Clinical effect of reduced-intensity conditioning regimen containing antithymocyte globulin for hematopoietic cell transplantation from unrelated-donors

Reduced-Intensity Conditioning with Busulfan, Fludarabine, and Antithymocyte Globulin for Hematopoietic Cell Transplantation from Unrelated or Haploidentical Family Donors in Patients with Acute Myeloid Leukemia in Remission

To investigate the role of antithymocyte globulin (ATG)-containing reduced-intensity conditioning (RIC) in hematopoietic cell transplantation (HCT) from unrelated (UD) or haploidentical family donors (HFD), we conducted a phase 2 trial of 237 patients (age range, 16 to 69 years) with acute myeloid leukemia (AML) in remission. Patients undergoing UD-HCT (n = 93) or HFD-HCT (n = 59) received RIC comprising busulfan, fludarabine, and ATG, 9 mg/kg, whereas those undergoing HCT from matched sibling donors (MSD, n = 85) received myeloablative busulfan and cyclophosphamide conditioning or aforementioned RIC with ATG, 4.5 mg/kg. For graft-versus-host disease (GVHD) prophylaxis, cyclosporine and methotrexate were administered. The median follow-up period was 44.7 months after HCT for 161 survivors. For UD-HCT versus HFD-HCT, there were no significant differences in leukemia recurrence, nonrelapse mortality, relapse-free survival, grades 2 to 4 acute GVHD, and moderate-to-severe chronic GVHD. Furthermore, when the outcomes of UD-HCT and HFD-HCT were combined and compared with those of MSD-HCT, there were no significant differences in leukemia recurrence (3-year cumulative incidence, 30% versus 29%), nonrelapse mortality (3-year cumulative incidence, 7% versus 8%), relapse-free survival (3-year estimate, 63% versus 63%), and grades 2 to 4 acute GVHD (120-day cumulative incidence, 16% versus 13%). Moderate-to-severe chronic GVHD, however, occurred less frequently in UD/HFD-HCT (2-year cumulative incidence, 22% versus 40%; P = .006). The addition of ATG to conditioning regimen was a significant predictor for less chronic GVHD (subdistribution hazard ratio, .59). In AML in remission, UD/HFD-HCT after ATG-containing RIC achieved leukemia control equivalent to that of MSD-HCT. Despite HLA disparity in UD/HFD-HCT, chronic GVHD occurred less frequently after ATG-containing RIC, suggesting a strong GVHD-modulating effect of ATG.

Donor-Derived Natural Killer Cell Infusion after Human Leukocyte Antigen-Haploidentical Hematopoietic Cell Transplantation in Patients with Refractory Acute Leukemia

The optimum method of donor natural killer cell infusion (DNKI) after allogeneic hematopoietic cell transplantation (HCT) remains unclear. Fifty-one patients (age range, 19 years to 67 years) with refractory acute leukemia underwent HLA-haploidentical HCT and underwent DNKI on days 6, 9, 13, and 20 of HCT. Median DNKI doses were .5, .5, 1.0, and 2.0 × 10⁸/kg cells, respectively. During DNKI, 33 of the 45 evaluated patients (73%) developed fever (>38.3°C) along with weight gain (median, 13%; range, 2% to 31%) and/or hyperbilirubinemia (median, 6.2 mg/dL; range, 1.0 mg/dL to 35.1 mg/dL); the toxicity was reversible in 90% of patients. After transplantation, we observed cumulative incidences of neutrophil engraftment (≥500/µL), grade 2 to 4 acute graft-versus-host disease (GVHD), chronic GVHD, and nonrelapse mortality of 84%, 28%, 30%, and 16%, respectively. The leukemia complete remission rate was 57% at 1 month after HCT and 3-year cumulative incidence of leukemia progression was 75%. When analyzed together with our historical cohort of 40 patients with refractory acute leukemia who underwent haploidentical HCT and DNKI on days 14 and 21 only, higher expression of NKp30 (>90%) on donor NK cells was an independent predictor of higher complete remission (hazard ratio, 5.59) and less leukemia progression (hazard ratio, .57). Additional DNKI on days 6 and 9 was not associated with less leukemia progression (75% versus 55%).

