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Original Research

TIME (Tumor Immunity in the MicroEnvironment) classification based on tumor CD274 (PD-L1) expression status and tumor-infiltrating lymphocytes in colorectal carcinomas

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Article: e1442999 | Received 12 Dec 2017, Accepted 15 Feb 2018, Published online: 19 Mar 2018

ABSTRACT

Inhibitors targeting the PDCD1 (programmed cell death 1, PD-1) immune checkpoint pathway have revolutionized cancer treatment strategies. The TIME (Tumor Immunity in the MicroEnvironment) classification based on tumor CD274 (PDCD1 ligand 1, PD-L1) expression and tumor-infiltrating lymphocytes (TIL) has been proposed to predict response to immunotherapy. It remains to be determined clinical, pathological, and molecular features of TIME subtypes of colorectal cancer. Using 812 colon and rectal carcinoma cases from the Nurses' Health Study and Health Professionals Follow-up Study, we examined the association of tumor characteristics and survival outcomes with four TIME subtypes (TIME 1, CD274low/TILabsent; TIME 2, CD274high/TILpresent; TIME 3, CD274low/TILpresent; and TIME 4, CD274high/TILabsent). In survival analyses, Cox proportional hazards models were adjusted for potential confounders, including microsatellite instability (MSI) status, CpG island methylator phenotype (CIMP) status, LINE-1 methylation level, and KRAS, BRAF, and PIK3CA mutation status. TIME subtypes 1, 2, 3 and 4 had 218 (27%), 117 (14%), 103 (13%), and 374 (46%) colorectal cancer cases, respectively. Compared with TIL-absent subtypes (TIME 1 and 4), TIL-present subtypes (TIME 2 and 3) were associated with high-level MSI, high-degree CIMP, BRAF mutation, and higher amounts of neoantigens (p < 0.001). TIME subtypes were not significantly associated with colorectal cancer-specific or overall survival. In conclusion, TIL-present TIME subtypes of colorectal cancer are associated with high levels of MSI and neoantigen load, supporting better responsiveness to cancer immunotherapy. Further studies examining tumor molecular alterations and additional factors in the tumor microenvironment may inform development of immunoprevention and immunotherapy strategies.

Introduction

Immunotherapy has emerged in recent years as an attractive therapeutic modality in cancer management.Citation1-Citation3 In particular, immune checkpoint inhibitors that block the PDCD1 (programmed cell death 1, PD-1) or CD274 (PDCD1 ligand 1, PD-L1) protein have shown great promise in treating various malignancies with durable clinical remissions.Citation4-Citation8 How to effectively identify patients who would derive clinical benefits from immune checkpoint blockade therapy has therefore become a clinical question of paramount importance.

The TIME (Tumor Immunity in the MicroEnvironment) classification system has been proposed as a first-step framework to predict immunotherapeutic response based on cross-classified levels of tumor CD274 (PD-L1) expression (low vs. high) and tumor-infiltrating lymphocytes (TIL, absent vs. present).Citation9-Citation12 However, how this proposed scheme may correlate with tumor molecular features and clinical outcomes in general and in colorectal cancer remains to be determined. The CD274 protein expressed on cancer cells impairs T cell-mediated tumor-specific immune response by binding to PDCD1 (PD-1) on T cells.Citation5,Citation7 In colorectal cancer, tumor CD274 expression has been inversely correlated with FOXP3+ regulatory T cells in tumor, suggesting mutually exclusive immunosuppressive mechanisms.Citation13 Immune reaction plays a key role in suppressing tumor development and progression,Citation14-Citation16 and high-level infiltrates of lymphocytes in colorectal cancer have been associated with better clinical outcomes.Citation17-Citation22 Four tumor subtypes can be created based on the TIME framework,Citation9-Citation12 including the CD274high/TILpresent subtype (TIME 2) which generally responds to immunotherapy, the CD274low/TILpresent subtype (TIME 3) which suggests presence of other suppressor pathways in immune tolerance, the CD274high/TILabsent subtype (TIME 4) which indicates intrinsic induction of the CD274 pathway, and the CD274low/TILabsent subtype (TIME 1) which reflects immune “ignorance.”

