Tumor Junction Burden and Antigen Presentation as Predictors of Survival in Mesothelioma Treated With Immune Checkpoint Inhibitors

Introduction: The favorable outcomes with immunotherapy for mesothelioma were somewhat unexpected because this tumor has a low tumor mutation burden which has been associated with benefit in other cancers. Because chromosomal rearrangements are common in mesothelioma and have neoantigenic potential, we sought to determine whether they are associated with survival in patients treated with immunotherapy. Methods: Pleural biopsies of mesothelioma after at least one line of therapy were obtained from patients (n = 44) before treatment with nivolumab alone (NCT29908324) or in combination with ipilimumab (NCT30660511). RNA and whole-genome sequencing were performed to identify the junctions resulting from chromosomal rearrangements and antigen processing and presentation gene set expression. Associations with overall survival (OS) were estimated using Cox models. An OS cutoff of 1.5 years was used to distinguish patients with and without durable benefit for use in receiving operating characteristic curves. Results: Although tumor junction burdens were not predictive of OS, we identified significant interactions between the junction burdens and multiple antigen processing and presentation gene sets. The regulation of antigen processing and presentation of peptide antigen gene set revealed an interaction with tumor junction burden and was predictive of OS. This interaction also predicted 1.5-year or greater survival with an area under the receiving operating characteristic curve of 0.83. This interaction was not predictive of survival in a separate cohort of patients with mesothelioma who did not receive immune checkpoint inhibitors. Conclusions: Analysis of structural variants and antigen presentation gene set expression may facilitate patient selection for immune checkpoint inhibitors. (C) 2021 International Association for the Study of Lung Cancer. Published by Elsevier Inc.

Automated summary

This study found that the interaction between tumor junction burdens and antigen presentation gene sets in mesothelioma patients is associated with overall survival, providing further insight into the potential mechanisms of immunotherapy.