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Purpose: The treatment efficacy of nivolumab was evaluated in patients with advanced, treatment-refractory solid mismatch repair deficiency/microsatellite-instable (dMMR/MSI) tumors, and in-depth biomarker analyses were performed to inform precision immunotherapy approaches., Patients and Methods: Patients with dMMR/MSI tumors who exhausted standard-of-care treatment options were enrolled in the Drug Rediscovery Protocol, a pan-cancer clinical trial that treats patients with cancer based on their tumor molecular profile with off-label anticancer drugs (NCT02925234). Patients received nivolumab (four cycles of 240 mg every 2 weeks, thereafter 480 mg every 4 weeks). The primary endpoint was clinical benefit (CB: objective response or stable disease ≥16 weeks). Whole-genome sequencing and RNA sequencing were performed on pretreatment tumor biopsies., Results: A total of 130 evaluable patients were enrolled with 16 different cancer types. CB was observed in 62% [95% confidence interval (CI), 53-70], with an objective response in 45% (95% CI, 36-54). After a median follow-up of 14.5 months (95% CI, 13-19), the median progression-free survival was 18 months (95% CI, 9-not reached), and the median overall survival was not reached. Whereas CB was not, or only weakly, associated with markers of adaptive immune cell infiltration, CB was strongly associated with expression of a broad set of innate immune receptors/ligands. This clearly contrasted findings in melanoma, in which markers of adaptive immunity dominated the biomarker landscape., Conclusions: Nivolumab proved highly effective in advanced dMMR/MSI tumors. Expression of key innate immune receptors/ligands was the main predictor of a good treatment outcome, contrasting findings in melanoma and strengthening the rationale for tumor type-specific biomarkers for guiding immunotherapy., (©2024 American Association for Cancer Research.)

Immune checkpoint inhibition (ICI) with chemotherapy is now the standard of care for stage II-III triple-negative breast cancer; however, it is largely unknown for which patients ICI without chemotherapy could be an option and what the benefit of combination ICI could be. The adaptive BELLINI trial explored whether short combination ICI induces immune activation (primary end point, twofold increase in CD8 + T cells or IFNG), providing a rationale for neoadjuvant ICI without chemotherapy. Here, in window-of-opportunity cohorts A (4 weeks of anti-PD-1) and B (4 weeks of anti-PD-1 + anti-CTLA4), we observed immune activation in 53% (8 of 15) and 60% (9 of 15) of patients, respectively. High levels of tumor-infiltrating lymphocytes correlated with response. Single-cell RNA sequencing revealed that higher pretreatment tumor-reactive CD8 + T cells, follicular helper T cells and shorter distances between tumor and CD8 + T cells correlated with response. Higher levels of regulatory T cells after treatment were associated with nonresponse. Based on these data, we opened cohort C for patients with high levels of tumor-infiltrating lymphocytes (≥50%) who received 6 weeks of neoadjuvant anti-PD-1 + anti-CTLA4 followed by surgery (primary end point, pathological complete response). Overall, 53% (8 of 15) of patients had a major pathological response (<10% viable tumor) at resection, with 33% (5 of 15) having a pathological complete response. All cohorts met Simon's two-stage threshold for expansion to stage II. We observed grade ≥3 adverse events for 17% of patients and a high rate (57%) of immune-mediated endocrinopathies. In conclusion, neoadjuvant immunotherapy without chemotherapy demonstrates potential efficacy and warrants further investigation in patients with early triple-negative breast cancer. ClinicalTrials.gov registration: NCT03815890 ., (© 2024. The Author(s).)

Purpose: Platinum-based chemotherapy and immune checkpoint inhibitors are key components of systemic treatment for muscle-invasive and advanced urothelial cancer. The ideal integration of these two treatment modalities remains unclear as clinical trials have led to inconsistent results. Modulation of the tumor-immune microenvironment by chemotherapy is poorly characterized. We aimed to investigate this modulation, focusing on potential clinical implications for immune checkpoint inhibitor response., Experimental Design: We assessed immune cell densities, spatial relations, and tumor/stromal components from 116 patients with urothelial bladder cancer (paired data for 95 patients) before and after platinum-based chemotherapy., Results: Several published biomarkers for immunotherapy response changed upon chemotherapy treatment. The intratumoral CD8+ T-cell percentage increased after treatment and was associated with increased TNFα-via-NF-κB signaling. The percentage of PDL1+ immune cells was higher after chemotherapy. An increase in chemo-induced changes that potentially inhibit an antitumor immune response was also observed, including increased fibroblast-based TGFβ signaling and distances from immune cells to the nearest cancer cell. The latter two parameters correlated significantly in posttreatment samples, suggesting that TGFβ signaling in fibroblasts may play a role in spatially separating immune cells from cancer cells. We examined specific chemotherapy regimens and found that treatment with methotrexate, vinblastine, doxorubicin, and cisplatin was associated with an increase in the macrophage cell percentage. Gemcitabine-containing chemotherapy was associated with upregulation of fibroblast TGFβ signaling., Conclusions: The opposing effects of platinum-based chemotherapy on the immune cell composition and stromal context of the tumor-immune microenvironment may explain the inconsistent results of clinical trials investigating chemotherapy and immune checkpoint inhibitor combinations in bladder cancer., (©2024 American Association for Cancer Research.)

