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An accumulating body of evidence suggests that xenogeneic vaccines can be very effective in breaking the immune tolerance to human tumor-associated antigens (TAAs). We assessed adverse effects, as well as clinical and immune responses induced by a lyophilized xenogeneic polyantigenic vaccine (XPV) prepared from murine melanoma B16 and carcinoma LLC cells in 60 stage IV colorectal cancer patients. Neither grade III/IV toxicities, nor laboratory and clinical signs of systemic severe autoimmune disorders were documented in any XPV-treated patient. Clinical effects of various grades (complete response, partial response and disease stabilization) with duration of no shorter than 6 months was observed in 25 (41.67%) vaccinated patients. The average survival time of the XPV-treated patients was markedly longer than that of the clinically matched control patients (20 vs. 7 months). The overall 3-year survival rate in the XPV-treated and control group was 16.7% (10 patients) and 0%, respectively. Following a course of ten XPV vaccinations, peripheral blood mononuclear cell (PBMC) proliferation assays revealed increased T-cell immune responses to human Caco-2 colon adenocarcinoma-associated antigens. In addition, relative contents of CD25+ FoxP3+regulatory T-cells in patients with proven immunotherapy-mediated clinical effects (responders) were significantly decreased in the blood, which was paralleled by marked increases in serum levels of proinflammatory cytokines, such as interferon-alpha (IFN-α), IFN-ɣ, and interleukin-8 (IL-8). Serum levels of tumor necrosis factor-alpha (TNF-α), IL-1, IL-4, and IL-6 were not affected in both responder and non-responder patients. In conclusion, this study provides evidence for the safety, clinical feasibility and immunogenicity of xenogeneic composite cell vaccine administration in colorectal cancer patients. This is the first demonstration that clinical effects of such a vaccine are associated with vaccine-induced, proinflammatory immune responses., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

New therapies for melanoma have yielded promising results, but their application is limited because of serious side-effects and only moderate impact on patient survival. Vaccine therapies may offer some hope by targeting tumor-specific responses, considering the immunogenic nature of melanomas. To investigate the safety profile and efficiency of a xenogeneic cell-based vaccine therapy in stage III melanoma patients and evaluate the survival rate in treated patients. Twenty-seven stage III melanoma patients were immunized with a lyophilized xenogeneic polyantigenic vaccine (XPV) prepared from murine melanoma B16 and carcinoma LLC cells. Neither grade III/IV toxicities, nor clinically significant changes in blood and biochemical parameters were noted after an induction course of 10 XPV subcutaneous immunizations. No laboratory or clinical signs of systemic autoimmunity were documented. Following 10 vaccinations, a relative increase in the numbers of circulating memory CD4+CD45RO+ T cells (but not CD8+ CD45RO+ T cells) was observed. Peripheral blood mononuclear cells obtained from XPV-treated patients demonstrated increased proliferative responses to human BRO melanoma-associated antigens and marked increases in serum levels of IFN-γ and IL-8. Serum levels of TNF-α, IL-4 and IL-6 were not affected. The overall five-year survival rate in the treated patients was significantly higher than that in 27 control patients with matched clinical and prognostic characteristics (55% vs 18%). XPV-based immunotherapy could be maximally effective when started as early as possible before or after surgical excision of the primary tumor and local metastases, i.e. when tumor-mediated suppressive effects on immunity are minimal.