Serial immunomonitoring of cancer patients receiving combined antagonistic anti-CD40 and chemotherapy reveals consistent and cyclical modulation of T cell and dendritic cell parameters

Triple-modality therapy maximizes antitumor immune responses in a mouse model of mesothelioma

Malignant pleural mesothelioma (MPM) is an intractable disease with an extremely poor prognosis. Our clinical protocol for MPM of subablative radiotherapy (RT) followed by radical surgery achieved better survival compared to other multimodal treatments, but local relapse and metastasis remain a problem. This subablative RT elicits an antitumoral immune response that is limited by the immunosuppressive microenvironment generated by regulatory T (T_reg) cells. The antitumor effect of immunotherapy to simultaneously modulate the immune activation and the immune suppression after subablative RT has not been investigated in MPM. Herein, we demonstrated a rationale to combine interleukin-15 (IL-15) superagonist (IL-15SA) and glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) agonist (DTA-1) with subablative RT in mesothelioma. IL-15SA boosted the systemic expansion of specific antitumoral memory CD8⁺ T cells that were induced by RT in mice. Their effect, however, was limited by the up-regulation and activation of T_reg cells in the radiated tumor microenvironment. Hence, selective depletion of intratumoral T_reg cells through DTA-1 enhanced the benefit of subablative RT in combination with IL-15SA. The addition of surgical resection of the radiated tumor in combination with IL-15SA and DTA-1 maximized the benefit of RT and was accompanied by a reproducible abscopal response in a concomitant tumor model. These data support the development of clinical trials in MPM to test such treatment options for patients with locally advanced or metastatic tumors.

Systemic inflammation is a determinant of outcomes of CD40 agonist-based therapy in pancreatic cancer patients

Agonistic anti-CD40 monoclonal antibody (mAb) therapy in combination with chemotherapy (chemoimmunotherapy) shows promise for the treatment of pancreatic ductal adenocarcinoma (PDA). To gain insight into immunological mechanisms of response and resistance to chemoimmunotherapy, we analyzed blood samples from patients (n = 22) with advanced PDA treated with an anti-CD40 mAb (CP-870,893) in combination with gemcitabine. We found a stereotyped cellular response to chemoimmunotherapy characterized by transient B cell, CD56⁺CD11c⁺HLA-DR⁺CD141⁺ cell, and monocyte depletion and CD4⁺ T cell activation. However, these cellular pharmacodynamics did not associate with outcomes. In contrast, we identified an inflammatory network in the peripheral blood consisting of neutrophils, cytokines (IL-6 and IL-8), and acute phase reactants (C-reactive protein and serum amyloid A) that was associated with outcomes. Furthermore, monocytes from patients with elevated plasma IL-6 and IL-8 showed distinct transcriptional profiles, including upregulation of CCR2 and GAS6, genes associated with regulation of leukocyte chemotaxis and response to inflammation. Patients with systemic inflammation, defined by neutrophil/lymphocyte ratio (NLR) greater than 3.1, had a shorter median overall survival (5.8 vs. 12.3 months) as compared with patients with NLR less than 3.1. Taken together, our findings identify systemic inflammation as a potential resistance mechanism to a CD40-based chemoimmunotherapy and suggest biomarkers for future studies.

Trial watch: chemotherapy-induced immunogenic cell death in immuno-oncology

The term ‘immunogenic cell death’ (ICD) denotes an immunologically unique type of regulated cell death that enables, rather than suppresses, T cell-driven immune responses that are specific for antigens derived from the dying cells. The ability of ICD to elicit adaptive immunity heavily relies on the immunogenicity of dying cells, implying that such cells must encode and present antigens not covered by central tolerance (antigenicity), and deliver immunostimulatory molecules such as damage-associated molecular patterns and cytokines (adjuvanticity). Moreover, the host immune system must be equipped to detect the antigenicity and adjuvanticity of dying cells. As cancer (but not normal) cells express several antigens not covered by central tolerance, they can be driven into ICD by some therapeutic agents, including (but not limited to) chemotherapeutics of the anthracycline family, oxaliplatin and bortezomib, as well as radiation therapy. In this Trial Watch, we describe current trends in the preclinical and clinical development of ICD-eliciting chemotherapy as partner for immunotherapy, with a focus on trials assessing efficacy in the context of immunomonitoring.