The TIME model has been developed based on the findings in melanoma,Citation9 and has been applied to other tumor types.Citation23-Citation26 The prevalence and clinical implications of different TIME subtypes likely vary by tumor-specific genetic aberrations and oncogenic drivers as well as other factors defining the tumor microenvironment.Citation26,Citation27 In colorectal cancer, it is known that high-level microsatellite instability (MSI) and resultant frameshift mutations are associated with abundant immunogenic peptides (“neoantigens”), leading to increased likelihood of clinical benefits from immune checkpoint blockade.Citation8,Citation28-Citation30 The carcinogenesis of colorectal carcinoma, however, is by itself a fairly heterogeneous process which involves stepwise accumulation of multiple genetic and epigenetic aberrations, as well as complex interactions with environmental exposures and host features.Citation31-Citation34 Phenotypic profiling of colorectal carcinomas that would respond to immunotherapy would therefore likely require consideration of multiple factors in association with TIME categories to precisely predict tumor immune resistance.Citation35,Citation36

Using a molecular pathological epidemiology database derived from two large prospective cohort studies in the U.S., we examined the association of TIME subtypes of colorectal cancer with clinical, pathological, and molecular characteristics, and patient survival.

Results

Among 812 colorectal carcinoma cases with available data on tumor CD274 (PD-L1) expression status and TIL, TIME subtypes 1, 2, 3 and 4 had 218 (27%), 117 (14%), 103 (13%), and 374 (46%) cases, respectively. summarizes clinical, pathological, and molecular characteristics of colorectal cancer cases according to TIME subtypes. Compared with TIL-absent subtypes (TIME 1 and 4), TIL-present subtypes (TIME 2 and 3) were statistically significantly associated with tumor location at the proximal colon, high-level MSI, high-degree CpG island methylator phenotype (CIMP), high-level long interspersed nucleotide element-1 (LINE-1) methylation, BRAF mutation, negative nuclear CTNNB1 expression, and high neoantigen load (p < 0.001 with adjusted α level of 0.003). Interestingly, TIL-present subtypes were more likely to have more poorly-differentiated tumors but lower disease stage (p < 0.003). There were no significant differences in characteristics by tumor CD274 expression status in strata of levels of TIL (p > 0.01 with adjusted α level of 0.003).

Table 1. Clinical, pathological, and molecular characteristics of colorectal cancer cases according to TIME (Tumor Immunity in the MicroEnvironment) subtypes based on tumor CD274 (PD-L1) expression status and tumor-infiltrating lymphocytes (TIL).

We also examined the association of TIME subtypes with colorectal cancer survival. During the median follow-up time of 12.1 years (interquartile range, 8.4–16.1 years) for all censored cases, there were 479 all-cause deaths, including 247 colorectal cancer-specific deaths. shows Kaplan-Meier survival curves of colorectal cancer cases by TIME subtypes. In multivariable Cox regression analyses, TIME subtypes were not statistically significantly associated with colorectal cancer-specific or overall survival ( and Table S1). Compared with TIME subtype 1, multivariable-adjusted hazard ratios for colorectal cancer-specific mortality were 0.61 [95% confidence interval (CI), 0.37–1.01] for subtype 2, 0.76 (95% CI, 0.46–1.25) for subtype 3, and 0.93 (95% CI, 0.69–1.26) for subtype 4. We did not observe a statistically significant interaction between tumor CD274 expression status and TIL in relation to cancer-specific or overall survival (p interaction > 0.67).

Figure 1. Kaplan-Meier survival curves of colorectal cancer patients according to TIME (Tumor Immunity in the MicroEnvironment) subtypes based on tumor CD274 (PD-L1) expression status and tumor-infiltrating lymphocytes (TIL). The p values were calculated using the log-rank test (two-sided). (A), colorectal cancer-specific survival; (B), overall survival.

Figure 1. Kaplan-Meier survival curves of colorectal cancer patients according to TIME (Tumor Immunity in the MicroEnvironment) subtypes based on tumor CD274 (PD-L1) expression status and tumor-infiltrating lymphocytes (TIL). The p values were calculated using the log-rank test (two-sided). (A), colorectal cancer-specific survival; (B), overall survival.

Table 2. Colorectal cancer survival according to TIME (Tumor Immunity in the MicroEnvironment) subtypes based on tumor CD274 (PD-L1) expression status and tumor-infiltrating lymphocytes (TIL).

