Summary Clear cell renal cell carcinoma (ccRCC) is characterized by near-universal loss of the short arm of chromosome 3, deleting several tumor suppressor genes. We analyzed whole genomes from 95 biopsies across 33 patients with clear cell renal cell carcinoma. We find hotspots of point mutations in the 5′ UTR of TERT, targeting a MYC-MAX-MAD1 repressor associated with telomere lengthening. The most common structural abnormality generates simultaneous 3p loss and 5q gain (36% patients), typically through chromothripsis. This event occurs in childhood or adolescence, generally as the initiating event that precedes emergence of the tumor’s most recent common ancestor by years to decades. Similar genomic changes drive inherited ccRCC. Modeling differences in age incidence between inherited and sporadic cancers suggests that the number of cells with 3p loss capable of initiating sporadic tumors is no more than a few hundred. Early development of ccRCC follows well-defined evolutionary trajectories, offering opportunity for early intervention.

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.

Background Agreement on the utility of imaging follow-up in patients with high-risk melanoma is lacking. A UK consensus statement recommends a surveillance schedule of CT or positron-emission tomography-CT and MRI brain (every 6 months for 3 years, then annually in years 4 and 5) as well as clinical examination for high-risk resected Stages II and III cutaneous melanoma. Our aim was to assess patterns of relapse and whether imaging surveillance could be of clinical benefit. Patients and methods A retrospective study of patients enrolled between July 2013 and June 2015 from three UK tertiary cancer centres followed-up according to this protocol was undertaken. We evaluated time-to-recurrence (TTR), recurrence-free survival (RFS), method of detection and characteristics of recurrence, treatment received and overall survival (OS). Results A total of 173 patients were included. Most (79%) had treated Stages IIIB and IIIC disease. With a median follow-up of 23.3 months, 82 patients (47%) had relapsed. Median TTR was 10.1 months and median RFS was 21.2 months. The majority of recurrences (66%) were asymptomatic and detected by scheduled surveillance scan. Fifty-six (68%) patients recurred with Stage IV disease, with a median OS of 25.3 months; 26 (31.7%) patients had a locoregional recurrence, median OS not reached (P=0.016). Patients who underwent surgery at recurrence for either Stage III (27%) or IV (18%) disease did not reach their median OS. The median OS for the 33 patients (40%) who received systemic therapy was 12.9 months. Conclusion Imaging appears to reliably detect subclinical disease and identify patients suitable for surgery, conferring favourable outcomes. The short median TTR provides rationale to intensify imaging schedule in the first year of surveillance. The poor OS of patients treated with systemic therapy probably reflects the relatively inferior treatment options during this time and requires further evaluation in the current era.

Summary Immune evasion is a hallmark of cancer. Losing the ability to present neoantigens through human leukocyte antigen (HLA) loss may facilitate immune evasion. However, the polymorphic nature of the locus has precluded accurate HLA copy-number analysis. Here, we present loss of heterozygosity in human leukocyte antigen (LOHHLA), a computational tool to determine HLA allele-specific copy number from sequencing data. Using LOHHLA, we find that HLA LOH occurs in 40% of non-small-cell lung cancers (NSCLCs) and is associated with a high subclonal neoantigen burden, APOBEC-mediated mutagenesis, upregulation of cytolytic activity, and PD-L1 positivity. The focal nature of HLA LOH alterations, their subclonal frequencies, enrichment in metastatic sites, and occurrence as parallel events suggests that HLA LOH is an immune escape mechanism that is subject to strong microenvironmental selection pressures later in tumor evolution. Characterizing HLA LOH with LOHHLA refines neoantigen prediction and may have implications for our understanding of resistance mechanisms and immunotherapeutic approaches targeting neoantigens. Video Abstract

