Table 1. PPA and NPA for each of the PD-L1 IHC assays using the 22C3 antibody concentrate on the Dako ASL48 and VENTANA BenchMark ULTRA platforms (LDTs) relative to the PD-L1 IHC 22C3 pharmDx kit on the Dako ASL48 platform (gold standard).
| LDT | TPS cut point | Pathologist | pharmDx NPA | pharmDx PPA | Total agreement |
|---|---|---|---|---|---|
| 22C3 on Dako ASL48 | ≥1% | A | 66/66 (100%) | 54/54 (100%) | 120/120 (100%) |
| B | 66/66 (100%) | 54/54 (100%) | 120/120 (100%) | ||
| C | 66/66 (100%) | 54/54 (100%) | 120/120 (100%) | ||
| 22C3 on VENTANA BenchMark ULTRA | ≥1% | A | 66/66 (100%) | 54/54 (100%) | 120/120 (100%) |
| B | 66/66 (100%) | 54/54 (100%) | 120/120 (100%) | ||
| C | 66/66 (100%) | 54/54 (100%) | 120/120 (100%) | ||
| 22C3 on Dako ASL48 | ≥50% | A | 91/91 (100%) | 29/29 (100%) | 120/120 (100%) |
| B | 91/91 (100%) | 29/29 (100%) | 120/120 (100%) | ||
| C | 90/90 (100%) | 30/30 (100%) | 120/120 (100%) | ||
| 22C3 on VENTANA BenchMark ULTRA | ≥50% | A | 91/91 (100%) | 29/29 (100%) | 120/120 (100%) |
| B | 91/91 (100%) | 29/29 (100%) | 120/120 (100%) | ||
| C | 90/90 (100%) | 29/30 (97%) | 119/120 (99%) |
PPA, positive percentage agreement; NPA, negative percentage agreement; IHC, immunohistochemistry; LDT, laboratory-developed test; ASL48, Autostainer Link 48; PD-L1, programmed death ligand 1; TPS, tumour proportion score.