Labcorp announced the nationwide availability of Agilent Technologies’ PD-L1 IHC 22C3 pharmDx, the only FDA-approved companion diagnostic designed to identify patients with platinum-resistant ovarian cancer who may be eligible for Merck’s Keytruda treatment. According to PharmaBiz.com, this milestone represents a crucial breakthrough for patients facing one of the most challenging forms of ovarian cancer, finally offering a pathway to identify those who could benefit from newly approved immunotherapy options.
The Ovarian Cancer Crisis
Ovarian cancer remains devastatingly difficult to treat, with approximately 80% of patients experiencing recurrence following initial therapy. Even more concerning, many of these patients develop resistance to platinum-based chemotherapy, the traditional backbone of ovarian cancer treatment, leaving them with severely limited options and poor survival prospects. Platinum-resistant ovarian cancer is particularly aggressive and incurable with current conventional therapies, making the emergence of new treatment strategies urgently needed.
A New Hope
In February 2026, the FDA approved Keytruda (pembrolizumab) and Keytruda Qlex (pembrolizumab and berahyaluronidase alfa-pmph) as the first-ever PD-1 inhibitors for platinum-resistant ovarian cancer. These immunotherapy options represent a paradigm shift, offering meaningful clinical benefits including reduced risk of disease progression and improved overall survival—outcomes that were previously unattainable for this patient population.
The Diagnostic Advantage
Before patients can access these life-changing therapies, clinicians need a reliable way to identify who will benefit most. The PD-L1 IHC 22C3 pharmDx companion diagnostic fills this critical gap by measuring programmed death-ligand 1 (PD-L1) expression in tumor samples. This standardized test allows healthcare providers to rapidly and accurately identify eligible patients, enabling faster treatment initiation for those who could benefit most from Keytruda therapy.
Dr. Marcia Eisenberg, chief scientific officer at Labcorp, emphasized the significance of this diagnostic availability, noting that platinum-resistant ovarian cancer currently offers “limited and short-lived benefits” despite being one of the most challenging malignancies. By making the diagnostic accessible nationwide, Labcorp is helping bridge the gap between diagnosis and treatment opportunity.
Swift Path to Accessibility
Labcorp’s rapid nationwide rollout was facilitated through participation in Agilent Technologies’ Early Validation Programme. Through standardized training and comprehensive readiness activities, Labcorp prepared its laboratory network to implement testing immediately following FDA approval, ensuring minimal delays between diagnostic availability and patient access.
Clinical Significance
The combination of FDA-approved immunotherapy with an FDA-approved companion diagnostic represents best-practice precision medicine. This coordinated approach ensures that only patients most likely to benefit receive treatment, optimizing therapeutic outcomes while reducing unnecessary exposure for those unlikely to respond.
Looking Forward
For platinum-resistant ovarian cancer patients and their families, the convergence of breakthrough immunotherapy with accurate diagnostic testing offers genuine hope. Labcorp’s nationwide availability of PD-L1 IHC 22C3 pharmDx removes geographic barriers and ensures that patients across the United States can quickly determine their eligibility for Keytruda, potentially transforming outcomes in a disease historically defined by limited options and poor prognosis.