In exploratory secondary analyses, characteristics and survival of colorectal carcinoma cases were evaluated according to a modified TIME classification scheme defined by tumor CD274 expression status and intratumoral periglandular reaction. The analyses did not yield significant differences in associations (Tables S2 and S3). When modified TIME subtypes were defined by tumor CD274 expression status and density of CD3+ cells in tumor tissue (Tables S4 and S5), no significant differences across TIME subtypes in association with colorectal cancer characteristics or survival were observed.

Discussion

We conducted this study based on two large prospective cohorts to examine the association of TIME subtypes with characteristics and survival outcomes of colorectal cancer. Our findings suggest that TIL-present TIME subtypes are more likely to present with high levels of MSI, CIMP, and neoantigens, and less likely to present with LINE-1 hypomethylation and nuclear CTNNB1 expression when compared with TIL-absent subtypes. There were no significant differences in colorectal cancer-specific or overall survival by TIME subtypes, which may be supported by our previous findings of the lack of a prognostic role of tumor CD274 (PD-L1) expression status in colorectal cancer.Citation13 No statistically significant interaction was noted between tumor CD274 expression and TIL in relation to patient survival.

TIL has been demonstrated in multiple tumor types to reflect local immune effector response, and, along with regulatory T cells, has generally been associated with improved survival in colorectal carcinomas.Citation17,Citation37,Citation38 Tumor CD274 (PD-L1) expression was previously shown to inversely associate with FOXP3+ regulatory T cells, but not with CD3+ pan-T cells or CD8+ cytotoxic T cells in colorectal cancer,Citation13 suggesting the potential influence of CD274-expressing cells on the tumor microenvironment via immune regulation. The TIME classification framework based on tumor CD274 expression status and TIL was hence proposed as a pragmatic approach to predict the immune resistance of tumors.Citation9-Citation12 Evidence suggests that the CD274 protein can be selectively expressed on tumor cells in response to proinflammatory cytokine IFNG (interferon-gamma) released from activated antigen-specific CD8+ T cells,Citation6,Citation9,Citation36 rather than through oncogenic pathways. In TIME 2 (CD274high/TILpresent) tumors containing abundant TIL, the CD274-PDCD1 pathway is adaptively activated as negative feedback to help cancer cells evade immune attack; therefore, these tumors are believed to represent the group that would largely benefit from immune checkpoint blockade therapy. TIME 3 (CD274low/TILpresent) tumors, while harboring high-level TIL, utilize tumor suppressive pathways other than the CD274-PDCD1 axis, and hence, might better respond to non-CD274 immune checkpoint inhibitors. TIME 1 and 4 subtypes lack intrinsic TIL and may therefore require complementary therapeutic strategies to recruit lymphocytes into local tumors to increase efficacy of immune checkpoint inhibitors, such as via combination CTLA4 blockade or radiotherapy to induce T cell response.Citation39-Citation41 Application of the TIME classification needs to be interpreted in the context of other variables defining the tumor microenvironment for precise disease management and response prediction in the era of precision medicine. In this study, we sought to evaluate the implications of TIME subtypes on colorectal cancer in association with patient survival as well as tumor histopathologic and molecular features.

Integrated analyses of tumor, immunity, and microenvironment including the microbiota are important.Citation16,Citation42-Citation45 While the TIME model does not correlate significantly with survival outcomes, our findings highlight a distinct molecular profile correlated with TIL-present TIME subtypes regardless of tumor CD274 expression status. TIL-present TIME subtypes were shown to be associated with presence of BRAF mutation, as well as high levels of MSI and neoantigens, which have been among the most well-documented predictive factors for tumor CD274 expression and/or response to immune checkpoint inhibitors regardless of primary organ site.Citation8,Citation30,Citation46 Of note, a smaller proportion of CD274high/TILpresent subtype showed positive nuclear CTNNB1 (beta-catenin) expression when compared to CD274low/TILpresent subtype, although both subtypes were associated with high-level MSI. Nuclear expression or accumulation of CTNNB1 has been associated with more aggressive cancer behavior and suppression of anti-tumor immune response.Citation47,Citation48 Its presence in a greater proportion of CD274low/TILpresent TIME subtype could reflect potential mutations in the WNT signaling pathway or tumor-intrinsic activated WNT signaling which could contribute in part to no response to immunotherapy due to immune resistance and/or carcinogenic effects.Citation47,Citation48 Another observation of interest is that PTGS2 (cyclooxygenase-2) overexpression was commonly observed across TIME subtypes. PTGS2 produces inflammatory mediator prostaglandin E2, which contributes to immunosuppressive tumor microenvironment via recruitment of myeloid-derived suppressor cells and suppression of tumor-specific T cells.Citation49,Citation50 Intriguingly, experimental and clinical evidence supports a synergistic effect of PTGS suppression and immune checkpoint blockade on stimulating T cell-mediated anti-tumor immune response,Citation49,Citation51 suggesting potential benefit of considering PTGS suppression combined with CD274-PDCD1 immune checkpoint blockade.

