What is the rationale for using polyepitope vaccines in cancer immunotherapy?

• A. To broaden T cell responses across multiple tumor antigens, reducing escape probability
• B. To limit responses to a single antigen
• C. To avoid T cell activation
• D. To enhance innate immune evasion by tumors

Answer: (A)

The rationale for polyepitope vaccines is to broaden T cell responses across multiple tumor antigens. Cancers are often heterogeneous and can evolve by losing or mutating a single antigen, which lets tumor cells escape immune attack. By presenting a panel of epitopes from different antigens (and including both CD8 and CD4 epitopes), these vaccines recruit a wider pool of T cells that can recognize and kill a broader range of tumor cells. This makes it harder for the tumor to escape by altering one target and supports more durable immunity through helper and cytotoxic T cell interactions. In contrast, focusing on a single antigen or trying to avoid T cell activation would leave a vulnerable, narrow target and undermine immunotherapy’s purpose.