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While BRAF inhibitor combinations with EGFR and/or MEK inhibitors have improved clinical efficacy in BRAF V600E colorectal cancer (CRC), response rates remain low and lack durability. Preclinical data suggest that BRAF/MAPK pathway inhibition may augment the tumor immune response. We performed a proof-of-concept single-arm phase 2 clinical trial of combined PD-1, BRAF and MEK inhibition with sparatlizumab (PDR001), dabrafenib and trametinib in 37 patients with BRAF V600E CRC. The primary end point was overall response rate, and the secondary end points were progression-free survival, disease control rate, duration of response and overall survival. The study met its primary end point with a confirmed response rate (24.3% in all patients; 25% in microsatellite stable patients) and durability that were favorable relative to historical controls of BRAF-targeted combinations alone. Single-cell RNA sequencing of 23 paired pretreatment and day 15 on-treatment tumor biopsies revealed greater induction of tumor cell-intrinsic immune programs and more complete MAPK inhibition in patients with better clinical outcome. Immune program induction in matched patient-derived organoids correlated with the degree of MAPK inhibition. These data suggest a potential tumor cell-intrinsic mechanism of cooperativity between MAPK inhibition and immune response, warranting further clinical evaluation of optimized targeted and immune combinations in CRC. ClinicalTrials.gov registration: NCT03668431. Patients with BRAF V600E -mutated colorectal cancer have encouraging overall response rates to inhibition of PD-1, BRAF and MEK, with translational analyses suggesting that induction of tumor-intrinsic programs and immune programs contributes to improved outcomes via MAPK inhibition.

ObjectiveWhile oesophageal squamous cell carcinoma remains infrequent in Western populations, the incidence of oesophageal adenocarcinoma (EAC) has increased sixfold to eightfold over the past four decades. We aimed to characterise oesophageal cancer-specific and subtypes-specific gene regulation patterns and their upstream transcription factors (TFs). DesignTo identify regulatory elements, we profiled fresh-frozen oesophageal normal samples, tumours and cell lines with chromatin immunoprecipitation sequencing (ChIP-Seq). Mathematical modelling was performed to establish (super)-enhancers landscapes and interconnected transcriptional circuitry formed by master TFs. Coregulation and cooperation between master TFs were investigated by ChIP-Seq, circularised chromosome conformation capture sequencing and luciferase assay. Biological functions of candidate factors were evaluated both in vitro and in vivo.ResultsWe found widespread and pervasive alterations of the (super)-enhancer reservoir in both subtypes of oesophageal cancer, leading to transcriptional activation of a myriad of novel oncogenes and signalling pathways, some of which may be exploited pharmacologically (eg, leukemia inhibitory factor (LIF) pathway). Focusing on EAC, we bioinformatically reconstructed and functionally validated an interconnected circuitry formed by four master TFs—ELF3, KLF5, GATA6 and EHF—which promoted each other’s expression by interacting with each super-enhancer. Downstream, these master TFs occupied almost all EAC super-enhancers and cooperatively orchestrated EAC transcriptome. Each TF within the transcriptional circuitry was highly and specifically expressed in EAC and functionally promoted EAC cell proliferation and survival.ConclusionsBy establishing cancer-specific and subtype-specific features of the EAC epigenome, our findings promise to transform understanding of the transcriptional dysregulation and addiction of EAC, while providing molecular clues to develop novel therapeutic modalities against this malignancy.

DNA is an organic molecule that is highly vulnerable to chemical alterations and breaks caused by both internal and external factors. Cells possess complex and advanced mechanisms, including DNA repair, damage tolerance, cell cycle checkpoints, and cell death pathways, which together minimize the potentially harmful effects of DNA damage. However, in cancer cells, the normal DNA damage tolerance and response processes are disrupted or deregulated. This results in increased mutagenesis and genomic instability within the cancer cells, a known driver of cancer progression and therapeutic resistance. On the other hand, the inherent instability of the genome in rapidly dividing cancer cells can be exploited as a tool to kill by imposing DNA damage with radiopharmaceuticals. As the field of targeted radiopharmaceutical therapy (RPT) is rapidly growing in oncology, it is crucial to have a deep understanding of the impact of systemic radiation delivery by radiopharmaceuticals on the DNA of tumors and healthy tissues. The distribution and activation of DNA damage and repair pathways caused by RPT can be different based on the characteristics of the radioisotope and molecular target. Here we provide a comprehensive discussion of the biological effects of RPTs, with the main focus on the role of varying radioisotopes in inducing direct and indirect DNA damage and activating DNA repair pathways.

