Human γδ T Cell Subsets and Their Clinical Applications for Cancer Immunotherapy

Gamma delta (gamma delta) T cells are a minor population of T cells that share adaptive and innate immune properties. In contrast to MHC-restricted alpha beta (alpha beta) T cells, gamma delta T cells are activated in an MHC-independent manner, making them ideal candidates for developing allogeneic, off-the-shelf cell-based immunotherapies. As the field of cancer immunotherapy progresses rapidly, different subsets of gamma delta T cells have been explored. In addition, gamma delta T cells can be engineered using different gene editing technologies that augment their tumor recognition abilities and antitumor functions. In this review, we outline the unique features of different subsets of human gamma delta T cells and their antitumor properties. We also summarize the past and the ongoing pre-clinical studies and clinical trials utilizing gamma delta T cell-based cancer immunotherapy.