Single-cell analysis reveals clonally expanded tumor-associated CD57+ CD8 T cells are enriched in the periphery of patients with metastatic urothelial cancer responding to PD-L1 blockade

T-cell Senescence in the Tumor Microenvironment

T-cell senescence occurs in the tumor microenvironment (TME) and influences cancer outcomes as well as the effectiveness of immunotherapies. The TME triggers this T-cell senescence via multiple pathways, including persistent stimulation with tumor-associated antigens, altered metabolic pathways, and activation of chronic inflammatory responses. Senescent T cells exhibit characteristics such as genomic instability, loss of protein homeostasis, metabolic dysregulation, and epigenetic alterations. Direct cross-talk between senescent T cells and other immune cells further exacerbates the immunosuppressive TME. This immune-tumor cell interaction within the TME contributes to impaired tumor antigen recognition and surveillance by T cells. The presence of senescent T cells is often associated with poor prognosis and reduced efficacy of immunotherapies; thus, targeting the tumor-promoting mechanisms of T-cell senescence may provide novel insights into improving tumor immunotherapy and patient outcomes. This review explores the contributors to tumor-derived T-cell senescence, the link between T-cell senescence and tumor prognosis, and the potential for targeting T-cell senescence to enhance tumor immunotherapy.

The role of CD57+γδ T cells in the immune pathogenesis of patients with sepsis

The immune responses are dysregulated during sepsis. This study aimed to investigate the role of CD57+γδ T cells in the immune pathogenesis of patients with sepsis. We characterized the transcriptomic profile of peripheral γδ T cells from patients with sepsis using smart RNA sequencing. Additionally, we assessed the ratios and immune functional signatures of CD57+γδ T cells in sepsis through flow cytometry. The cytotoxic capacity of the CD57+γδ T-cell subset was also validated in vitro. Our findings revealed a reduction in the proportion of peripheral CD57+γδ T cells in patients with sepsis, which was correlated with clinical outcomes. Compared with CD57-γδ T cells, CD57+γδ T cells exhibited a markedly altered immunophenotype, including decreased expression of costimulatory molecules and increased expression of proinflammatory factors and cytotoxic granules. Our study proposed a potential role of CD57 in sepsis and its utility as a novel biomarker for patients with sepsis.

Peripheral immune biomarkers associated with response to adoptive cell therapy with tumor infiltrating lymphocytes

Adoptive cell therapy (ACT) with ex-vivo expanded tumor-infiltrating lymphocytes (TILs, TIL-ACT) has shown clinical efficacy in a significant proportion of patients with metastatic melanoma. To further target TIL-ACT toward responsive patients, identifying predictive biomarkers and understanding broader immune dynamics remain critical. This study investigated the peripheral blood immune landscape in 47 patients with metastatic melanoma undergoing TIL-ACT, assessing antitumor reactivity and peripheral immune cell profiles before and after treatment. Responders displayed increased frequency of circulating tumor-reactive cells post-treatment, and higher baseline levels of activated CD57-expressing T cells, serving as potential biomarkers of response. In contrast, persistent high serum levels of interleukin (IL)-6 and IL-8, higher frequencies of CD38-expressing T cells, and regulatory T cells (Tregs) post-treatment, correlated with unfavorable outcomes. These findings contribute to understanding the peripheral immune landscape associated with response to TIL-ACT, offering valuable insights into predictive biomarkers and mechanisms to improve patient selection.

