Genome and Transcriptome Biomarkers of Response to Immune Checkpoint Inhibitors in Advanced Solid Tumors

• Published in: Clinical cancer research Vol. 27; no. 1; pp. 202 - 212
• Main Authors: Pender, Alexandra, Titmuss, Emma, Pleasance, Erin D, Fan, Kevin Y, Pearson, Hillary, Brown, Scott D, Grisdale, Cameron J, Topham, James T, Shen, Yaoqing, Bonakdar, Melika, Taylor, Gregory A, Williamson, Laura M, Mungall, Karen L, Chuah, Eric, Mungall, Andrew J, Moore, Richard A, Lavoie, Jean-Michel, Yip, Stephen, Lim, Howard, Renouf, Daniel J, Sun, Sophie, Holt, Robert A, Jones, Steven J M, Marra, Marco A, Laskin, Janessa
• Format: Journal Article
• Language: English
• Published: United States 01.01.2021
• Subjects: Adult; Aged; Aged, 80 and over; Biomarkers, Tumor - genetics; Canada; Clinical Decision-Making; Drug Resistance, Neoplasm - genetics; Female; Follow-Up Studies; Genetic Testing - methods; Humans; Immune Checkpoint Inhibitors - pharmacology; Immune Checkpoint Inhibitors - therapeutic use; Kaplan-Meier Estimate; Male; Middle Aged; Mutation; Neoplasm Staging; Neoplasms - diagnosis; Neoplasms - drug therapy; Neoplasms - genetics; Neoplasms - mortality; Patient Selection; Precision Medicine - methods; Treatment Outcome; Tumor Microenvironment - genetics; Tumor Microenvironment - immunology; Canada
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.CCR-20-1163

Immune checkpoint inhibitors (ICI) have revolutionized the treatment of solid tumors with dramatic and durable responses seen across multiple tumor types. However, identifying patients who will respond to these drugs remains challenging, particularly in the context of advanced and previously treated cancers. We characterized fresh tumor biopsies from a heterogeneous pan-cancer cohort of 98 patients with metastatic predominantly pretreated disease through the Personalized OncoGenomics program at BC Cancer (Vancouver, Canada) using whole genome and transcriptome analysis (WGTA). Baseline characteristics and follow-up data were collected retrospectively. We found that tumor mutation burden, independent of mismatch repair status, was the most predictive marker of time to progression ( = 0.007), but immune-related CD8 T-cell and M1-M2 macrophage ratio scores were more predictive for overall survival (OS; = 0.0014 and 0.0012, respectively). While [programmed death-ligand 1 (PD-L1)] gene expression is comparable with protein levels detected by IHC, we did not observe a clinical benefit for patients with this marker. We demonstrate that a combination of markers based on WGTA provides the best stratification of patients ( = 0.00071, OS), and also present a case study of possible acquired resistance to pembrolizumab in a patient with non-small cell lung cancer. Interpreting the tumor-immune interface to predict ICI efficacy remains challenging. WGTA allows for identification of multiple biomarkers simultaneously that in combination may help to identify responders, particularly in the context of a heterogeneous population of advanced and previously treated cancers, thus precluding tumor type-specific testing.