Purpose: To evaluate the efficacy of pembrolizumab across multiple cancer types harboring different levels of whole-genome sequencing-based tumor mutational load (TML; total of nonsynonymous mutations across the genome) in patients included in the Drug Rediscovery Protocol (NCT02925234)., Patients and Methods: Patients with solid, treatment-refractory, microsatellite-stable tumors were enrolled in cohort A: breast cancer cohort harboring a TML of 140 to 290, cohort B: tumor-agnostic cohort harboring a TML of 140 to 290, and cohort C: tumor-agnostic cohort harboring a TML >290. Patients received pembrolizumab 200 mg every 3 weeks. The primary endpoint was clinical benefit [CB; objective response or stable disease (SD) ≥16 weeks]. Pretreatment tumor biopsies were obtained for whole-genome sequencing and RNA sequencing., Results: Seventy-two evaluable patients with 26 different histotypes were enrolled. The CB rate was 13% in cohort A [3/24 with partial response (PR)], 21% in cohort B (3/24 with SD; 2/24 with PR), and 42% in cohort C (4/24 with SD; 6/24 with PR). In cohort C, neoantigen burden estimates and expression of inflammation and innate immune biomarkers were significantly associated with CB. Similar associations were not identified in cohorts A and B. In cohort A, CB was significantly associated with mutations in the chromatin remodeling gene PBRM1, whereas in cohort B, CB was significantly associated with expression of MICA/MICB and butyrophilins. CB and clonal TML were not significantly associated., Conclusions: Although pembrolizumab lacked activity in cohort A, cohorts B and C met the study's primary endpoint. Further research is warranted to refine the selection of patients with tumors harboring lower TMLs and may benefit from a focus on innate immunity. See related commentary by Hsu and Yen, p. 3652., (©2024 American Association for Cancer Research.)

Combining drugs can enhance their clinical efficacy, but the number of possible combinations and inter-tumor heterogeneity make identifying effective combinations challenging, while existing approaches often overlook clinically relevant activity. We screen one of the largest cell line panels (N = 757) with 51 clinically relevant combinations and identify responses at the level of individual cell lines and tissue populations. We establish three response classes to model cellular effects beyond monotherapy: synergy, Bliss additivity, and independent drug action (IDA). Synergy is rare (11% of responses) and frequently efficacious (>50% viability reduction), whereas Bliss and IDA are more frequent but less frequently efficacious. We introduce "efficacious combination benefit" (ECB) to describe high-efficacy responses classified as either synergy, Bliss, or IDA. We identify ECB biomarkers in vitro and show that ECB predicts response in patient-derived xenografts better than synergy alone. Our work here provides a valuable resource and framework for preclinical evaluation and the development of combination treatments., Competing Interests: Declaration of interests L.F.A.W. has received funding from Genmab BV and Bristol Myers Squibb. M.J.G. has received research grants from AstraZeneca, GlaxoSmithKline, Astex Pharmaceuticals, and Mosaic Therapeutics and is the Director and consultant for Mosaic Therapeutics., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The primary objective of the prospective, randomized, multicenter, phase 3 biomarker Microarray Analysis in breast cancer to Taylor Adjuvant Drugs Or Regimens trial (MATADOR: ISRCTN61893718) is to generate a gene expression profile that can predict benefit from either docetaxel, doxorubicin, and cyclophosphamide (TAC) or dose-dense scheduled doxorubicin and cyclophosphamide (ddAC). Patients with a pT1-3, pN0-3 tumor were randomized 1:1 between ddAC and TAC. The primary endpoint was a gene profile-treatment interaction for recurrence-free survival (RFS). We observed 117 RFS events in 664 patients with a median follow-up of 7 years. Hallmark gene set analyses showed significant association between enrichment in immune-related gene expression and favorable outcome after TAC in hormone receptor-negative, human epidermal growth factor receptor 2 (HER2)-negative breast cancer (BC) (triple-negative breast cancer [TNBC]). We validated this association in TNBC patients treated with TAC on H&E slides; stromal tumor-infiltrating lymphocytes (sTILs) ≥20% was associated with longer RFS (hazard ratio 0.18, p  = 0.01), while in patients treated with ddAC no difference in RFS was seen (hazard ratio 0.92, p  = 0.86, p interaction  = 0.02)., Competing Interests: S.C.L. and H.M.O. received an institutional unrestricted research grant from Sanofi and Amgen to conduct the MATADOR study (ISRCTN61893718); H.M.O. received institutional research support funding from Roche; M.K. received institutional research support funding from Roche, BMS, and AZ; S.C.L. received institutional research support funding from Agendia, Amgen, AstraZeneca, Eurocept, Genentech, Immunomedics (now Gilead), Roche, Sanofi, and TESARO (now GSK). S.C.L. is an advisory board member for AstraZeneca for which the institute receives compensation, and for Cergentis (pro bono). S.C.L. receives funding for educational activities from Daiichi Sankyo, paid to the institute. H.M.O. is an advisory board member for Roche, Pfizer, and Novartis. M.K. is an advisory board member for AZ, BMS, Roche, MSD, and Daiichi for which the institute receives compensation., (© 2024 The Authors.)

