Single-cell RNA sequencing of human double-negative T cells reveals a favorable cellular signature for cancer therapy

Background: Allogeneic double-negative T-cell (DNT) therapy has emerged as a novel, off-the-shelf cellular treatment with clinical feasibility, safety, and promising efficacy against leukemia. However, the biology of DNTs is less well characterized, and how DNT therapy distinguishes from conventional γδ T-cell therapy remains unclear. Collectively, this hinders our ability to bolster DNT functionalities in cancer therapy. Here, we performed single-cell RNA sequencing with in vitro and in vivo functional analysis on DNTs. As a significant proportion of DNTs express Vγ9Vδ2 (Vδ2) TCR chain, we compared DNTs with donor-matched conventional Vδ2 T cells expanded with zoledronic acid.

Methods: Healthy donor-derived allogeneic DNTs and Vδ2 T cells were expanded ex vivo. Single-cell RNA sequencing analysis was performed on both cellular products to identify the transcriptional landscape and inferred cellular interactions within DNTs, followed by comparisons with donor-matched Vδ2 T cells. Unique cellular subsets found only in DNTs were depleted to identify their contributions to the overall efficacy of DNTs against acute myeloid leukemia. The anti-leukemic activity and in vivo persistence of DNTs and Vδ2 T-cells were explored using flow cytometry-based cytotoxicity assays, memory phenotyping, and xenograft models.

Results: Despite a shared Vδ2 expression between cellular products, we identified unique cellular compositions in DNTs that contribute to distinct transcriptional and cellular communication patterns relative to the donor-matched Vδ2 T cells, including higher expression of genes identified in chimeric antigen receptor T cells that persist in patients with durable cancer-remission. Vδ2– DNTs exhibited strong persistence characteristics, and their presence promoted the cytotoxic capabilities of Vδ2+ DNTs in repeated stimulation assays. This unique genetic signature and diverse cellular composition of DNTs resulted in better overall ex vivo expansion, prolonged persistence, and superior anti-leukemic activity compared with Vδ2 T cells in vitro and in vivo.

Conclusions: These results highlight the unique transcriptional, cellular, and functional profile of human DNTs and support the continued clinical investigation of allogeneic DNT therapy. The data also provide a reference gene signature that may help improve the efficacy of other types of allogeneic adoptive cellular therapies.