Successful adoptive transfer and in vivo expansion of haploidentical γδ T cells

Abstract

Background: The primary aim of this pilot study was to determine the feasibility and safety of an adoptive transfer and in vivo expansion of human haploidentical γδ T lymphocytes.

Methods: Patients with advanced haematological malignancies who are not eligible for allogeneic transplantation received peripheral blood mononuclear cells from half-matched family donors. For that, a single unstimulated leukapheresis product was incubated with both the anti-CD4 and anti-CD8 antibodies conjugated to paramagnetic particles. The depletion procedure was performed on a fully automated CliniMACS device according to the manufacturer's instructions. On average, patients received 2.17 × 10⁶/kg (range 0.9-3.48) γδ T cells with <1% CD4- or CD8-positive cells remaining in the product. All patients received prior lymphopenia-inducing chemotherapy (fludarabine 20-25 mg/m² day -6 until day -2 and cyclophosphamide 30-60 mg/kg day -6 and -5) and were treated with 4 mg zoledronate on day 0 and 1.0 x 10⁶ IU/m² IL-2 on day +1 until day +6 for the induction of γδ T cell proliferation in vivo.

Results: This resulted in a marked in vivo expansion of donor γδ T cells and, to a lower extent, natural killer cells and double-negative αβ T cells (mean 68-fold, eight-fold, and eight-fold, respectively). Proliferation peaked by around day +8 and donor cells persisted up to 28 days. Although refractory to all prior therapies, three out of four patients achieved a complete remission, which lasted for 8 months in a patient with plasma cell leukaemia. One patient died from an infection 6 weeks after treatment.

Conclusion: This pilot study shows that adoptive transfer and in vivo expansion of haploidentical γδ T lymphocytes is feasible and suggests a potential role of these cells in the treatment of haematological diseases.

Figures

Figure 1

Treatment protocol and cell engraftment. Number of donor natural killer (NK) cells (A), γδ T cells (B), and αβ T cells (C) per microlitre. The individual symbols represent patient samples obtained at the different time points. Peripheral blood lymphocytes were analysed using fluorochrome-labelled TCRαβ, TCRγδ, CD56, and donor-specific HLA antibodies by four-colour FACS analysis. (D) Fold increase is calculated as the ratio of the cell number per microlitre on day 8 to the initial value. (E) Treatment and adoptive transfer of donor innate lymphocytes in patient 3, who had a refractory plasma cell leukaemia. In vivo expansion of HLA-B8+ haploidentical γδ T cells within the HLA-B8- recipient was followed by FACS-based chimerism analysis. Right upper quadrant shows the percentage of donor γδ T cells over time.