Autogene cevumeran with or without atezolizumab in advanced solid tumors: a phase 1 trial

Effective targeting of somatic cancer mutations to enhance the efficacy of cancer immunotherapy requires an individualized approach. Autogene cevumeran is a uridine messenger RNA lipoplex-based individualized neoantigen-specific immunotherapy designed from tumor-specific somatic mutation data obtained from tumor tissue of each individual patient to stimulate T cell responses against up to 20 neoantigens. This ongoing phase 1 study evaluated autogene cevumeran as monotherapy (n = 30) and in combination with atezolizumab (n = 183) in pretreated patients with advanced solid tumors. The primary objective was safety and tolerability; exploratory objectives included evaluation of pharmacokinetics, pharmacodynamics, preliminary antitumor activity and immunogenicity. Non-prespecified interim analysis showed that autogene cevumeran was well tolerated and elicited poly-epitopic neoantigen-specific responses, encompassing CD4+ and/or CD8+ T cells, in 71% of patients, most of them undetectable at baseline. Responses were detectable up to 23 months after treatment initiation. CD8+ T cells specific for several neoantigens constituted a median of 7.3% of circulating CD8+ T cells, reaching up to 23% in some patients. Autogene cevumeran-induced T cells were found within tumor lesions constituting up to 7.2% of tumor-infiltrating T cells. Clinical activity was observed, including one objective response in monotherapy dose escalation and in two patients with disease characteristics unfavorable for response to immunotherapy treated in combination with atezolizumab. These findings support the continued development of autogene cevumeran in earlier treatment lines. ClinicalTrials.gov registration: NCT03289962 .

Leveraging Vγ9Vδ2 T cells against prostate cancer through a VHH-based PSMA-Vδ2 bispecific T cell engager

Vγ9Vδ2 T cells constitute a homogeneous effector T cell population that lyses tumors of different origin, including the prostate. We generated a bispecific T cell engager (bsTCE) to direct Vγ9Vδ2 T cells to PSMA+ prostate cancer (PCa) cells. The PSMA-Vδ2 bsTCE triggered healthy donor and PCa patient-derived Vγ9Vδ2 T cells to lyse PSMA+ PCa cell lines and patient-derived tumor cells while sparing normal prostate cells and enhanced Vγ9Vδ2 T cell antigen cross-presentation to CD8+ T cells. Vγ9Vδ2 T cell expressed NKG2D and DNAM-1 contributed to Vγ9Vδ2 T cell activation and tumor lysis at low PSMA-Vδ2 bsTCE concentrations. In vivo models confirmed the antitumor efficacy of the bsTCE and demonstrated a half-life of 6-7 days. Tissue-cross reactivity analysis was in line with known tissue distribution of PSMA and Vγ9Vδ2 T cells. Together these data show the PSMA-Vδ2 bsTCE to represent a promising anti-tumor strategy and supports its ongoing evaluation in a phase 1/2a clinical trial in therapy refractory metastatic castration-resistant PCa.

The implications for urological malignancies of non-coding RNAs in the the tumor microenvironment

Urological malignancies are a major global health issue because of their complexity and the wide range of ways they affect patients. There's a growing need for in-depth research into these cancers, especially at the molecular level. Recent studies have highlighted the importance of non-coding RNAs (ncRNAs) – these don't code for proteins but are crucial in controlling genes – and the tumor microenvironment (TME), which is no longer seen as just a background factor but as an active player in cancer progression. Understanding how ncRNAs and the TME interact is key for finding new ways to diagnose and predict outcomes in urological cancers, and for developing new treatments. This article reviews the basic features of ncRNAs and goes into detail about their various roles in the TME, focusing specifically on how different ncRNAs function and act in urological malignancies.

Cell Identity and Spatial Distribution of PD-1/PD-L1 Blockade Responders

The programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) axis inhibits T cell activity, impairing anti-tumor immunity. Blocking this axis with therapeutic antibodies is one of the most promising anti-tumor immunotherapies. It has long been recognized that PD-1/PD-L1 blockade reinvigorates exhausted T (TEX) cells already present in the tumor microenvironment (TME). However, recent advancements in high-throughput gene sequencing and bioinformatic tools have provided researchers with a more granular and dynamic insight into PD-1/PD-L1 blockade-responding cells, extending beyond the TME and TEX populations. This review provides an update on the cell identity, spatial distribution, and treatment-induced spatiotemporal dynamics of PD-1/PD-L1 blockade responders. It also provides a synopsis of preliminary reports of potential PD-1/PD-L1 blockade responders other than T cells to depict a panoramic picture. Important questions to answer in further studies and the translational and clinical potential of the evolving understandings are also discussed.

