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.
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•CD25 expression is largely restricted to Treg cells in mice and humans•FcγRIIb inhibits anti-CD25-mediated depletion of intra-tumoral Treg cells•Fc-optimized anti-CD25 efficiently depletes intra-tumoral Treg cells•Anti-CD25 synergizes with PD-1 blockade to reject established tumors
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 FcγRIIb within tumors. Fc-optimized anti-CD25 mediates effective depletion of tumor-infiltrating Treg cells and synergizes with PD-1 blockade to promote tumor eradication.
Purpose of Review
Liquid biopsies, including circulating tumour DNA (ctDNA), can inform a variety of clinical questions. This review examines the potential role of ctDNA as a clinical tool to inform ...clinical decision-making from early to late stage cutaneous melanoma.
Recent Findings
In pre-clinical studies, ctDNA has been shown to detect minimal residual disease and molecular relapse; predict and monitor response to therapy; and identify key resistance mechanisms. Here, we examine the potential utility of ctDNA and discuss its limitations for use in patients with melanoma. We present novel clinical trials, which are testing its value as a tool to augment clinical decision-making. Finally, we discuss the steps that are needed to ensure that ctDNA is used optimally in order to improve outcomes for patients with melanoma.
Summary
Preclinical studies have shown that ctDNA has huge potential to provide real-time information about disease status in patients with melanoma. It is now time to test it rigorously within clinical trials to assess how it can be optimally used to benefit patients in the clinic.
Whole-genome doubling (WGD) is a prevalent event in cancer, involving a doubling of the entire chromosome complement. However, despite its prevalence and prognostic relevance, the evolutionary ...selection pressures for WGD in cancer have not been investigated. Here, we combine evolutionary simulations with an analysis of cancer sequencing data to explore WGD during cancer evolution. Simulations suggest that WGD can be selected to mitigate the irreversible, ratchet-like, accumulation of deleterious somatic alterations, provided that they occur at a sufficiently high rate. Consistent with this, we observe an enrichment for WGD in tumor types with extensive loss of heterozygosity, including lung squamous cell carcinoma and triple-negative breast cancers, and we find evidence for negative selection against homozygous loss of essential genes before, but not after, WGD. Finally, we demonstrate that loss of heterozygosity and temporal dissection of mutations can be exploited to identify novel tumor suppressor genes and to obtain a deeper characterization of known cancer genes.
Approximately 50% of patients with early-stage non-small-cell lung cancer (NSCLC) who undergo surgery with curative intent will relapse within 5 years
. Detection of circulating tumor cells (CTCs) at ...the time of surgery may represent a tool to identify patients at higher risk of recurrence for whom more frequent monitoring is advised. Here we asked whether CellSearch-detected pulmonary venous CTCs (PV-CTCs) at surgical resection of early-stage NSCLC represent subclones responsible for subsequent disease relapse. PV-CTCs were detected in 48% of 100 patients enrolled into the TRACERx study
, were associated with lung-cancer-specific relapse and remained an independent predictor of relapse in multivariate analysis adjusted for tumor stage. In a case study, genomic profiling of single PV-CTCs collected at surgery revealed higher mutation overlap with metastasis detected 10 months later (91%) than with the primary tumor (79%), suggesting that early-disseminating PV-CTCs were responsible for disease relapse. Together, PV-CTC enumeration and genomic profiling highlight the potential of PV-CTCs as early predictors of NSCLC recurrence after surgery. However, the limited sensitivity of PV-CTCs in predicting relapse suggests that further studies using a larger, independent cohort are warranted to confirm and better define the potential clinical utility of PV-CTCs in early-stage NSCLC.
Somatic mutations together with immunoediting drive extensive heterogeneity within non-small-cell lung cancer (NSCLC). Herein we examine heterogeneity of the T cell antigen receptor (TCR) repertoire. ...The number of TCR sequences selectively expanded in tumors varies within and between tumors and correlates with the number of nonsynonymous mutations. Expanded TCRs can be subdivided into TCRs found in all tumor regions (ubiquitous) and those present in a subset of regions (regional). The number of ubiquitous and regional TCRs correlates with the number of ubiquitous and regional nonsynonymous mutations, respectively. Expanded TCRs form part of clusters of TCRs of similar sequence, suggestive of a spatially constrained antigen-driven process. CD8
tumor-infiltrating lymphocytes harboring ubiquitous TCRs display a dysfunctional tissue-resident phenotype. Ubiquitous TCRs are preferentially detected in the blood at the time of tumor resection as compared to routine follow-up. These findings highlight a noninvasive method to identify and track relevant tumor-reactive TCRs for use in adoptive T cell immunotherapy.
