Tolerance induction between two different strains of parental mice prevents graft-versus-host disease in haploidentical hematopoietic stem cell transplantation to F1 mice

Haploidentical hematopoietic stem cell transplantation (Haplo-HSCT) has been employed worldwide in recent years and led to favorable outcome in a group of patients who do not have human leukocyte antigen (HLA)-matched donors. However, the high incidence of severe graft-versus-host disease (GVHD) is a major problem for Haplo-HSCT. In the current study, we performed a proof of concept mouse study to test whether induction of allogeneic tolerance between two different parental strains was able to attenuate GVHD in Haplo-HSCT to the F1 mice. We induced alloantigen tolerance in C3H mice (H-2k) using ultraviolet B (UVB) irradiated immature dendritic cells (iDCs) derived from the cultures of Balb/c bone marrow cells. Then, we performed Haplo-HSCT using tolerant C3H mice as donors to F1 mice (C3H×Balb/c). The results demonstrated that this approach markedly reduced GVHD-associated death and significantly prolonged the survival of recipient mice in contrast to the groups with donors (C3H mice) that received infusion of non-UVB-irradiated DCs. Further studies showed that there were enhanced Tregs in the tolerant mice and alloantigen-specific T cell response was skewed to more IL-10-producing T cells, suggesting that these regulatory T cells might have contributed to the attenuation of GVHD. This study suggests that it is a feasible approach to preventing GVHD in Haplo-HSCT in children by pre-induction of alloantigen tolerance between the two parents. This concept may also lead to more opportunities in cell-based immunotherapy for GVHD post Haplo-HSCT.

Peripheral blood hematopoietic stem cells for transplantation of hematological diseases from related, haploidentical donors after reduced-intensity conditioning

In a multicenter collaboration, we carried out T cell-replete, peripheral blood stem cell (PBSC) transplantations from related, HLA-haploidentical donors with reduced-intensity conditioning (RIC) and post-transplantation cyclophosphamide (Cy) as graft-versus-host disease (GVHD) prophylaxis in 55 patients with high-risk hematologic disorders. Patients received 2 doses of Cy 50 mg/kg i.v. on days 3 and 4 after infusion of PBSC (mean, 6.4 × 10(6)/kg CD34(+) cells; mean, 2.0 × 10(8)/kg CD3(+) cells). The median times to neutrophil (500/μL) and platelet (>20,000/μL) recovery were 17 and 21 days respectively. All but 2 of the patients achieved full engraftment. The 1-year cumulative incidences of grade II and grade III acute GVHD were 53% and 8%, respectively. There were no cases of grade IV GVHD. The 2-year cumulative incidence of chronic GHVD was 18%. With a median follow-up of 509 days, overall survival and event-free survival at 2 years were 48% and 51%, respectively. The 2-year cumulative incidences of nonrelapse mortality and relapse were 23% and 28%, respectively. Our results suggest that PBSC can be substituted safely and effectively for bone marrow as the graft source for haploidentical transplantation after RIC.

HLA-haploidentical donor lymphocyte infusions for patients with relapsed hematologic malignancies after related HLA-haploidentical bone marrow transplantation

Treatment of relapse after related HLA-haploidentical T cell-replete bone marrow transplantation (haploBMT) with post-transplantation cyclophosphamide (PTCy) using haploidentical donor lymphocyte infusion (haploDLI) is not documented. All patients who received haploDLI after haploBMT with PTCy between June 2003 and October 2012 were identified and assessed for graft-versus-host disease (GVHD) and outcomes. Forty patients received 52 haploDLI doses. Sixteen patients had acute myeloid leukemia, 11 had lymphomas, and 34 had nonmyeloablative conditioning before haploBMT. The median time from haploBMT to relapse was 183 (range, 0 to 1399) days. The median age at haploDLI was 48 (range, 3 to 70) years. The first haploDLI doses were 1 × 10(5) CD3(+) cells/kg with subsequent escalation. The most commonly used first haploDLI dose was 1 × 10(6) CD3(+) cells/kg. The median follow-up after haploDLI was 7 (mean, 15.4; range, .5 to 96) months for the entire cohort, and 17.5 (mean, 28; range, 2.4 to 96) months for the responders. Acute GVHD developed in 10 patients (25%), 6 patients had grade 3 to 4, and 3 developed chronic GVHD. Twelve (30%) patients achieved a complete response (CR) with a median duration of 11.8 (mean, 22.5; range, .4 to 94) months. At last follow-up, 8 responders were alive in CR; 6 for over a year. HaploDLI for relapse after haploBMT is associated with acceptable toxicities and can result in durable responses.

Reduced-intensity allogeneic transplantation using alemtuzumab from HLA-matched related, unrelated, or haploidentical related donors for patients with hematologic malignancies

We present a comparative study on 124 patients with hematologic malignancies who had undergone reduced-intensity conditioning and then received a transplant from an HLA-matched related (MRD), an HLA-matched unrelated (MUD), or an HLA-haploidentical related (HAPLO) donor. The conditioning regimen, which consisted of fludarabine, melphalan or busulfan, and alemtuzumab was administered to patients with lymphoid (n = 62) or myeloid disease (n = 62). Mycophenolate mofetil was used as prophylaxis for graft-versus-host disease (GVHD), and 38, 58, and 33 patients received transplants from MRD, MUD, and HAPLO donors, respectively. Only 2 patients experienced primary graft failure (GF) after melphalan-based regimen, whereas 8 of the 17 patients who received a transplant from HAPLO donors experienced a primary GF after busulfan-based regimen. The cumulative incidence of grade III to IV acute GVHD in engrafted patients who had received transplants from MRD, MUD, or HAPLO donors was 3%, 11%, and 27%, respectively, and the 2-year overall survival (OS) rates were 51%, 22%, and 23%, respectively. According to multivariate analysis, transplantation from either MUD or HAPLO donors compared with MRD were adverse factors that affected the OS (P = .006 and P = .002, respectively). In conclusion, the reduced-intensity regimen that included fludarabine, busulfan, or melphalan and alemtuzumab using only mycophenolate mofetil as the GVHD prophylaxis conferred favorable outcomes in the MRD group but lower survival rates in the MUD and HAPLO groups. The busulfan-based regimen led to a high incidence of GF in the HAPLO group, suggesting the need for modification or intensification of immunosuppression.

Innovative platforms for haploidentical stem cell transplantation: the role of unmanipulated donor graft

We exploited the dual positive effects of rapamycin to prevent GvHD and control malignant cells upon infusion of unmanipulated grafts from family haploidentical donors to patients affected by advanced hematological malignancies. Preliminary results on 45 patients show the feasibility of this platform with an appreciable low rate of GvHD.