Checkpoint-blocker-induced autoimmunity is associated with favourable outcome in metastatic melanoma and distinct T-cell expression profiles.

BACKGROUND: Immune checkpoint blockers (ICBs) activate CD8+ T cells, eliciting both anti-cancer activity and immune-related adverse events (irAEs). The relationship of irAEs with baseline parameters and clinical outcome is unclear. METHODS: Retrospective evaluation of irAEs on survival was performed across primary (N = 144) and secondary (N = 211) independent cohorts of patients with metastatic melanoma receiving single agent (pembrolizumab/nivolumab-sICB) or combination (nivolumab and ipilimumab-cICB) checkpoint blockade. RNA from pre-treatment and post-treatment CD8+ T cells was sequenced and differential gene expression according to irAE development assessed. RESULTS: 58.3% of patients developed early irAEs and this was associated with longer progression-free (PFS) and overall survival (OS) across both cohorts (log-rank test, OS: P < 0.0001). Median survival for patients without irAEs was 16.6 months (95% CI: 10.9-33.4) versus not-reached (P = 2.8 × 10-6). Pre-treatment monocyte and neutrophil counts, but not BMI, were additional predictors of clinical outcome. Differential expression of numerous gene pathway members was observed in CD8+ T cells according to irAE development, and patients not developing irAEs demonstrating upregulated CXCR1 pre- and post-treatment. CONCLUSIONS: Early irAE development post-ICB is associated with favourable survival in MM. Development of irAEs is coupled to expression of numerous gene pathways, suggesting irAE development in-part reflects baseline immune activation.

FBH1 helicase disrupts RAD51 filaments in vitro and modulates homologous recombination in mammalian cells.

Efficient repair of DNA double strand breaks and interstrand cross-links requires the homologous recombination (HR) pathway, a potentially error-free process that utilizes a homologous sequence as a repair template. A key player in HR is RAD51, the eukaryotic ortholog of bacterial RecA protein. RAD51 can polymerize on DNA to form a nucleoprotein filament that facilitates both the search for the homologous DNA sequences and the subsequent DNA strand invasion required to initiate HR. Because of its pivotal role in HR, RAD51 is subject to numerous positive and negative regulatory influences. Using a combination of molecular genetic, biochemical, and single-molecule biophysical techniques, we provide mechanistic insight into the mode of action of the FBH1 helicase as a regulator of RAD51-dependent HR in mammalian cells. We show that FBH1 binds directly to RAD51 and is able to disrupt RAD51 filaments on DNA through its ssDNA translocase function. Consistent with this, a mutant mouse embryonic stem cell line with a deletion in the FBH1 helicase domain fails to limit RAD51 chromatin association and shows hyper-recombination. Our data are consistent with FBH1 restraining RAD51 DNA binding under unperturbed growth conditions to prevent unwanted or unscheduled DNA recombination.

Severe acute myositis and myocarditis on initiation of 6-weekly pembrolizumab post-COVID-19 mRNA vaccination.

We describe three cases of critical acute myositis with myocarditis occurring within 22 days of each other at a single institution, all within 1 month of receiving the initial cycle of the anti-PD-1 drug pembrolizumab. Analysis of T cell receptor repertoires from peripheral blood and tissues revealed a high degree of clonal expansion and public clones between cases, with several T cell clones expanded within the skeletal muscle putatively recognizing viral epitopes. All patients had recently received a COVID-19 mRNA booster vaccine prior to treatment and were positive for SARS-CoV2 Spike antibody. In conclusion, we report a series of unusually severe myositis and myocarditis following PD-1 blockade and the COVID-19 mRNA vaccination.

IL7 genetic variation and toxicity to immune checkpoint blockade in patients with melanoma.

Treatment with immune checkpoint blockade (ICB) frequently triggers immune-related adverse events (irAEs), causing considerable morbidity. In 214 patients receiving ICB for melanoma, we observed increased severe irAE risk in minor allele carriers of rs16906115, intronic to IL7. We found that rs16906115 forms a B cell-specific expression quantitative trait locus (eQTL) to IL7 in patients. Patients carrying the risk allele demonstrate increased pre-treatment B cell IL7 expression, which independently associates with irAE risk, divergent immunoglobulin expression and more B cell receptor mutations. Consistent with the role of IL-7 in T cell development, risk allele carriers have distinct ICB-induced CD8+ T cell subset responses, skewing of T cell clonality and greater proportional repertoire occupancy by large clones. Finally, analysis of TCGA data suggests that risk allele carriers independently have improved melanoma survival. These observations highlight key roles for B cells and IL-7 in both ICB response and toxicity and clinical outcomes in melanoma.

Intravenous high-dose interferon with or without maintenance treatment in melanoma at high risk of recurrence: meta-analysis of three trials.

