Does Lymphocyte Count Impact Dosing of Anti-Thymocyte Globulin in Unrelated Donor Stem Cell Transplantation?

Anti­thymocyte globulin (ATG) is used to reduce the incidence and severity of graft-versus-host disease (GVHD) with hematopoietic cell transplantation, yet optimum dosing has yet to be determined. We have previously demonstrated that 2.5 mg/kg ATG in conditioning can reduce the incidence of GVHD in unrelated donor transplants. Recent literature has suggested that ATG dosing based on absolute lymphocyte count (ALC) could lead to more optimum exposure of the drug. We sought to determine if ALC at the time of transplant could impact clinical outcomes. We conducted a retrospective single-center study analyzing all consecutive patients at The Ottawa Hospital who received a matched unrelated donor stem cell transplant with ATG between 2009 and 2014. Patients received rabbit ATG (thymoglobulin) at 0.5 mg/kg on day –2 and 2.0 mg/kg on day –1. Univariate and multivariate analyses were used to determine if any patient- or transplant-related factors, including weight, ALC, and total ATG dose given, impacted GVHD, relapse, or mortality. In total, 111 patients met inclusion, with a median age of 50 years (range, 19 to 70). The most common diagnoses were acute myelogenous leukemia (43%), Myelodysplasia/myeloproliferative neoplasms (13%), and lymphoma (12%). The median weight at time of conditioning was 80.3 kg (range, 45 to 216). The median ALC on the first day of ATG administration was 0.1 × 10⁹/L (range, 0 to 190). The median total dose of ATG received was 201 mg (range, 112 to 540 mg). The incidence of acute and chronic GVHD was 35.1% and 21.6%, respectively. In the multivariate model, the actual dose of ATG given to patients was not associated with GVHD (hazard ratio [HR], 1.11; 95% confidence interval [CI], 0.99 to 1.25; P = .07), relapse (HR, 1.13; 95% CI, 0.98 to 1.30; P = .1), or mortality (HR, 1.09; 95% CI, 0.92 to 1.28; P = .32). Similarly, the pretransplant ALC was not associated with GVHD (HR, 1; P = .82), relapse (HR, 1; P = .90), or mortality (HR, 1; P = .39). If patients had received ALC-based dosing according to previously published work (Admiraal et al., Lancet Haematol 2017), the mean total dose of ATG received would have been 1205 mg, more than 5 times the mean dose that was actually given based on weight. With GVHD outcomes being similar to that published by Admiraal et al. and ALC not independently associated with outcomes in our study, further studies are still needed to compare standard weight-based dosing to ALC-based dosing of ATG in matched unrelated donor stem cell transplant.     

Effect of Antithymocyte Globulin Source on Outcomes of HLA-Matched Sibling Allogeneic Hematopoietic Stem Cell Transplantation for Patients with Severe Aplastic Anemia

We wanted to evaluate efficacy of porcine antithymocyte globulin (ATG) in HLA-matched sibling donor allogeneic hematopoietic stem cell transplantation (MSD-HSCT) for patients with severe aplastic anemia (SAA). The clinical data of 113 SAA patients who received MSD-HSCT from January 2005 to November 2016 were analyzed retrospectively. Of these, 58 patients received rabbit ATG as a part of conditioning regimen (R-ATG group), whereas the other 55 patients received porcine ATG (P-ATG group). Patient baseline characteristics and donor conditions of the 2 groups were similar, except patients were older and more received peripheral blood stem cell transplantation in the P-ATG group. All patients engrafted in 2 groups. There were significant differences in the incidence of acute (20.7%?±?5.3% versus 43.4%?±?7.0%, P?=?.015) and chronic graft-versus- host disease (GVHD; 20.1%?±?5.8% versus 46.0%?±?7.9%, P?=?.003) between the R-ATG and P-ATG groups. However, there were no significant differences in terms of 3-year overall survival (93.1%?±?3.3% versus 84.4%?±?5.7%, P?=?.235), grades III to IV acute GVHD (3.4%?±?2.4% versus 12.3%?±?4.7%, P?=?.098), moderate to severe chronic GVHD (12.6%?±?4.9% versus 11.5%?±?4.9%, P?=?.905), or graft rejection (7.4%?±?3.6% versus 5.5%?±?3.1%, P?=?.852). There was also no significant difference with regard to the incidence of severe bacterial infection (P?=?.075), invasive fungal disease (P?=?.701), or cytomeglovirus viremia (P?=?.770). P-ATG showed satisfactory efficacy and safety compared with R-ATG in the setting of MSD-HSCT for SAA patients. P-ATG could be a potential alternative preparation for R-ATG, further offering the advantage of lower costs.     