In response to excessive DNA damage, human cells can activate p53 to induce apoptosis. Cells lacking p53 can still undergo apoptosis upon DNA damage, yet the responsible pathways are unknown. We observed that p53-independent apoptosis in response to DNA damage coincided with translation inhibition, which was characterized by ribosome stalling on rare leucine-encoding UUA codons and globally curtailed translation initiation. A genetic screen identified the transfer RNAse SLFN11 and the kinase GCN2 as factors required for UUA stalling and global translation inhibition, respectively. Stalled ribosomes activated a ribotoxic stress signal conveyed by the ribosome sensor ZAKα to the apoptosis machinery. These results provide an explanation for the frequent inactivation of SLFN11 in chemotherapy-unresponsive tumors and highlight ribosome stalling as a signaling event affecting cell fate in response to DNA damage.

Objective: To assess the feasibility of scalable, objective, and minimally invasive liquid biopsy-derived biomarkers such as cell-free DNA copy number profiles, human epididymis protein 4 (HE4), and cancer antigen 125 (CA125) for pre-operative risk assessment of early-stage ovarian cancer in a clinically representative and diagnostically challenging population and to compare the performance of these biomarkers with the Risk of Malignancy Index (RMI)., Methods: In this case-control study, we included 100 patients with an ovarian mass clinically suspected to be early-stage ovarian cancer. Of these 100 patients, 50 were confirmed to have a malignant mass (cases) and 50 had a benign mass (controls). Using WisecondorX, an algorithm used extensively in non-invasive prenatal testing, we calculated the benign-calibrated copy number profile abnormality score. This score represents how different a sample is from benign controls based on copy number profiles. We combined this score with HE4 serum concentration to separate cases and controls., Results: Combining the benign-calibrated copy number profile abnormality score with HE4, we obtained a model with a significantly higher sensitivity (42% vs 0%; p<0.002) at 99% specificity as compared with the RMI that is currently employed in clinical practice. Investigating performance in subgroups, we observed especially large differences in the advanced stage and non-high-grade serous ovarian cancer groups., Conclusion: This study demonstrates that cell-free DNA can be successfully employed to perform pre-operative risk of malignancy assessment for ovarian masses; however, results warrant validation in a more extensive clinical study., Competing Interests: Competing interests: DHKG: No conflicting interests. PL: No conflicting interests. EAS: Received funding for a PhD student (not involved in this project) from MRC-Holland; participation on a Data Safety Monitoring Board or Advisory Board of GenQA (unpaid); leadership role at VKGL. TM: Employee and shareholder at Pacific Biosciences. HMH: No conflicting interests. CHM: No conflicting interests. MJTR: Institute received funding from the Dutch Cancer Society for this work; institute receives royalties for commercial use of Wisecondor but with application in non-invasive prenatal testing setting, not in cancer diagnostics, as is the subject of this work. FA: No conflicting interests. DvdB: Institute received ZonMW grant for personalised medicine research; unpaid KWF research board member on biomarkers; ZonMW research board member for early detection. LFAW: Institute received funding from the Dutch Cancer Society for this work; received grant from Bristol Myers Squibb. CARL: No conflicting interests. HE4 Study Group members: MDJMvG: No conflicting interests. MH: No conflicting interests. WMvB: No conflicting interests. MV: No conflicting interests. FMFR-vD: No conflicting interests; BBJH: No conflicting interests., (© IGCS and ESGO 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: The clinical value of STK11, KEAP1, and EGFR alterations for guiding immune checkpoint blockade (ICB) therapy in non-small cell lung cancer (NSCLC) remains controversial, as some patients with these proposed resistance biomarkers show durable ICB responses. More specific combinatorial biomarker approaches are urgently needed for this disease., Experimental Design: To develop a combinatorial biomarker strategy with increased specificity for ICB unresponsiveness in NSCLC, we performed a comprehensive analysis of 254 patients with NSCLC treated with ligand programmed death-ligand 1 (PD-L1) blockade monotherapy, including a discovery cohort of 75 patients subjected to whole-genome sequencing (WGS), and an independent validation cohort of 169 patients subjected to tumor-normal large panel sequencing. The specificity of STK11/KEAP1/EGFR alterations for ICB unresponsiveness was assessed in the contexts of a low (<10 muts/Mb) or high (≥10 muts/Mb) tumor mutational burden (TMB)., Results: In low TMB cases, STK11/KEAP1/EGFR alterations were highly specific biomarkers for ICB resistance, with 0/15 (0.0%) and 1/34 (2.9%) biomarker-positive patients showing treatment benefit in the discovery and validation cohorts, respectively. This contrasted with high TMB cases, where 11/13 (85%) and 15/34 (44%) patients with at least one STK11/KEAP1/EGFR alteration showed durable treatment benefit in the discovery and validation cohorts, respectively. These findings were supported by analyses of progression-free survival and overall survival., Conclusions: The unexpected ICB responses in patients carrying resistance biomarkers in STK11, KEAP1, and EGFR were almost exclusively observed in patients with a high TMB. Considering these alterations in context, the TMB offered a highly specific combinatorial biomarker strategy for limiting overtreatment in NSCLC., (©2024 The Authors; Published by the American Association for Cancer Research.)

