ESDR289 - The effect of immune checkpoint Inhibitors on the CD4+ T-cell population by patients with advanced melanoma and the role of these cells in immune related adverse events
The clinical success of immune checkpoint inhibitors has highlighted the central role of the immune system in cancer control. Immune checkpoint inhibitors can reinvigorate anti-cancer immunity and are now the standard of care in a number of malignancies. However, research on immune checkpoint blockade has largely been framed with the central dogma that checkpoint therapies intrinsically target the T cell, triggering the tumoricidal potential of the adaptive immune system. Although T cells undoubtedly remain a critical piece of the story, mounting evidence, reviewed herein, indicates that much of the efficacy of checkpoint therapies may be attributable to the innate immune system. Emerging research suggests that T cell-directed checkpoint antibodies such as anti-programmed cell death protein-1 (PD-1) or programmed death-ligand-1 (PD-L1) can impact innate immunity by both direct and indirect pathways, which may ultimately shape clinical efficacy. However, the mechanisms and impacts of these activities have yet to be fully elucidated, and checkpoint therapies have potentially beneficial and detrimental effects on innate antitumor immunity. Further research into the role of innate subsets during checkpoint blockade may be critical for developing combination therapies to help overcome checkpoint resistance. The potential of checkpoint therapies to amplify innate antitumor immunity represents a promising new field that can be translated into innovative immunotherapies for patients fighting refractory malignancies.
AbstractImmune checkpoint inhibitors are novel biologic agents to treat cancer by inhibiting the regulatory interactions that limit T cell cytotoxicity to tumours. Current agents target either CTLA-4 or the PD-1/PD-L1 axis. Because checkpoints may also regulate autoreactivity, immune checkpoint inhibitor therapy is complicated by side effects known as immune-related adverse events (irAEs). The aim of this article is to review the mechanisms of these events. irAEs can involve different tissues and include arthritis and other rheumatic manifestations. The frequency of irAEs is related to the checkpoint inhibited, with the combination of agents more toxic. Because of their severity, irAEs can limit therapy and require immunosuppressive treatment. The mechanisms leading to irAEs are likely similar to those promoting anti-tumour responses and involve expansion of the T cell repertoire; furthermore, immune checkpoint inhibitors can affect B cell responses and induce autoantibody production. Better understanding of the mechanisms of irAEs will be important to improve patient outcome as well as quality of life during treatment.
BackgroundAlthough antibodies blocking immune checkpoints have already been approved for clinical cancer treatment, the mechanisms involved are not yet completely elucidated. Here we used a λ-MYC transgenic model of endogenously growing B-cell lymphoma to analyze the requirements for effective therapy with immune checkpoint inhibitors.MethodsGrowth of spontaneous lymphoma was monitored in mice that received antibodies targeting programmed cell death protein 1 and cytotoxic T lymphocyte-associated protein-4, and the role of different immune cell compartments and cytokines was studied by in vivo depletion experiments. Activation of T and natural killer cells and the induction of tumor senescence were analyzed by flow cytometry.ResultsOn immune checkpoint blockade, visible lymphomas developed at later time points than in untreated controls, indicating an enhanced tumor control. Importantly, 20% to 30% of mice were even long-term protected and did never develop clinical signs of tumor growth. The therapeutic effect was dependent on cytokine-induced senescence in malignant B cells. The proinflammatory cytokines interferon-γ (IFN-γ) and tumor necrosis factor (TNF) were necessary for the survival benefit as well as for senescence induction in the λ-MYC model. Antibody therapy improved T-cell functions such as cytokine production, and long-time survivors were only observed in the presence of T cells. Yet, NK cells also had a pronounced effect on therapy-induced delay of tumor growth. Antibody treatment enhanced numbers, proliferation and IFN-γ expression of NK cells in developing tumors. The therapeutic effect was fully abrogated only after depletion of both, T cells and NK cells, or after ablation of either IFN-γ or TNF.ConclusionsTumor cell senescence may explain why patients responding to immune checkpoint blockade frequently show stable growth arrest of tumors rather than complete tumor regression. In the lymphoma model studied, successful therapy required both, tumor-directed T-cell responses and NK cells, which control, at least partly, tumor development through cytokine-induced tumor senescence.
Immune checkpoint inhibitors, such as ipilimumab and nivolumab, reverse the imbalance of antitumor self-tolerance and enhance T-cell responses. Currently, ipilimumab and nivolumab have a reported therapeutic impact on unresectable or metastatic melanomas; however, they also induce immune-related adverse events (irAEs). Ipilimumab-induced cutaneous irAEs are mostly low grade and manageable, although all-grade rash may occur in approximately 45% of all patients. We here report the case of a young woman with erythema multiforme major, which developed after sequential use of these 2 immune checkpoint inhibitors for advanced melanoma of the scalp. Initially, she received 12 cycles of nivolumab monotherapy followed by ipilimumab. A week later, multiple erythematous papulo-erythemas appeared on almost her entire body, with high-grade fever, mucosal involvements, and dyspnea. Immunohistochemistry using the lesioned skin revealed lymphocytic infiltration predominantly positive for CD8, contrasting with those for CD4 and Foxp3. Ipilimumab was stopped but she continued to receive empirical antibiotics; additionally, she was treated with intravenous steroid pulse therapy and immunoglobulin, followed by oral prednisolone. Her symptoms subsided rapidly, allowing a restart of nivolumab monotherapy alone. In our case, the long-standing preceding nivolumab monotherapy may synergistically and/or complementary have contributed to – in combination with the later administration of ipilimumab – recover antigen-responsive T-cell immunity, which is similar to the concept of immune reconstitution inflammatory syndrome, resulting in the establishment of an underlying immunopathology of erythema multiforme and life-threatening airway obstruction.
289 The effect of immune checkpoint Inhibitors on the CD4+ T-cell population by patients with advanced melanoma and the role of these cells in immune related adverse events