Characteristics and mechanisms of T-cell senescence: A potential target for cancer immunotherapy

Immunosenescence, the aging of the immune system, leads to functional deficiencies, particularly in T cells, which undergo significant changes. While numerous studies have investigated age-related T-cell phenotypes in healthy aging, senescent T cells have also been observed in younger populations during pathological conditions like cancer. This review summarizes the recent advancements in age-associated alterations and markers of T cells, mechanisms, and the relationship between senescent T cells and the tumor microenvironment. We also discuss potential strategies for targeting senescent T cells to prevent age-related diseases and enhance tumor immunotherapy efficacy.

Comprehensive assessment of TECENTRIQ® and OPDIVO®: analyzing immunotherapy indications withdrawn in triple-negative breast cancer and hepatocellular carcinoma

Atezolizumab (TECENTRIQ®) and nivolumab (OPDIVO®) are both immunotherapeutic indications targeting programmed cell death 1 ligand 1 (PD-L1) and programmed cell death 1 (PD-1), respectively. These inhibitors hold promise as therapies for triple-negative breast cancer (TNBC) and hepatocellular carcinoma (HCC) and have demonstrated encouraging results in reducing the progression and spread of tumors. However, due to their adverse effects and low response rates, the US Food and Drug Administration (FDA) has withdrawn the approval of atezolizumab in TNBC and nivolumab in HCC treatment. The withdrawals of atezolizumab and nivolumab have raised concerns regarding their effectiveness and the ability to predict treatment responses. Therefore, the current study aims to investigate the immunotherapy withdrawal of PD-1/PD-L1 inhibitors, specifically atezolizumab for TNBC and nivolumab for HCC. This study will examine both the structural and clinical aspects. This review provides detailed insights into the structure of the PD-1 receptor and its ligands, the interactions between PD-1 and PD-L1, and their interactions with the withdrawn antibodies (atezolizumab and nivolumab) as well as PD-1 and PD-L1 modifications. In addition, this review further assesses these antibodies in the context of TNBC and HCC. It seeks to elucidate the factors that contribute to diverse responses to PD-1/PD-L1 therapy in different types of cancer and propose approaches for predicting responses, mitigating the potential risks linked to therapy withdrawals, and optimizing patient outcomes. By better understanding the mechanisms underlying responses to PD-1/PD-L1 therapy and developing strategies to predict these responses, it is possible to create more efficient treatments for TNBC and HCC.

Yttrium-90 Induces an Effector Memory Response with Neoantigen Clonotype Expansion: Implications for Immunotherapy

Yttrium-90 (90Y) transarterial radioembolization can safely and effectively treat hepatocellular carcinoma (HCC). Clinical trials combining 90Y with immunotherapy are aimed at improving treatment response rates. The impact of transient 90Y-induced lymphopenia on T-cell homeostasis and functional dynamics is unknown. Paired blood specimens were collected prior to first-cycle 90Y and at imaging follow-up in patients with HCC Barcelona Clinic Liver Cancer stages A-B. Flow cytometry and T-cell receptor (TCR) sequencing were used to monitor changes in T-cell subsets and TCR repertoire following 90Y. Objective response (OR) rates were determined using modified RECIST and defined as either OR or nonobjective response. Time-to-progression (TTP) was defined as progression to Barcelona Clinic Liver Cancer stage C within 6 months following 90Y. 90Y induced shifts in both CD4+ (P = 0.049) and CD8+ (P < 0.001) toward an effector memory T-cell response independent of treatment response rate. Nonresponders to 90Y were characterized by a sustained elevation in both naïve CD4+ cells (P = 0.019) and programmed cell death protein 1 expression in CD8+ cells (P = 0.003). Paired analysis of the TCR repertoire revealed a variable induction of neoantigen clonotypes and expansion of existing clonotypes independent of 90Y response. In patients with an OR, changes in TCR clonality did not influence TTP. However, polyclonal profiles in patients without an OR were associated with shorter TTP (P = 0.005; HR, 10.8) and 75% disease progression rates 6 months following treatment. 90Y induces a population shift from central to effector memory accompanied by neoantigen T-cell responses independent of treatment response rate. Monoclonal shifts in the post-90Y T-cell repertoire had superior overall TTP and improved TTP in patients with a first-cycle nonobjective response.