Immune checkpoint inhibitors (ICI) can achieve remarkable responses in urothelial cancer (UC), which may depend on tumor microenvironment (TME) characteristics. However, the relationship between the TME, usually characterized by immune cell density, and response to ICI is unclear. Here, we quantify the TME immune cell densities and spatial relationships (SRs) of 24 baseline UC samples, obtained before pre-operative combination ICI treatment, using multiplex immunofluorescence. We describe SRs by approximating the first nearest-neighbor distance distribution with a Weibull distribution and evaluate the association between TME metrics and ipilimumab+nivolumab response. Immune cell density does not discriminate between response groups. However, the Weibull SR metrics of CD8 + T cells or macrophages to their closest cancer cell positively associate with response. CD8 + T cells close to B cells are characteristic of non-response. We validate our SR response associations in a combination ICI cohort of head and neck tumors. Our data confirm that SRs, in contrast to density metrics, are strong biomarkers of response to pre-operative combination ICIs., (© 2024. The Author(s).)

Cells in the tumor microenvironment (TME) influence each other through secretion and sensing of soluble mediators, such as cytokines and chemokines. While signaling of interferon γ (IFNγ) and tumor necrosis factor α (TNFα) is integral to anti-tumor immune responses, our understanding of the spatiotemporal behavior of these cytokines is limited. Here, we describe a single cell transcriptome-based approach to infer which signal(s) an individual cell has received. We demonstrate that, contrary to expectations, CD8 + T cell-derived IFNγ is the dominant modifier of the TME relative to TNFα. Furthermore, we demonstrate that cell pools that show abundant IFNγ sensing are characterized by decreased expression of transforming growth factor β (TGFβ)-induced genes, consistent with IFNγ-mediated TME remodeling. Collectively, these data provide evidence that CD8 + T cell-secreted cytokines should be categorized into local and global tissue modifiers, and describe a broadly applicable approach to dissect cytokine and chemokine modulation of the TME., Competing Interests: Declaration of interests L.F.A.W. received project funding for unrelated work from Bristoll-Myers-Squibb. T.N.S. is advisor for Allogene Therapeutics, Asher Bio, Merus, Neogene Therapeutics, and Scenic Biotech; is a stockholder in Allogene Therapeutics, Asher Bio, Cell Control, Celsius, Merus, and Scenic Biotech; and is venture partner at Third Rock Ventures, all outside of the current work., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Targeting the PI3K-AKT-mTOR pathway is a promising therapeutic strategy for breast cancer treatment. However, low response rates and development of resistance to PI3K-AKT-mTOR inhibitors remain major clinical challenges. Here, we show that MYC activation drives resistance to mTOR inhibitors (mTORi) in breast cancer. Multiomic profiling of mouse invasive lobular carcinoma (ILC) tumors revealed recurrent Myc amplifications in tumors that acquired resistance to the mTORi AZD8055. MYC activation was associated with biological processes linked to mTORi response and counteracted mTORi-induced translation inhibition by promoting translation of ribosomal proteins. In vitro and in vivo induction of MYC conferred mTORi resistance in mouse and human breast cancer models. Conversely, AZD8055-resistant ILC cells depended on MYC, as demonstrated by the synergistic effects of mTORi and MYCi combination treatment. Notably, MYC status was significantly associated with poor response to everolimus therapy in metastatic breast cancer patients. Thus, MYC is a clinically relevant driver of mTORi resistance that may stratify breast cancer patients for mTOR-targeted therapies., (© 2023 Bhin et al.)

