BURLINGTON, N.C., April 22, 2026

Labcorp announced the nationwide availability of the FDA-approved PD-L1 IHC 22C3 pharmDx companion diagnostic, developed by Agilent Technologies, to identify patients with platinum-resistant ovarian cancer eligible for treatment with KEYTRUDA® (pembrolizumab) from Merck & Co., Inc.. This milestone represents a critical advancement in precision oncology, enabling clinicians to rapidly match patients with targeted immunotherapy options and improve treatment outcomes in a difficult-to-treat cancer population.

Companion Diagnostic Expands Targeted Treatment Access

The PD-L1 IHC 22C3 pharmDx test is the only FDA-approved companion diagnostic designed to detect PD-L1 expression in ovarian cancer, helping identify patients who may benefit from KEYTRUDA and KEYTRUDA QLEX™, the first PD-1 inhibitors approved as part of a complete treatment regimen for platinum-resistant ovarian cancer.

Approximately 80% of ovarian cancer patients experience recurrence, and many develop resistance to platinum-based chemotherapy, leading to limited treatment options and poor survival outcomes. By enabling accurate and timely patient identification, Labcorp’s nationwide rollout ensures that eligible patients can access newly approved immunotherapy treatments faster, bridging a critical gap between diagnostic testing and therapeutic intervention.

Supporting FDA-Approved Precision Oncology Approach

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The diagnostic launch follows the recent FDA approval of KEYTRUDA-based regimens, supported by results from the Phase 3 KEYNOTE-B96 (ENGOT-ov65) trial, which demonstrated statistically significant improvements in progression-free survival (PFS) and overall survival (OS) in patients with PD-L1 positive tumors (CPS ≥1).

The integration of the companion diagnostic with therapy ensures a biomarker-driven treatment strategy, allowing clinicians to select patients most likely to respond to immunotherapy. Labcorp’s participation in Agilent’s Early Validation Program enabled rapid readiness, ensuring immediate nationwide access following regulatory approval. This coordinated approach highlights the growing importance of companion diagnostics in enabling personalized medicine and optimizing clinical outcomes..

Enhancing Clinical Decision-Making and Patient Outcomes

By delivering the PD-L1 diagnostic at scale, Labcorp is helping clinicians streamline treatment decisions and improve patient stratification, ensuring that therapies like KEYTRUDA are used effectively and efficiently. The availability of this test supports faster turnaround times, standardized testing protocols, and broader accessibility, which are essential for managing aggressive cancers such as platinum-resistant ovarian cancer. The combination of advanced diagnostics and targeted immunotherapy reflects a shift toward integrated oncology care, where data-driven insights guide treatment pathways.

The initiative underscores Labcorp’s role in advancing precision diagnostics and oncology innovation, supporting healthcare providers in delivering personalized, evidence-based care. As the adoption of companion diagnostics continues to expand, their integration with targeted therapies is expected to transform cancer treatment paradigms, enabling more effective interventions and improved survival outcomes. This development marks a significant step forward in addressing unmet medical needs in ovarian cancer, offering new hope for patients facing limited therapeutic options.

Source: Labcorp press release