TGFß attenuates tumour response to PD-L1 blockade by contributing to exclusion of T cells.

Therapeutic antibodies that block the programmed death-1 (PD-1)-programmed death-ligand 1 (PD-L1) pathway can induce robust and durable responses in patients with various cancers, including metastatic urothelial cancer. However, these responses only occur in a subset of patients. Elucidating the determinants of response and resistance is key to improving outcomes and developing new treatment strategies. Here we examined tumours from a large cohort of patients with metastatic urothelial cancer who were treated with an anti-PD-L1 agent (atezolizumab) and identified major determinants of clinical outcome. Response to treatment was associated with CD8+ T-effector cell phenotype and, to an even greater extent, high neoantigen or tumour mutation burden. Lack of response was associated with a signature of transforming growth factor ß (TGFß) signalling in fibroblasts. This occurred particularly in patients with tumours, which showed exclusion of CD8+ T cells from the tumour parenchyma that were instead found in the fibroblast- and collagen-rich peritumoural stroma; a common phenotype among patients with metastatic urothelial cancer. Using a mouse model that recapitulates this immune-excluded phenotype, we found that therapeutic co-administration of TGFß-blocking and anti-PD-L1 antibodies reduced TGFß signalling in stromal cells, facilitated T-cell penetration into the centre of tumours, and provoked vigorous anti-tumour immunity and tumour regression. Integration of these three independent biological features provides the best basis for understanding patient outcome in this setting and suggests that TGFß shapes the tumour microenvironment to restrain anti-tumour immunity by restricting T-cell infiltration.

A PP4 holoenzyme balances physiological and oncogenic nuclear factor-kappa B signaling in T lymphocytes.

Signal transduction to nuclear factor-kappa B (NF-κB) involves multiple kinases and phosphorylated target proteins, but little is known about signal termination by dephosphorylation. By RNAi screening, we have identified protein phosphatase 4 regulatory subunit 1 (PP4R1) as a negative regulator of NF-κB activity in T lymphocytes. PP4R1 formed part of a distinct PP4 holoenzyme and bridged the inhibitor of NF-κB kinase (IKK) complex and the phosphatase PP4c, thereby directing PP4c activity to dephosphorylate and inactivate the IKK complex. PP4R1 expression was triggered upon activation and proliferation of primary human T lymphocytes and deficiency for PP4R1 caused sustained and increased IKK activity, T cell hyperactivation, and aberrant NF-κB signaling in NF-κB-addicted T cell lymphomas. Collectively, our results unravel PP4R1 as a previously unknown activation-associated negative regulator of IKK activity in lymphocytes whose downregulation promotes oncogenic NF-κB signaling in a subgroup of T cell lymphomas.

Atezolizumab in patients with locally advanced and metastatic urothelial carcinoma who have progressed following treatment with platinum-based chemotherapy: a single-arm, multicentre, phase 2 trial.

