Manufacturing of highly functional and specific T cells for adoptive immunotherapy against virus from granulocyte colony-stimulating factor-mobilized donors

Abstract

Background aims: Cytomegalovirus (CMV) reactivation remains an important risk after hematopoietic stem cell transplantation, which can be effectively controlled through adoptive transfer of donor-derived CMV-specific T cells (CMV-T). CMV-T are usually obtained from donor peripheral blood mononuclear cells (PBMCs) collected before G-CSF mobilization. Despite previous studies that showed impaired T-cell function after granulocyte colony-stimulating factor (G-CSF) mobilization, recent publications suggest that G-CSF-primed PBMCs retain anti-viral function and are a suitable starting material for CMV-T manufacturing. The objective of this study was to assess the feasibility of generating CMV-T from G-CSF-mobilized donors by use of the activation marker CD137 in comparison with conventional non-primed PBMCs.

Methods: CMV-T were isolated from G-CSF-mobilized and non-mobilized donor PBMCs on the basis of CMVpp65 activation-induced CD137 expression and expanded during 3 weeks. Functional assays were performed to assess antigen-specific activation, cytokine release, cytotoxic activity and proliferation after anti-genic re-stimulation.

Results: We successfully manufactured highly specific, functional and cytotoxic CMV-T from G-CSF-mobilized donor PBMCs. Their anti-viral function was equivalent to non-mobilized CMV-T, and memory phenotype would suggest their long-term maintenance after adoptive transfer.

Conclusions: We confirm that the use of an aliquot from G-CSF-mobilized donor samples is suitable for the manufacturing of CMV cellular therapies and thereby abrogates the need for successive donations and ensures the availability for patients with unrelated donors.

Keywords: CD137; allogeneic hematopoietic stem cell transplantation; cytomegalovirus-specific T cells; granulocyte colony-stimulating factor; immunotherapy.