Background No phase 3 trial has yet shown improved survival for patients with pleural or peritoneal malignant mesothelioma who have progressed following platinum-based chemotherapy. The aim of this study was to assess the efficacy and safety of nivolumab, an anti-PD-1 antibody, in these patients.Methods This was a multicentre, placebo-controlled, double-blind, parallel group, randomised, phase 3 trial done in 24 hospitals in the UK. Adult patients (aged ≥18 years) with an Eastern Cooperative Oncology Group performance status of 0 or 1, with histologically confirmed pleural or peritoneal mesothelioma, who had received previous first-line platinum-based chemotherapy and had radiological evidence of disease progression, were randomly assigned (2:1) to receive nivolumab at a flat dose of 240 mg every 2 weeks over 30 min intravenously or placebo until disease progression or a maximum of 12 months. The randomisation sequence was generated within an interactive web response system (Alea); patients were stratified according to epithelioid versus non-epithelioid histology and were assigned in random block sizes of 3 and 6. Participants and treating clinicians were masked to group allocation. The co-primary endpoints were investigator-assessed progression-free survival and overall survival, analysed according to the treatment policy estimand (an equivalent of the intention-to-treat principle). All patients who were randomly assigned were included in the safety population, reported according to group allocation. This trial is registered with Clinicaltrials.gov, NCT03063450.

Malignant Pleural Mesothelioma (MPM) is typically diagnosed 20–50 years after exposure to asbestos and evolves along an unknown evolutionary trajectory. To elucidate this path, we conducted multi-regional exome sequencing of 90 tumour samples from 22 MPMs acquired at surgery. Here we show that exomic intratumour heterogeneity varies widely across the cohort. Phylogenetic tree topology ranges from linear to highly branched, reflecting a steep gradient of genomic instability. Using transfer learning, we detect repeated evolution, resolving 5 clusters that are prognostic, with temporally ordered clonal drivers. BAP1/−3p21 and FBXW7/-chr4 events are always early clonal. In contrast, NF2/−22q events, leading to Hippo pathway inactivation are predominantly late clonal, positively selected, and when subclonal, exhibit parallel evolution indicating an evolutionary constraint. Very late somatic alteration of NF2/22q occurred in one patient 12 years after surgery. Clonal architecture and evolutionary clusters dictate MPM inflammation and immune evasion. These results reveal potentially drugable evolutionary bottlenecking in MPM, and an impact of clonal architecture on shaping the immune landscape, with potential to dictate the clinical response to immune checkpoint inhibition.

No abstract

and PFS (RECIST v1.1; blinded, independent central review) were assessed by the stratified log-rank test in the ITT population. The protocol-specified first interim analysis (IA1) was planned to occur when w255 deaths occurred and w12 months after the last participant was randomized. Nonbinding futility criteria at IA1 were differences in the restricted mean survival time (RMST) between pembroeipi and pembroeplacebo of 0.2 at the maximum observation time and 0.1 at 24 months of follow-up. Results: Between 12-January-2018 and 22-August-2019, 568 participants were randomized to pembroeipi (n¼284; 282 treated) and pembroeplacebo (n¼284; 281 treated). As of 01-September-2020, median (range) study follow-up was 20.6 months (12.4-31.7), treatment was ongoing in 21.3% in the pembroe ipi arm vs 23.8% in the pembroeplacebo arm, and median number of treatment cycles was 10 vs 15. Baseline characteristics were balanced between arms. With 272 deaths, median OS was 21.4 months for pembroeipi vs 21.9 months for pembroeplacebo (HR, 1.08 [95% CI, 0.85-1.37]; P ¼ 0.74). RMST differences were e0.56 at the maximum observation time and e0.52 at 24 months, which met the futility criteria. With 372 events, median PFS was 8.2 months for pembroeipi vs 8.4 months for pembroeplacebo (HR, 1.06 [95% CI, 0.86-1.30]; P ¼ 0.72). ORR was 45.4% in both arms; median DOR was 16.1 months for pembroeipi vs 17.3 months for pembroeplacebo. Treatment-related AEs occurred in 76.2% of pembroeipi recipients vs 68.3% of pembroeplacebo recipients, were of grade 3-5 in 35.1% vs 19.6%, led to death in 2.5% vs 0%, and led to discontinuation of any treatment in 25.2% vs 10.7%. Immune-mediated AEs and infusion reactions occurred in 44.7% of pembroeipi recipients vs 32.4% of pembroe placebo recipients, were grade 3-5 in 20.2% vs 7.8%, led to death in 2.1% vs 0%, and led to discontinuation of any treatment in 14.9% vs 5.3%. Based on the observed efficacy and safety, the external data monitoring committee recommended that the study be stopped due to futility and that participants discontinue ipi/placebo. Conclusion: Adding ipilimumab to pembrolizumab does not improve efficacy and is associated with greater toxicity than pembrolizumab alone as first-line therapy for metastatic NSCLC with PD-L1 TPS 50% and no targetable EGFR or ALK aberrations. These data confirm pembrolizumab monotherapy as a standard-of-care for this population.

No abstract