Rebeca Sanz-Pamplona , Marilena Melas , Asaf Maoz, Stephanie L. Schmit, Hedy Rennert, Flavio Lejbkowicz, Joel K. Greenson, Xavier Sanjuan, Maria Lopez-Zambrano, M. Henar Alonso, Chenxu Qu, Kevin J. McDonnell, Gregory E. Idos, Victor Moreno
Identifying stage II patients with colorectal cancer (CRC) at higher risk of progression is a clinical priority in order to optimize the advantages of adjuvant chemotherapy while avoiding unnecessary toxicity. Recently, the intensity and the quality of the host immune response in the tumor microenvironment have been reported to have an important role in tumorigenesis and an inverse association with tumor progression. This association is well established in microsatellite instable CRC. In this work, we aim to assess the usefulness of measures of T-cell infiltration as prognostic biomarkers in 640 stage II, CRC tumors, 582 of them confirmed microsatellite stable.
Colorectal cancer (CRC) is the third most common cancer worldwide, with more than 1.4 million new cases diagnosed annually . A remarkable feature of CRC is the difference in prognosis of patients diagnosed at early versus late stages of the disease: Stage I and II have low to moderate risk of progression after surgical resection (about 5% and 20%, respectively), whereas patients with stage III have a higher chance of progression [2,3]. Postsurgical adjuvant chemotherapy is the standard of care for stage III patients, but guidelines differ with respect to recommendations for adjuvant therapy for patients with stage II disease. Recognized clinical risk factors for progression (emergency presentation, poorly differentiated tumor, depth of tumor invasion, and adjacent organ involvement) are insufficient to identify those patients with stage II CRC at higher risk of disease progression [4,5]. Recently, as in other cancer types, an effort has been made to develop gene expression signatures useful to identify CRC patients at higher risk of relapse like Oncotype . However, none of these signatures have translated into routine clinical practice. Indeed, a meta-analysis aimed to assess the predictive ability of these signatures revealed that although gene expression signatures may be associated with prognosis, their ability to accurately predict patients’ risk of progression was limited, probably due to the molecular heterogeneity of tumors . Therefore, the identification of new biomarkers to inform clinical decision-making for adjuvant chemotherapy is needed .
Patients and samples
The discovery dataset (named ICO/CLX) included a previously described set of 100 patients with colon cancer diagnosed at stage II and MSS paired normal-tumor samples (Colonomics study, “CLX”: www.colonomics.org; NCBI BioProject PRJNA188510). MSS status was determined by DNA-based microsatellite testing. None of the patients in CLX received adjuvant chemotherapy. All patients had been recruited at the Catalan Institute of Oncology (ICO) and the Bellvitge University Hospital (Barcelona, Spain). Gene expression profiling for 98 of these tumors was available  (GEO repository with accession GSE44076). All fresh frozen (FF) tumors and paired normal mucosa with available DNA (n = 95) were analyzed by means of immunosequencing.
Results from this study demonstrate that tumor lymphocytes, assessed by TCR repertoire quantification based on a sequencing method, are an independent prognostic factor in microsatellite stable stage II CRC. Patients with tumors exhibiting a higher abundance of T cells in the tumor microenvironment had a better prognosis. This result has been replicated in more than 600 tumor samples from 2 countries. A similar association has been previously reported in tumors other than CRC, including breast , ovarian , esophageal squamous cell carcinoma , head and neck squamous cell carcinoma , lung  or gastric cancer , among others.
Citation: Sanz-Pamplona R, Melas M, Maoz A, Schmit SL, Rennert H, Lejbkowicz F, et al. (2020) Lymphocytic infiltration in stage II microsatellite stable colorectal tumors: A retrospective prognosis biomarker analysis. PLoS Med 17(9): e1003292. https://doi.org/10.1371/journal.pmed.1003292
Academic Editor: Steven D. Shapiro, University of Pittsburgh, UNITED STATES
Received: October 14, 2019; Accepted: August 14, 2020; Published: September 24, 2020
Copyright: © 2020 Sanz-Pamplona et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: Data cannot be made publicly available because informed consent forms of the studies did not include public sharing of individual participant data, but data can be made available to interested researchers that meet criteria upon request to IDIBELL Institutional Data Access Committee (contact via email@example.com).
Funding: SBG was supported in part by R01 CA197350, R01 CA081488, P30 CA014089, the Ming Hsieh Institute for Cancer Engineering-Medicine of the University of Southern California, the Jane & Kris Popovich Chair in Cancer Research, and a generous gift from Daniel and Maryann Fong. AM was supported by The Marita and Gary Robb Postdoctoral Fellowship in Oncology. VM was supported by the Agency for Management of University and Research Grants (AGAUR) of the Catalan Government grant 2017SGR723; Instituto de Salud Carlos III, co-funded by FEDER funds –a way to build Europe– grant PI14-00613; Spanish Association Against Cancer (AECC) Scientific Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: SBG was consultant to Myriad Genetics, Fulgent Genetics (with equity), and founder (with equity) in Brogent International LLC. VM was consultant to Bioiberica S.A.U. and Grupo Ferrer S.A., received research funds from Universal DX and is co-investigator in grants with Aniling. HR had employment, equity, ownership, patents and royalties with Adaptive Biotechnologies.
Abbreviations: CI, confidence interval; CLR, Crohn’s-like Lymphoid Reaction; CLX, Colonomics study; CRC, colorectal cancer; DFS, disease-free survival; FF, fresh frozen; HE, hematoxylin and eosin; HR, hazard ratio; ICO, Catalan Institute of Oncology; MECC, Molecular Epidemiology of Colorectal Cancer study; MHC, major histocompatibility complex; MMR, mismatch repair; MSI, microsatellite instability; MSS, microsatellite stable; STL, stromal lymphocyte; TCR, T-cell receptor; TIL, tumor-infiltrating lymphocyte.