Background Immune checkpoint inhibitors are successfully introduced as anticancer treatment. However, they may induce severe immune-related adverse events (irAEs). One of the most frequent irAEs is diarrhoea. The main objective of this study was to analyse symptoms (ie, grade of diarrhoea), endoscopic and histological features and response to management in immune checkpoint inhibition-related colitis (IRC). Patients and methods We retrospectively analysed patients who developed diarrhoea on checkpoint inhibition and therefore underwent an endoscopy and/or were treated with corticosteroids. Patients were treated between August 2010 and March 2016 for metastatic melanoma or non-small cell lung cancer. Severity of IRC was scored using the endoscopic Mayo score and the van der Heide score. Results Out of a cohort of 781 patients, 92 patients were identified who developed diarrhoea and therefore underwent an endoscopy and/or were treated with corticosteroids. Patients were treated with monotherapy anticytotoxic T-lymphocyte antigen-4, antiprogrammed death receptor-1 or a combination of both. All patients had symptoms of diarrhoea (grade 1: 16%; grade 2: 39% and grade 3: 44%). A complete colonoscopy was performed in 62 (67%) patients, of whom 42 (68%) had a pancolitis (≥3 affected segments). Ulcers were seen in 32% of endoscopies. There was no significant correlation between the grade of diarrhoea at presentation and endoscopic severity scores, the presence of ulcers or histological features. In 54 episodes of diarrhoea (56%), patients received one or more cycles infliximab for steroid-refractory colitis. Patients with higher endoscopic severity scores, ulcers and/or a pancolitis needed infliximab more often. Conclusions The correlation between grade of diarrhoea and endoscopic or histological features for severity of colitis is poor. Patients with higher endoscopic severity scores, ulcers or a pancolitis needed the addition of infliximab more often. Therefore, endoscopy may have value in the evaluation of the severity of IRC and may help in decision making for optimal management.

Lactate dehydrogenase (LDH) levels are inversely related with response to checkpoint inhibitors. Elevated LDH levels are the product of enhanced glycolytic activity of the tumor and tumor necrosis due to hypoxia, the latter being associated with high tumor burden. In this review, we elucidate the effects of glycolysis and hypoxia on antitumor immunity and set forth ways to improve response to immunotherapy in cancer patients with elevated LDH levels. We discuss the current knowledge on combining immunotherapy with glycolysis inhibitors, anti-acidifying drugs, anti-angiogenic or cytoreductive therapy.

Homologous recombination repair deficiency (HRD) can be observed in virtually all cancer types. Although HRD sensitizes tumors to DNA-damaging chemotherapy and poly(ADP-ribose) polymerase (PARP) inhibitors, all patients ultimately develop resistance to these therapies. Therefore, it is necessary to identify therapeutic regimens with a more durable efficacy. HRD tumors have been suggested to be more immunogenic and, therefore, more susceptible to treatment with checkpoint inhibitors. In this review, we describe how HRD might mechanistically affect antitumor immunity and summarize the available translational evidence for an association between HRD and antitumor immunity across multiple tumor types. In addition, we give an overview of all available clinical data on the efficacy of checkpoint inhibitors in HRD tumors and describe the evidence for using treatment strategies that combine checkpoint inhibitors with PARP inhibitors.

