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Summary CD25 is expressed at high levels on regulatory T (Treg) cells and was initially proposed as a target for cancer immunotherapy. However, anti-CD25 antibodies have displayed limited activity against established tumors. We demonstrated that CD25 expression is largely restricted to tumor-infiltrating Treg cells in mice and humans. While existing anti-CD25 antibodies were observed to deplete Treg cells in the periphery, upregulation of the inhibitory Fc gamma receptor (FcγR) IIb at the tumor site prevented intra-tumoral Treg cell depletion, which may underlie the lack of anti-tumor activity previously observed in pre-clinical models. Use of an anti-CD25 antibody with enhanced binding to activating FcγRs led to effective depletion of tumor-infiltrating Treg cells, increased effector to Treg cell ratios, and improved control of established tumors. Combination with anti-programmed cell death protein-1 antibodies promoted complete tumor rejection, demonstrating the relevance of CD25 as a therapeutic target and promising substrate for future combination approaches in immune-oncology. [ABSTRACT FROM AUTHOR]

Immunomodulatory antibodies influence the direction and magnitude of immune responses against cancer. Significant efficacy has been demonstrated across multiple solid tumour types within clinical trials. Recent preclinical studies indicate that successful outcome relies upon mechanistic activity extending beyond simple receptor stimulation or blockade. In addition to blocking co-inhibitory signals in secondary lymphoid organs, cytotoxic T-lymphocyte antigen (CTLA)-4 antibodies mediate depletion of tumour-infiltrating regulatory T cells by antibody-dependent cellular cytotoxicity (ADCC). This mechanism appears to be common to other immunomodulatory antibodies including those targeting OX40 and glucocorticoid-induced TNFR-related protein (GITR). If verified in the human setting, these findings have significant implications for antibody design, biomarker discovery, and the development of synergistic combinatorial therapies. [ABSTRACT FROM AUTHOR]

Summary With the use of a mouse model expressing human Fc-gamma receptors (FcγRs), we demonstrated that antibodies with isotypes equivalent to ipilimumab and tremelimumab mediate intra-tumoral regulatory T (Treg) cell depletion in vivo , increasing the CD8 + to Treg cell ratio and promoting tumor rejection. Antibodies with improved FcγR binding profiles drove superior anti-tumor responses and survival. In patients with advanced melanoma, response to ipilimumab was associated with the CD16a-V158F high affinity polymorphism. Such activity only appeared relevant in the context of inflamed tumors, explaining the modest response rates observed in the clinical setting. Our data suggest that the activity of anti-CTLA-4 in inflamed tumors may be improved through enhancement of FcγR binding, whereas poorly infiltrated tumors will likely require combination approaches. [ABSTRACT FROM AUTHOR]

To investigate the efficacy of PD-1-directed antibody-based therapy in patients with symptomatic melanoma brain metastases (MBM) and concurrent treatment with corticosteroids. This retrospective cohort study included patients with cutaneous melanoma with symptomatic MBM and concurrent treatment with corticosteroids who received PD-1-directed antibody-based treatment at the Royal Marsden Hospital London between 2016 and 2021. The primary outcome was overall survival (OS), secondary outcomes were intracranial response rate (ORR) and duration of response (DOR). We used the Kaplan-Meier method to describe survival. Between 2016 and 2021, 256 patients presented with metastatic melanoma, of whom 29 were eligible with symptomatic MBM requiring corticosteroids and receiving ipilimumab plus nivolumab. Median age was 54 (interquartile range 44, 66). Median OS was 5.45 months (95% confidence interval (CI) 2.89, 29.40), with 21% of patients (95% CI 9%, 47%) alive after 3 years. ORR was 28% (8/29) and DOR was 7.85 months (95% CI 7.85, not estimably [NE]). Responding patients had a median OS of 56.4 months (95% CI 46.03, NE). Elevated lactate dehydrogenase and Eastern Cooperative Oncology Group PS> 2 were associated with poorer outcomes (median OS 29.4 versus 3.12 months and 6.44 versus 5.13 months), no such association was observed for corticosteroid dose, number of lesions, or line of treatment. Patients with symptomatic MBM derive only modest benefit from combination immunotherapy treatment. Nevertheless, those with disease response have the potential to derive long-term benefit, justifying ipilimumab plus nivolumab in this group in the absence of other more effective treatment options. • Metastatic melanoma frequently presents with symptomatic brain metastasis. • Ipilimumab plus nivolumab has modest efficacy in those patients. • Responding patients to ipilimumab plus nivolumab may derive long-term benefit. • Even patients with high-dose corticosteroids may respond to ipilimumab & nivolumab. [ABSTRACT FROM AUTHOR]

Checkpoint inhibitors (CPIs) augment adaptive immunity. Systematic pan-tumor analyses may reveal the relative importance of tumor-cell-intrinsic and microenvironmental features underpinning CPI sensitization. Here, we collated whole-exome and transcriptomic data for >1,000 CPI-treated patients across seven tumor types, utilizing standardized bioinformatics workflows and clinical outcome criteria to validate multivariable predictors of CPI sensitization. Clonal tumor mutation burden (TMB) was the strongest predictor of CPI response, followed by total TMB and CXCL9 expression. Subclonal TMB, somatic copy alteration burden, and histocompatibility leukocyte antigen (HLA) evolutionary divergence failed to attain pan-cancer significance. Dinucleotide variants were identified as a source of immunogenic epitopes associated with radical amino acid substitutions and enhanced peptide hydrophobicity/immunogenicity. Copy-number analysis revealed two additional determinants of CPI outcome supported by prior functional evidence: 9q34 (TRAF2) loss associated with response and CCND1 amplification associated with resistance. Finally, single-cell RNA sequencing (RNA-seq) of clonal neoantigen-reactive CD8 tumor-infiltrating lymphocytes (TILs), combined with bulk RNA-seq analysis of CPI-responding tumors, identified CCR5 and CXCL13 as T-cell-intrinsic markers of CPI sensitivity. • Large-scale meta-analysis of >1,000 CPI-treated cases with exome/transcriptome data • Clonal TMB and CXCL9/CXCL13 expression are the strongest predictors of CPI response • A multivariable predictor of CPI response significantly outperforms TMB • 9q34 loss and CCND1 amplification are additional determinants of CPI response A whole-exome and transcriptome meta-analysis of over 1,000 patients treated with immune checkpoint blockade across seven tumor types highlights the potential of multivariable prediction models that consider both tumor- and T-cell-intrinsic mechanisms of response. [ABSTRACT FROM AUTHOR]