Comparable Allogeneic Hematopoietic Cell Transplantation Outcome of a Haplo-Identical Family Donor with an Alternative Donor in Adult Aplastic Anemia

We performed a study on allogeneic hematopoietic cell transplantation (alloHCT) from an HLA-haplo-identical familial donor (haploFD) using a busulfan-fludarabine-antithymocyte globulin conditioning regimen for severe aplastic anemia (sAA) and hypoplastic myelodysplastic syndrome. For the comparison between a haploFD and an alternative donor (AD; matched unrelated or partially matched donor) for sAA in adults, we collected haploFD data retrospectively and prospectively. Forty-eight AD cases were selected for the comparison with 16 haploFD cases. All transplantation outcomes except for extensive chronic graft versus host disease (GvHD) were similar. The frequencies of hepatic sinusoidal obstruction syndrome (p = 1.000), acute GvHD (p = 0.769), grade 3/4 acute GvHD (p = 0.258), chronic GvHD (p = 0.173), extensive chronic GvHD (p = 0.099), primary neutrophil engraftment failure (p = 1.000), secondary graft failure (p = 1.000) and platelet engraftment failure (p = 0.505) were similar. Time to neutrophil engraftment was faster in haploFD (p = 0.003), while the cumulative incidence of platelet engraftment was similar (p = 0.505). Overall survival was also similar between AD and haploFD (p = 0.730). In conclusion, alloHCT from haploFD in sAA was comparable with alloHCT from AD, but extensive chronic GvHD seemed frequent in haploFD. Therefore alloHCT from haploFD could be an alternative approach for alloHCT from AD in adult sAA.

Feasible outcomes of T cell-replete haploidentical stem cell transplantation with reduced-intensity conditioning in patients with myelodysplastic syndrome

Even with the recent optimization of haploidentical stem cell transplantation (SCT), its role for patients with myelodysplastic syndrome (MDS) or acute myeloid leukemia evolving from MDS (sAML) should be validated. We analyzed the outcomes of consecutive 60 patients with MDS or sAML who received T cell-replete haploidentical SCT after reduced-intensity conditioning with fludarabine, busulfan, and rabbit antithymocyte globuline ± 800 cGy total body irradiation. Patients achieved a rapid neutrophil engraftment after a median of 12 days (range, 8 to 23) and an early immune reconstitution without high incidences of acute graft-versus-host disease (GVHD) II to IV and chronic GVHD (36.7% and 48.3%, respectively). After a median follow-up of 4 years, incidence of relapse and nonrelapse mortality and rate of overall survival and disease-free survival was 34.8%, 23.3%, 46.8%, and 41.9%, respectively. In multivariate analysis, the disease status at peak was a significant predictor for relapse (lower-risk MDS versus higher-risk MDS or sAML; hazard ratio [HR], 5.69; 95% confidence interval [CI], 1.45 to 22.29; P = .013) and disease-free survival (HR, 4.44; 95% CI, 1.14 to 17.34; P = .032). Chronic GVHD was an additional significant predictor for relapse (no versus yes; HR, 2.87; 95% CI, 1.03 to 7.51; P = .043). Our T cell-replete haploidentical SCT may be a feasible option for patients with MDS and sAML without conventional donors.

GVHD prophylaxis with sirolimus-tacrolimus may overcome the deleterious effect on survival of HLA mismatch after reduced-intensity conditioning allo-SCT

Large studies, mostly based on series of patients receiving CSA/tacrolimus (TKR) plus MTX as immunoprophylaxis, have demonstrated a deleterious effect on survival of the presence of a single mismatch out of eight loci after allogeneic hematopoietic SCT (alloHSCT). We retrospectively analyzed a series of 159 adult patients who received sirolimus(SRL)/TKR prophylaxis after alloHSCT. We compared overall outcomes according to HLA compatibility in A, B, C and DRB1 loci at the allele level: 7/8 (n=20) vs 8/8 (n=139). Donor type was unrelated in 95% vs 70% among 7/8 vs 8/8 pairs, respectively (P=0.01). No significant differences were observed in 3-year OS (68 vs 62%), 3-year EFS (53 vs 49%) and 1-year non-relapse mortality (9 vs 13%). Cumulative incidence of grades II-IV acute GVHD (aGVHD) was significantly higher in 7/8 alloHSCT (68% vs 42%, P<0.001) but no significant differences were found for III-IV aGVHD (4.5% vs 11%), overall (35% vs 53%) and extensive (20% vs 35%) chronic GHVD in 7/8 vs 8/8 subgroups, respectively. In summary, the present study indicates favorable outcomes after alloHSCT using the combination of SRL/TKR combination as GVHD prophylaxis with OS in the range of 55-70%, and non-significant differences in overall outcomes, irrespective of the presence of any mismatches at obligatory loci.