BRCA1 and BRCA2 both function in DNA double-strand break repair by homologous recombination (HR). Due to their HR defect, BRCA1/2-deficient cancers are sensitive to poly(ADP-ribose) polymerase inhibitors (PARPis), but they eventually acquire resistance. Preclinical studies yielded several PARPi resistance mechanisms that do not involve BRCA1/2 reactivation, but their relevance in the clinic remains elusive. To investigate which BRCA1/2-independent mechanisms drive spontaneous resistance in vivo, we combine molecular profiling with functional analysis of HR of matched PARPi-naive and PARPi-resistant mouse mammary tumors harboring large intragenic deletions that prevent reactivation of BRCA1/2. We observe restoration of HR in 62% of PARPi-resistant BRCA1-deficient tumors but none in the PARPi-resistant BRCA2-deficient tumors. Moreover, we find that 53BP1 loss is the prevalent resistance mechanism in HR-proficient BRCA1-deficient tumors, whereas resistance in BRCA2-deficient tumors is mainly induced by PARG loss. Furthermore, combined multi-omics analysis identifies additional genes and pathways potentially involved in modulating PARPi response., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Ductal carcinoma in situ (DCIS) is a non-obligate precursor of invasive breast cancer (IBC). Due to a lack of biomarkers able to distinguish high- from low-risk cases, DCIS is treated similar to early IBC even though the minority of untreated cases eventually become invasive. Here, we characterized 115 patient-derived mouse-intraductal (MIND) DCIS models reflecting the full spectrum of DCIS observed in patients. Utilizing the possibility to follow the natural progression of DCIS combined with omics and imaging data, we reveal multiple prognostic factors for high-risk DCIS including high grade, HER2 amplification, expansive 3D growth, and high burden of copy number aberrations. In addition, sequential transplantation of xenografts showed minimal phenotypic and genotypic changes over time, indicating that invasive behavior is an intrinsic phenotype of DCIS and supporting a multiclonal evolution model. Moreover, this study provides a collection of 19 distributable DCIS-MIND models spanning all molecular subtypes., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: High-dimensional prediction considers data with more variables than samples. Generic research goals are to find the best predictor or to select variables. Results may be improved by exploiting prior information in the form of co-data, providing complementary data not on the samples, but on the variables. We consider adaptive ridge penalised generalised linear and Cox models, in which the variable-specific ridge penalties are adapted to the co-data to give a priori more weight to more important variables. The R-package ecpc originally accommodated various and possibly multiple co-data sources, including categorical co-data, i.e. groups of variables, and continuous co-data. Continuous co-data, however, were handled by adaptive discretisation, potentially inefficiently modelling and losing information. As continuous co-data such as external p values or correlations often arise in practice, more generic co-data models are needed., Results: Here, we present an extension to the method and software for generic co-data models, particularly for continuous co-data. At the basis lies a classical linear regression model, regressing prior variance weights on the co-data. Co-data variables are then estimated with empirical Bayes moment estimation. After placing the estimation procedure in the classical regression framework, extension to generalised additive and shape constrained co-data models is straightforward. Besides, we show how ridge penalties may be transformed to elastic net penalties. In simulation studies we first compare various co-data models for continuous co-data from the extension to the original method. Secondly, we compare variable selection performance to other variable selection methods. The extension is faster than the original method and shows improved prediction and variable selection performance for non-linear co-data relations. Moreover, we demonstrate use of the package in several genomics examples throughout the paper., Conclusions: The R-package ecpc accommodates linear, generalised additive and shape constrained additive co-data models for the purpose of improved high-dimensional prediction and variable selection. The extended version of the package as presented here (version number 3.1.1 and higher) is available on ( https://cran.r-project.org/web/packages/ecpc/ )., (© 2023. The Author(s).)