SIGNIFICANCE

90Y can safely treat HCC; however, it causes transient lymphopenia. In this article, 90Y stimulates a peripheral effector memory response independent of initial treatment response. TCR sequencing revealed that polyclonal profiles in patients without an OR to treatment were associated with rapid progression rates 6 months after 90Y.

Immune predictors of response to immune checkpoint inhibitors in mismatch repair-deficient endometrial cancer

BACKGROUND

Patients with mismatch repair-deficient (MMRd) endometrial cancer (EC) can derive great benefit from immune checkpoint inhibitors (ICI). However not all responses and predictors of primary resistance are lacking.

METHODS

We compared the immune tumor microenvironment of MMRd EC ICI-responders (Rs) and ICI non-responders (NRs), using spatial multiplexed immune profiling and unsupervised hierarchical clustering analysis.

RESULTS

Overall, NRs exhibited drastically lower CD8+, absent terminally differentiated T cells, lack of mature tertiary lymphoid structures and dendritic cells, as well as loss of human leukocyte antigen class I. However, no single marker could predict R versus NR with confidence. Clustering analysis identified a combination of four immune features that demonstrated that accurately predicted ICI response, with a discriminative power of 92%. Finally, 80% of NRs lacked programmed death-ligand 1, however, 60% exhibited another actionable immune checkpoint (T-cell immunoglobulin and mucin containing protein-3, indoleamine 2,3-dioxygenase 1, or lymphocyte activation gene 3).

CONCLUSIONS

These findings underscore the potential of immune tumor microenvironment features for identifying patients with MMRd EC and primary resistance to ICI who should be oriented towards trials testing novel immunotherapeutic combinations.

CD28-CD57+ T cells from head and neck cancer patients produce high levels of cytotoxic granules and type II interferon but are not senescent

T lymphocytes expressing CD57 and lacking costimulatory receptors CD27/CD28 have been reported to accumulate with aging, chronic infection, and cancer. These cells are described as senescent, with inability to proliferate but enhanced cytolytic and cytokine-producing capacity. However, robust functional studies on these cells taken directly from cancer patients are lacking. We isolated these T cells and their CD27/28+ counterparts from blood and tumor samples of 50 patients with previously untreated head and neck cancer. Functional studies confirmed that these cells have enhanced ability to degranulate and produce IFN-γ. They also retain the ability to proliferate, thus are not senescent. These data suggest that CD27/28-CD57+ CD8+ T cells are a subset of highly differentiated, CD45RA+ effector memory (TEMRA) cells with retained proliferative capacity. Patients with > 34% of these cells among CD8+ T cells in the blood had a higher rate of locoregional disease relapse, suggesting these cells may have prognostic significance.

