Allogeneic hematopoietic stem cell transplant for hematological malignancies from mismatched 9/10 human leukocyte antigen unrelated donors: comparison with transplants from 10/10 unrelated donors and human leukocyte antigen identical siblings

T-Cell Replete Myeloablative Haploidentical Bone Marrow Transplantation Is an Effective Option for Pediatric and Young Adult Patients With High-Risk Hematologic Malignancies

Twenty-one pediatric and young adult patients (1.1-24.7 years) with hematologic malignancies underwent myeloablative T-cell replete haploidentical bone marrow transplant (haplo-BMT) between October 2015 to December 2019. Fifty-seven percent of the patients were ethnic or racial minorities. Thirteen patients had B-cell precursor acute lymphoblastic leukemia (B-ALL) with 10 receiving 1,200 cGy fractionated total body irradiation with fludarabine while the remaining 11 patients had targeted dose-busulfan, fludarabine, melphalan conditioning. Graft-vs.-host disease (GvHD) prophylaxis consisted of post-transplant cyclophosphamide (15 patients) or cyclophosphamide and bendamustine (six patients), with all patients receiving tacrolimus and mycophenolate mofetil. Twelve patients were in first or second remission at time of transplant with five in >2nd remission and four with measurable disease. Three patients had failed prior transplants and three CAR-T cell therapies. Only one patient developed primary graft failure but engrafted promptly after a second conditioned T-replete peripheral blood stem cell transplant from the same donor. An absolute neutrophil count of 0.5 × 109/L was achieved at a median time of 16 days post-BMT while platelet engraftment occurred at a median of 30 days. The cumulative incidence of grades III to IV acute GvHD and chronic GvHD was 15.2 and 18.1%, respectively. With a median follow-up of 25.1 months the relapse rate is 17.6% with an overall survival of 84.0% and a progression-free survival of 74.3%. The chronic graft-vs.-host-free relapse-free survival (CRFS) is 58.5% while acute and chronic graft-vs.-host-free relapse-free survival (GRFS) is 50.1%. Myeloablative conditioned T-replete haploidentical BMT is a viable alternative to matched unrelated transplantation for children and young adults with high-risk hematologic malignancies.

Single Antigen-Mismatched Unrelated Hematopoietic Stem Cell Transplantation Using High-Dose Post-Transplantation Cyclophosphamide Is a Suitable Alternative for Patients Lacking HLA-Matched Donors

The optimal prophylaxis regimen for graft-versus-host disease (GVHD) in the setting of mismatched unrelated donor (MMUD) allogeneic hematopoietic stem cell transplantation (alloHSCT) is not defined. The use of high-dose post-transplant cyclophosphamide (PTCy) in haploidentical transplantation has proven feasible and effective in overcoming the negative impact of HLA disparity on survival. We hypothesized that PTCy could also be effective in the setting of MMUD transplantation. We retrospectively analyzed 86 consecutive adult recipients of alloHSCT in our institution, comparing 2 contemporaneous groups: PTCy MMUD (n = 26) versus matched unrelated donor (MUD) (n = 60). Graft source was primarily peripheral blood (92%). All PTCy MMUD were HLA 7/8 (differences in HLA class I loci in 92% of patients) and received PTCy plus tacrolimus ± mofetil mycophenolate as GVHD prophylaxis. No differences were observed between PTCy MMUD and MUD in the 100-day cumulative incidence of acute GVHD grades II to IV (31% versus 22%, respectively; P = .59) and III to IV (8% versus 10%, P = .67). There was a trend for a lower incidence of moderate to severe chronic GVHD at 1 year after PTCy MMUD in comparison with MUD (22% versus 41%, P = .098). No differences between PTCy MMUD and MUD were found regarding nonrelapse mortality (25% versus 18%, P = .52) or relapse rate (11% versus 19%, P = .18). Progression-free survival and overall survival at 2 years were similar in both cohorts (67% versus 54% [HR, .84; 95% CI, .38 to 1.88; P = .68] and 72% versus 57% [HR, .71; 95% CI, .31 to 1.67; P = .44], respectively). The 2-year cumulative incidence of survival free of moderate to severe chronic GVHD and relapse tended to be higher in the PTCy MMUD group (47% versus 24%; HR, .60; 95% CI, .31 to 1.14; P = .12). We conclude that HLA 7/8 MMUD transplantation using PTCy plus tacrolimus is a suitable alternative for those patients who lack a MUD.