Cisplatin-based neoadjuvant chemotherapy (NAC) followed by radical cystectomy is recommended for patients with muscle-invasive bladder cancer (MIBC). It has been shown that somatic deleterious mutations in ERCC2, gain-of-function mutations in ERBB2, and alterations in ATM, RB1, and FANCC are correlated with pathological response to NAC in MIBC. The objective of this study was to validate these genomic biomarkers in pretreatment transurethral resection material from an independent retrospective cohort of 165 patients with MIBC who subsequently underwent NAC and radical surgery. Patients with ypT0/Tis/Ta/T1N0 disease after surgery were defined as responders. Somatic deleterious mutations in ERCC2 were found in nine of 68 (13%) evaluable responders and two of 95 (2%) evaluable nonresponders (p = 0.009; FDR = 0.03). No correlation was observed between response and alterations in ERBB2 or in ATM, RB1, or FANCC alone or in combination. In an exploratory analysis, no additional genomic alterations discriminated between responders and nonresponders to NAC. No further associations were identified between the aforementioned biomarkers and pathological complete response (ypT0N0) after surgery. In conclusion, we observed a positive association between deleterious mutations in ERCC2 and pathological response to NAC, but not overall survival or recurrence-free survival. Other previously reported genomic biomarkers were not validated. PATIENT SUMMARY: It is currently unknown which patients will respond to chemotherapy before definitive surgery for bladder cancer. Previous studies described several gene mutations in bladder cancer that correlated with chemotherapy response. This study confirmed that patients with bladder cancer with a mutation in the ERCC2 gene often respond to chemotherapy., (Copyright © 2022 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Invasive lobular breast cancer (ILC) is the second most common histological breast cancer subtype, but ILC-specific trials are lacking. Translational research revealed an immune-related ILC subset, and in mouse ILC models, synergy between immune checkpoint blockade and platinum was observed. In the phase II GELATO trial ( NCT03147040 ), patients with metastatic ILC were treated with weekly carboplatin (area under the curve 1.5 mg ml -1 min -1 ) as immune induction for 12 weeks and atezolizumab (PD-L1 blockade; triweekly) from the third week until progression. Four of 23 evaluable patients had a partial response (17%), and 2 had stable disease, resulting in a clinical benefit rate of 26%. From these six patients, four had triple-negative ILC (TN-ILC). We observed higher CD8 + T cell infiltration, immune checkpoint expression and exhausted T cells after treatment. With this GELATO trial, we show that ILC-specific clinical trials are feasible and demonstrate promising antitumor activity of atezolizumab with carboplatin, particularly for TN-ILC, and provide insights for the design of highly needed ILC-specific trials., (© 2023. The Author(s).)

Background: Studies have shown that blood platelets contain tumour-specific mRNA profiles tumour-educated platelets (TEPs). Here, we aim to train a TEP-based breast cancer detection classifier., Methods: Platelet mRNA was sequenced from 266 women with stage I-IV breast cancer and 212 female controls from 6 hospitals. A particle swarm optimised support vector machine (PSO-SVM) and an elastic net-based classifier (EN) were trained on 71% of the study population. Classifier performance was evaluated in the remainder (29%) of the population, followed by validation in an independent set (37 cases and 36 controls). Potential confounding was assessed in post hoc analyses., Results: Both classifiers reached an area under the curve (AUC) of 0.85 upon internal validation. Reproducibility in the independent validation set was poor with an AUC of 0.55 and 0.54 for the PSO-SVM and EN classifier, respectively. Post hoc analyses indicated that 19% of the variance in gene expression was associated with hospital. Genes related to platelet activity were differentially expressed between hospitals., Conclusions: We could not validate two TEP-based breast cancer classifiers in an independent validation cohort. The TEP protocol is sensitive to within-protocol variation and revision might be necessary before TEPs can be reconsidered for breast cancer detection., (© 2023. The Author(s).)

Genomics has greatly improved how patients with cancer are being treated; however, clinical-grade genomic biomarkers for chemotherapies are currently lacking. Using whole-genome analysis of 37 patients with metastatic colorectal cancer (mCRC) treated with the chemotherapy trifluridine/tipiracil (FTD/TPI), we identified KRAS codon G12 (KRAS G12 ) mutations as a potential biomarker of resistance. Next, we collected real-world data of 960 patients with mCRC receiving FTD/TPI and validated that KRAS G12 mutations were significantly associated with poor survival, also in analyses restricted to the RAS/RAF mutant subgroup. We next analyzed the data of the global, double-blind, placebo-controlled, phase 3 RECOURSE trial (n = 800 patients) and found that KRAS G12 mutations (n = 279) were predictive biomarkers for reduced overall survival (OS) benefit of FTD/TPI versus placebo (unadjusted interaction P = 0.0031, adjusted interaction P = 0.015). For patients with KRAS G12 mutations in the RECOURSE trial, OS was not prolonged with FTD/TPI versus placebo (n = 279; hazard ratio (HR) = 0.97; 95% confidence interval (CI) = 0.73-1.20; P = 0.85). In contrast, patients with KRAS G13 mutant tumors showed significantly improved OS with FTD/TPI versus placebo (n = 60; HR = 0.29; 95% CI = 0.15-0.55; P < 0.001). In isogenic cell lines and patient-derived organoids, KRAS G12 mutations were associated with increased resistance to FTD-based genotoxicity. In conclusion, these data show that KRAS G12 mutations are biomarkers for reduced OS benefit of FTD/TPI treatment, with potential implications for approximately 28% of patients with mCRC under consideration for treatment with FTD/TPI. Furthermore, our data suggest that genomics-based precision medicine may be possible for a subset of chemotherapies., (© 2023. The Author(s).)

