Diffuse intrinsic pontine glioma (DIPG) is a pediatric brainstem tumor with a very poor prognosis, characterized by immunosuppressive tumor microenvironment (TME) that limits immune infiltration, including a significant reduction in circulating natural killer (NK) cells. This drop in NK cell levels and activity may promote tumor growth and immune evasion, making NK cells a promising target for immunotherapy. NK cells can attack and eliminate DIPG tumor cells, including glioma stem cells, while counteracting certain immune evasion strategies. Although the DIPG microenvironment and blood-brain barrier present challenges, NK cell-based therapies have shown encouraging tumor control and survival benefits in animal models with promising safety results. Current clinical trials for DIPG mostly focus on chimeric antigen receptor (CAR)-T cells targeting disialoganglioside (GD2) and cluster of differentiation 276 (CD276 or B7-H3) antigens with early signs of success, while NK cell therapies, such as CAR-NK cells, are still in preclinical or early stages, requiring further development. The tumor’s immunosuppressive nature poses challenges that may need combination strategies or immune priming. Despite these obstacles, NK cell-based immunotherapy is an exciting and growing field. Upcoming clinical trials emphasize the potential for NK cell therapies to play a critical role in treating this aggressive pediatric brain cancer.

Gamma delta (γδ) T cells and invariant natural killer T (iNKT) cells are unconventional T cells with limited T cell receptor (TCR) diversity. Both can recognize lipid or non-peptide antigens, often through cluster of differentiation 1d (CD1d), rapidly produce cytokines, express natural killer (NK) cell markers, and are mainly found in mucosal and barrier tissues. Acting as a bridge between innate and adaptive immunity, they show great promise for cancer immunotherapy. Developing γδ T and iNKT cells for treatment involves shared features like thymic origin, MHC-independent recognition, rapid cytotoxicity, low graft-vs.-host disease (GvHD) risk, ex vivo expansion, and genetic modification, making them suitable for adoptive cell therapies. While their mechanisms are similar, iNKT cells rely on CD1d-mediated antigen presentation, provided by CD1d-expressing antigen-presenting cells (APCs) or engineered cell lines, to activate their invariant TCR and expand effectively. Chimeric antigen receptors (CAR)-induced functional activations make these cell types viable alternatives to conventional cell-based or CAR-T therapies with additional safety benefits. Early clinical trials have shown encouraging results, and their completion will confirm their potential for future treatments. This review explores the biology and mechanisms of γδ T and iNKT cells, focusing on how APCs, cytokines, feeder cells, and CARs contribute to boosting their cytotoxic function, cytokine production, and expansion, enhancing their promise as cancer immunotherapies. It also explores the advancements and challenges in developing γδ T and iNKT cell-based immunotherapies, with preclinical and early clinical outcomes offering promising insights.