Prospective study of nonmyeloablative, HLA-mismatched unrelated BMT with high-dose posttransplantation cyclophosphamide

Allogeneic blood or marrow transplantation (BMT) candidates may lack HLA-matched, related haploidentical, and unrelated umbilical cord options. Barriers to partially HLA-mismatched, unrelated donor (mMUD) BMT include excess graft-versus-host disease (GVHD), graft failure, and death. We prospectively studied nonmyeloablative (NMA) mMUD BMT with high-dose posttransplantation cyclophosphamide (PTCy) for patients with hematologic malignancies. Three transplants were performed with busulfan/fludarabine conditioning, with subsequent change to fludarabine/Cy/total body irradiation (flu/Cy/TBI). Twenty mMUD transplants are reported using flu/Cy/TBI, T-cell replete bone marrow grafts, and PTCy, mycophenolate mofetil, and sirolimus or tacrolimus (1 patient) for GVHD prophylaxis. The median patient age was 56. Ofthese unrelated grafts, 45% had ≥2 mismatched HLA loci, 25% had ≥3 mismatched loci, and 50% had HLA-C mismatches. No graft failure or grades 3-4 acute GVHD occurred. The median times to neutrophil recovery (≥500/μL) and platelet recovery (≥20 000/μL) were 19 days and 31 days, respectively. Full-donor chimerism was achieved in 95% of evaluable patients by day 60. The 180-day probability of grades 2-4 acute GVHD (all grade 2) was 25%, and the 1-year probability of any chronic GVHD was 16% (none severe). The 2-year nonrelapse mortality probability was 6%. With 4-year median follow-up, the 1-year progression-free and overall survival probabilities were 65% and 75%, respectively. NMA, T-cell replete mMUD BMT is thus a potentially viable option for patients without other suitable donors. This trial was registered at www.clinicaltrials.gov as #NCT01203722.

Matched and mismatched unrelated donor compared to autologous stem cell transplantation for acute myeloid leukemia in first complete remission: a retrospective, propensity score-weighted analysis from the ALWP of the EBMT

BACKGROUND

Optimal post-remission strategy for patients with acute myeloid leukemia (AML) is matter of intense debate. Recent reports have shown stronger anti-leukemic activity but similar survival for allogeneic stem cell transplantation (allo-HSCT) from matched sibling donor compared to autologous transplantation (auto-HSCT); however, there is scarcity of literature confronting auto-HSCT with allo-HSCT from unrelated donor (UD-HSCT), especially mismatched UD-HSCT.

METHODS

We retrospectively compared outcome of allogeneic transplantation from matched (10/10 UD-HSCT) or mismatched at a single HLA-locus unrelated donor (9/10 UD-HSCT) to autologous transplantation in patients with AML in first complete remission (CR1). A total of 2879 patients were included; 1202 patients received auto-HSCT, 1302 10/10 UD-HSCT, and 375 9/10 UD-HSCT. A propensity score-weighted analysis was conducted to control for disease risk imbalances between the groups.

RESULTS

Matched 10/10 UD-HSCT was associated with the best leukemia-free survival (10/10 UD-HSCT vs auto-HSCT: HR 0.7, p = 0.0016). Leukemia-free survival was not statistically different between auto-HSCT and 9/10 UD-HSCT (9/10 UD-HSCT vs auto-HSCT: HR 0.8, p = 0.2). Overall survival was similar across the groups (10/10 UD-HSCT vs auto-HSCT: HR 0.98, p = 0.84; 9/10 UD-HSCT vs auto-HSCT: HR 1.1, p = 0.49). Notably, in intermediate-risk patients, OS was significantly worse for 9/10 UD-HSCT (9/10 UD-HSCT vs auto-HSCT: HR 1.6, p = 0.049), while it did not differ between auto-HSCT and 10/10 UD-HSCT (HR 0.95, p = 0.88). In favorable risk patients, auto-HSCT resulted in 3-year LFS and OS rates of 59 and 78 %, respectively.

CONCLUSIONS

Our findings suggest that in AML patients in CR1 lacking an HLA-matched sibling donor, 10/10 UD-HSCT significantly improves LFS, but this advantage does not translate in better OS compared to auto-HSCT. In intermediate-risk patients lacking a fully HLA-matched donor, auto-HSCT should be considered as a valid option, as better survival appears to be provided by auto-HSCT compared to mismatched UD-HSCT. Finally, auto-HSCT provided an encouraging outcome in patients with favorable risk AML.

Stem cell transplantation in adults with acute myelogenous leukemia, normal cytogenetics, and the FLT3-ITD mutation

Following chemotherapy, patients with acute myelogenous leukemia (AML), normal cytogenetics, and the FLT3-ITD mutation have shorter survival compared to wild type (WT) patients. To determine the role of stem cell transplantation (SCT), we performed a retrospective review of adult patients with AML who underwent SCT at our center between January 1, 2007 and December 31, 2011. Of the 200 patients transplanted, 79 patients (40%) had normal cytogenetics; of these, 17 (22%) had the FLT3-ITD mutation, 35 were WT (44%), and 27 (34%) did not have FLT3 testing performed. Clinical characteristics were similar in each group. At four years, overall survival (OS) between FLT3 positive and WT groups was similar: 0.54 (95% CI 0.29-0.75) versus 0.73 (95% CI 0.53-0.99), p=0.18. Relapse rates were also similar, 0.09 (95% CI 0.02-0.21) versus 0.12 (95% CI: 0.02-0.32); p=0.67. We conclude that SCT can abrogate the poor prognosis in FLT3-ITD positive patients.