Resected stage IIB-IIIC malignant melanoma has a poor prognosis with a high risk of relapse and death. Treatment with adjuvant interferon alfa-2b (IFN-α-2b) is associated with improved relapse-free and overall survivals (OS), but the most appropriate dose and duration of treatment are unknown. In this article, we present an individual patient data random effects meta-analysis of melanoma patients from the U.K., Greek, and Chinese randomized trials. All patients were randomized either to IFN-α-2b 15-20 MIU/m(2) IV daily 5 days per week for 4 weeks (IV) or to the same regimen followed by IFN-α-2b 9-10 MIU/m(2) administered three times per week for 48 weeks (IV and SC). Allowing for dose interruptions and reductions, an equivalent total dose of IFN-α-2b was delivered in all three studies. We assessed whether IV was noninferior to IV and SC in terms of relapse-free survival (RFS) and investigated tumor and patient characteristics that impacted on outcomes. Median follow-up of 716 stage IIB-IIIC patients was 5.4 years. Noninferiority of IV compared to IV and SC could not be conferred for RFS (hazard ratio [HR] 1.16, 95% confidence interval [CI] 0.89-1.52; noninferior P = 0.17). Stage (P < 0.0001), site (acral vs. other, P < 0.0001), and Breslow thickness (P = 0.02) were significant predictors of RFS. The HR for death was 1.13 for IV compared to IV and SC, (95% CI 0.91-1.39). Stage (P < 0.0001) and Breslow thickness (P = 0.001) were significant independent predictors of OS. The available data suggest that where adjuvant high-dose interferon is being considered there is no evidence to deviate from the year long regimen described in the Eastern Cooperative Oncology Group and Intergroup studies.

FBH1 influences DNA replication fork stability and homologous recombination through ubiquitylation of RAD51.

Unscheduled homologous recombination (HR) can lead to genomic instability, which greatly increases the threat of neoplastic transformation in humans. The F-box DNA helicase 1 (FBH1) is a 3'-5' DNA helicase with a putative function as a negative regulator of HR. It is the only known DNA helicase to contain an F-box, suggesting that one of its functions is to act as a ubiquitin ligase as part of an SCF (SKP1, CUL1 and F-box) complex. Here we report that the central player in HR, RAD51, is ubiquitylated by the SCF(FBH1) complex. Expression of an ubiquitylation-resistant form of RAD51 in human cells leads to hyperrecombination, as well as several phenotypes indicative of an altered response to DNA replication stress. These effects are likely to be mediated by the enhanced nuclear matrix association of the ubiquitylation-resistant RAD51. These data are consistent with FBH1 acting as a negative regulator of RAD51 function in human cells.

Phase II pilot study of intravenous high-dose interferon with or without maintenance treatment in melanoma at high risk of recurrence.

PURPOSE: High-dose interferon alfa-2b (HDI) has emerged as a potentially effective adjuvant therapy in patients with resected melanoma at high risk of recurrence. Evidence suggests it may be the early, very-high-dose part of the regimen that is critical. This pilot study sought to provide an early indication of whether the same effects can be achieved with the intravenous component of HDI alone and inform the feasibility and design of a phase III trial. PATIENTS AND METHODS: Patients with stage 2B, 2C, 3B, and 3C melanoma were randomly assigned to receive interferon alfa-2b (IFN-α-2b) 20 MIU/m(2) intravenously (IV) daily 5 days per week for 4 weeks (arm A) versus the same regimen followed by IFN-α-2b 10 MIU/m(2) administered subcutaneously three times per week for 48 weeks (arm B) and observed for relapse-free survival (RFS) and overall survival. RESULTS: Between 2003 and 2009, 194 patients were enrolled (arm A, 96; arm B, 98). After median follow-up of 39.5 months, RFS was 22.7 months (95% CI, 14.1 to 38.1 months) in arm A versus 33.3 months (95% CI, 18.2 to not reached) in arm B (P = .28). The proportions of patients free of relapse at 2 years were 50% and 54.1% (P = .569; hazard ratio, 0.89), respectively. Overall survival favored arm B (median, 41.5 months v not reached; P = .05). CONCLUSION: Clinical outcomes were better in patients who had the longer regimen. Our results do not support either the use of a month of IV HDI alone in place of the year-long regimen or the initiation of a larger trial on this question.

FBH1 co-operates with MUS81 in inducing DNA double-strand breaks and cell death following replication stress.

The molecular events occurring following the disruption of DNA replication forks are poorly characterized, despite extensive use of replication inhibitors such as hydroxyurea in the treatment of malignancies. Here, we identify a key role for the FBH1 helicase in mediating DNA double-strand break formation following replication inhibition. We show that FBH1-deficient cells are resistant to killing by hydroxyurea, and exhibit impaired activation of the pro-apoptotic factor p53, consistent with decreased DNA double-strand break formation. Similar findings were obtained in murine ES cells carrying disrupted alleles of Fbh1. We also show that FBH1 through its helicase activity co-operates with the MUS81 nuclease in promoting the endonucleolytic DNA cleavage following prolonged replication stress. Accordingly, MUS81 and EME1-depleted cells show increased resistance to the cytotoxic effects of replication stress. Our data suggest that FBH1 helicase activity is required to eliminate cells with excessive replication stress through the generation of MUS81-induced DNA double-strand breaks.