Abstract 62P
Background
In advanced stage non-small cell lung cancer (NSCLC), tumor proportion score (TPS) is typically used to predict the efficacy of immune checkpoint inhibitors (ICI). However, in other cancer types, the combined positive score (CPS), which covers PD-L1 expression on both tumor and surrounding immune cells, is used. We investigated the predictive value of CPS in comparison to TPS in advanced NSCLC.
Methods
A monocenter retrospective study was performed in advanced NSCLC patients treated with ICI monotherapy between 2015 and 2021. H&E and PD-L1 were stained on baseline tumor biopsies to score PD-L1 by both TPS and CPS. Positivity for TPS and CPS was defined as a score of 1% or above. Progression-free survival (PFS) and overall survival (OS) were assessed for TPS and CPS scores.
Results
Amongst the 187 included patients, PD-L1 positivity was found in 112 patients (59.9%) by TPS and 135 patients (72.2%) by CPS. In terms of PFS, no significant differences were observed between TPS− and TPS+ or CPS− and CPS+ patients (HR 0.86, p = 0.37 and HR 0.72, p = 0.065, respectively). There was no significant difference in OS between TPS− and TPS+ patients (HR 0.81, 95%CI 0.59–1.12, p = 0.20). However, CPS+ patients did show a longer OS than CPS− patients (HR 0.62, 95%CI 0.44–0.87, p = 0.006). OS was superior in both TPS−/CPS+ and TPS+/CPS+ as compared to TPS−/CPS− cases (HR 0.52, p = 0.018 and HR 0.64, p = 0.015, respectively). Cases that were TPS−/CPS+ had a comparable OS to TPS+/CPS+ cases (11.3 vs 9.7 months, p = 0.016).
Conclusions
To our knowledge, this is the largest real-world population study comparing TPS and CPS in NSCLC. We showed that CPS differentiated OS better than TPS in advanced NSCLC patients with ICI monotherapy. Remarkably, this was driven by the performance of the TPS−/CPS+ subgroup, indicating that CPS may be a better predictive biomarker for ICI efficacy. These findings support the notion that ICI also have an anti-cancer efficacy through inhibiting the immune suppressive immune cells in the tumor microenvironment.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
S. Hashemi: Other, Institutional, Other, Research contracts to the institution, outside of the current study: AstraZeneca, Boehringer Ingelheim, BMS, Eli Lilly, Janssen, GSK, MSD, Novartis, Roche, Takeda. All other authors have declared no conflicts of interest.