Dataset Information

PD-L1 Immunohistochemistry Assay Comparison in Atezolizumab plus nab-Paclitaxel-Treated Advanced Triple-Negative Breast Cancer.

ABSTRACT:

Background

In the Phase III IMpassion130 study, atezolizumab plus nab-paclitaxel (A+nP) showed clinical benefit in advanced/metastatic triple-negative breast cancer (TNBC) patients who were programmed death-ligand 1 (PD-L1) + (tumor-infiltrating immune cells [IC] ≥1%) using the SP142 immunohistochemistry (IHC) assay. Here we evaluate 2 other PD-L1 assays for analytical concordance with SP142 and patient-associated clinical outcomes.

Methods

Samples from 614 patients (68.1% of intention-to-treat population) were centrally evaluated by IHC for PD-L1 status on IC (VENTANA SP142, SP263, Dako 22C3) or as a combined positive score (CPS; 22C3).

Results

Using SP142, SP263, and 22C3 assays, PD-L1 IC ≥ 1% prevalence was 46.4% (95% confidence interval [CI] = 42.5-50.4%), 74.9% (95% CI = 71.5-78.3%), and 73.1% (95% CI = 69.6-76.6%), respectively; 80.9% were 22C3 at CPS ≥1. At IC ≥ 1% (+), the analytical concordance between SP142 and SP263 and 22C3 was 69.2% and 68.7%, respectively. Almost all SP142+ cases were captured by other assays (double positive), but several SP263 + (29.6%) or 22C3 + (29.0%) cases were SP142- (single positive). A+nP clinical activity vs placebo+nP in SP263+ and 22C3+ patients (progression-free survival [PFS] hazard ratios [HRs] = 0.64-0.68; overall survival [OS] HRs = 0.75-0.79) was driven by double-positive (PFS HRs = 0.60-0.61; OS HRs = 0.71-0.75) rather than single-positive cases (PFS HRs = 0.68-0.81; OS HRs = 0.87-0.95). Concordance for harmonized cutoffs for SP263 (IC ≥ 4%) and 22C3 (CPS ≥10) to SP142 IC ≥ 1% was subpar (approximately 75%).

Conclusions

22C3 and SP263 assays identified more patients as PD-L1 + (IC ≥ 1%) than SP142. No inter-assay analytical equivalency was observed. Consistent improved A+nP efficacy was captured by the SP142 PD-L1 IC ≥ 1% subgroup nested within 22C3 and SP263 PD-L1 + (IC ≥ 1%) populations.

SUBMITTER: Rugo HS

PROVIDER: S-EPMC8634452 | biostudies-literature |

REPOSITORIES: biostudies-literature

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