Trial watch: chemotherapy-induced immunogenic cell death in oncology

Immunogenic cell death (ICD) refers to an immunologically distinct process of regulated cell death that activates, rather than suppresses, innate and adaptive immune responses. Such responses culminate into T cell-driven immunity against antigens derived from dying cancer cells. The potency of ICD is dependent on the immunogenicity of dying cells as defined by the antigenicity of these cells and their ability to expose immunostimulatory molecules like damage-associated molecular patterns (DAMPs) and cytokines like type I interferons (IFNs). Moreover, it is crucial that the host's immune system can adequately detect the antigenicity and adjuvanticity of these dying cells. Over the years, several well-known chemotherapies have been validated as potent ICD inducers, including (but not limited to) anthracyclines, paclitaxels, and oxaliplatin. Such ICD-inducing chemotherapeutic drugs can serve as important combinatorial partners for anti-cancer immunotherapies against highly immuno-resistant tumors. In this Trial Watch, we describe current trends in the preclinical and clinical integration of ICD-inducing chemotherapy in the existing immuno-oncological paradigms.

FOCUS on FOCIS: combined chemo-immunotherapy for the treatment of hormone-refractory metastatic prostate cancer

Immunotherapy has emerged as another treatment modality in cancer. The goal of immunotherapy in advanced cancer patients does not have to be the complete eradication of tumor cells but rather the restoration of a dynamic balance between tumor cells and the immune response. Appropriate combination of tumor mass reduction (by surgery and/or chemotherapy) and neutralization of tumor-induced immunosuppression might set the right conditions for the induction of anti-tumor immune response by active immunotherapy. We review experimental basis and key concepts of combined chemo-immunotherapy and document its principles in the case report of patient with hormone refractory metastatic prostate cancer with sinister prognosis. More than four hundred prostate cancer patients have been treated with DC-based immunotherapy and tumor-specific immune responses have been reported in two-thirds of them. In half of these patients, DC immunotherapy resulted in transient clinical responses. Tregs, among other factors, potently inhibit tumor-specific T cells. Prostate cancer patients have elevated numbers of circulating and tumor infiltrating Tregs and there is evidence that Tregs increase tumor growth in vivo. Because of the high frequency of circulating Tregs in our patients, we first administered metronomic cyclophosphamide. After obtaining IRB approval, we started regular vaccinations with dendritic cells (DCs) loaded with killed prostate cancer cells. In accordance with the principles of combined immunotherapy, we continued palliative chemotherapy with docetaxel to reduce the tumor cell burden. DC-based vaccination induced prostate cancer cell-specific immune response. Combined chemo-immunotherapy consisting of alternate courses of chemotherapy and vaccination with mature DCs pulsed with LNCap prostate cancer cell line led to the marked improvement in the clinical and laboratory presentation and to the decrease of PSA levels by more than 90%.