Our findings would inform further studies to elucidate the associations between TIME subtypes and other parameters within the tumor microenvironment to better tailor combination immunotherapies. Additional analyses with other local immune effector cells (e.g., memory and regulatory T cells, tumor-associated macrophagesCitation52), as well as their densities and spatial distribution in relation to tumor invasive fronts, would enrich the TIME model in predicting tumor immune deficits and resistance. Sequencing-based assessment of intratumoral genetic heterogeneity of tumors at primary and metastatic sites in relation to CD274 expression and TIL would also facilitate understanding of the tumor microenvironment and its implications on therapeutic options. Other factors that could influence tumor recruitment and extravasation of immune effector cells to tumor sites, such as the gut microbiome, tumor vasculature, and related expression of adhesion molecules, would also warrant further investigations to correlate with TIME subtypes and their prognosis.Citation15

Our study has notable strengths including the use of a molecular pathological epidemiology database derived from two U.S. prospective cohort studies with long duration of follow-up.Citation53,Citation54 Integrated data on tumor molecular characteristics and pathological findings allowed us to comprehensively characterize TIME subtypes of colorectal cancer. Of note, our study population was derived from a large number of cases from hospitals located throughout the U.S., contributing to increased generalizability of our findings.

Limitations should be considered in our study. While we cannot entirely exclude the possibility of potential unmeasured or residual confounding in survival analyses, we collected detailed data on a comprehensive panel of colorectal cancer characteristics and evaluated them by multivariable models to control for potential confounding. Our study was also limited in information on cancer treatments. This lack of data, however, was unlikely to differ substantially by tumor CD274 expression or TIL levels as such information would not have been available for decision-making in management upfront. Our study was also based on relatively selected populations as most participants were non-Hispanic health professionals; therefore, our findings would need to be validated in independent cohorts. In addition, due to cellular structural changes caused by tissue processing and lack of standardized antibodies for CD274,Citation10,Citation55 assessment of tumor CD274 expression status and TIL in tissue samples could pose challenges that might have resulted in potential misclassifications. Intratumoral spatial heterogeneity and inter-observer variability in evaluating tumor CD274 expression and TIL might also lead to misclassifications.Citation10,Citation55 Our previous studies on that regard, however, did not reveal considerable intratumoral heterogeneity in CD274 expression in whole tissue sections,Citation13 and showed reasonable agreement between two pathologists in the assessment of tumor CD274 expression status and TIL.Citation13,Citation17 Finally, tumor CD274 expression and TIL were scored on only one sample per participant in this study. As immunotherapies are commonly used to treat refractory advanced tumors, changes in tumor CD274 expression and TIL along the clinical course might occurCitation14,Citation55; as such, assessment of TIME subtypes with biopsies at sites of progression in relation to clinical course may be relevant to update subtype designation in guiding immunotherapeutic treatments.

In summary, our findings suggest distinctive pathologic and molecular characteristics of colorectal cancer associated with subtypes defined by the TIME classification. Consistent with prior literature, our data support the role of TIL as an important effector in tumor-immune interactions. Our findings would likely inform future studies to better understand tumor-immune microenvironment of colorectal carcinomas in the era of immunotherapy.

Patients and methods

Study population

We utilized two prospective cohort studies in the U.S., the Nurses' Health Study (NHS, 121,701 women aged 30–55 years followed since 1976) and the Health Professionals Follow-up Study (HPFS, 51,529 men aged 40–75 years followed since 1986).Citation56 Participants are followed with biennial questionnaires on lifestyle factors and newly-diagnosed diseases including colorectal cancer. The response rate has been more than 90% for each follow-up questionnaire in both cohorts. In both studies, the National Death Index was used to ascertain deaths of participants and to identify unreported lethal colorectal cancer cases. Study physicians, who were blinded to exposure data, reviewed medical records of identified colorectal cancer cases to confirm the disease diagnosis and to collect data on tumor clinical characteristics including tumor size, anatomical location, and disease stage.

