PD-1-expressing macrophages and CD8 T cells are independent predictors of clinical benefit from PD-1 inhibition in advanced mesothelioma.

BACKGROUND: Few tissue biomarkers exist to date that could enrich patient with cancer populations to benefit from immune checkpoint blockade by programmed cell death protein 1/ligand-1 (PD-/L-1) inhibitors. PD-L1 expression has value in this context in some tumor types but is an imperfect predictor of clinical benefit. In malignant pleural mesothelioma, PD-L1 expression is not predictive of the benefit from PD-1 blockade. We aimed to identify novel markers in malignant pleural mesothelioma to select patients better. METHODS: We performed a multiplex-immune histochemistry analysis of tumor samples from the phase III PROMISE-meso study, which randomized 144 pretreated patients to receive either pembrolizumab or standard second-line chemotherapy. Our panel focused on CD8+T cell, CD68+macrophages, and the expression of PD-1 and PD-L1 on these and cancer cells. We analyzed single and double positive cells within cancer tissues (infiltrating immune cells) and in the stroma. In addition, we performed cell neighborhood analysis. The cell counts were compared with clinical outcomes, including responses, progression-free and overall survivals. RESULTS: We confirmed the absence of predictive value for PD-L1 in this cohort of patients. Furthermore, total CD8 T cells, CD68+macrophages, or inflammatory subtypes (desert, excluded, inflamed) did not predict outcomes. In contrast, PD-1-expressing CD8+T cells (exhausted T cells) and PD-1-expressing CD68+macrophages were both independent predictors of progression-free survival benefit from pembrolizumab. Patients with tumors simultaneously harboring PD1+T cells and PD-1+macrophages benefited the most from immune therapy. CONCLUSION: We analyzed a large cohort of patients within a phase III study and found that not only PD-1+CD8 T cells but also PD-1+CD68+ macrophages are predictive. This data provides evidence for the first time for the existence of PD-1+macrophages in mesothelioma and their clinical relevance for immune checkpoint blockade.

Bedside formulation of a personalized multi-neoantigen vaccine against mammary carcinoma.

BACKGROUND: Harnessing the immune system to purposely recognize and destroy tumors represents a significant breakthrough in clinical oncology. Non-synonymous mutations (neoantigenic peptides) were identified as powerful cancer targets. This knowledge can be exploited for further improvements of active immunotherapies, including cancer vaccines, as T cells specific for neoantigens are not attenuated by immune tolerance mechanism and do not harm healthy tissues. The current study aimed at developing an optimized multitarget vaccine using short or long neoantigenic peptides utilizing virus-like particles (VLPs) as an efficient vaccine platform. METHODS: Mutations of murine mammary carcinoma cells were identified by integrating mass spectrometry-based immunopeptidomics and whole exome sequencing. Neoantigenic peptides were synthesized and covalently linked to virus-like nanoparticles using a Cu-free click chemistry method for easy preparation of vaccines against mouse mammary carcinoma. RESULTS: As compared with short peptides, vaccination with long peptides was superior in the generation of neoantigen-specific CD4+ and CD8+ T cells, which readily produced interferon gamma (IFN-γ) and tumor-necrosis factor α (TNF-α). The resulting anti-tumor effect was associated with favorable immune re-polarization in the tumor microenvironment through reduction of myeloid-derived suppressor cells. Vaccination with long neoantigenic peptides also decreased post-surgical tumor recurrence and metastases, and prolonged mouse survival, despite the tumor's low mutational burden. CONCLUSION: Integrating mass spectrometry-based immunopeptidomics and whole exome sequencing is an efficient approach for identifying neoantigenic peptides. Our multitarget VLP-based vaccine shows a promising anti-tumor effect in an aggressive murine mammary carcinoma model. Future clinical application using this strategy is readily feasible and practical, as click chemistry coupling of personalized synthetic peptides to the nanoparticles can be done at the bedside directly before injection.

Optimized combinatorial pMHC class II multimer labeling for precision immune monitoring of tumor-specific CD4 T cells in patients.