Exploratory mass cytometry analysis reveals immunophenotypes of cancer treatment-related pneumonitis

Anticancer treatments can result in various adverse effects, including infections due to immune suppression/dysregulation and drug-induced toxicity in the lung. One of the major opportunistic infections is Pneumocystis jirovecii pneumonia (PCP), which can cause severe respiratory complications and high mortality rates. Cytotoxic drugs and immune-checkpoint inhibitors (ICIs) can induce interstitial lung diseases (ILDs). Nonetheless, the differentiation of these diseases can be difficult, and the pathogenic mechanisms of such diseases are not yet fully understood. To better comprehend the immunophenotypes, we conducted an exploratory mass cytometry analysis of immune cell subsets in bronchoalveolar lavage fluid from patients with PCP, cytotoxic drug-induced ILD (DI-ILD), and ICI-associated ILD (ICI-ILD) using two panels containing 64 markers. In PCP, we observed an expansion of the CD16+ T cell population, with the highest CD16+ T proportion in a fatal case. In ICI-ILD, we found an increase in CD57+ CD8+ T cells expressing immune checkpoints (TIGIT+ LAG3+ TIM-3+ PD-1+), FCRL5+ B cells, and CCR2+ CCR5+ CD14+ monocytes. These findings uncover the diverse immunophenotypes and possible pathomechanisms of cancer treatment-related pneumonitis.

Circulating T cells: a promising biomarker of anti-PD-(L)1 therapy

Anti-PD-(L)1 therapy has shown great efficacy in some patients with cancer. However, a significant proportion of patients with cancer do not respond to it. Another unmet clinical need for anti-PD-(L)1 therapy is the dynamic monitoring of treatment effects. Therefore, identifying biomarkers that can stratify potential responders before PD-(L)1 treatment and timely monitoring of the efficacy of PD-(L)1 treatment are crucial in the clinical setting. The identification of biomarkers by liquid biopsy has attracted considerable attention. Among the identified biomarkers, circulating T cells are one of the most promising because of their indispensable contribution to anti-PD-(L)1 therapy. The present review aimed to thoroughly explore the potential of circulating T cells as biomarkers of anti-PD-(L)1 therapy and its advantages and limitations.

Clinical implications of single cell sequencing for bladder cancer

Bladder cancer (BC) is the 10th most common cancer worldwide, with about 0.5 million reported new cases and about 0.2 million deaths per year. In this scoping review, we summarize the current evidence regarding the clinical implications of single-cell sequencing for bladder cancer based on PRISMA guidelines. We searched PubMed, CENTRAL, Embase, and supplemented with manual searches through the Scopus, and Web of Science for published studies until February 2023. We included original studies that used at least one single-cell technology to study bladder cancer. Forty-one publications were included in the review. Twenty-nine studies showed that this technology can identify cell subtypes in the tumor microenvironment that may predict prognosis or response to immune checkpoint inhibition therapy. Two studies were able to diagnose BC by identifying neoplastic cells through single-cell sequencing urine samples. The remaining studies were mainly a preclinical exploration of tumor microenvironment at single cell level. Single-cell sequencing technology can discriminate heterogeneity in bladder tumor cells and determine the key molecular properties that can lead to the discovery of novel perspectives on cancer management. This nascent tool can advance the early diagnosis, prognosis judgment, and targeted therapy of bladder cancer.

TGFβ-specific T cells induced by a TGFβ-derived immune modulatory vaccine both directly and indirectly modulate the phenotype of tumor-associated macrophages and fibroblasts