Successfully extending immunotherapies to solid tumors involves addressing several key challenges, importantly the “antigen dilemma”, the expression of a solid tumor target antigen on the normal tissue of tumor origin. Claudin 18.2 (CLDN18.2) has emerged as an important target for upper gastrointestinal (GI) cancer therapies (such as Zolbetuximab, a naked antibody, recently approved; or CT041, a second-generation chimeric antigen receptor (CAR) T cell therapy with promising clinical data). However, GI toxicities are reported from clinical use of both Zolbetuximab and CT041. Here, we describe clinical Zolbetuximab treatment associated cases of gastric erosive lesions. We also demonstrate and characterize on-target/off-tumor gastric toxicity targeting CLDN18.2 in a preclinical mouse model of CT041-scFv derived CAR T cell therapy. By developing CLDN18.2 fully-human VH-only single domain CARs, we demonstrate that on-target/off-tumor toxicity inversely correlates with affinity of the binder, and that a lower affinity CAR may widen the therapeutic window for CLDN18.2 by decreasing on-target/off-tumor toxicity while preserving efficacy. Claudin 18.2 (CLDN18.2) has emerged as a target for gastrointestinal cancer, however, on-target/off-tumor toxicities have been also reported. Here, after reporting evidence of erosive gastritis in patients treated with CLDN18.2 targeted immunotherapies, the authors develop and characterize CLDN18.2 fully-human VH-only single domain CARs, showing that a lower affinity CAR mitigates on-target/off-tumor toxicity while preserving anti-tumor efficacy in gastric cancer models.

BackgroundDespite unprecedented benefit from immune checkpoint inhibitors (ICIs) in patients with mismatch repair deficient (dMMR)/microsatellite instability high (MSI-H) advanced gastrointestinal cancers, a relevant proportion of patients shows primary resistance or short-term disease control. Since malignant effusions represent an immune-suppressed niche, we investigated whether peritoneal involvement with or without ascites is a poor prognostic factor in patients with dMMR/MSI-H metastatic colorectal cancer (mCRC) and gastric cancer (mGC) receiving ICIs.MethodsWe conducted a global multicohort study at Tertiary Cancer Centers and collected clinic-pathological data from a cohort of patients with dMMR/MSI-H mCRC treated with anti-PD-(L)1 ±anti-CTLA-4 agents at 12 institutions (developing set). A cohort of patients with dMMR/MSI-high mGC treated with anti-PD-1 agents±chemotherapy at five institutions was used as validating dataset.ResultsThe mCRC cohort included 502 patients. After a median follow-up of 31.2 months, patients without peritoneal metastases and those with peritoneal metastases and no ascites had similar outcomes (adjusted HR (aHR) 1.15, 95% CI 0.85 to 1.56 for progression-free survival (PFS); aHR 0.96, 95% CI 0.65 to 1.42 for overall survival (OS)), whereas inferior outcomes were observed in patients with peritoneal metastases and ascites (aHR 2.90, 95% CI 1.70 to 4.94; aHR 3.33, 95% CI 1.88 to 5.91) compared with patients without peritoneal involvement. The mGC cohort included 59 patients. After a median follow-up of 17.4 months, inferior PFS and OS were reported in patients with peritoneal metastases and ascites (aHR 3.83, 95% CI 1.68 to 8.72; aHR 3.44, 95% CI 1.39 to 8.53, respectively), but not in patients with only peritoneal metastases (aHR 1.87, 95% CI 0.64 to 5.46; aHR 2.15, 95% CI 0.64 to 7.27) when compared with patients without peritoneal involvement.ConclusionsPatients with dMMR/MSI-H gastrointestinal cancers with peritoneal metastases and ascites should be considered as a peculiar subgroup with highly unfavorable outcomes to current ICI-based therapies. Novel strategies to target the immune-suppressive niche in malignant effusions should be investigated, as well as next-generation ICIs or intraperitoneal approaches.