Among participants diagnosed with colorectal cancer until 2012, we analyzed 812 cases with available data on tumor CD274 (PD-L1) expression status and TIL in tissue samples. We included both colon and rectal carcinomas based on the colorectal continuum model.Citation57,Citation58 Participants with a history of inflammatory bowel disease or cancer (except for non-melanoma skin cancer) were excluded from this study. Participants were followed until death or the end of follow-up (30 June 2014 for the NHS; and 1 January 2014 for the HPFS), whichever came first.

Informed consent was obtained from all participants at enrollment. This study was approved by the institutional review boards at Harvard T.H. Chan School of Public Health and Brigham and Women's Hospital (Boston, MA, USA).

Histopathologic evaluation of colorectal cancer

Formalin-fixed paraffin-embedded tumor tissue blocks were collected from hospitals throughout the U.S. where colorectal cancer patients had undergone surgical resection. Hematoxylin and eosin-stained tissue sections were examined by a pathologist (S.O.) who was blinded to other data. Tumor differentiation was categorized as well to moderate vs. poor (> 50% vs. ≤ 50% gland formation, respectively). Lymphocytic reaction to tumor was histopathologically evaluated, as previously described.Citation17 TIL was defined as lymphocytes on top of cancer cells (Fig. S1). Intratumoral periglandular reaction was defined as lymphocytic reaction in intratumoral stroma. Each lymphocytic reaction pattern was graded as negative/low, intermediate, or high. Lymphocytic reaction patterns in a subset of cases were independently reviewed by a second pathologist (J.N.G.) with a good inter-observer correlation, as previously described.Citation17 In the present study, TIL was categorized into absent (negative/low) vs. present (intermediate to high), and intratumoral periglandular reaction was categorized into low (negative/low to intermediate) vs. high.

Immunohistochemical evaluation

We constructed tissue microarrays of colorectal cancer cases with sufficient tissue materials, including up to four tumor cores approximately 600 µm in diameter from each case in one tissue microarray block.Citation59 Immunohistochemical study for CD274 (PD-L1) was performed using an anti-CD274 antibody (dilution, 1:50; eBioscience, San Diego, CA, USA; Fig. S2). As previously described,Citation13,Citation51 a single pathologist (Y.M.) scored overall tumor CD274 expression level as an ordinal scale of 0–4 by summing cytoplasmic intensity score [absent (0), weak (1), moderate (2), or strong (3)] and membrane expression score [absent (0) or present (1; if distinct membrane staining above cytoplasmic expression level existed)]. When the staining intensity was different across tumor cores in the same case, predominant staining pattern in tumor cells was recorded. CD274 expression in selected tumors (n = 148) was independently examined by a second pathologist (A.dS.), and the concordance between the two observers was reasonable with a weighted κ of 0.65 (95% CI, 0.57–0.73).Citation13 We categorized CD274 levels as low (scale of 0 to 1) vs. high (scale of 2 to 4), as consistent with our previous study.Citation51

As previously described,Citation59,Citation60 immunohistochemical analyses for PTGS2 (cyclooxygenase-2) and nuclear CTNNB1 (beta-catenin) expression were performed using an anti-PTGS2 antibody (dilution, 1:300; Cayman Chemical, Ann Arbor, MI, USA) and anti-CTNNB1 antibody (dilution, 1:400; BD Transduction Laboratories, Franklin Lakes, NJ, USA), respectively. We measured densities (cells/mm2) of CD3+ cells in colorectal cancer tissue, based on immunohistochemistry using an anti-CD3 antibody (dilution, 1:250; Dako Cytomation, Carpinteria, CA, USA) and image analysis using an automated scanning microscope and the Ariol image analysis system (Genetix, San Jose, CA, USA), as previously described.Citation18

