CD4 T cell effector subsets not only profoundly affect cancer progression, but recent evidence also underscores their critical contribution to the anticancer efficacy of immune checkpoint inhibitors. In 2012, the two seminal studies suggested the superior antimelanoma activity of T_H9 cells over other T cell subsets upon adoptive T cell transfer. While these findings provided great impetus to investigate further the unique functions of T_H9 cells and explore their relevance in cancer immunotherapy, the following questions still remain outstanding: are T_H9 cell anticancer functions restricted to melanoma? What are the factors favouring T_H9 cell effector functions? What is the contribution of T_H9 cells to cancer immunotherapy treatments? Can T_H9 cells be identified in humans and, if so, what is their clinical relevance? By reviewing the studies addressing these questions, we will discuss how T_H9 cells could be therapeutically harnessed for cancer immunotherapy strategies.

CD4 T 细胞效应子亚群不仅深刻影响癌症进展，而且最近的证据也强调了它们对免疫检查点抑制剂抗癌功效的关键贡献。2012 年，两项开创性研究表明，在过继性 T 细胞转移后，TH 9 细胞的抗黑色素瘤活性_优于其他 T 细胞亚群。虽然这些发现极大地推动了进一步研究 T _H 9 细胞的独特功能并探索它们在癌症免疫治疗中的相关性，但以下问题仍然悬而未决： T _H 9 细胞的抗癌功能是否仅限于黑色素瘤？有哪些因素有利于 T _H 9 细胞效应功能？_{T H}的贡献是什么9 细胞对癌症免疫疗法的治疗？T _H 9 细胞能否在人类中被鉴定出来，如果可以，它们的临床意义是什么？通过回顾解决这些问题的研究，我们将讨论如何将 T _H 9 细胞用于癌症免疫治疗策略。