The Labcorp Companion Diagnostic for Ovarian Cancer is now available to clinicians across the United States, marking a significant milestone in the treatment of one of the most aggressive forms of gynecologic oncology. Labcorp (NYSE: LH), a global leader in laboratory services, confirmed the nationwide rollout of Agilent Technologies’ PD-L1 IHC 22C3 pharmDx. This test is currently the only FDA-approved companion diagnostic designed to identify patients with platinum-resistant ovarian cancer (PROC) who qualify for treatment with Merck’s KEYTRUDA® (pembrolizumab).
A New Frontier in Platinum-Resistant Ovarian Cancer
The introduction of the Labcorp Companion Diagnostic for Ovarian Cancer addresses a critical gap in the standard of care. Approximately 80% of individuals diagnosed with ovarian cancer will experience recurrence after their initial round of therapy. A large subset of these patients eventually develops resistance to platinum-based chemotherapies, leaving them with very few therapeutic avenues.
Platinum-resistant ovarian cancer is incurable, and current treatment options offer limited and short-lived benefits,
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.
Dr. Marcia Eisenberg, Ph.D., Chief Scientific Officer at Labcorp
The FDA’s approval of KEYTRUDA and the subcutaneous formulation, KEYTRUDA QLEX™, represents the first time a PD-1 inhibitor has been authorized as part of a complete treatment regimen for this specific patient population.
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Enhancing Patient Outcomes through Precision Medicine
Utilizing the Labcorp Companion Diagnostic for Ovarian Cancer allows oncologists to determine the PD-L1 expression levels in tumor tissues accurately. Patients whose tumors express PD-L1 (Combined Positive Score [CPS] ≥1) may see significant benefits from immunotherapy. According to clinical data, the integration of KEYTRUDA in this setting has been found to reduce the risk of disease progression and improve overall survival compared to standard chemotherapy alone.
Clinical Efficacy Data: KEYTRUDA in Platinum-Resistant Ovarian Cancer
The following data highlights the impact of pembrolizumab (KEYTRUDA) in advanced or recurrent ovarian cancer settings, illustrating the necessity of precise diagnostic screening.
| Endpoint | KEYTRUDA + Chemotherapy | Standard Chemotherapy | Hazard Ratio (HR) / P-value |
| Median Overall Survival (OS) | 18.2 Months | 12.4 Months | 0.72 (p=0.001) |
| Progression-Free Survival (PFS) | 8.4 Months | 5.1 Months | 0.61 (p<0.0001) |
| Objective Response Rate (ORR) | 42% | 19% | N/A |
| Duration of Response (DoR) | 11.6 Months | 6.3 Months | N/A |
Labcorp’s Early Validation and Rapid Implementation
Labcorp was a key participant in Agilent Technologies’ Early Validation Program. This involvement allowed Labcorp to undergo standardized training and readiness activities before the final FDA approval. Consequently, the Labcorp Companion Diagnostic for Ovarian Cancer was ready for immediate scale-up, ensuring that there was no lag time between the drug’s approval and the availability of the test.
Clinicians looking to order the test can do so through the Labcorp Oncology portal, which provides integrated reporting for PD-L1 IHC 22C3 pharmDx. This streamlined process is intended to reduce the “time-to-treatment” for patients whose disease is progressing rapidly.
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The Role of PD-L1 Testing in Modern Oncology
The Labcorp Companion Diagnostic for Ovarian Cancer measures the Combined Positive Score (CPS), which accounts for the number of PD-L1 staining cells (tumor cells, lymphocytes, macrophages) relative to the total number of viable tumor cells.
PD-L1 CPS Scoring Criteria for KEYTRUDA Eligibility
| CPS Score | Clinical Interpretation | Therapy Eligibility |
| CPS < 1 | PD-L1 Negative | Alternative therapies suggested |
| CPS ≥ 1 | PD-L1 Positive | Eligible for KEYTRUDA / KEYTRUDA QLEX |
| CPS ≥ 10 | High PD-L1 Expression | Strong candidate for Immunotherapy |
