Equivalence of laboratory-developed test and PD-L1 IHC 22C3 pharmDx across all combined positive score indications

We conducted an analysis across multiple PD-L1 combined positive score (CPS) indications to establish concordance of a 22C3 antibody-based laboratory-developed test (LDT) on the Ventana BenchMark XT or BenchMark ULTRA platform and the regulatory-approved PD-L1 IHC 22C3 pharmDx in cervical cancer (CC), esophageal squamous cell carcinoma (ESCC), head and neck squamous cell carcinoma (HNSCC), triple-negative breast cancer (TNBC), and urothelial carcinoma (UC). Tumor specimens from each tumor type were stained with 22C3 antibody and scored using the 22C3 antibody-based LDT, and scores were compared with those using PD-L1 IHC 22C3 pharmDx. PD-L1 status was measured by the pathologist using CPS as a continuous score and using clinically relevant cutoffs (CC, >= 1 and >= 10; HNSCC, >= 1 and >= 20; ESCC, TNBC, and UC, >= 10). The agreement between the BenchMark platforms and PD-L1 IHC 22C3 pharmDx was assessed by intraclass correlation coefficient (ICC) and a contingency table for clinical interpretation. A total of 522 samples were evaluated for the pan-tumor analysis (CC, n = 77; ESCC, n = 80; HNSCC, n = 126; TNBC, n = 118, UC, n = 121). Most clinical interpretations of PD-L1 status were concordant between the BenchMark XT and PD-L1 IHC 22C3 pharmDx for all five tumor types with regard to negative percentage agreement (NPA; 83-97%), positive percentage agreement (PPA; 86-100%), and overall percentage agreement (OPA; 90-97%); the ICC by tumor type was high (>= 0.88). Importantly, the pan-tumor ICC was 0.95 (95% CI 0.94-0.96). Thirty additional TNBC samples were evaluated using the BenchMark ULTRA and PD-L1 IHC 22C3 pharmDx; the NPA, PPA, and OPA were 100%. The 22C3 antibody-based LDT on Ventana BenchMark XT and BenchMark ULTRA platforms demonstrated high concordance with the regulatory-approved PD-L1 IHC 22C3 pharmDx across multiple tumor types. These findings suggest the comparability of PD-L1 IHC 22C3 pharmDx with an LDT based on the 22C3 antibody.

Automated summary

We analyzed the concordance of a laboratory-developed test (LDT) based on the 22C3 antibody with the regulatory-approved PD-L1 IHC 22C3 pharmDx in multiple tumor types. The LDT showed high agreement with the pharmDx in terms of negative percentage agreement (NPA), positive percentage agreement (PPA), and overall percentage agreement (OPA) across all tumor types. The findings suggest the comparability of the LDT with the regulatory-approved pharmDx.