BACKGROUND: Patients with metastatic urothelial carcinoma have few treatment options after failure of platinum-based chemotherapy. In this trial, we assessed treatment with atezolizumab, an engineered humanised immunoglobulin G1 monoclonal antibody that binds selectively to programmed death ligand 1 (PD-L1), in this patient population. METHODS: For this multicentre, single-arm, two-cohort, phase 2 trial, patients (aged ≥18 years) with inoperable locally advanced or metastatic urothelial carcinoma whose disease had progressed after previous platinum-based chemotherapy were enrolled from 70 major academic medical centres and community oncology practices in Europe and North America. Key inclusion criteria for enrolment were Eastern Cooperative Oncology Group performance status of 0 or 1, measurable disease defined by Response Evaluation Criteria In Solid Tumors version 1.1 (RECIST v1.1), adequate haematological and end-organ function, and no autoimmune disease or active infections. Formalin-fixed paraffin-embedded tumour specimens with sufficient viable tumour content were needed from all patients before enrolment. Patients received treatment with intravenous atezolizumab (1200 mg, given every 3 weeks). PD-L1 expression on tumour-infiltrating immune cells (ICs) was assessed prospectively by immunohistochemistry. The co-primary endpoints were the independent review facility-assessed objective response rate according to RECIST v1.1 and the investigator-assessed objective response rate according to immune-modified RECIST, analysed by intention to treat. A hierarchical testing procedure was used to assess whether the objective response rate was significantly higher than the historical control rate of 10% at an α level of 0·05. This study is registered with ClinicalTrials.gov, number NCT02108652. FINDINGS: Between May 13, 2014, and Nov 19, 2014, 486 patients were screened and 315 patients were enrolled into the study. Of these patients, 310 received atezolizumab treatment (five enrolled patients later did not meet eligibility criteria and were not dosed with study drug). The PD-L1 expression status on infiltrating immune cells (ICs) in the tumour microenvironment was defined by the percentage of PD-L1-positive immune cells: IC0 (<1%), IC1 (≥1% but <5%), and IC2/3 (≥5%). The primary analysis (data cutoff May 5, 2015) showed that compared with a historical control overall response rate of 10%, treatment with atezolizumab resulted in a significantly improved RECIST v1.1 objective response rate for each prespecified immune cell group (IC2/3: 27% [95% CI 19-37], p<0·0001; IC1/2/3: 18% [13-24], p=0·0004) and in all patients (15% [11-20], p=0·0058). With longer follow-up (data cutoff Sept 14, 2015), by independent review, objective response rates were 26% (95% CI 18-36) in the IC2/3 group, 18% (13-24) in the IC1/2/3 group, and 15% (11-19) overall in all 310 patients. With a median follow-up of 11·7 months (95% CI 11·4-12·2), ongoing responses were recorded in 38 (84%) of 45 responders. Exploratory analyses showed The Cancer Genome Atlas (TCGA) subtypes and mutation load to be independently predictive for response to atezolizumab. Grade 3-4 treatment-related adverse events, of which fatigue was the most common (five patients [2%]), occurred in 50 (16%) of 310 treated patients. Grade 3-4 immune-mediated adverse events occurred in 15 (5%) of 310 treated patients, with pneumonitis, increased aspartate aminotransferase, increased alanine aminotransferase, rash, and dyspnoea being the most common. No treatment-related deaths occurred during the study. INTERPRETATION: Atezolizumab showed durable activity and good tolerability in this patient population. Increased levels of PD-L1 expression on immune cells were associated with increased response. This report is the first to show the association of TCGA subtypes with response to immune checkpoint inhibition and to show the importance of mutation load as a biomarker of response to this class of agents in advanced urothelial carcinoma. FUNDING: F Hoffmann-La Roche Ltd.

Rituximab efficiently depletes increased CD20-expressing T cells in multiple sclerosis patients.

In multiple sclerosis (MS), B cell-depleting therapy using monoclonal anti-CD20 Abs, including rituximab (RTX) and ocrelizumab, effectively reduces disease activity. Based on indirect evidence, it is generally believed that elimination of the Ag-presenting capabilities and Ag nonspecific immune functions of B cells underlie the therapeutic efficacy. However, a small subset of T lymphocytes (T cells) was shown to also express CD20, but controversy prevails surrounding the true existence of this T cell subpopulation. Using single-cell imaging flow cytometry and expression profiling of sorted lymphocyte subsets, we unequivocally demonstrate the existence of CD3(+)CD20(dim) T cells. We show that in MS patients, increased levels of CD3(+)CD20(dim) T cells are effectively depleted by RTX. The pathological relevance of this T cell subset in MS remains to be determined. However, given their potential proinflammatory functionality, depletion of CD20-expressing T cells may also contribute to the therapeutic effect of RTX and other mAbs targeting CD20.

Blood RNA profiling in a large cohort of multiple sclerosis patients and healthy controls.