Abstract
Despite patients with stage II melanoma being relatively high risk, contributing to 30% of melanoma-associated deaths, there remains a relatively low individual chance of melanoma ...recurrence. Therefore, strategies are required to better select those patients at highest risk of recurrence. We have developed assays using circulating tumour DNA (ctDNA) to detect minimal residual disease (MRD) or molecular recurrence of melanoma. Originally, the DETECTION trial was designed to perform ctDNA sampling in addition to clinical follow-up in patients with stage IIB/C melanoma. Those with ctDNA detected were randomized 1 : 1 in a double-blind fashion to continue routine follow-up with the investigators’ choice of treatment if they developed disease recurrence or were unblinded and treated with nivolumab. Since its opening, adjuvant therapy has been licensed, with trials showing approximately 6% absolute reduction in distant metastasis in stage IIB/C melanoma with 1 year of antiprogrammed cell death protein 1 therapy; however, grade 3 or 4 toxicity was observed in 16% of patients, with 25% experiencing lifelong endocrine disorders. Better enrichment of patients at high risk of recurrence, and avoiding treatment toxicity in those who do not require it, therefore remains highly relevant. As DETECTION had only started recruitment, there was opportunity to redesign it, which we present here. We have designed tumour-informed assays targeting BRAF (V600E/K/R), NRAS (G12D, Q61K/L/R) and the H-TERT promoter region (−124 and −146) mutations for ctDNA detection using droplet digital polymerase chain reaction. DETECTION has been redesigned as a phase III trial with the primary objectives of elucidating (i) whether MRD/molecular relapse following curative intent surgery can be identified earlier than clinical relapse and (ii) whether early treatment of molecular recurrence based on ctDNA detection is noninferior to adjuvant therapy in preventing distant metastasis. Patients (n = 1000) with stage IIB/C/III/IV resected BRAF/NRAS/TERT promoter mutant cutaneous melanoma, ECOG 0/1 and adequate organ function, with complete resection performed within 12 weeks and radiological/clinical disease-free status confirmed and no prior immune/targeted therapy will be included. Patients will be randomized 1 : 1 to either 1 year of adjuvant therapy (arm A) or longitudinal ctDNA monitoring (arm B) and treatment only if a local recurrence (surgery followed by 1 year of adjuvant therapy with ongoing ctDNA monitoring) or ctDNA detection (2 years of the investigators’ choice of therapy). The primary endpoint is distant metastasis-free survival. CtDNA is a useful tool to monitor for MRD/molecular relapse. The DETECTION trial will assess whether it can be used to safely monitor patients and systemically treat only those at highest risk of melanoma progression.
An aim of molecular biomarkers is to stratify patients with cancer into disease subtypes predictive of outcome, improving diagnostic precision beyond clinical descriptors such as tumor stage
. ...Transcriptomic intratumor heterogeneity (RNA-ITH) has been shown to confound existing expression-based biomarkers across multiple cancer types
. Here, we analyze multi-region whole-exome and RNA sequencing data for 156 tumor regions from 48 patients enrolled in the TRACERx study to explore and control for RNA-ITH in non-small cell lung cancer. We find that chromosomal instability is a major driver of RNA-ITH, and existing prognostic gene expression signatures are vulnerable to tumor sampling bias. To address this, we identify genes expressed homogeneously within individual tumors that encode expression modules of cancer cell proliferation and are often driven by DNA copy-number gains selected early in tumor evolution. Clonal transcriptomic biomarkers overcome tumor sampling bias, associate with survival independent of clinicopathological risk factors, and may provide a general strategy to refine biomarker design across cancer types.
