Lenalidomide augments the antitumor activities of Eps8 peptide-specific cytotoxic T lymphocytes against multiple myeloma

Cancer immunotherapy is a promising new approach to cancer treatment. It has been demonstrated that a high number of tumor-specific cytotoxic T cells (CTLs) is associated with increased survival in multiple myeloma (MM) patients. Here, we focused on Epidermal growth factor receptor pathway substrate 8 (Eps8) as a candidate tumor-associated antigen (TAA) in MM. Previous work has shown that Eps8-based immunotherapy in HLA-A2+ cancer patients may result in efficient antitumor immune responses against diverse tumor types. To improve immunotherapy for patients with MM, we constructed a cocktail vaccine by combining several HLA-A2-restricted epitopes derived from Eps8 (Eps8cocktail), including Eps8101-2L (WLQDMILQV), Eps8276-1Y9V (YLDDIEFFV) and Eps8455-1Y (YLAESVANV). The CTLs induced by Eps8cocktail (Eps8cocktail-CTLs) showed highly effective anti-MM activity, including Th1 cytokines production, cell proliferation, and cytotoxicity against HLA-A2+ MM cells. This study highlights the importance of using a cocktail vaccine instead of a single-peptide vaccine to induce a robust response. Importantly, we revealed that lenalidomide effectively stimulated the antitumor activity of the Eps8cocktail-CTLs, with increasing expression trends for T cell markers (CD28, CD40L, 41BB, and OX40). Compared with unstimulated CTLs and Eps8cocktail-CTLs, lenalidomide-treated Eps8cocktail-CTLs showed superior anti-MM activity in humanized MM models, including delaying tumor burden increases due to enhanced immune function. These results provide the framework for an Eps8 cocktail vaccination therapy to induce effective Eps8-specific CTLs in HLA-A2+ patients with MM. Moreover, these studies further demonstrate that lenalidomide augments the immune response, providing a possibility for its use in combination with peptide vaccines to improve patient outcomes.