In another set of assays, the investigators used the E11340 XP antibody (Cell Signaling Technology) and considered tumors to be strongly positive if more than 50% of cells stained with intensity of 2 or higher (ASCO 2015, abstract 11051).
Here, 24% of primaries were strongly positive. In a multivariate analysis, patients with stage III disease who had high PD-L1 expression in both the primary and node had better disease-free survival (hazard ratio, 0.49; P = .031) and overall survival (HR, 0.46; P = .006).
Among the 53 patients who had paired primary and nodal tumor, PD-L1 staining was concordant in these sites in 89% of patients.
“These data do suggest that PD-L1 status in general in the primary NSCLC predicts the PD-L1 status in metastases as well as in the nodes,” Dr. Mitchell said. “However, if the PD-L1 expression status is critical in the decision to treat metastatic NSCLC with a PD-1 pathway inhibitor, then rebiopsy of a metastasis may be warranted,” he added.
Dr. Sheffield reported that he had no relevant disclosures; Bristol-Myers Squibb Canada performed some of the IHC staining. Dr. Mitchell disclosed ties with AstraZeneca, Roche, Boehringer-Ingelheim, Bristol-Myers Squibb, and MSD. Bristol-Myers Squibb performed IHC staining and some of the scoring.
The conference was sponsored by the International Association for the Study of Lung Cancer.