Study of Adoptive Immunotherapy With Donor-derived CMV-specific T Cells for Recipients of Allo-HSCT (CMV_TCR-001)

Reactivation of the latent human herpes virus, Cytomegalovirus (CMV), post allogeneic haematopoietic stem cell transplantation (Allo-HSCT) can result in significant morbidity and mortality unless treated promptly. Anti-viral therapy is usually effective, but has serious side effects typically requiring prolonged inpatient admission, such as myelosuppression (Ganciclovir) or nephrotoxicity (Foscarnet). Cellular immunotherapy for CMV has been tested in Phase I/II trials in the UK and Europe. In these trials CMV-specific T cells were isolated from the peripheral blood of CMV seropositive donors and re-infused into recipients following CMV reactivation resulting in sustained anti-viral responses. It is clear that post-transplant recovery of CD8+ CMV-specific cytotoxic T-cells (CTL) abrogates the development of CMV-related disease. An advantage of cellular therapy for CMV reactivation is the transfer of immunological memory, which can reduce the number of subsequent reactivations. This is important, as rapidly increasing numbers of highly immunosuppressive (or T cell depleted) reduced intensity conditioning Allo-HSCTs are being performed in the UK. These approaches reduce the toxicity of transplantation in older patients with more co-morbidities. Reduced intensity allogeneic transplants are currently part of the UK MRC AML15 trial and are to be recommended in the proposed MRC/ECOG UKALL14 study and again in UK MRC AML17. In addition, a number of NCRN approved UK multicentre extended Phase II studies have recently started using reduced intensity Allo-HSCT in various lymphoma subtypes.

Transplant recipients with CMV seronegative donors cannot benefit from currently available cellular immunotherapy approaches due to the lack of CMV-specific memory T cells in these donors. At present, there is no reliable strategy to isolate virus specific T cells from uninfected naïve individuals, as the precursor frequency is low or absent and the in vitro priming of T-cell responses is inefficient. T-cell receptor (TCR) gene transfer offers a strategy to produce antigen-specific T cells independent of precursor frequency and without the need for T-cell priming. As approximately 50% of adult individuals have been previously infected with CMV, there are significant numbers of CMV 'mismatched' Allo-HSCT performed, where the donor is CMV seronegative and the recipient CMV seropositive. The proposed study will test the feasibility of generating donor-derived CMV-specific T cells via the ex vivo introduction of a CMV-specific T cell receptor using a GMP grade retroviral vector.