Unmanipulated Haploidentical Hematopoietic Stem Cell Transplantation Achieved Outcomes Comparable With Matched Unrelated Donor Transplantation in Young Acquired Severe Aplastic Anemia

Salvage haploidentical hematopoietic stem cell transplantation (haplo-HSCT) is considered in patients with severe aplastic anemia (SAA) if a matched unrelated donor (MUD) is unavailable. However, studies on haplo- and MUD transplantation in SAA are lacking. The present study retrospectively analyzed the outcomes of 89 young SAA patients who underwent unmanipulated alternative HSCT between September 2012 and September 2016 at our single center. Forty-one patients received haploidentical donors and forty-eight patients MUDs for HSCT. Most were heavily transfused and refractory to previous immunotherapy. The median durations for myeloid engraftment in the haplo- and MUD cohorts were 14 (range, 10 to 21) and 13 (range, 10 to 18) days, respectively. Compared with the MUD cohort, haplo-HSCT cohorts had an increased cumulative incidence of acute graft-versus-host disease (GVHD) grades II to IV (43.9%?±?7.8% versus 12.5%?±?4.8%, P?=?.001) and grades III to IV (21.1%?±?6.7% versus 6.6%?±?3.7%, P?=?.045) and similar limited chronic GVHD (47.7%?±?8.5% versus 38.5%?±?7.3%, P?=?.129) and extensive chronic GVHD (12.1%?±?6.8% versus 9.1%?±?4.3%, P?=?.198). The median follow-up time of the surviving patients was 26 months (range, 6 to 45). No significant differences were observed between haplo-HSCT and MUD HSCT cohorts in 3-year overall survival (80.3%?±?5.1% versus 89.6%?±?7.0%, P?=?.210), disease-free survival (76.4%?±?5.1% versus 89.4%?±?7.7%, P?=?.127), and GVHD-free failure-free survival (79.0%?±?8.6% versus 71.6%?±?9.3%, P?=?.976). Thus, haplo-HSCT, as salvage therapy, achieved similar outcomes as MUD HSCT in young SAA patients, thereby rendering it as an effective and safe option for SAA.     

Thiotepa-Based Intensified Reduced-Intensity Conditioning Adult Double-Unit Cord Blood Hematopoietic Stem Cell Transplantation Results in Decreased Relapse Rate and Improved Survival Compared with Transplantation Following Standard Reduced-Intensity Conditioning: A Retrospective Cohort Comparison

The “Minnesota” reduced-intensity conditioning (RIC) cord blood transplantation (CBT) regimen (standard RIC) of fludarabine (Flu) (200?mg/m²), cyclophosphamide (Cy) (50?mg/kg), and 200- or 300-cGy total body irradiation (TBI) is the most published RIC CBT regimen. Though well tolerated, high relapse rates remain a concern with this regimen. Intensification of conditioning may reduce relapse without increasing transplant-related mortality (TRM). We performed a retrospective cohort comparison of outcomes in adult patients who underwent first double-unit CBT with standard RIC as compared with the intensified regimen of Flu 150?mg/m², Cy 50?mg/kg, thiotepa 10?mg/kg, and 400-cGy TBI (intensified RIC). Of the 99 patients studied, 47 received intensified RIC. Acute myelogenous leukemia was the major indication for transplant. The median age at transplant was 67 years (range, 24 to 74 years) and 54 years (range, 25 to 67 years) in standard RIC and intensified RIC, respectively. Median hematopoietic stem cell transplantation comorbidity index was 3 (range, 0 to 5) and 1 (range, 0 to 6) in the standard RIC and intensified RIC groups, respectively. Median follow-up among survivors was 22 months (range, 3.7 to 79 months) following standard RIC and 15 months (range, 2.8 to 36 months) following intensified RIC. The cumulative incidence (CI) of relapse was significantly lower following intensified RIC compared with standard RIC (P?=?.0013); this finding maintained significance in multivariate analysis (P?=?.045). TRM was comparable between the 2 groups (P?=?.99). Overall survival (OS) was significantly improved following intensified RIC as compared with standard RIC (P?=?.03). Median OS was 17 months following standard RIC versus not reached followed intensified RIC. The CI of grade II to IV acute graft-versus-host disease (GVHD) was significantly higher in the intensified RIC cohort than the standard RIC-cohort (P?=?.007), while CI of grade III to IV acute GVHD, any chronic GVHD, and moderate-to-severe chronic GVHD was comparable in each cohort (P?=?.20, P?=?.21, and P?=?.61, respectively). This retrospective analysis shows an improvement in OS and decreased relapse without increase in TRM in patients receiving intensified RIC as compared with standard RIC. Our data suggest that consideration of thiotepa-based intensified RIC may improve outcomes in fit, older patients undergoing double-unit CBT.     