Multiple sclerosis (MS) is the most common autoimmune disease of the central nervous system (CNS). It is characterized by the infiltration of autoreactive immune cells into the CNS, which target the myelin sheath, leading to the loss of neuronal function. Although it is accepted that MS is a multifactorial disorder with both genetic and environmental factors influencing its development and course, the molecular pathogenesis of MS has not yet been fully elucidated. Here, we studied the longitudinal gene expression profiles of whole-blood RNA from a cohort of 195 MS patients and 66 healthy controls. We analyzed these transcriptomes at both the individual transcript and the biological pathway level. We found 62 transcripts to be significantly up-regulated in MS patients; the expression of 11 of these genes was counter-regulated by interferon treatment, suggesting partial restoration of a 'healthy' gene expression profile. Global pathway analyses linked the proteasome and Wnt signaling to MS disease processes. Since genotypes from a subset of individuals were available, we were able to identify expression quantitative trait loci (eQTL), a number of which involved two genes of the MS gene signature. However, all these eQTL were also present in healthy controls. This study highlights the challenge posed by analyzing transcripts from whole blood and how these can be mitigated by using large, well-characterized cohorts of patients with longitudinal follow-up and multi-modality measurements.

The autoimmune disease-associated transcription factors EOMES and TBX21 are dysregulated in multiple sclerosis and define a molecular subtype of disease.

We have identified a marked over-representation of transcription factors controlling differentiation of T, B, myeloid and NK cells among the 110 MS genes now known to be associated with multiple sclerosis (MS). To test if the expression of these genes might define molecular subtypes of MS, we interrogated their expression in blood in three independent cohorts of untreated MS (from Sydney and Adelaide) or clinically isolated syndrome (CIS, from San Francisco) patients. Expression of the transcription factors (TF) controlling T and NK cell differentiation, EOMES, TBX21 and other TFs was significantly lower in MS/CIS compared to healthy controls in all three cohorts. Expression was tightly correlated between these TFs, with other T/NK cell TFs, and to another downregulated gene, CCL5. Expression was stable over time, but did not predict disease phenotype. Optimal response to therapy might be indicated by normalization of expression of these genes in blood.

T cell-Dependent Bispecific Therapy Enhances Innate Immune Activation and Antibody-Mediated Killing.

T cell-retargeting therapies have transformed the therapeutic landscape for hematologic diseases. T cell-dependent bispecific antibodies (TDB) function as conditional agonists that induce a polyclonal T-cell response, resulting in target cell destruction and cytokine release. The relationship between this response and its effects on surrounding innate immune populations has not been fully explored. Here we show that treatment with mosunetuzumab in patients results in natural killer (NK) cell activation in the peripheral blood. We modeled this phenomenon in vitro and found that TDB-mediated killing activated NK cells, increasing NK function and antibody-dependent cellular cytotoxicity (ADCC), and enhanced the capability of macrophages to perform antibody-dependent cellular phagocytosis (ADCP). This enhancement was triggered by cytokines released through TDB treatment, with IL2 and IFNγ being major drivers for increased ADCC and ADCP, respectively. Surprisingly, cytolytic ability could be further augmented through neutralization of IL10 for NK cells and TNFα for macrophages. Finally, we showed that TDB treatment enhanced the efficacy of Fc-driven killing to an orthogonal solid tumor target in vivo. These results provide rationale for novel antibody therapy combinations that take advantage of both adaptive and innate immune responses.

ZBP1 and TRIF trigger lethal necroptosis in mice lacking caspase-8 and TNFR1.