The tumor microenvironment (TME) of pancreatic cancer is highly immunosuppressive. We recently developed a transforming growth factor (TGF)β-based immune modulatory vaccine that controlled tumor growth in a murine model of pancreatic cancer by targeting immunosuppression and desmoplasia in the TME. We found that treatment with the TGFβ vaccine not only reduced the percentage of M2-like tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs) in the tumor but polarized CAFs away from the myofibroblast-like phenotype. However, whether the immune modulatory properties of the TGFβ vaccine on TAM and CAF phenotypes are a direct consequence of the recognition and subsequent targeting of these subsets by TGFβ-specific T cells or an indirect consequence of the overall modulation induced within the TME remains unknown. Recognition of M2 macrophages and fibroblast by TGFβ-specific T cells was assessed by ELISpot and flow cytometry. The indirect and direct effects of the TGFβ vaccine on these cell subsets were evaluated by culturing M2 macrophages or fibroblasts with tumor-conditioned media or with T cells isolated from the spleen of mice treated with the TGFβ vaccine or a control vaccine, respectively. Changes in phenotype were assessed by flow cytometry and Bio-Plex multiplex system (Luminex). We found that TGFβ-specific T cells induced by the TGFβ vaccine can recognize M2 macrophages and fibroblasts. Furthermore, we demonstrated that the phenotype of M2 macrophages and CAFs can be directly modulated by TGFβ-specific T cells induced by the TGFβ vaccine, as well as indirectly modulated as a result of the immune-modulatory effects of the vaccine within the TME. TAMs tend to have tumor-promoting functions, harbor an immunosuppressive phenotype and are linked to decreased overall survival in pancreatic cancer when they harbor an M2-like phenotype. In addition, myofibroblast-like CAFs create a stiff extracellular matrix that restricts T cell infiltration, impeding the effectiveness of immune therapies in desmoplastic tumors, such as pancreatic ductal adenocarcinoma. Reducing immunosuppression and immune exclusion in pancreatic tumors by targeting TAMs and CAFs with the TGFβ-based immune modulatory vaccine emerges as an innovative strategy for the generation of a more favorable environment for immune-based therapies, such as immune checkpoint inhibitors.

CD57-positive CD8 + T cells define the response to anti-programmed cell death protein-1 immunotherapy in patients with advanced non-small cell lung cancer

Immune checkpoint inhibitors have transformed the treatment landscape of non-small cell lung cancer (NSCLC). However, accurately identifying patients who will benefit from immunotherapy remains a challenge. This study aimed to discover potential biomarkers for predicting immunotherapy response in NSCLC patients. Single-cell mass cytometry (CyTOF) was utilized to analyze immune cell subsets in peripheral blood mononuclear cells (PBMCs) obtained from NSCLC patients before and 12 weeks after single-agent immunotherapy. The CyTOF findings were subsequently validated using flow cytometry and multiplex immunohistochemistry/immunofluorescence in PBMCs and tumor tissues, respectively. RNA sequencing (RNA-seq) was performed to elucidate the underlying mechanisms. In the CyTOF cohort (n = 20), a high frequency of CD57+CD8+ T cells in PBMCs was associated with durable clinical benefit from immunotherapy in NSCLC patients (p = 0.034). This association was further confirmed in an independent cohort using flow cytometry (n = 27; p < 0.001), with a determined cutoff value of 12.85%. The cutoff value was subsequently validated in another independent cohort (AUC = 0.733). We also confirmed the CyTOF findings in pre-treatment formalin-fixed and paraffin-embedded tissues (n = 90; p < 0.001). RNA-seq analysis revealed 475 differentially expressed genes (DEGs) between CD57+CD8+ T cells and CD57-CD8+ T cells, with functional analysis identifying DEGs significantly enriched in immune-related signaling pathways. This study highlights CD57+CD8+ T cells as a promising biomarker for predicting immunotherapy success in NSCLC patients.

Impact of immunosenescence and inflammaging on the effects of immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) are employed in immunotherapeutic applications for patients with weakened immune systems and can improve the ability of T cells to kill cancer cells. Although ICIs can potentially treat different types of cancers in various groups of patients, their effectiveness may differ among older individuals. The reason ICIs are less effective in older adults is not yet clearly understood, but age-related changes in the immune system, such as immunosenescence and inflammation, may play a role. Therefore, this review focuses on recent advances in understanding the effects of immunosenescence and inflammation on the efficacy of ICIs.

