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ImportanceThe absolute benefit of chemotherapy for all patients with stage I triple-negative breast cancer (TNBC) is unclear, and biomarkers are not currently available for selecting patients with an excellent outcome for whom neoadjuvant or adjuvant chemotherapy may have negligible benefit. High levels of stromal tumor-infiltrating lymphocytes (sTILs) are associated with favorable survival in TNBC, but data solely in stage I TNBC are lacking.ObjectiveTo examine the outcomes of patients of all ages with stage I TNBC solely and who received neither neoadjuvant nor adjuvant chemotherapy, according to centrally reviewed sTIL levels at prespecified cutoffs.Design, Setting, and ParticipantsThis cohort study used the Netherlands Cancer Registry to identify patients diagnosed with stage I TNBC between January 1, 2005, and December 31, 2015, who were not treated with chemotherapy. Only patients who did not receive neoadjuvant and/or adjuvant chemotherapy were selected. The clinical data were matched with their corresponding pathology data provided by the Dutch Pathology Registry. Data analysis was performed between February and October 2023.Main Outcomes and MeasuresThe primary end point was breast cancer–specific survival (BCSS) at 5, 10, and 15 years for the prespecified sTIL level cutoffs of 30%, 50%, and 75%. Hematoxylin and eosin–stained slides were used for central review of histologic subtype, grade, and lymphovascular invasion. The International Immuno-Oncology Biomarker Working Group guidelines were used to score the sTIL levels; these levels were determined for 1041 patients.ResultsOf a total of 4511 females with stage I TNBC, patients who were not treated with chemotherapy were selected and tissue blocks requested; sTILs were scored in 1041 patients (mean [SD] age at diagnosis, 64.4 [11.1] years, median follow-up 11.4 [95% CI, 10.9-11.9] years) who were included in the analyses.. Most tumors (952 [91.5%]) were invasive carcinomas of nonspecial histologic subtype. Most patients (548 [52.6%]) had pT1cN0 tumors. Median (range) sTIL level was 5% (1%-99%). A total of 775 patients (74.4%) had sTIL levels below 30%, 266 (25.6%) had 30% or greater, 203 (19.5%) had 50% or greater, and 141 (13.5%) had 75% or greater. Patients with pT1abN0 tumors had a more favorable outcome vs patients with pT1cN0 tumors, with a 10-year BCSS of 92% (95% CI, 89%-94%) vs 86% (95% CI, 82%-89%). In the overall cohort, sTIL levels of at least 30% were associated with better BCSS compared with sTIL levels less than 30% (96% and 87%, respectively; hazard ratio [HR], 0.45; 95% CI, 0.26-0.77). High sTIL levels of 50% or greater were associated with a better outcome than low sTIL levels of less than 50% (HR, 0.27; 95% CI, 0.10-0.74) in patients with pT1C tumors, with a 10-year BCSS of 95% increasing to 98% with sTIL levels of 75% or greater.Conclusions and RelevanceResults of this study showed that patients with stage I TNBC and high level of sTILs who did not receive neoadjuvant or adjuvant chemotherapy had excellent 10-year BCSS. The findings further support the role of sTILs as integral biomarkers in prospective clinical trials of therapy optimization for this patient population.

Abstract Recent advances in the field of immuno‐oncology have brought transformative changes in the management of cancer patients. The immune profile of tumours has been found to have key value in predicting disease prognosis and treatment response in various cancers. Multiplex immunohistochemistry and immunofluorescence have emerged as potent tools for the simultaneous detection of multiple protein biomarkers in a single tissue section, thereby expanding opportunities for molecular and immune profiling while preserving tissue samples. By establishing the phenotype of individual tumour cells when distributed within a mixed cell population, the identification of clinically relevant biomarkers with high‐throughput multiplex immunophenotyping of tumour samples has great potential to guide appropriate treatment choices. Moreover, the emergence of novel multi‐marker imaging approaches can now provide unprecedented insights into the tumour microenvironment, including the potential interplay between various cell types. However, there are significant challenges to widespread integration of these technologies in daily research and clinical practice. This review addresses the challenges and potential solutions within a structured framework of action from a regulatory and clinical trial perspective. New developments within the field of immunophenotyping using multiplexed tissue imaging platforms and associated digital pathology are also described, with a specific focus on translational implications across different subtypes of cancer. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Abstract Modern histologic imaging platforms coupled with machine learning methods have provided new opportunities to map the spatial distribution of immune cells in the tumor microenvironment. However, there exists no standardized method for describing or analyzing spatial immune cell data, and most reported spatial analyses are rudimentary. In this review, we provide an overview of two approaches for reporting and analyzing spatial data (raster versus vector‐based). We then provide a compendium of spatial immune cell metrics that have been reported in the literature, summarizing prognostic associations in the context of a variety of cancers. We conclude by discussing two well‐described clinical biomarkers, the breast cancer stromal tumor infiltrating lymphocytes score and the colon cancer Immunoscore, and describe investigative opportunities to improve clinical utility of these spatial biomarkers. © 2023 The Pathological Society of Great Britain and Ireland.