4130 Background: In NET-02, nal-IRI/5-FU, but not docetaxel, met the primary endpoint of 6-month (mo) progression-free survival (PFS) rate in pts with progressive PD-EP-NEC (1). The prognostic ...potential of cfDNA in progressive PD-EP-NEC has not been explored in a prospective randomised trial. Methods: NET-02 was a multi-centre, randomised (1:1), phase II trial of IV nal-IRI/5-FU/folinic acid, Q14 days (ARM A), or IV docetaxel, Q21 days (ARM B), as 2L therapy in pts with progressive PD-EP-NEC. Plasma samples were taken at baseline (T0), following 6 weeks of treatment (T1) and at progression (T2). Samples were analysed using a multi-omic next-generation sequencing (NGS) approach (T7-MBD-seq) (measures genome-wide methylation and low pass whole genome copy number alterations (CNA)). The tumour fraction (TF) of cfDNA was determined using ichorCNA and correlated with clinical outcomes using Cox proportional hazards model and Logistic regression. Results: Of 56 pts evaluable for efficacy, there were 54 (96%) T0 samples (48 passed quality control), 31 (55%) at T1 and 20 (36%) at T2. At T0, 36/48 (75%) samples had detectable TF by copy number (using 3% TF cut-off). For the entire cohort, T0 TF was negatively prognostic for overall survival (OS) (Hazard Ratio (HR) 1.17, 95% Confidence interval (CI) 1.00-1.37, P=.044), but not for 6 mo PFS rate (Odds ratio (OR) 1.25, 95% CI 0.91-1.73, P=.17), response rate (RR) (OR 1.11, 95% CI 0.67-1.76, P=.65) or PFS (HR 1.04, 95%CI 0.91-1.20, P=.53). In the entire cohort, median OS split by TF (N=16 each) was 10.2 mo (95% CI 4.1-not available (NA)) for low (TF≤8.6%), 6.9 mo (95% CI 3.4-14.8) for medium (8.6<TF≤24.3%) and 3.7 mo (95% CI 2.8-NA) for high (TF>24.3%). T0 TF was also negatively prognostic for 6 mo PFS rate and OS in ARM A (P=.02, P=.03), but not ARM B (P=.61, P=.48), but was not prognostic for RR or PFS (Table). TF correlated with the presence of liver metastases (Wilcoxon Rank Sum P=.009), but not with ECOG PS (P=.14), sex (P=.10), Ki-67 (P=.39) or age (Spearman rank correlation P=.45). Longitudinal copy number and methylation cfDNA analysis is on-going. Conclusions: These results suggest that it may be possible to stratify prognosis based on amount of baseline TF in patients with progressive PD-EP-NEC, and may also identify patients who would benefit most from the nal-IRI combination. 1. McNamara 2023, EClin Med. Clinical trial information: 03837977. Table: see text
The immune microenvironment influences tumour evolution and can be both prognostic and predict response to immunotherapy
. However, measurements of tumour infiltrating lymphocytes (TILs) are limited ...by a shortage of appropriate data. Whole-exome sequencing (WES) of DNA is frequently performed to calculate tumour mutational burden and identify actionable mutations. Here we develop T cell exome TREC tool (T cell ExTRECT), a method for estimation of T cell fraction from WES samples using a signal from T cell receptor excision circle (TREC) loss during V(D)J recombination of the T cell receptor-α gene (TCRA (also known as TRA)). TCRA T cell fraction correlates with orthogonal TIL estimates and is agnostic to sample type. Blood TCRA T cell fraction is higher in females than in males and correlates with both tumour immune infiltrate and presence of bacterial sequencing reads. Tumour TCRA T cell fraction is prognostic in lung adenocarcinoma. Using a meta-analysis of tumours treated with immunotherapy, we show that tumour TCRA T cell fraction predicts immunotherapy response, providing value beyond measuring tumour mutational burden. Applying T cell ExTRECT to a multi-sample pan-cancer cohort reveals a high diversity of the degree of immune infiltration within tumours. Subclonal loss of 12q24.31-32, encompassing SPPL3, is associated with reduced TCRA T cell fraction. T cell ExTRECT provides a cost-effective technique to characterize immune infiltrate alongside somatic changes.
Lung adenocarcinomas (LUADs) display a broad histological spectrum from low-grade lepidic tumors through to mid-grade acinar and papillary and high-grade solid, cribriform and micropapillary tumors. ...How morphology reflects tumor evolution and disease progression is poorly understood. Whole-exome sequencing data generated from 805 primary tumor regions and 121 paired metastatic samples across 248 LUADs from the TRACERx 421 cohort, together with RNA-sequencing data from 463 primary tumor regions, were integrated with detailed whole-tumor and regional histopathological analysis. Tumors with predominantly high-grade patterns showed increased chromosomal complexity, with higher burden of loss of heterozygosity and subclonal somatic copy number alterations. Individual regions in predominantly high-grade pattern tumors exhibited higher proliferation and lower clonal diversity, potentially reflecting large recent subclonal expansions. Co-occurrence of truncal loss of chromosomes 3p and 3q was enriched in predominantly low-/mid-grade tumors, while purely undifferentiated solid-pattern tumors had a higher frequency of truncal arm or focal 3q gains and SMARCA4 gene alterations compared with mixed-pattern tumors with a solid component, suggesting distinct evolutionary trajectories. Clonal evolution analysis revealed that tumors tend to evolve toward higher-grade patterns. The presence of micropapillary pattern and 'tumor spread through air spaces' were associated with intrathoracic recurrence, in contrast to the presence of solid/cribriform patterns, necrosis and preoperative circulating tumor DNA detection, which were associated with extra-thoracic recurrence. These data provide insights into the relationship between LUAD morphology, the underlying evolutionary genomic landscape, and clinical and anatomical relapse risk.
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