CD40 Agonist Antibodies in Cancer Immunotherapy

CD40 is a cell-surface member of the TNF (tumor necrosis factor) receptor superfamily. Upon activation, CD40 can license dendritic cells to promote antitumor T cell activation and re-educate macrophages to destroy tumor stroma. Numerous agonist CD40 antibodies of varying formulations have been evaluated in the clinic and found to be tolerable and feasible. Administration is associated with mild to moderate (but transient) cytokine release syndrome, readily managed in the outpatient setting. Antitumor activity with or without anti-CTLA4 monoclonal antibody (mAb) therapy has been observed in patients with melanoma, and major tumor regressions have been observed in patients with pancreatic cancer, mesothelioma, and other tumors in combination with chemotherapy. In a recent study of chemotherapy plus CD40 mAb, with or without PD-1 mAb, the objective response rate in patients with untreated, metastatic pancreatic cancer was >50%. Mechanistically, the combination of chemotherapy followed by CD40 mAb functions as an in situ vaccine; in addition, destruction of stroma by CD40-activated macrophages may enhance chemotherapy delivery. Evidence to date suggests that CD40 activation is a critical and nonredundant mechanism to convert so-called cold tumors to hot ones (with prominent tumor infiltration of T cells), sensitizing them to checkpoint inhibition.

Tumour associated lymphocytes in the pleural effusions of patients with mesothelioma express high levels of inhibitory receptors

OBJECTIVE

Pleural effusion (PE) is a common feature of malignant pleural mesothelioma. These effusions typically contain lymphocytes and malignant cells. We postulated that the PE would be a source of lymphocytes for analysis of tumor immune milieu. The aim of this study was to compare the phenotype and T cell receptor usage of pleural effusion T cells with paired concurrently drawn peripheral blood lymphocytes. We used multi-parameter flow cytometry and high-throughput T cell receptor sequencing to analyse peripheral blood and pleural effusion mononuclear cells.

RESULTS

Both CD8⁺ and CD4⁺ T cells from effusion showed increased expression of T cell inhibitory receptors PD-1, LAG-3 and Tim-3 compared to blood. Comprehensive T cell receptor sequencing on one of the patients showed a discordant distribution of clonotypes in the antigen-experienced (PD-1⁺) compartment between effusion and blood, suggesting an enrichment of antigen specific clonotypes in the effusion, with potential as an immunological response biomarker.

The Immune Revolution: A Case for Priming, Not Checkpoint

Most tumors are unresponsive to immune checkpoint blockade, especially if deep immunosuppression in the tumor develops prior to and prevents T cell immunosurveillance. Failed or frustrated T cell priming often needs repair before successful sensitization to PD-1/PD-L1 blockade. CD40 activation plays a critical role in generating T cell immunity, by activating dendritic cells, and converting cold tumors to hot. In preclinical studies, agonistic CD40 antibodies demonstrate T cell-dependent anti-tumor activity, especially in combination with chemotherapy, checkpoint inhibitory antibodies, and other immune modulators. With the advent of multiple CD40 agonists with acceptable single-agent toxicity, clinical evaluation of CD40 combinations has accelerated.

Trial watch: Immunogenic cell death induction by anticancer chemotherapeutics

The expression "immunogenic cell death" (ICD) refers to a functionally unique form of cell death that facilitates (instead of suppressing) a T cell-dependent immune response specific for dead cell-derived antigens. ICD critically relies on the activation of adaptive responses in dying cells, culminating with the exposure or secretion of immunostimulatory molecules commonly referred to as "damage-associated molecular patterns". Only a few agents can elicit bona fide ICD, including some clinically established chemotherapeutics such as doxorubicin, epirubicin, idarubicin, mitoxantrone, bleomycin, bortezomib, cyclophosphamide and oxaliplatin. In this Trial Watch, we discuss recent progress on the development of ICD-inducing chemotherapeutic regimens, focusing on studies that evaluate clinical efficacy in conjunction with immunological biomarkers.