Therapy of relapsed leukemia after allogeneic hematopoietic cell transplantation with T cells specific for minor histocompatibility antigens.

The adoptive transfer of donor T cells that recognize recipient minor histocompatibility antigens (mHAgs) is a potential strategy for preventing or treating leukemic relapse after allogeneic hematopoietic cell transplantation (HCT). A total of 7 patients with recurrent leukemia after major histocompatibility complex (MHC)-matched allogeneic HCT were treated with infusions of donor-derived, ex vivo-expanded CD8(+) cytotoxic T lymphocyte (CTL) clones specific for tissue-restricted recipient mHAgs. The safety of T-cell therapy, in vivo persistence of transferred CTLs, and disease response were assessed. Molecular characterization of the mHAgs recognized by CTL clones administered to 3 patients was performed to provide insight into the antileukemic activity and safety of T-cell therapy. Pulmonary toxicity of CTL infusion was seen in 3 patients, was severe in 1 patient, and correlated with the level of expression of the mHAg-encoding genes in lung tissue. Adoptively transferred CTLs persisted in the blood up to 21 days after infusion, and 5 patients achieved complete but transient remissions after therapy. The results of these studies illustrate the potential to selectively enhance graft-versus-leukemia activity by the adoptive transfer of mHAg-specific T-cell clones and the challenges for the broad application of this approach in allogeneic HCT. This study has been registered at http://clinicaltrials.gov as NCT00107354.

DDX3Y encodes a class I MHC-restricted H-Y antigen that is expressed in leukemic stem cells.

The Y chromosome encodes male-specific minor histocompatibility (H-Y) antigens that stimulate T- and B-lymphocyte responses after sex-mismatched allogeneic hematopoietic cell transplantation (HCT). A CD8(+) cytotoxic T lymphocyte (CTL) clone that recognizes a novel HLA-B*2705-restricted H-Y antigen encoded by the DDX3Y gene was isolated from a male who had received a hematopoietic cell graft from his human leukocyte antigen (HLA)-identical sister. The antigenic peptide is a decamer that differs from the homologous DDX3X-encoded peptide at 4 positions. Expression of DDX3Y and of the H-Y epitope that it encodes was examined by quantitative polymerase chain reaction (PCR) and by CTL recognition assays. Expression of DDX3Y is detected in all myeloid and lymphoid leukemic cells that carry an intact Y chromosome. Moreover, the DDX3Y-encoded H-Y epitope is presented on the surface of both myeloid and lymphoid leukemic cells from male HLA-B*2705(+) patients. DDX3Y-specific CTLs prevent engraftment of human acute leukemia in nonobese diabetic/severe combined immune deficient mice, demonstrating that the DDX3Y-encoded H-Y antigen is also expressed in leukemic stem cells. These results demonstrate that CD8(+) T-cell responses against DDX3Y have the potential to contribute to graft-versus-leukemia (GVL) activity after female into male allogeneic HCT. This study is registered at http://clinicaltrials.gov as NCT00107354.