Immune checkpoint blockade (ICB) has heralded a new era in cancer therapy. Research into the mechanisms underlying response to ICB has predominantly focused on T cells; however, effective immune responses require tightly regulated crosstalk between innate and adaptive immune cells. Here, we combine unbiased analysis of blood and tumors from metastatic breast cancer patients treated with ICB with mechanistic studies in mouse models of breast cancer. We observe an increase in systemic and intratumoral eosinophils in patients and mice responding to ICB treatment. Mechanistically, ICB increased IL-5 production by CD4 + T cells, stimulating elevated eosinophil production from the bone marrow, leading to systemic eosinophil expansion. Additional induction of IL-33 by ICB-cisplatin combination or recombinant IL-33 promotes intratumoral eosinophil infiltration and eosinophil-dependent CD8 + T cell activation to enhance ICB response. This work demonstrates the critical role of eosinophils in ICB response and provides proof-of-principle for eosinophil engagement to enhance ICB efficacy., Competing Interests: Declaration of interests O.S.B., H.G., L.S., L.V., O.I.I., E.v.D., N.B., C.K., M.D., K. Kersten, M.B., D.P., C.-S.H., K.V., E.A.M.R., D.K., L.H., K. Kos, I.S.A., P.K., R.B., and D.S.T. have no competing interests to declare. M.C. reports funding to the institute from BMS and Roche/Genentech and an advisory role for BMS, outside the submitted work. W.S.M.E.T. reports receiving grants from MSD during the conduct of the PEMBRO-RT trial. P.B. reports receiving grants and medication delivery from MSD during the conduct of the PEMBRO-RT trial as well as grants and consultancy fees from BMS outside the submitted work. E.E.V. is legally responsible for all contracts with pharmaceutical companies at the NKI and reports research funding from BMS, outside the submitted work. L.F.A.W. reports funding to the institute from Genmab BV. K.E.d.V. reports research funding from Roche/Genentech and is consultant for Macomics, outside the scope of this work. M.K. reports funding to the institute from BMS, Roche/Genentech, AZ, and an advisory role for BMS, Roche, MSD, and Daiichi Sankyo, outside the submitted work., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

DNA mismatch repair-deficient (MMR-d) cancers present an abundance of neoantigens that is thought to explain their exceptional responsiveness to immune checkpoint blockade (ICB) 1,2 . Here, in contrast to other cancer types 3-5 , we observed that 20 out of 21 (95%) MMR-d cancers with genomic inactivation of β2-microglobulin (encoded by B2M) retained responsiveness to ICB, suggesting the involvement of immune effector cells other than CD8 + T cells in this context. We next identified a strong association between B2M inactivation and increased infiltration by γδ T cells in MMR-d cancers. These γδ T cells mainly comprised the Vδ1 and Vδ3 subsets, and expressed high levels of PD-1, other activation markers, including cytotoxic molecules, and a broad repertoire of killer-cell immunoglobulin-like receptors. In vitro, PD-1 + γδ T cells that were isolated from MMR-d colon cancers exhibited enhanced reactivity to human leukocyte antigen (HLA)-class-I-negative MMR-d colon cancer cell lines and B2M-knockout patient-derived tumour organoids compared with antigen-presentation-proficient cells. By comparing paired tumour samples from patients with MMR-d colon cancer that were obtained before and after dual PD-1 and CTLA-4 blockade, we found that immune checkpoint blockade substantially increased the frequency of γδ T cells in B2M-deficient cancers. Taken together, these data indicate that γδ T cells contribute to the response to immune checkpoint blockade in patients with HLA-class-I-negative MMR-d colon cancers, and underline the potential of γδ T cells in cancer immunotherapy., (© 2023. The Author(s).)

Background: How molecular profiles are associated with tumor microenvironment (TME) in high-grade serous ovarian cancer (HGSOC) is incompletely understood. Therefore, we analyzed the TME and molecular profiles of HGSOC and assessed their associations with overall survival (OS)., Methods: Patients with advanced-stage HGSOC treated in three Dutch hospitals between 2008-2015 were included. Patient data were collected from medical records. BRCA1/2 mutation, BRCA1 promotor methylation analyses, and copy number variations were used to define molecular profiles. Immune cells were assessed with immunohistochemical staining., Results: 348 patients were categorized as BRCA mutation ( BRCA m) ( BRCA m or promotor methylation) (30%), non- BRCA mutated HRD (19%), Cyclin E1 ( CCNE1 )-amplification (13%), non- BRCA mut HRD and CCNE1 -amplification (double classifier) (20%), and no specific molecular profile (NSMP) (18%). BRCA m showed highest immune cell densities and CCNE1 -amplification lowest. BRCA m showed the most favorable OS (52.5 months), compared to non- BRCA mut HRD (41.0 months), CCNE1 -amplification (28.0 months), double classifier (27.8 months), and NSMP (35.4 months). Higher immune cell densities showed a favorable OS compared to lower, also within the profiles. CD8+, CD20+, and CD103+ cells remained associated with OS in multivariable analysis., Conclusions: Molecular profiles and TME are associated with OS. TME differs per profile, with higher immune cell densities showing a favorable OS, even within the profiles. HGSOC does not reflect one entity but comprises different entities based on molecular profiles and TME.

