Bortolomeazzi, Keddar, and Montorsi et al. integrated multiomics, histopathologic, and immune-phenotypic data from 738 tumor regions from 29 CRC patients prior to anti-PD-1 therapy to determine the molecular factors associated with the response. TMB below 12 mutations/Mbp predicted resistance to therapy, however, higher TMB failed to predict response. In high TMB patients, response was associated with high clonality of immunogenic mutations, higher cytotoxic and proliferating PD1+CD8+ T cells, low WNT signaling, and higher levels of CD74+PD-L1+ macrophages, which co-located with PD-1+CD8+ T cells and, surprisingly, low B2M expression.
Contributed by Shishir Pant
ABSTRACT
BACKGROUND & AIMS: Colorectal cancer (CRC) shows variable response to immune checkpoint blockade, which can only partially be explained by high tumour mutational burden (TMB). We conducted an integrated study of the cancer tissue and associated tumour microenvironment (TME) from patients treated with Pembrolizumab (KEYNOTE 177 clinical trial) or Nivolumab to dissect the cellular and molecular determinants of response to anti-PD1 immunotherapy. METHODS: We selected multiple regions per tumour showing variable T cell infiltration for a total of 738 regions from 29 patients, divided into discovery and validation cohorts. We performed multi-regional whole exome and RNA sequencing of the tumour cells and integrated these with T-cell receptor sequencing, high-dimensional imaging mass cytometry, detection of PD1-PDL1 interaction in situ, multiplexed immunofluorescence, and computational spatial analysis of the TME. RESULTS: In hypermutated CRCs, response to anti-PD1 immunotherapy was not associated with TMB but with high clonality of immunogenic mutations, clonally expanded T cells, low activation of WNT signalling, deregulation of the interferon gamma pathway and active immune escape mechanisms. Responsive hypermutated CRCs were also rich in cytotoxic and proliferating PD1(+)CD8 T cells interacting with PDL1(+) antigen-presenting macrophages. CONCLUSIONS: Our study clarified the limits of TMB as a predictor of response of CRC to anti-PD1 immunotherapy. It identified a population of antigen-presenting macrophages interacting with CD8 T cells that consistently segregate with response. We therefore concluded that anti-PD1 agents release the PD1-PDL1 interaction between CD8 T cells and macrophages to promote cytotoxic anti-tumour activity.
Author Info: (1) Cancer Systems Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK; School of Cancer and Pharmaceutical Sciences, King's College London, London SE11UL, UK. (2)
Author Info: (1) Cancer Systems Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK; School of Cancer and Pharmaceutical Sciences, King's College London, London SE11UL, UK. (2) Cancer Systems Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK; School of Cancer and Pharmaceutical Sciences, King's College London, London SE11UL, UK. (3) Cancer Systems Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK; School of Cancer and Pharmaceutical Sciences, King's College London, London SE11UL, UK. (4) Cancer Systems Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK; School of Cancer and Pharmaceutical Sciences, King's College London, London SE11UL, UK. (5) Cancer Systems Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK; School of Cancer and Pharmaceutical Sciences, King's College London, London SE11UL, UK. (6) Cancer Systems Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK; School of Cancer and Pharmaceutical Sciences, King's College London, London SE11UL, UK. (7) Cancer Systems Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK; School of Cancer and Pharmaceutical Sciences, King's College London, London SE11UL, UK. (8) Biomedical Research Centre, Guy's and St. Thomas' NHS Trust, London SE1 9RT, UK. (9) Biomedical Research Centre, Guy's and St. Thomas' NHS Trust, London SE1 9RT, UK. (10) State-Dependent Neural Processing Laboratory, The Francis Crick Institute, London NW1 1AT, UK. (11) State-Dependent Neural Processing Laboratory, The Francis Crick Institute, London NW1 1AT, UK. (12) Experimental Histopathology, The Francis Crick Institute, London NW1 1AT, UK. (13) Experimental Histopathology, The Francis Crick Institute, London NW1 1AT, UK. (14) Advanced Sequencing Facility, the Francis Crick Institute, London NW1 1AT, UK. (15) Advanced Sequencing Facility, the Francis Crick Institute, London NW1 1AT, UK. (16) Cancer Evolution and Genome Instability Laboratory Francis Crick Institute, London NW1 1AT, UK; CRUK Lung Cancer Centre of Excellence, UCL Cancer Institute, London WC1E 6DD, UK. (17) Cancer Evolution and Genome Instability Laboratory Francis Crick Institute, London NW1 1AT, UK; CRUK Lung Cancer Centre of Excellence, UCL Cancer Institute, London WC1E 6DD, UK. (18) Cancer Evolution and Genome Instability Laboratory Francis Crick Institute, London NW1 1AT, UK; CRUK Lung Cancer Centre of Excellence, UCL Cancer Institute, London WC1E 6DD, UK. (19) School of Immunology and Microbial Sciences, King's College London, London SE1 9RT, UK. (20) FASTBASE Solutions S.L, Astondo bidea, Kabi 612 Scientific and Technology Park of Bizkaia 48160 Derio, Spain. (21) FASTBASE Solutions S.L, Astondo bidea, Kabi 612 Scientific and Technology Park of Bizkaia 48160 Derio, Spain; Cell Biophysics Laboratory, Ikerbasque, Basque Foundation for Science, Research Centre for Experimental Marine Biology and Biotechnology & Biophysics Institute, University of the Basque Country, Spain; Centre for Therapeutic Innovation, Cell Biophysics Laboratory, Department of Pharmacy and Pharmacology & Department of Physics, University of Bath, Bath, BA2 7AY UK. (22) University Hospitals Birmingham NHS Foundation Trust, Birmingham, B15 2GW. (23) Drug Development Unit, Sarah Cannon Research Institute UK, 93 Harley Street, Marylebone, W1G 6AD London, United Kingdom. (24) Drug Development Unit, Sarah Cannon Research Institute UK, 93 Harley Street, Marylebone, W1G 6AD London, United Kingdom; Department of Oncology, University College Hospital, 235 Euston Road, London NW1 2BU, UK. (25) School of Cancer and Pharmaceutical Sciences, King's College London, London SE11UL, UK; Protein Phosphorylation Laboratory, Francis Crick Institute, 1 Midland Rd, London NW1 1AT, UK. (26) Department of Histopathology, University College London Cancer Institute, London WC1E 6JJ, UK. (27) University College London Hospital NHS Foundation Trust, London NW1 2PG, UK. (28) School of Immunology and Microbial Sciences, King's College London, London SE1 9RT, UK. (29) Cancer Systems Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK; School of Cancer and Pharmaceutical Sciences, King's College London, London SE11UL, UK.