T-cell response to checkpoint blockade immunotherapies: from fundamental mechanisms to treatment signatures

Immune checkpoint immunotherapies act to block inhibitory receptors on the surface of T cells and other cells of the immune system. This can increase activation of immune cells and promote tumour clearance. Whilst this is very effective in some types of cancer, significant proportions of patients do not respond to single-agent immunotherapy. To improve patient outcomes, we must first mechanistically understand what drives therapy resistance. Many studies have utilised genetic, transcriptional, and histological signatures to find correlates of effective responses to treatment. It is key that we understand pretreatment predictors of response, but also to understand how the immune system becomes treatment resistant during therapy. Here, we review our understanding of the T-cell signatures that are critical for response, how these immune signatures change during treatment, and how this information can be used to rationally design therapeutic strategies. We highlight how chronic antigen recognition drives heterogeneous T-cell exhaustion and the role of T-cell receptor (TCR) signal strength in exhausted T-cell differentiation and molecular response to therapy. We explore how dynamic changes in negative feedback pathways can promote resistance to single-agent therapy. We speculate that this resistance may be circumvented in the future through identifying the most effective combinations of immunotherapies to promote sustained and durable antitumour responses.

Immune checkpoint therapy for solid tumours: clinical dilemmas and future trends

Immune-checkpoint inhibitors (ICBs), in addition to targeting CTLA-4, PD-1, and PD-L1, novel targeting LAG-3 drugs have also been approved in clinical application. With the widespread use of the drug, we must deeply analyze the dilemma of the agents and seek a breakthrough in the treatment prospect. Over the past decades, these agents have demonstrated dramatic efficacy, especially in patients with melanoma and non-small cell lung cancer (NSCLC). Nonetheless, in the field of a broad concept of solid tumours, non-specific indications, inseparable immune response and side effects, unconfirmed progressive disease, and complex regulatory networks of immune resistance are four barriers that limit its widespread application. Fortunately, the successful clinical trials of novel ICB agents and combination therapies, the advent of the era of oncolytic virus gene editing, and the breakthrough of the technical barriers of mRNA vaccines and nano-delivery systems have made remarkable breakthroughs currently. In this review, we enumerate the mechanisms of each immune checkpoint targets, associations between ICB with tumour mutation burden, key immune regulatory or resistance signalling pathways, the specific clinical evidence of the efficacy of classical targets and new targets among different tumour types and put forward dialectical thoughts on drug safety. Finally, we discuss the importance of accurate triage of ICB based on recent advances in predictive biomarkers and diagnostic testing techniques.

Multiparameter single-cell proteomic technologies give new insights into the biology of ovarian tumors

High-grade serous ovarian cancer (HGSOC) is the most lethal gynecological malignancy. Its diagnosis at advanced stage compounded with its excessive genomic and cellular heterogeneity make curative treatment challenging. Two critical therapeutic challenges to overcome are carboplatin resistance and lack of response to immunotherapy. Carboplatin resistance results from diverse cell autonomous mechanisms which operate in different combinations within and across tumors. The lack of response to immunotherapy is highly likely to be related to an immunosuppressive HGSOC tumor microenvironment which overrides any clinical benefit. Results from a number of studies, mainly using transcriptomics, indicate that the immune tumor microenvironment (iTME) plays a role in carboplatin response. However, in patients receiving treatment, the exact mechanistic details are unclear. During the past decade, multiplex single-cell proteomic technologies have come to the forefront of biomedical research. Mass cytometry or cytometry by time-of-flight, measures up to 60 parameters in single cells that are in suspension. Multiplex cellular imaging technologies allow simultaneous measurement of up to 60 proteins in single cells with spatial resolution and interrogation of cell-cell interactions. This review suggests that functional interplay between cell autonomous responses to carboplatin and the HGSOC immune tumor microenvironment could be clarified through the application of multiplex single-cell proteomic technologies. We conclude that for better clinical care, multiplex single-cell proteomic technologies could be an integral component of multimodal biomarker development that also includes genomics and radiomics. Collection of matched samples from patients before and on treatment will be critical to the success of these efforts.