Necroptosis is a lytic form of cell death that is mediated by the kinase RIPK3 and the pseudokinase MLKL when caspase-8 is inhibited downstream of death receptors, toll-like receptor 3 (TLR3), TLR4, and the intracellular Z-form nucleic acid sensor ZBP1. Oligomerization and activation of RIPK3 is driven by interactions with the kinase RIPK1, the TLR adaptor TRIF, or ZBP1. In this study, we use immunohistochemistry (IHC) and in situ hybridization (ISH) assays to generate a tissue atlas characterizing RIPK1, RIPK3, Mlkl, and ZBP1 expression in mouse tissues. RIPK1, RIPK3, and Mlkl were co-expressed in most immune cell populations, endothelial cells, and many barrier epithelia. ZBP1 was expressed in many immune populations, but had more variable expression in epithelia compared to RIPK1, RIPK3, and Mlkl. Intriguingly, expression of ZBP1 was elevated in Casp8-/- Tnfr1-/- embryos prior to their succumbing to aberrant necroptosis around embryonic day 15 (E15). ZBP1 contributed to this embryonic lethality because rare Casp8-/- Tnfr1-/- Zbp1-/- mice survived until after birth. Necroptosis mediated by TRIF contributed to the demise of Casp8-/- Tnfr1-/- Zbp1-/- pups in the perinatal period. Of note, Casp8-/- Tnfr1-/- Trif-/- Zbp1-/- mice exhibited autoinflammation and morbidity, typically within 5-7 weeks of being born, which is not seen in Casp8-/- Ripk1-/- Trif-/- Zbp1-/-, Casp8-/- Ripk3-/-, or Casp8-/- Mlkl-/- mice. Therefore, after birth, loss of caspase-8 probably unleashes RIPK1-dependent necroptosis driven by death receptors other than TNFR1.

Sequencing of the IL6 gene in a case-control study of cerebral palsy in children.

BACKGROUND: Cerebral palsy (CP) is a group of nonprogressive disorders of movement and posture caused by abnormal development of, or damage to, motor control centers of the brain. A single nucleotide polymorphism (SNP), rs1800795, in the promoter region of the interleukin-6 (IL6) gene has been implicated in the pathogenesis of CP by mediating IL-6 protein levels in amniotic fluid and cord plasma and within brain lesions. This SNP has been associated with other neurological, vascular, and malignant processes as well, often as part of a haplotype block. METHODS: To refine the regional genetic association with CP, we sequenced (Sanger) the IL6 gene and part of the promoter region in 250 infants with CP and 305 controls. RESULTS: We identified a haplotype of 7 SNPs that includes rs1800795. In a recessive model of inheritance, the variant haplotype conferred greater risk (OR = 4.3, CI = [2.0-10.1], p = 0.00007) than did the lone variant at rs1800795 (OR = 2.5, CI = [1.4-4.6], p = 0.002). The risk haplotype contains one SNP (rs2069845, CI = [1.2-4.3], OR = 2.3, p = 0.009) that disrupts a methylation site. CONCLUSIONS: The risk haplotype identified in this study overlaps with previously identified haplotypes that include additional promoter SNPs. A risk haplotype at the IL6 gene likely confers risk to CP, and perhaps other diseases, via a multi-factorial mechanism.

In depth comparison of an individual's DNA and its lymphoblastoid cell line using whole genome sequencing.

BACKGROUND: A detailed analysis of whole genomes can be now achieved with next generation sequencing. Epstein Barr Virus (EBV) transformation is a widely used strategy in clinical research to obtain an unlimited source of a subject's DNA. Although the mechanism of transformation and immortalization by EBV is relatively well known at the transcriptional and proteomic level, the genetic consequences of EBV transformation are less well understood. A detailed analysis of the genetic alterations introduced by EBV transformation is highly relevant, as it will inform on the usefulness and limitations of this approach. RESULTS: We used whole genome sequencing to assess the genomic signature of a low-passage lymphoblastoid cell line (LCL). Specifically, we sequenced the full genome (40X) of an individual using DNA purified from fresh whole blood as well as DNA from his LCL. A total of 217.33 Gb of sequence were generated from the cell line and 238.95 Gb from the normal genomic DNA. We determined with high confidence that 99.2% of the genomes were identical, with no reproducible changes in structural variation (chromosomal rearrangements and copy number variations) or insertion/deletion polymorphisms (indels). CONCLUSIONS: Our results suggest that, at this level of resolution, the LCL is genetically indistinguishable from its genomic counterpart and therefore their use in clinical research is not likely to introduce a significant bias.

Genetics of multiple sclerosis: swimming in an ocean of data.

