2193P - Real-world evidence of the impact of immunotherapy (IT) on overall survival (OS) of patients (p) with malignant pleural mesothelioma (MPM) adjusted for tumor histology

Background

In 1^st-line setting in MPM CheckMate-743 trial demonstrated better outcomes for IT over chemotherapy in p with no-epithelioid histology. However, another trials (MAPS2, DREAM) demonstrated efficacy of IT in all tumors. The objective of this study is to characterize the impact of IT according to histology in p with MPM.

Methods

Clinical records of MPM p treated with IT (anti-PD1/L1) at Vall d´Hebron University Hospital were reviewed. Associations between clinical variables and outcome were assessed with multivariate time-dependent Cox regression models to adjust for inmortal-time bias and histology. Survival data were calculated by the Kaplan-Meier method.

Results

228 p were reviewed: median age 68 years (29-88), males: 70%, performance status (PS)1: 69%, epithelioid: 82%. Median overall survival (OS) of the entire cohort was 21.4 months (m) (CI95% 18-23.8). Epithelioid histology, PS 0, stage 1-2 and treatment with cisplatin were associated with significant improvements in OS (p<0.001). Thirty-six p (16%) were treated with antiPD1/L1 (13 p in 1^st line, 23 p in 2^nd or further lines). In the multivariable time-dependent model, both histology (HR=0.51) and exposure to IT (HR=0.66) had significant impact on OS (P-values <0.1). Patients with epithelioid tumors treated with anti-PD1/L1 at any line had a median OS of 33.1 m (vs 23.8 m for p without IT), while p with non-epithelioid tumors exposed to anti-PD1/L1 had median OS of 19.5 m (vs 14.1 m without IT). In p exposed to IT in 2^nd or further lines, median OS for p with epithelioid tumors treated with IT was 24.2 m (vs 13.7 m in p without IT), and for non-epithelioid cases median OS was 6.6 m and 10.0 m for p treated with or without IT respectively.

Conclusions

In our series of real-word MPM treated with IT we did demonstrate a benefit of IT for MPM p. Considering the prognostic effect of histology and the potential immortal time bias for IT exposure, we demonstrated improved OS for p receiving IT with a trend of higher benefit in epithelioid tumors. Ongoing studies combining checkpoint inhibitors plus chemotherapy are evaluating the impact of histology in the outcomes.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.