Financial Upside
Companion diagnostics typically command premium reimbursement rates, and this test could drive incremental oncology testing volume that leverages Labcorp’s capacity. Labcorp served over 85% of new FDA drug approvals in 2025 and performed 750 million patient tests, positioning it to capture significant market share in biomarker testing.