Evaluation of tumor molecular characteristics

DNA was extracted from colorectal cancer tissue in archival formalin-fixed paraffin-embedded tissue sections using QIAamp DNA FFPE Tissue Kit (Qiagen, Hilden, Germany). MSI status was analyzed using 10 microsatellite markers (D2S123, D5S346, D17S250, BAT25, BAT26, BAT40, D18S55, D18S56, D18S67, and D18S487). MSI-high was defined as presence of instability in ≥ 30% of the markers, and non-MSI-high as instability in < 30% of the markers, as previously described.Citation61 Using bisulfite-treated DNA, methylation status of eight CIMP-specific promoters (CACNA1G, CDKN2 A, CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1) and LINE-1 was determined, as previously described.Citation40,Citation41 CIMP-high was defined as ≥ 6 methylated promoters of eight promoters, and CIMP-low/negative as 0–5 methylated promoters, as previously described.Citation62 Polymerase chain reaction and pyrosequencing were performed for KRAS (codons 12, 13, 61, and 146),Citation63 BRAF (codon 600),Citation61 and PIK3CA (exons 9 and 20).Citation64 Neoantigen load, the number of immunogenic peptides, was predicted by using a neoantigen prediction pipeline for somatic mutations based on whole-exome sequencing and identifying peptides that bind to personal HLA molecules with high affinity (< 500 nM), as previously described.Citation29 Using NetMHCpan (version 2.4),Citation65 we predicted the binding affinities of all possible 9- and 10-mer mutant peptides to the corresponding HLA alleles inferred by the POLYSOLVER algorithm.

Definitions of TIME (Tumor Immunity in the MicroEnvironment) subtypes

TIME subtypes of colorectal carcinoma were assessed as the primary outcome in cross-sectional analyses with tumor characteristics, and as the primary exposure in survival analyses with colorectal cancer survival outcomes. As described previously,Citation9-Citation12 TIME subtypes were defined based on tumor CD274 (PD-L1) expression status (low vs. high) and TIL (absent vs. present): TIME 1, CD274 expression-low and TIL-absent; TIME 2, CD274 expression-high and TIL-present; TIME 3, CD274 expression-low and TIL-present; and TIME 4, CD274 expression-high and TIL-absent.

Exploratory secondary analyses with modified TIME classification schemes were also performed with assessment of intratumoral periglandular reaction (low vs. high), as well as density of CD3+ cells (dichotomized by median value), instead of TIL as markers for tumor immune status.

Statistical analyses

All statistical analyses were performed using SAS software (version 9.4; SAS Institute, Cary, NC, USA), and all p values were two-sided.

We used the chi-square test for categorical variables, and analysis of variance for continuous variables to compare tumor characteristic across TIME subtypes. The α level was set at 0.003 (≈ 0.05/17) with Bonferroni correction to adjust for multiple hypothesis testing. In subgroup analyses, results were interpreted cautiously in addition to the use of adjusted α level of 0.003.

Cumulative survival probabilities were estimated using the Kaplan-Meier method and compared using the log-rank test. Deaths from other causes were dealt as censored. Univariable and multivariable Cox proportional hazards models were used to evaluate the association of TIME subtypes with colorectal cancer-specific and overall mortality. Covariates assessed as potential confounders included sex (female vs. male), age at diagnosis (continuous variable), year of diagnosis (continuous variable), family history of colorectal cancer (absent vs. present), prediagnosis body mass index (< 25 kg/m2 vs. 25–29.9 kg/m2 vs. ≥ 30 kg/m2), tumor location (proximal colon vs. distal colon vs. rectum), tumor differentiation (well to moderate vs. poor), disease stage (I/II vs. III/IV), MSI status (high vs. non-high), CIMP status (high vs. low/negative), LINE-1 methylation level (continuous variable), KRAS mutation (wild-type vs. mutant), BRAF mutation (wild-type vs. mutant), PIK3CA mutation (wild-type vs. mutant), PTGS2 expression (negative vs. positive), and nuclear CTNNB1 expression (negative vs. positive). Backward eliminations with a threshold p of 0.05 were used to determine the most parsimonious final multivariable models. The two-sided α level in survival analyses was adjusted to 0.01 to account for multiple hypothesis testing. Cases with missing data were assigned to the majority category of a given categorical covariate to limit the degrees of freedom of the models: family history of colorectal cancer (1.1%), prediagnosis body mass index (0.7%), tumor location (0.5%), tumor differentiation (0.3%), MSI status (3.0%), CIMP status (8.4%), KRAS mutation (3.3%), BRAF mutation (2.5%), PIK3CA mutation (8.7%), PTGS2 expression (2.2%), and nuclear CTNNB1 expression (4.1%). For cases with missing data on LINE-1 methylation level (2.8%), a separate indicator variable was used. Excluding cases with missing data on any of the covariates did not yield substantial differences in our results (data not shown). Statistical interaction between tumor CD274 expression status (low vs. high) and TIL (absent vs. present) was evaluated using the Wald test on the cross-product. The assumption of proportional hazards was validated using a time-varying covariate in the models; i.e., cross-product of TIME subtype and survival time (p > 0.06).