PURPOSE OF REVIEW: Major advances in the genetics of multiple sclerosis (MS) have been reported in 2011. These include studies in gene mapping, functional characterization of previously associated genes, and the relationship between genes and the environment. While particularly true for gene discovery, each of these efforts requires substantial statistics and computational resources for adequate analysis. This review describes the major advances in the genetics of MS with a slight emphasis on data handling and analysis. RECENT FINDINGS: Articles discussed include a new genome-wide association study (GWAS) with almost 10 000 cases (a collaboration between the Wellcome Trust and the international MS Genetics Consortium) that identified new susceptibility loci, taking the total number of risk alleles to more than 50. An article describing the use of next-generation sequencing to identify a rare mutation in CYP27B1 in a MS family is also discussed. Moreover, a summary of recent reports describing functional studies of MS-associated genes as well as the latest research on the interactions between genes and the environment is provided. SUMMARY: This review provides a concise summary of the most relevant studies in the genetics of MS in the past year. We raise awareness about analytical resources to successfully analyze the massive datasets characteristic of today's genetic studies.

An RNAi screen identifies USP2 as a factor required for TNF-α-induced NF-κB signaling.

Tumor necrosis factor α (TNF-α) signaling pathways play important roles during tumorigenesis and inflammation. Ubiquitin-dependent processes are central to the regulation of TNF-α and nuclear factor κB (NF-κB) signaling. We performed a targeted siRNA screen for ubiquitin-specific proteases (USPs) and identified USP2 as a modulator of TNF-α-induced NF-κB signaling. We showed that USP2 is required for the phosphorylation of IκB, nuclear translocation of NF-κB and expression of NF-κB-dependent target genes and IL-8 secretion. Our study also provides evidence for isoform-specific functions of USP2. The immunohistochemical analysis of breast carcinomas revealed that USP2 expression is frequently downregulated. Together, our results implicate USP2 as a novel positive regulator of TNF-α-induced NF-κB signaling and show that its expression is altered in tumor cells.

NRF2 Activation Promotes Aggressive Lung Cancer and Associates with Poor Clinical Outcomes.

PURPOSE: Stabilization of the transcription factor NRF2 through genomic alterations in KEAP1 and NFE2L2 occurs in a quarter of patients with lung adenocarcinoma and a third of patients with lung squamous cell carcinoma. In lung adenocarcinoma, KEAP1 loss often co-occurs with STK11 loss and KRAS-activating alterations. Despite its prevalence, the impact of NRF2 activation on tumor progression and patient outcomes is not fully defined. EXPERIMENTAL DESIGN: We model NRF2 activation, STK11 loss, and KRAS activation in vivo using novel genetically engineered mouse models. Furthermore, we derive a NRF2 activation signature from human non-small cell lung tumors that we use to dissect how these genomic events impact outcomes and immune contexture of participants in the OAK and IMpower131 immunotherapy trials. RESULTS: Our in vivo data reveal roles for NRF2 activation in (i) promoting rapid-onset, multifocal intrabronchiolar carcinomas, leading to lethal pulmonary dysfunction, and (ii) decreasing elevated redox stress in KRAS-mutant, STK11-null tumors. In patients with nonsquamous tumors, the NRF2 signature is negatively prognostic independently of STK11 loss. Patients with lung squamous cell carcinoma with low NRF2 signature survive longer when receiving anti-PD-L1 treatment. CONCLUSIONS: Our in vivo modeling establishes NRF2 activation as a critical oncogenic driver, cooperating with STK11 loss and KRAS activation to promote aggressive lung adenocarcinoma. In patients, oncogenic events alter the tumor immune contexture, possibly having an impact on treatment responses. Importantly, patients with NRF2-activated nonsquamous or squamous tumors have poor prognosis and show limited response to anti-PD-L1 treatment.

Anti-LYPD1/CD3 T-Cell-Dependent Bispecific Antibody for the Treatment of Ovarian Cancer.