BACKGROUND: With immunotherapy gaining increasing approval for treatment of different tumor types, scientists rely on cutting edge methods for the monitoring of immune responses and biomarker development in patients. Due to the lack of tools to efficiently detect rare circulating human tumor-specific CD4 T cells, their characterization in patients still remains very limited. METHODS: We have used combinatorial staining strategies with peptide major histocompatibility complex class II (pMHCII) multimer constructs of different alleles to establish an optimized staining procedure for in vitro and direct ex-vivo visualization of tumor-specific CD4 T cells, in patient samples. Furthermore, we have generated reversible multimers to achieve optimal cell staining and yet disassemble prior to in vitro cell expansion, thus preventing activation induced cell death. RESULTS: We observed a vastly improved detection of tumor-specific, viral-specific and bacterial-specific cells with our optimization methods compared with the non-optimized staining procedure. By increasing the variety of fluorochromes used to label the pMHCII multimers, we were also able to increase the parallel detection of different specificities within one sample, including antigen-specific CD8 T cells. A decrease in cell viability was observed when using the full optimization method, but this was mitigated by the removal of neuraminidase and the use of reversible multimers. CONCLUSION: This new optimized staining procedure represents an advance toward better detection and analysis of antigen-specific CD4 T cells. It should facilitate state-of-the art precision monitoring of tumor-specific CD4 T cells and contribute to accelerate the use and the targeting of these cells in cancer immunotherapy.

Adverse effects of immune-checkpoint inhibitors: epidemiology, management and surveillance.

Immune-checkpoint inhibitors (ICIs), including anti-cytotoxic T lymphocyte antigen 4 (CTLA-4), anti-programmed cell death 1 (PD-1) and anti-programmed cell death 1 ligand 1 (PD-L1) antibodies, are arguably the most important development in cancer therapy over the past decade. The indications for these agents continue to expand across malignancies and disease settings, thus reshaping many of the previous standard-of-care approaches and bringing new hope to patients. One of the costs of these advances is the emergence of a new spectrum of immune-related adverse events (irAEs), which are often distinctly different from the classical chemotherapy-related toxicities. Owing to the growing use of ICIs in oncology, clinicians will increasingly be confronted with common but also rare irAEs; hence, awareness needs to be raised regarding the clinical presentation, diagnosis and management of these toxicities. In this Review, we provide an overview of the various types of irAEs that have emerged to date. We discuss the epidemiology of these events and their kinetics, risk factors, subtypes and pathophysiology, as well as new insights regarding screening and surveillance strategies. We also highlight the most important aspects of the management of irAEs.

New therapeutic perspectives to manage refractory immune checkpoint-related toxicities.

Immune checkpoint inhibitors are reshaping the prognosis of many cancer and are progressively becoming the standard of care in the treatment of many tumour types. Immunotherapy is bringing new hope to patients, but also a whole new spectrum of toxicities for healthcare practitioners to manage. Oncologists and specialists involved in the pluridisciplinary management of patients with cancer are increasingly confronted with the therapeutic challenge of treating patients with severe and refractory immune-related adverse events. In this Personal View, we summarise the therapeutic strategies that have been used to manage such toxicities resulting from immune checkpoint inhibitor treatment. On the basis of current knowledge about their pathogenesis, we discuss the use of new biological and non-biological immunosuppressive drugs to treat severe and steroid refractory immune-related adverse events. Depending on the immune infiltrate type that is predominant, we propose a treatment algorithm for personalised management that goes beyond typical corticosteroid use. We propose a so-called shut-off strategy that aims at inhibiting key inflammatory components involved in the pathophysiological processes of immune-related adverse events, and limits potential adverse effects of drug immunosuppression on tumour response. This approach develops on current guidelines and challenges the step-by-step increase approach to drug immunosuppression.

Consensus nomenclature for CD8+ T cell phenotypes in cancer.

Whereas preclinical investigations and clinical studies have established that CD8+ T cells can profoundly affect cancer progression, the underlying mechanisms are still elusive. Challenging the prevalent view that the beneficial effect of CD8+ T cells in cancer is solely attributable to their cytotoxic activity, several reports have indicated that the ability of CD8+ T cells to promote tumor regression is dependent on their cytokine secretion profile and their ability to self-renew. Evidence has also shown that the tumor microenvironment can disarm CD8+ T cell immunity, leading to the emergence of dysfunctional CD8+ T cells. The existence of different types of CD8+ T cells in cancer calls for a more precise definition of the CD8+ T cell immune phenotypes in cancer and the abandonment of the generic terms "pro-tumor" and "antitumor." Based on recent studies investigating the functions of CD8+ T cells in cancer, we here propose some guidelines to precisely define the functional states of CD8+ T cells in cancer.