A novel anti-CTLA-4 nanobody-IL12 fusion protein in combination with a dendritic cell/tumour fusion cell vaccine enhances the antitumour activity of CD8+ T cells in solid tumours.

Background: We previously developed a nanobody targeting CTLA-4 and demonstrated that it can boost antitumour T-cell responses in vitro; however, the resulting responses after the injection of T cells into cancer models are usually weak and transient. Here, we explored whether fusing our nanobody to IL-12 would enable it to induce stronger, longer-lasting T-cell immune responses after exposure to immature dendritic cell and tumour cell fusions.

Results: The fusion protein enhanced the response of CD8⁺ T cells to tumour antigens in vitro and led to stronger, more persistent immune responses after the T cells were injected into mice bearing different types of xenografts.

Conclusion: Our in vitro and in vivo results suggest the anticancer potential of our nanobody-interleukin fusion system and support the clinical application of this fusion approach for various nanobodies.