AbstractThe clinical significance of the tumor‐immune interaction in breast cancer is now established, and tumor‐infiltrating lymphocytes (TILs) have emerged as predictive and prognostic biomarkers for patients with triple‐negative (estrogen receptor, progesterone receptor, and HER2‐negative) breast cancer and HER2‐positive breast cancer. How computational assessments of TILs might complement manual TIL assessment in trial and daily practices is currently debated. Recent efforts to use machine learning (ML) to automatically evaluate TILs have shown promising results. We review state‐of‐the‐art approaches and identify pitfalls and challenges of automated TIL evaluation by studying the root cause of ML discordances in comparison to manual TIL quantification. We categorize our findings into four main topics: (1) technical slide issues, (2) ML and image analysis aspects, (3) data challenges, and (4) validation issues. The main reason for discordant assessments is the inclusion of false‐positive areas or cells identified by performance on certain tissue patterns or design choices in the computational implementation. To aid the adoption of ML for TIL assessment, we provide an in‐depth discussion of ML and image analysis, including validation issues that need to be considered before reliable computational reporting of TILs can be incorporated into the trial and routine clinical management of patients with triple‐negative breast cancer. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

AbstractImmune checkpoint inhibitor therapies targeting PD‐1/PD‐L1 are now the standard of care in oncology across several hematologic and solid tumor types, including triple negative breast cancer (TNBC). Patients with metastatic or locally advanced TNBC with PD‐L1 expression on immune cells occupying ≥1% of tumor area demonstrated survival benefit with the addition of atezolizumab to nab‐paclitaxel. However, concerns regarding variability between immunohistochemical PD‐L1 assay performance and inter‐reader reproducibility have been raised. High tumor‐infiltrating lymphocytes (TILs) have also been associated with response to PD‐1/PD‐L1 inhibitors in patients with breast cancer (BC). TILs can be easily assessed on hematoxylin and eosin–stained slides and have shown reliable inter‐reader reproducibility. As an established prognostic factor in early stage TNBC, TILs are soon anticipated to be reported in daily practice in many pathology laboratories worldwide. Because TILs and PD‐L1 are parts of an immunological spectrum in BC, we propose the systematic implementation of combined PD‐L1 and TIL analyses as a more comprehensive immuno‐oncological biomarker for patient selection for PD‐1/PD‐L1 inhibition‐based therapy in patients with BC. Although practical and regulatory considerations differ by jurisdiction, the pathology community has the responsibility to patients to implement assays that lead to optimal patient selection. We propose herewith a risk‐management framework that may help mitigate the risks of suboptimal patient selection for immuno‐therapeutic approaches in clinical trials and daily practice based on combined TILs/PD‐L1 assessment in BC. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