Indications and outcomes of reduced-toxicity hematopoietic stem cell transplantation in adult patients with hematological malignancies

Hematopoietic stem cell transplantation (HCT) utilizing non-myeloablative (NMA) and reduced-intensity conditioning (RIC) regimens (collectively referred to as reduced-toxicity HCT, RT-HCT) has become a viable therapeutic option for patients with hematological malignancies who are ineligible for standard myeloablative conditioning transplantation (MA-HCT). RT-HCT has been shown to induce stable engraftment with low toxicity, and to produce similar overall and progression-free survival (PFS) when compared to MA-HCT in acute myeloid leukemia and myelodysplastic syndrome. The best results for RT-HCT have been reported for patients with disease that is in remission, indolent and chemosensitive, and with a strong graft-versus-malignancy effect. Chronic graft-versus-host disease seems to correlate with a lower relapse rate and better PFS. RT-HCT is inferior when performed in poor risk or advanced disease, due to high relapse rates. A search for novel strategies that includes the most appropriate conditioning regimens and post-transplant immunomodulation protocols with more intensive anti-malignancy activity but limited toxicity is in progress. This review provides an update on the results of clinical studies of RT-HCT, and discusses possible indications and investigative strategies for improving the clinical outcomes of RT-HCT for the major hematological malignancies.

Does antithymocyte globulin have a place in reduced-intensity conditioning for allogeneic hematopoietic stem cell transplantation?

A 63-year-old male patient without siblings is treated for acute myeloid leukemia with poor prognostic cytogenetics. Despite achieving a first complete remission, he relapsed within the first year of diagnosis. He then achieved a second complete remission. A search for an HLA-identical unrelated donor identified a 10/10 possible match. The patient has several comorbidities (hematopoietic stem cell comorbidity index = 3) and it is recommended that he undergo a reduced-intensity conditioning regimen for allogeneic peripheral blood stem cell transplantation. The patient is well-read on allogeneic stem cell transplantation and asks you the merits of antithymocyte globulin that you propose to include in the conditioning regimen.

Clinical implications of non-A-type NPM1 and FLT3 mutations in patients with normal karyotype acute myeloid leukemia

Mutations in the nucleophosmin (NPM1) and fms-like tyrosine kinase-3 (FLT3) genes are the most commonly observed mutations in patients with normal-karyotype acute myeloid leukemia (AML-NK). We analyzed the prognostic effects and interactions of these mutations in 201 AML-NK patients. NPM1 and FLT3 mutations were found in 38.3 and 24.9% of AML-NK patients, respectively. NPM1 mutations (NPM1mut), especially in patients without FLT3 mutations (FLT3mut), were associated with a favorable outcome. However, NPM1mut did not affect survival. FLT3mut tended to be associated with a poor survival outcome. FLT3mut showed no prognostic effects in patients with A-type NPM1mut. However, FLT3mut were associated with a significantly worse prognosis in patients with non-A-type NPM1mut. The prognostic interaction between the NPM1 and FLT3 mutations was significant in patients with non-A-type NPM1mut.

Reduced-intensity conditioning therapy with busulfan, fludarabine, and antithymocyte globulin for HLA-haploidentical hematopoietic cell transplantation in acute leukemia and myelodysplastic syndrome

Any role for reduced-intensity conditioning (RIC) before hematopoietic cell transplantation (HCT) from a human leukocyte antigen (HLA)-haploidentical donor remains to be defined. We therefore assessed 83 patients (age, 16-70 years): 68 with acute leukemia (including 34 in remission and 34 with refractory disease) and 15 patients with myelodysplastic syndrome, in HCT trials using RIC with busulfan, fludarabine, and antithymocyte globulin. The HLA-haploidentical donors, offspring (n = 38), mothers (n = 24), or siblings (n = 21) of patients, underwent leukapheresis after receiving granulocyte colony-stimulating factor, and donated cells were transplanted without further manipulation. Cyclosporine and methotrexate were given for GVHD prophylaxis. The cumulative incidences of neutrophil engraftment, grade 2 to 4 acute GVHD, chronic GVHD, and transplantation-related mortality after HCT, were 92%, 20%, 34%, and 18%, respectively. After a median follow-up time of 26.6 months (range, 16.8-78.8 months), the event-free and overall survival rates were 56% and 45%, respectively, for patients with acute leukemia in remission; 9% and 9%, respectively, for patients with refractory acute leukemia; and 53% and 53%, respectively, for patients with myelodysplastic syndrome. HCT from an HLA-haploidentical family member resulted in favorable outcomes when RIC containing antithymocyte globulin was performed. This study is registered at www.clinicaltrials.gov as #NCT00521430 and #NCT00732316.