Androgen receptor (AR) drives prostate cancer (PCa) development and progression. AR chromatin binding profiles are highly plastic and form recurrent programmatic changes that differentiate disease stages, subtypes and patient outcomes. While prior studies focused on concordance between patient subgroups, inter-tumor heterogeneity of AR enhancer selectivity remains unexplored. Here we report high levels of AR chromatin binding heterogeneity in human primary prostate tumors, that overlap with heterogeneity observed in healthy prostate epithelium. Such heterogeneity has functional consequences, as somatic mutations converge on commonly-shared AR sites in primary over metastatic tissues. In contrast, less-frequently shared AR sites associate strongly with AR-driven gene expression, while such heterogeneous AR enhancer usage also distinguishes patients' outcome. These findings indicate that epigenetic heterogeneity in primary disease is directly informative for risk of biochemical relapse. Cumulatively, our results illustrate a high level of AR enhancer heterogeneity in primary PCa driving differential expression and clinical impact., (© 2022. The Author(s).)

In prostate cancer, androgen receptor (AR)-targeting agents are very effective in various disease stages. However, therapy resistance inevitably occurs, and little is known about how tumor cells adapt to bypass AR suppression. Here, we performed integrative multiomics analyses on tissues isolated before and after 3 months of AR-targeting enzalutamide monotherapy from patients with high-risk prostate cancer enrolled in a neoadjuvant clinical trial. Transcriptomic analyses demonstrated that AR inhibition drove tumors toward a neuroendocrine-like disease state. Additionally, epigenomic profiling revealed massive enzalutamide-induced reprogramming of pioneer factor FOXA1 from inactive chromatin sites toward active cis-regulatory elements that dictate prosurvival signals. Notably, treatment-induced FOXA1 sites were enriched for the circadian clock component ARNTL. Posttreatment ARNTL levels were associated with patients' clinical outcomes, and ARNTL knockout strongly decreased prostate cancer cell growth. Our data highlight a remarkable cistromic plasticity of FOXA1 following AR-targeted therapy and revealed an acquired dependency on the circadian regulator ARNTL, a novel candidate therapeutic target., Significance: Understanding how prostate cancers adapt to AR-targeted interventions is critical for identifying novel drug targets to improve the clinical management of treatment-resistant disease. Our study revealed an enzalutamide-induced epigenomic plasticity toward prosurvival signaling and uncovered the circadian regulator ARNTL as an acquired vulnerability after AR inhibition, presenting a novel lead for therapeutic development. See related commentary by Zhang et al., p. 2017. This article is highlighted in the In This Issue feature, p. 2007., (©2022 American Association for Cancer Research.)

Somatic hotspot mutations and structural amplifications and fusions that affect fibroblast growth factor receptor 2 (encoded by FGFR2) occur in multiple types of cancer 1 . However, clinical responses to FGFR inhibitors have remained variable 1-9 , emphasizing the need to better understand which FGFR2 alterations are oncogenic and therapeutically targetable. Here we apply transposon-based screening 10,11 and tumour modelling in mice 12,13 , and find that the truncation of exon 18 (E18) of Fgfr2 is a potent driver mutation. Human oncogenomic datasets revealed a diverse set of FGFR2 alterations, including rearrangements, E1-E17 partial amplifications, and E18 nonsense and frameshift mutations, each causing the transcription of E18-truncated FGFR2 (FGFR2 ΔE18 ). Functional in vitro and in vivo examination of a compendium of FGFR2 ΔE18 and full-length variants pinpointed FGFR2-E18 truncation as single-driver alteration in cancer. By contrast, the oncogenic competence of FGFR2 full-length amplifications depended on a distinct landscape of cooperating driver genes. This suggests that genomic alterations that generate stable FGFR2 ΔE18 variants are actionable therapeutic targets, which we confirmed in preclinical mouse and human tumour models, and in a clinical trial. We propose that cancers containing any FGFR2 variant with a truncated E18 should be considered for FGFR-targeted therapies., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Targeted inhibition of aberrant signaling is an important treatment strategy in cancer, but responses are often short-lived. Multi-drug combinations have the potential to mitigate this, but to avoid toxicity such combinations must be selective and given at low dosages. Here, we present a pipeline to identify promising multi-drug combinations. We perturbed an isogenic PI3K mutant and wild-type cell line pair with a limited set of drugs and recorded their signaling state and cell viability. We then reconstructed their signaling networks and mapped the signaling response to changes in cell viability. The resulting models, which allowed us to predict the effect of unseen combinations, indicated that no combination selectively reduces the viability of the PI3K mutant cells. However, we were able to validate 25 of the 30 combinations that we predicted to be anti-selective. Our pipeline enables efficient prioritization of multi-drug combinations from the enormous search space of possible combinations., Competing Interests: The authors declare no competing interests., (© 2022 The Authors.)