Abbreviations

CI=

confidence interval

CIMP=

CpG island methylator phenotype

HPFS=

Health Professionals Follow-up Study

LINE-1=

long interspersed nucleotide element-1

MSI=

microsatellite instability

NHS=

Nurses' Health Study

TIL=

tumor-infiltrating lymphocytes

TIME=

tumor immunity in the microenvironment

Disclosure of potential conflict of interest

A.T.C. previously served as a consultant for Bayer Healthcare, Pfizer Inc., and Aralez Pharmaceuticals. This study was not funded by Bayer Healthcare, Pfizer Inc., or Aralez Pharmaceuticals. No other conflicts of interest exist. The other authors declare that they have no conflicts of interest.

Use of standardized official symbols: We use HUGO (Human Genome Organisation)-approved official symbols (or root symbols) for genes and gene products, including BRAF, CACNA1G, CD3, CD8, CD274, CDKN2 A, CRABP1, CTLA4, CTNNB1, FOXP3, HLA, IFNG, IGF2, KRAS, MLH1, NEUROG1, PDCD1, PIK3CA, PTGS2, RUNX3, SOCS1, and WNT; all of which are described at www.genenames.org. The official symbols are italicized to differentiate from non-italicized colloquial names that are used along with the official symbols. This format enables readers to familiarize themselves with the official symbols for genes and gene products together with common colloquial names.

Supplemental material

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Acknowledgments

We would like to thank the participants and staff of the Nurses' Health Study and the Health Professionals Follow-up Study for their valuable contributions as well as the following state cancer registries for their help: AL, AZ, AR, CA, CO, CT, DE, FL, GA, ID, IL, IN, IA, KY, LA, ME, MD, MA, MI, NE, NH, NJ, NY, NC, ND, OH, OK, OR, PA, RI, SC, TN, TX, VA, WA, WY. The authors assume full responsibility for analyses and interpretation of these data.

Additional information

Funding

This work was supported by U.S. National Institutes of Health (NIH) grants (P01 CA87969 to M.J. Stampfer; UM1 CA186107 to M.J. Stampfer; P01 CA55075 to W.C. Willett; UM1 CA167552 to W.C. Willett; U01 CA167552 to W.C. Willett and L.A. Mucci; P50 CA127003 to C.S.F.; R01 CA118553 to C.S.F.; R01 CA169141 to C.S.F.; R01 CA137178 to A.T.C.; K24 DK098311 to A.T.C.; R35 CA197735 to S.O.; R01 CA151993 to S.O.; K07 CA190673 to R.N.; and K07 CA188126 to X.Z.); by Nodal Award from the Dana-Farber Harvard Cancer Center (to S.O.); and by grants from the Project P Fund, The Friends of the Dana-Farber Cancer Institute, Bennett Family Fund, and the Entertainment Industry Foundation through National Colorectal Cancer Research Alliance. This work was additionally supported by the Stand Up to Cancer (SU2C) Colorectal Cancer Dream Team Translational Research Grant (grant number, SU2C-AACR-DT22-17 to C.S.F. and M.Gi.). The SU2C is a program of the Entertainment Industry Foundation. Research grants are administered by the American Association for Cancer Research, a scientific partner of SU2C. K.K. was supported by grants from Overseas Research Fellowship (grant number, JP2017-775) and Program for Advancing Strategic International Networks to Accelerate the Circulation of Talented Researchers, from Japan Society for the Promotion of Science. M.S. was supported by the 2017 AACR-AstraZeneca Fellowship in Immuno-oncology Research (grant number, 17-40-12-SONG). L.L. was supported by a scholarship grant from Chinese Scholarship Council and a fellowship grant from Huazhong University of Science and Technology. The content is solely the responsibility of the authors and does not necessarily represent the official views of NIH. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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