The Food and Drug Administration (FDA) expanded the approval of the first and only companion diagnostic to Keytruda (pembrolizumab) in non-small cell lung cancer (NSCLC), the PD-L1 IHC 22C3 pharmDx assay, according to Agilent Technologies, the diagnostic’s manufacturer.

The assay is now approved to identify a broader range of patients with stage 3 or metastatic NSCLC that qualify for first-line treatment with Keytruda, a targeted anti-PD-1 therapy. The diagnostic was previously approved to identify patients with metastatic NSCLC whose tumors express PD-L1 expression levels of 50% or more and would benefit from first-line treatment with Keytruda.

Patients with stage 3 NSCLC who are not candidates for surgical resection or definitive chemoradiation, those with metastatic NSCLC and patients whose tumors show PD-L1 expression of 1% or more are eligible for first-line treatment, per the updated indication. This will allow pathologists to identify a larger population of previously untreated patients who are now appropriate for first-line treatment with Keytruda.

“Anti-PD-1 therapies are a promising treatment class for many cancer types, and PD-L1 testing provides key information to physicians managing stage 3 or metastatic NSCLC patients,” Sam Raha, president of Agilent’s Diagnostics and Genomics Group, said in a press release. Expanding the use of PD-L1 IHC 22C3 pharmDx “broadens the scope of patients that can be identified for first-line treatment with Keytruda and offers new hope to the many patients diagnosed with stage 3 or metastatic NSCLC,” Raha added.

NSCLC accounts for nearly 85% of all lung cancer diagnoses and carries a five-year survival rate of 15%. PD-L1 is a critical biomarker for response to anti-PD-1 therapy, and pathology labs play a crucial role in identifying patients that are eligible for first-line treatments, the release said.