Ovarian cancer is a diverse class of tumors with very few effective treatment options and suboptimal response rates in early clinical studies using immunotherapies. Here we describe LY6/PLAUR domain containing 1 (LYPD1) as a novel target for therapeutic antibodies for the treatment of ovarian cancer. LYPD1 is broadly expressed in both primary and metastatic ovarian cancer with ∼70% prevalence in the serous cancer subset. Bispecific antibodies targeting CD3 on T cells and a tumor antigen on cancer cells have demonstrated significant clinical activity in hematologic cancers. We have developed an anti-LYPD1/CD3 T-cell-dependent bispecific antibody (TDB) to redirect T-cell responses to LYPD1 expressing ovarian cancer. Here we characterize the nonclinical pharmacology of anti-LYPD1/CD3 TDB and show induction of a robust polyclonal T-cell activation and target dependent killing of LYPD1 expressing ovarian cancer cells resulting in efficient in vivo antitumor responses in PBMC reconstituted immune-deficient mice and human CD3 transgenic mouse models. Anti-LYPD1/CD3 TDB is generally well tolerated at high-dose levels in mice, a pharmacologically relevant species, and showed no evidence of toxicity or damage to LYPD1 expressing tissues.

Molecular determinants of response to PD-L1 blockade across tumor types.

Immune checkpoint inhibitors targeting the PD-1/PD-L1 axis lead to durable clinical responses in subsets of cancer patients across multiple indications, including non-small cell lung cancer (NSCLC), urothelial carcinoma (UC) and renal cell carcinoma (RCC). Herein, we complement PD-L1 immunohistochemistry (IHC) and tumor mutation burden (TMB) with RNA-seq in 366 patients to identify unifying and indication-specific molecular profiles that can predict response to checkpoint blockade across these tumor types. Multiple machine learning approaches failed to identify a baseline transcriptional signature highly predictive of response across these indications. Signatures described previously for immune checkpoint inhibitors also failed to validate. At the pathway level, significant heterogeneity is observed between indications, in particular within the PD-L1+ tumors. mUC and NSCLC are molecularly aligned, with cell cycle and DNA damage repair genes associated with response in PD-L1- tumors. At the gene level, the CDK4/6 inhibitor CDKN2A is identified as a significant transcriptional correlate of response, highlighting the association of non-immune pathways to the outcome of checkpoint blockade. This cross-indication analysis reveals molecular heterogeneity between mUC, NSCLC and RCC tumors, suggesting that indication-specific molecular approaches should be prioritized to formulate treatment strategies.

Anti-PD-L1 Treatment Results in Functional Remodeling of the Macrophage Compartment.

Checkpoint inhibitors like anti-PD1/PD-L1 have demonstrated significant therapeutic efficacy in a subset of patients partly through reinvigoration of CD8 T cells. However, their impact on myeloid cells remains largely unknown. Here, we report that anti-PD-L1 treatment favorably impacts the phenotype and function of tumor macrophages by polarizing the macrophage compartment toward a more proinflammatory phenotype. This phenotype was characterized by a decrease in Arginase-I (ARG1) expression and an increase in iNOS, MHCII, and CD40 expression. Whole-transcriptome profiling further confirmed extensive polarization of both tumor monocytes and macrophages from a suppressive to a proinflammatory, immunostimulatory phenotype. This polarization was driven mainly through IFNγ and was associated with enhanced T-cell activity. Transfer of monocytes into anti-PD-L1-treated tumor-bearing mice led to macrophage differentiation into a more proinflammatory phenotype, with an increase in CD8 T cells expressing granzyme-B and an increase in the CD8/Treg ratio compared with control-treated mice. Although in responsive tumor models, anti-PD-L1 treatment remodeled the macrophage compartment with beneficial effects on T cells, both macrophage reprogramming and depletion were needed to maximize anti-PD-L1 responses in a tumor immune contexture with high macrophage burden. Our results demonstrate that anti-PD-L1 treatment can favorably remodel the macrophage compartment in responsive tumor models toward a more proinflammatory phenotype, mainly through increased IFNγ levels. They also suggest that directly targeting these cells with reprogramming and depleting agents may further augment the breadth and depth of response to anti-PD-L1 treatment in less responsive or more macrophage-dense tumor microenvironments. SIGNIFICANCE: This work demonstrates that increased IFNγ signaling following anti-PD-L1 treatment can remodel the macrophage compartment to enhance T-cell responses.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/7/1493/F1.large.jpg.