Preclinical studies suggest that simultaneous HER2/VEGF blockade may have cooperative effects in gastroesophageal adenocarcinomas. In a single-arm investigator initiated clinical trial for patients with untreated advanced HER2+ gastroesophageal adenocarcinoma, bevacizumab was added to standard of care capecitabine, oxaliplatin, and trastuzumab in 36 patients (NCT01191697). Primary endpoint was objective response rate and secondary endpoints included safety, duration of response, progression free survival, and overall survival. The study met its primary endpoint with an objective response rate of 81% (95% CI 65–92%). Median progression free and overall survival were 14.0 (95% CI, 11.3–36.4) and 23.2 months (95% CI, 16.6–36.4), respectively. The median duration of response was 14.9 months. The regimen was well tolerated without unexpected or severe toxicities. In post-hoc ctDNA analysis, baseline ctDNA features were prognostic: Higher tumor fraction and alternative MAPK drivers portended worse outcomes. ctDNA at resistance identified oncogenic mutations and these were detectable 2–8 cycles prior to radiographic progression. Capecitabine, oxaliplatin, trastuzumab and bevacizumab shows robust clinical activity in HER2+ gastroesophageal adenocarcinoma. Combination of VEGF inhibitors with chemoimmunotherapy and anti-PD1 regimens is warranted. Preclinical studies indicate that simultaneous HER2 and VEGF blockade may be beneficial in gastroesophageal adenocarcinoma (GEA). Here, the authors report the efficacy and biomarker analysis of a phase II clinical trial investigating the combination of bevacizumab (anti-VEGF) and standard-of-care CAPOX (capecitabine, oxaliplatin) and trastuzumab in previously untreated advanced HER2 + GEA.

Biomarker-enriched, chemotherapy-free treatments for patients with advanced gastric and gastroesophageal junction cancer have not been widely explored. In this multicenter, phase 2 trial (NCT04363801), we evaluated the efficacy and safety of second-line doublet immunotherapy, combining DKN-01, an immunomodulating antibody targeting Dickkopf-related protein 1 (DKK1), with the anti-programmed cell death-1 (PD1) antibody, tislelizumab in patients with advanced gastric/gastroesophageal junction cancer and elevated tumor DKK1 expression, a putative predictive biomarker for DKN-01. Here we report part B (second line cohort) of the larger DisTinGuish trial. The primary endpoint was safety and tolerability, with secondary endpoints including objective response rate (ORR), overall survival (OS), progression free survival (PFS), and disease control rate (DCR). The trial met the prespecified primary endpoint. In the safety population ( n  = 52), 21 (40.4%) patients reported at least 1 DKN-01-related adverse event, most of which were low-grade, with fatigue (15.4%) and nausea (9.6%) being most common. The ORR was 21.7% in the overall population ( n  = 46) and 31.8% in the programmed death-ligand 1 (PD-L1) ≥ 5% population. The median OS was 8.2 months, median PFS 1.4 months, and DCR rate 34.8% in the overall population. Although exploratory, the results of this trial compare favorably against second-line benchmarks of Keynote-061 and RAINBOW and support the safety and tolerability of DKN-01 combined with tislelizumab. Dickkopf-related protein 1 (DKK1) is a secreted protein associated with poorer outcomes in patients with gastric cancer. Here, the authors report part B of the DisTinGuish phase II trial reporting the safety and efficacy of DKN-01 (DKK1 neutralising antibody) in combination with tislelizumab (anti-PD-1) in patients with advanced gastric/gastoesophageal junction cancer and elevated DKK1 expression.