1088 Background: Standard first-line treatment for mTNBC is chemotherapy. However, outcomes are poor, and new treatment options are needed. Cohort B of KEYNOTE-086 (NCT02447003) assessed the safety and antitumor activity of pembrolizumab as first-line therapy for patients (pts) with PD-L1–positive mTNBC. Methods: Men and women with centrally confirmed mTNBC, no prior systemic anticancer therapy for metastatic disease, ECOG PS 0-1, and a tumor PD-L1 combined positive score (CPS) ≥1% received pembrolizumab 200 mg Q3W for 24 mo or until disease progression, intolerable toxicity, or investigator or pt decision. Tumor imaging was performed Q9W for 12 mo and Q12W thereafter. Clinically stable pts with PD could remain on pembrolizumab until PD was confirmed on subsequent assessment. Primary end point was safety. Secondary end points included ORR, DOR, and PFS (RECIST v1.1, central review). Planned enrollment was 80 pts. This analysis included all pts who had ≥18 wk of follow-up as of Nov 10, 2016. Results: 79 of the first 137 pts with PD-L1–evaluable tumors (58%) had PD-L1 CPS ≥1%. Of the first 52 pts enrolled, 100% were women, median age was 53 y, 40% had elevated LDH, 69% had visceral metastases, and 87% received prior (neo)adjuvant therapy. After a median follow-up of 7.0 mo (range 4.4-12.5), 15 (29%) pts remained on pembrolizumab. Treatment-related AEs occurred in 37 (71%) pts, most commonly fatigue (31%), nausea (15%), and diarrhea (13%). 4 (8%) pts experienced 5 grade 3-4 treatment-related AEs: back pain, fatigue, hyponatremia, hypotension, and migraine (n = 1 each). No pts died or discontinued pembrolizumab due to an AE. ORR was 23% (95% CI 14%-36%). Best overall response was CR in 4%, PR in 19%, SD in 17%, PD in 58%, and not assessed in 2%. Median time to response was 8.7 wk (range 8.1-17.7). Median DOR was 8.4 mo (range, 2.1+ to 8.4), with 8 (67%) responses ongoing at cutoff. Median PFS was 2.1 mo (95% CI, 2.0-3.9); estimated 6-mo PFS rate was 29%. Conclusions: Data from the first 52 pts enrolled in KEYNOTE-086 cohort B suggest that pembrolizumab monotherapy has a manageable safety profile and promising antitumor activity as first-line therapy for PD-L1–positive mTNBC. Clinical trial information: NCT02447003.

Abstract Background: Patients with previously untreated mTNBC typically receive cytotoxic chemotherapy as first-line therapy for metastatic disease. However, efficacy and safety are suboptimal. KEYNOTE-086 (NCT02447003) is a multicohort, single-arm, phase 2 study of pembrolizumab monotherapy for mTNBC. In cohort B, we assessed the safety and antitumor activity of pembrolizumab as first-line therapy for patients with PD-L1-positive mTNBC. Methods: Key eligibility criteria for cohort B were age ≥18 y, centrally confirmed TNBC, no prior systemic anticancer therapy for metastatic disease, ECOG performance status 0-1, measurable disease per RECIST v1.1 by central review, no radiographic evidence of brain metastases, and a tumor PD-L1 combined positive score (CPS) ≥1. Pembrolizumab 200 mg was given once every 3 wk for 24 mo or until disease progression, intolerable toxicity, or investigator or patient decision. Tumor imaging was performed every 9 wk for 12 mo and every 12 wk thereafter. Clinically stable patients with radiologic progression could remain on pembrolizumab until progression was confirmed on subsequent assessment. Primary end point was safety. Secondary end points included ORR, duration of response, and PFS (all RECIST v1.1 by central review) and OS. Results: Of the 206 patients with tumors evaluable for PD-L1 expression, 128 (62%) had PD-L1 CPS ≥1. Of these, 84 met all eligibility criteria and enrolled. All patients were women, median age was 52.5 y, 29 (35%) had ECOG PS 1, 40 (48%) had elevated LDH, 55 (65%) had visceral ± nonvisceral metastases, and 73 (87%) received prior (neo)adjuvant therapy. All patients received ≥1 pembrolizumab dose, and after median follow-up of 10.6 mo, 18 (21%) remained on pembrolizumab. Treatment-related AEs occurred in 53 (63%) patients and were of grade 3-4 severity in 7 (8%); no patients died or discontinued pembrolizumab because of treatment-related AEs. The most common treatment-related AEs were fatigue (26%), nausea (13%), and diarrhea (12%). No grade 3-4 treatment-related AE occurred in >1 patient. The most common immune-mediated AE was hypothyroidism (10%). Three patients had complete response and 16 had partial response for an ORR of 23% (95% CI 15-33). Of the 11 patients with a best response of stable disease, 1 had stable disease for ≥24 wk, leading to a disease control rate of 24% (95% CI 16-34). 12 of 19 (63%) responses were ongoing at data cutoff, and median duration of response was 8.4 mo (range 2.1+ to 13.9+). Median PFS was 2.1 mo (95% CI 2.0-2.2), with an estimated 6-mo PFS rate of 26%. Median OS was 16.1 mo (95% CI 11.3-NR), with an estimated 6-mo OS rate of 83%. Conclusions: Pembrolizumab monotherapy continues to demonstrate a favorable safety profile and robust, durable antitumor activity in patients with PD-L1-positive, previously untreated mTNBC. Citation Format: Adams S, Loi S, Toppmeyer DL, Cescon DW, De Laurentiis M, Nanda R, Winer EP, Mukai H, Tamura K, Armstrong AC, Liu MC, Iwata H, Ryvo L, Wimberger P, Rugo HS, Tan A, D'Aquanno C, Ding Y, Karantza V, Schmid P. KEYNOTE-086 cohort B: Pembrolizumab monotherapy for PD-L1–positive, previously untreated, metastatic triple-negative breast cancer (mTNBC) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD6-10.