Coexpression of Inhibitory Receptors Enriches for Activated and Functional CD8+ T Cells in Murine Syngeneic Tumor Models.

Exhausted T cells have been described in cancer patients and murine tumor models largely based on their expression of various inhibitory receptors. Understanding of the functional attributes of these cells is limited. Here, we report that among CD8+ T cells in commonly used syngeneic tumor models, the coexpression of inhibitory receptors PD-1, LAG3, and TIM3 defined a group of highly activated and functional effector cells. Coexpression of these receptors further enriched for antigen-specific cells with increased T-cell receptor clonality. Anti-PD-L1 treatment increased the number and activation of these triple-positive CD8+ T cells without affecting the density of PD-1- cells. The intratumoral density of CD8+ T cells coexpressing inhibitory receptors negatively correlated with tumor burden. The density ratio and pretreatment phenotype of CD8+ T cells coexpressing inhibitory receptors was positively correlated with response across a variety of tumor models. Our results demonstrate that coexpression of inhibitory receptors is not a signifier of exhausted T cells, but rather can define a group of activated and functional effector cells in syngeneic tumor models. In the cancer setting, these cells could represent a heterogeneous population of not only exhausted but also highly activated cells responsive to treatment.

Therapeutic resistance and susceptibility is shaped by cooperative multi-compartment tumor adaptation.

Emerging research suggests that multiple tumor compartments can influence treatment responsiveness and relapse, yet the search for therapeutic resistance mechanisms remains largely focused on acquired genomic alterations in cancer cells. Here we show how treatment-induced changes occur in multiple tumor compartments during tumor relapse and can reduce benefit of follow-on therapies. By using serial biopsies, next-generation sequencing, and single-cell transcriptomics, we tracked the evolution of multiple cellular compartments within individual lesions during first-line treatment response, relapse, and second-line therapeutic interventions in an autochthonous model of melanoma. We discovered that although treatment-relapsed tumors remained genetically stable, they converged on a shared resistance phenotype characterized by dramatic changes in tumor cell differentiation state, immune infiltration, and extracellular matrix (ECM) composition. Similar alterations in tumor cell differentiation were also observed in more than half of our treatment-relapsed patient tumors. Tumor cell-state changes were coincident with ECM remodeling and increased tumor stiffness, which alone was sufficient to alter tumor cell fate and reduce treatment responses in melanoma cell lines in vitro. Despite the absence of acquired mutations in the targeted pathway, resistant tumors showed significantly decreased responsiveness to second-line therapy intervention within the same pathway. The ability to preclinically model relapse and refractory settings-while capturing dynamics within and crosstalk between all relevant tumor compartments-provides a unique opportunity to better design and sequence appropriate clinical interventions.

End-stage dying glioma cells are engulfed by mouse microglia with a strain-dependent efficacy.

Microglia phagocytic activity for apoptotic glioma cells is hardly analysed inspite of its relevance to tissue damage prevention. We provide evidence for a phosphatidylserine-independent clearance of mouse glioma cells at an advanced stage of death, suggesting microglia recognition of late apoptotic markers. Dying cells were immediately cleared or stayed for hours in that stage before engulfment occurred. This phagocytic activity was restricted to a microglia subset representing 30 to 70% of the population according to the used strain. Expression of receptors involved in late apoptotic markers recognition therefore seems confined to a subpopulation of microglia and to be strain-dependent.

Publisher Correction: Clinical activity and molecular correlates of response to atezolizumab alone or in combination with bevacizumab versus sunitinib in renal cell carcinoma.

In the version of this article originally published, there was an error in Fig. 2n. The top line of the HR comparison chart originally was Atezo + bev vs sun. It should have been Atezo + bev vs atezo. The error has been corrected in the HTML and PDF versions of this article.