Background Neoadjuvant chemoradiation and chemotherapy are recommended for the treatment of nonmetastatic esophageal cancer. The benefit of neoadjuvant treatment is mostly limited to patients who exhibit pathologic complete response (pCR). Existing estimates of pCR rates among patients receiving neoadjuvant therapy have not been synthesized and lack precision. Methods We conducted an independently funded systematic review and meta‐analysis (PROSPERO CRD42023397402) of pCR rates among patients diagnosed with esophageal cancer treated with neoadjuvant chemo(radiation). Studies were identified from Medline, EMBASE, and CENTRAL database searches. Eligible studies included trials published from 1992 to 2022 that focused on nonmetastatic esophageal cancer, including the gastroesophageal junction. Histology‐specific pooled pCR prevalence was determined using the Freeman–Tukey transformation and a random effects model. Results After eligibility assessment, 84 studies with 6451 patients were included. The pooled prevalence of pCR after neoadjuvant chemotherapy in squamous cell carcinomas was 9% (95% CI: 6%–14%), ranging from 0% to 32%. The pooled prevalence of pCR after neoadjuvant chemoradiation in squamous cell carcinomas was 32% (95% CI: 26%–39%), ranging from 8% to 66%. For adenocarcinoma, the pooled prevalence of pCR was 6% (95% CI: 1%–12%) after neoadjuvant chemotherapy, and 22% (18%–26%) after neoadjuvant chemoradiation. Conclusions Under one‐third of patients with esophageal cancer who receive neoadjuvant chemo(radiation) experience pCR. Patients diagnosed with squamous cell carcinomas had higher rates of pCR than those with adenocarcinomas. As pCR represents an increasingly utilized endpoint in neoadjuvant trials, these estimates of pooled pCR rates may serve as an important benchmark for future trial design. This systematic review and meta‐analysis revealed that less than one‐third of nonmetastatic esophageal cancer patients achieve pathologic complete response (pCR) after neoadjuvant chemoradiation or chemotherapy, with squamous cell carcinomas exhibiting higher pCR rates than adenocarcinomas. These findings derived from a robust pool of 84 studies could offer a critical benchmark for future trial design.

BackgroundThere is uncertainty around clinical applicability of tumor mutational burden (TMB) across cancer types, in part because of inconsistency between TMB measurements from different platforms. The KEYNOTE 158 trial supported United States Food and Drug Administration (FDA) approval of the Foundation Medicine test (FoundationOneCDx) at TMB≥10 mut/Mb as a companion diagnostic (CDx) for single-agent pembrolizumab in second+line. Using a large real-world dataset with validated survival endpoint data, we evaluated clinical validity of TMB measurement by the test in over 8000 patients across 24 cancer types who received single-agent immune checkpoint inhibitor (ICI).MethodsPatients with advanced-stage cancers from 24 cancer types treated with single-agent anti-PD(L)1 therapy in standard-of-care settings were included. Deidentified data from electronic health records from approximately 280 cancer treatment facilities were captured into a clinico-genomic database. This study used the TMB algorithm from the FDA-approved test supporting solid tumor CDx and composite mortality variable validated against the national death index: real-world overall survival (rwOS). Following a prespecified analysis plan, rwOS by TMB level was assessed using Cox PH models adjusted for Eastern Cooperative Oncology Group performance status, prior treatment, microsatellite instability, sex, age, opioid rx pretherapy, and socioeconomic assessment.Results8440 patients met inclusion criteria. Adjusting for aforementioned factors, increasing TMB was significantly associated with rwOS across tumor types; HRs (95% CIs) relative to TMB<5: TMB 5 to <10: 0.95 (0.89 to 1.02), TMB 10 to <20: 0.79 (0.73 to 0.85), TMB≥20: 0.52 (0.47 to 0.58). For individual cancer types with prespecified statistical power, adjusted rwOS comparing TMB≥10 vs TMB<10 significantly favored TMB≥10 in 9 of 10 cancer types. In microsatellite stable subcohorts (except colorectal cancer), TMB≥10 remained associated with enriched ICI benefit. Exploratory assessments of patients receiving ICI+chemotherapy (n=4369) observed more favorable rwOS only in TMB≥20.ConclusionsAcross >8000 patients treated with single-agent ICI, and within individual cancer types with sufficient power, elevated TMB based on the FDA-approved CDx was associated with more favorable rwOS compared with similar patients with lower TMB levels. This biomarker deserves further clinical investigation to potentially guide the use of immunotherapy in expanded clinical contexts.