Assessment of tumor-infiltrating lymphocytes (TILs) in histopathologic specimens can provide important prognostic information in diverse solid tumor types, and may also be of value in predicting response to treatments. However, implementation as a routine clinical biomarker has not yet been achieved. As successful use of immune checkpoint inhibitors and other forms of immunotherapy become a clinical reality, the need for widely applicable, accessible, and reliable immunooncology biomarkers is clear. In part 1 of this review we briefly discuss the host immune response to tumors and different approaches to TIL assessment. We propose a standardized methodology to assess TILs in solid tumors on hematoxylin and eosin sections, in both primary and metastatic settings, based on the International Immuno-Oncology Biomarker Working Group guidelines for TIL assessment in invasive breast carcinoma. A review of the literature regarding the value of TIL assessment in different solid tumor types follows in part 2. The method we propose is reproducible, affordable, easily applied, and has demonstrated prognostic and predictive significance in invasive breast carcinoma. This standardized methodology may be used as a reference against which other methods are compared, and should be evaluated for clinical validity and utility. Standardization of TIL assessment will help to improve consistency and reproducibility in this field, enrich both the quality and quantity of comparable evidence, and help to thoroughly evaluate the utility of TILs assessment in this era of immunotherapy.

Assessment of the immune response to tumors is growing in importance as the prognostic implications of this response are increasingly recognized, and as immunotherapies are evaluated and implemented in different tumor types. However, many different approaches can be used to assess and describe the immune response, which limits efforts at implementation as a routine clinical biomarker. In part 1 of this review, we have proposed a standardized methodology to assess tumor-infiltrating lymphocytes (TILs) in solid tumors, based on the International Immuno-Oncology Biomarkers Working Group guidelines for invasive breast carcinoma. In part 2 of this review, we discuss the available evidence for the prognostic and predictive value of TILs in common solid tumors, including carcinomas of the lung, gastrointestinal tract, genitourinary system, gynecologic system, and head and neck, as well as primary brain tumors, mesothelioma and melanoma. The particularities and different emphases in TIL assessment in different tumor types are discussed. The standardized methodology we propose can be adapted to different tumor types and may be used as a standard against which other approaches can be compared. Standardization of TIL assessment will help clinicians, researchers and pathologists to conclusively evaluate the utility of this simple biomarker in the current era of immunotherapy.

Purpose Recent studies suggest that tumor-infiltrating lymphocytes (TILs) are associated with disease-free (DFS) and overall survival (OS) in operable triple-negative breast cancer (TNBC). We seek to validate the prognostic impact of TILs in primary TNBCs in two adjuvant phase III trials conducted by the Eastern Cooperative Oncology Group (ECOG). Patients and Methods Full-face hematoxylin and eosin–stained sections of 506 tumors from ECOG trials E2197 and E1199 were evaluated for density of TILs in intraepithelial (iTILs) and stromal compartments (sTILs). Patient cases of TNBC from E2197 and E1199 were randomly selected based on availability of sections. For the primary end point of DFS, association with TIL scores was determined by fitting proportional hazards models stratified on study. Secondary end points were OS and distant recurrence–free interval (DRFI). Reporting recommendations for tumor marker prognostic studies criteria were followed, and all analyses were prespecified. Results The majority of 481 evaluable cancers had TILs (sTILs, 80%; iTILs, 15%). With a median follow-up of 10.6 years, higher sTIL scores were associated with better prognosis; for every 10% increase in sTILs, a 14% reduction of risk of recurrence or death (P = .02), 18% reduction of risk of distant recurrence (P = .04), and 19% reduction of risk of death (P = .01) were observed. Multivariable analysis confirmed sTILs to be an independent prognostic marker of DFS, DRFI, and OS. Conclusion In two national randomized clinical trials using contemporary adjuvant chemotherapy, we confirm that stromal lymphocytic infiltration constitutes a robust prognostic factor in TNBCs. Studies assessing outcomes and therapeutic efficacies should consider stratification for this parameter.