BACKGROUND The focus of tumour-specific antigen analyses has been on single nucleotide variants (SNVs), with the contribution of small insertions and deletions (indels) less well characterised. We investigated whether the frameshift nature of indel mutations, which create novel open reading frames and a large quantity of mutagenic peptides highly distinct from self, might contribute to the immunogenic phenotype. METHODS We analysed whole-exome sequencing data from 5777 solid tumours, spanning 19 cancer types from The Cancer Genome Atlas. We compared the proportion and number of indels across the cohort, with a subset of results replicated in two independent datasets. We assessed in-silico tumour-specific neoantigen predictions by mutation type with pan-cancer analysis, together with RNAseq profiling in renal clear cell carcinoma cases (n=392), to compare immune gene expression across patient subgroups. Associations between indel burden and treatment response were assessed across four checkpoint inhibitor datasets. FINDINGS We observed renal cell carcinomas to have the highest proportion (0·12) and number of indel mutations across the pan-cancer cohort (p<2·2 × 10-16), more than double the median proportion of indel mutations in all other cancer types examined. Analysis of tumour-specific neoantigens showed that enrichment of indel mutations for high-affinity binders was three times that of non-synonymous SNV mutations. Furthermore, neoantigens derived from indel mutations were nine times enriched for mutant specific binding, as compared with non-synonymous SNV derived neoantigens. Immune gene expression analysis in the renal clear cell carcinoma cohort showed that the presence of mutant-specific neoantigens was associated with upregulation of antigen presentation genes, which correlated (r=0·78) with T-cell activation as measured by CD8-positive expression. Finally, analysis of checkpoint inhibitor response data revealed frameshift indel count to be significantly associated with checkpoint inhibitor response across three separate melanoma cohorts (p=4·7 × 10-4). INTERPRETATION Renal cell carcinomas have the highest pan-cancer proportion and number of indel mutations. Evidence suggests indels are a highly immunogenic mutational class, which can trigger an increased abundance of neoantigens and greater mutant-binding specificity. FUNDING Cancer Research UK, UK National Institute for Health Research (NIHR) at the Royal Marsden Hospital National Health Service Foundation Trust, Institute of Cancer Research and University College London Hospitals Biomedical Research Centres, the UK Medical Research Council, the Rosetrees Trust, Novo Nordisk Foundation, the Prostate Cancer Foundation, the Breast Cancer Research Foundation, the European Research Council.

The early detection of relapse following primary surgery for non-small-cell lung cancer and the characterization of emerging subclones, which seed metastatic sites, might offer new therapeutic approaches for limiting tumour recurrence. The ability to track the evolutionary dynamics of early-stage lung cancer non-invasively in circulating tumour DNA (ctDNA) has not yet been demonstrated. Here we use a tumour-specific phylogenetic approach to profile the ctDNA of the first 100 TRACERx (Tracking Non-Small-Cell Lung Cancer Evolution Through Therapy (Rx)) study participants, including one patient who was also recruited to the PEACE (Posthumous Evaluation of Advanced Cancer Environment) post-mortem study. We identify independent predictors of ctDNA release and analyse the tumour-volume detection limit. Through blinded profiling of postoperative plasma, we observe evidence of adjuvant chemotherapy resistance and identify patients who are very likely to experience recurrence of their lung cancer. Finally, we show that phylogenetic ctDNA profiling tracks the subclonal nature of lung cancer relapse and metastasis, providing a new approach for ctDNA-driven therapeutic studies.

&NA; 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 (Fc&ggr;R) 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 Fc&ggr;Rs 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. Graphical Abstract Figure. No caption available. HighlightsCD25 expression is largely restricted to Treg cells in mice and humansFc&ggr;RIIb inhibits anti‐CD25‐mediated depletion of intra‐tumoral Treg cellsFc‐optimized anti‐CD25 efficiently depletes intra‐tumoral Treg cellsAnti‐CD25 synergizes with PD‐1 blockade to reject established tumors &NA; Anti‐CD25 antibodies have displayed only modest therapeutic activity against established tumors. Arce Vargas et al. demonstrate that existing anti‐CD25 antibodies fail to deplete intra‐tumoral Treg cells due to upregulation of Fc&ggr;RIIb within tumors. Fc‐optimized anti‐CD25 mediates effective depletion of tumor‐infiltrating Treg cells and synergizes with PD‐1 blockade to promote tumor eradication.