Metastatic castration-resistant prostate cancer (mCRPC) typically exhibits resistance to immune checkpoint inhibitors (ICIs). However, a subset of mCRPC patients displays a more immunogenic profile. This study examines efficacy and safety of dual ICI therapy in molecularly selected mCRPC. This single-arm, phase II trial, included 69 molecularly selected mCRPC patients with mismatch repair deficiency (MMRd), non-synonymous tumour mutational burden ≥7.1 muts/Mb (hTMB), a BRCA2 mutation (BRCAm), or biallelic CDK12 inactivation (CDK12i). Efficacy was assessed in ICI-naïve patients (cohort A) with RECIST1.1 (A1) and PCWG3 (A2) measurable disease. Safety was evaluated in cohorts A and B (prior ICI monotherapy). Treatment included nivolumab 3 mg/kg and ipilimumab 1 mg/kg every 3 weeks for 4 cycles, followed by nivolumab 480 mg every 4 weeks for up to 1 year. The primary endpoint was disease control rate beyond 6 months (DCR>6), aiming to surpass a DCR>6 of 22%. Patients initiated treatment between January 2021 and February 2024. Cohort A included 65 patients. Of these, 21 had MMRd (32%), 8 hTMB (12%), 20 BRCAm (31%), and 16 CDK12i (25%). DCR>6 was achieved in 38% (95% CI 27-51), and was highest in MMRd (81%), followed by hTMB (25%), CDK12i (19%), and BRCAm (15%). Objective and PSA50 response rates in cohort A were 38% (95% CI 22-55) and 47% (95% CI 34-60), respectively. Median progression-free survival was 4.0 months (95% CI 3.5-12.0) in cohort A, and 32.7 months (95% CI 21.8-NR) in MMRd patients. Treatment-related adverse events (TRAEs) led to permanent discontinuation in 14 of 69 patients (20%). Grade ≥3 TRAEs occurred in 48% of patients, with diarrhoea and elevated transaminases each in 10%. There was one treatment-related death due to a bowel perforation and a second following euthanasia after grade 4 toxicity. This trial of dual ICIs in molecularly selected mCRPC met its primary endpoint, showing DCR>6 in 40% of patients. Dual ICIs exhibited modest responses in the hTMB, BRCAm and CDK12i subgroups, but demonstrated exceptional efficacy in MMRd.

The prognosis and responsiveness to chemotherapy and checkpoint inhibitors differs substantially among patients with bladder cancer (BC). There is an unmet need for biomarkers that can accurately predict prognosis and treatment outcome. Here, we describe the available literature on the prognostic and predictive value of tumor-infiltrating immune cells in BC. Current evidence indicates that a high density of tumor-infiltrating CD8⁺ T cells is a favorable prognostic factor, whereas PD-L1 expression and tumor-associated macrophages are unfavorable prognostic features. While PD-L1 expression appears unsuccessful as a biomarker for the response to checkpoint inhibitors, there are some indications that high CD8⁺ T cell infiltration, low transforming growth factor-beta signaling and low densities of myeloid-derived suppressor cells are associated with response. Future studies should focus on combinations of biomarkers to accurately predict survival and response to treatment.

Up to 5% of patients with metastatic castration-resistant prostate cancer (mCRPC) harbour loss-of-function alterations in mismatch repair genes (dMMR) resulting in microsatellite instability (MSI-H). Data on the efficacy of immune checkpoint inhibitors (ICIs) in dMMR mCRPC are limited, and reimbursement for these agents is not universally available. We performed an international, multicentre, retrospective study to investigate the efficacy of anti-PD-(L)1 monotherapy in dMMR mCRPC. dMMR was defined as MMR protein loss on immunohistochemistry (IHC), and/or a deleterious alteration in an MMR gene or MSI-H status according to polymerase chain reaction analysis or next-generation sequencing. The primary endpoint was progression-free survival (PFS). Between July 2016 and July 2024, 93 patients with a median age of 70 yr (range 46-90) started anti-PD-(L)1 treatment. Patients were classified as dMMR on the basis of IHC results (n = 37, 40%), genomic alterations in MMR genes (n = 55, 59%), and/or an MSI-H phenotype (n = 64, 69%). Among evaluable patients according to Response Evaluation Criteria in Solid Tumours v1.1, the objective response rate was 46% (n = 84; 95% confidence interval [CI] 35-58%). A prostate-specific antigen decline ≥50% was observed in 60% of evaluable patients (n = 68; 95% CI 48-72%). Median PFS across the entire cohort was 7.7 mo (95% CI 5.3-12.4), with 1-yr, 2-yr, and 3-yr PFS rates of 39%, 27%, and 26%, respectively. Median overall survival was 27.0 mo (95% CI 17.7-43.5). PFS was significantly longer for patients with positive dMMR status on two or more tests than for patients with just one positive dMMR test. These data confirm the efficacy of anti-PD-(L)1 therapy in patients with dMMR mCRPC and warrant consideration of reimbursement for anti-PD-(L)1 agents in dMMR mCRPC by health authorities.