Labcorp Launches FDA-Approved Companion Diagnostic to Identify Patients with Ovarian Cancer Eligible for KEYTRUDA®

BURLINGTON, N.C., April 22, 2026 /PRNewswire/ -- Labcorp (NYSE: LH), a global leader of innovative and comprehensive laboratory services, today announced the nationwide availability of Agilent Technologies' PD-L1 IHC 22C3 pharmDx, the only companion diagnostic approved by the U.S. Food and Drug Administration (FDA) to identify patients with platinum-resistant ovarian cancer who may be eligible for Merck's KEYTRUDA®.ⁱ KEYTRUDA (pembrolizumab) and KEYTRUDA QLEX™ (pembrolizumab and berahyaluronidase alfa-pmph) are the first FDA-approved PD-1 inhibitors available as part of a complete treatment regimen for eligible patients with platinum-resistant ovarian cancer.ⁱⁱ

Helping Patients Access Critical New Treatment Options
Approximately 80% of individuals with ovarian cancer experience recurrence after initial therapy, and many develop resistance to platinum-based chemotherapy, leading to limited treatment options and poor survival outcomes. The approval of KEYTRUDA and KEYTRUDA QLEX in this setting introduces meaningful new treatment options that have been found to reduce the risk of disease progression and improve overall survival.ⁱⁱⁱ Labcorp's nationwide availability of PD-L1 IHC 22C3 pharmDx enables clinicians to quickly identify patients who may benefit from these newly approved treatments.

"Platinum-resistant ovarian cancer is incurable, and current treatment options offer limited and short-lived benefits for patients—making it one of the most challenging forms of the disease to treat," said Dr. Marcia Eisenberg, Ph.D., chief scientific officer at Labcorp. "By making this companion diagnostic available nationwide, Labcorp is helping clinicians rapidly identify eligible patients and connecting them with a therapy that offers new hope."

Supporting Early Access Following FDA Approvals
Following the FDA's February approval of KEYTRUDA and KEYTRUDA QLEX alongside PD-L1 IHC 22C3 pharmDx,ⁱⁱ Labcorp participated in Agilent Technologies' Early Validation Program to help support rapid testing availability. Through standardized training and readiness activities, Labcorp was prepared to expand nationwide access quickly following approval.

For more information about Labcorp's Oncology solutions, contact us at https://oncology.labcorp.com/contact-us.

About Labcorp
Labcorp (NYSE: LH) is a global leader of innovative and comprehensive laboratory services that helps doctors, hospitals, pharmaceutical companies, researchers and patients make clear and confident decisions. We provide insights and advance science to improve health and improve lives through our unparalleled diagnostics and drug development laboratory capabilities. The company's nearly 71,000 employees serve clients in approximately 100 countries, provided support for more than 85% of the new drugs and therapeutic products approved by the FDA in 2025 and performed more than 750 million tests for patients around the world. Learn more at www.labcorp.com.

KEYTRUDA® is a registered trademark and KEYTRUDA QLEX™ is a registered trademark of Merck Sharp & Dohme LLC., a subsidiary of Merck & Co., Inc., Rahway, NJ, USA

ⁱThe FDA approved the PD-L1 IHC 22C3 pharmDx test from Agilent Technologies as a companion diagnostic that detects PD-L1 expression in epithelial ovarian, fallopian tube, or primary peritoneal carcinoma (EOC), and is indicated as an aid in identifying patients for treatment with KEYTRUDA, Merck's anti-PD-1 therapy.

ⁱⁱThe FDA simultaneously approved KEYTRUDA (pembrolizumab) and KEYTRUDA QLEX (pembrolizumab and berahyaluronidase alfa-pmph) plus paclitaxel, with or without bevacizumab, for the treatment of adults with PD-L1+ (Combined Positive Score [CPS] ≥1), as determined by an FDA-authorized test, platinum-resistant epithelial ovarian, fallopian tube or primary peritoneal carcinoma, who have received one or two prior systemic treatment regimens.

ⁱⁱⁱThe Phase 3 KEYNOTE‑B96 (ENGOT‑ov65) trial showed KEYTRUDA plus paclitaxel, with or without bevacizumab, demonstrated a statistically significant and clinically meaningful improvement in progression-free survival (PFS), the trial's primary endpoint, and overall survival (OS), a key secondary endpoint, for patients with platinum-resistant recurrent ovarian cancer whose tumors expressed PD-L1 (CPS ≥1) compared to placebo plus paclitaxel, with or without bevacizumab.

SOURCE Labcorp