Low CD34+ Cell Doses Are Associated with Increased Cost and Worse Outcome after Tandem Autologous Stem Cell Transplantation in Patients with Relapsed or Refractory Germ Cell Tumors

Tandem autologous stem cell transplantation (ASCT) improves long-term survival of platinum-refractory germ cell tumors (GCT) patients. Studies, predominantly in lymphoma, showed that CD34⁺ cell doses > 5.0 × 10⁶/kg/single transplant led to decreased resource utilization. Because most GCT patients have received prior cisplatin-based treatment, collecting >10 × 10⁶ CD34⁺ cells/kg is challenging. We analyzed the effect of CD34⁺?cell dose on resource utilization and outcome in 131 GCT patients, median age 29.5 years (range, 16 to 58), undergoing tandem ASCT. Of 262 individual transplants performed, 120 were performed as inpatient and 142 as planned outpatient. Overall, median CD34⁺ dose per transplant was 3.1 × 10⁶/kg (range, 0.8 to 16.0), with no significant difference between inpatient and outpatient transplants. Patients were divided into quartiles based on the CD34 cell dose infused: Q1, 0.8 to 1.9 × 10⁶/kg; Q2, 2.0 to 2.9 × 10⁶/kg; Q3, 3.0 to 4.1 × 10⁶/kg; and Q4, 4.2 to 16.0 × 10⁶/kg. For all patients higher CD34⁺ cell doses were associated with significantly shorter times to neutrophil (P?<.001) and platelet recovery (P?<.001). For inpatient transplants higher CD34⁺ doses were significantly associated with shorter length of hospital stay (P?<.001), fewer days of filgrastim (P?<.001), i.v. antibiotic (P?=?.012) and antifungal (P?=?.03) usage; and fewer RBC (P?=?.001) and platelet units transfused (P?<.001), resulting in overall lower cost of care (P?<?.001). Of the 142 planned outpatient transplants, 100 admissions were required for a median length of hospital stay of 7.0 days (range, 1 to 18). Although there was no significant difference in the rates of hospitalization between patients in different CD34⁺?cell dose quartiles, a significant trend was observed for shorter hospitalization (P?=?.01) and fewer RBC (P?=?.002) and platelet (P?=?.005) transfusions with higher CD34⁺ cell dose quartile. Patients receiving CD34⁺?cell doses in the lowest dose quartile (Q1) had significantly worse progression-free survival and overall survival compared with patients receiving higher CD34⁺?cell doses. Overall, resource utilization, including cost of care, is significantly reduced when patients receive higher CD34⁺?cell doses, indicating greater efforts to improve peripheral blood stem cell collection in this population are needed.     

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.     

Impact of T Cell Dose on Outcome of T Cell-Replete HLA-Matched Allogeneic Peripheral Blood Stem Cell Transplantation

Data on whether the T cell dose of allogeneic peripheral blood stem cell (PBSC) products influences transplantation outcomes are conflicting. Using the Center for International Blood and Marrow Transplant Research database, we identified 2736 adult patients who underwent first allogeneic PBSC transplantation for acute leukemia or myelodysplastic syndrome between 2008 and 2014 using an HLA-matched sibling donor (MSD) or an 8/8-matched unrelated donor (MUD). We excluded ex vivo and in vivo T cell-depleted transplantations. Correlative analysis was performed between CD3⁺ T cell dose and the risk of graft-versus-host-disease (GVHD), relapse, nonrelapse mortality (NRM), disease-free survival (DFS), and overall survival (OS). Using maximum likelihood estimation, we identified CD3⁺ T cell dose cutoff that separated the risk of acute GVHD (aGVHD) grade II-IV in both the MSD and MUD groups. A CD3⁺ T cell dose cutoff of 14 × 10⁷ cells/kg identified MSD/low CD3⁺ (n = 223) and MSD/high CD3⁺ (n = 1214), and a dose of 15 × 10⁷ cells/kg identified MUD/low CD3⁺ (n = 197) and MUD/high CD3⁺ (n = 1102). On univariate analysis, the MSD/high CD3⁺ group had a higher cumulative incidence of day +100 aGVHD grade II-IV compared with the MSD/low CD3⁺ group (33% versus 25%; P = .009). There were no differences between the 2 groups in engraftment rate, risk of aGVHD grade III-IV or chronic GVHD (cGVHD), NRM, relapse, DFS, or OS. The MUD/high CD3⁺ group had a higher cumulative incidence of day +100 aGVHD grade II-IV compared with the MUD/low CD3⁺ group (49% versus 41%; P = .04). There were no differences between the 2 groups in engraftment rate, risk of severe aGVHD or cGVHD, NRM, relapse, DFS, or OS. Multivariate analysis of the MSD and MUD groups failed to show an association between CD3⁺ T cell dose and the risk of either aGVHD grade II-IV (P = .10 and .07, respectively) or cGVHD (P = .80 and .30, respectively). Subanalysis of CD4⁺ T cells, CD8⁺ T cells, and CD4+/CD8+ ratio failed to identify cutoff values predictive of transplantation outcomes; however, using the log-rank test, the sample size was suboptimal for identifying a difference at this cutoff cell dose. In this registry study, the CD3⁺ T cell dose of PBSC products did not influence the risk of aGVHD or cGVHD or other transplantation outcomes when using an MSD or an 8/8-matched MUD. Subset analyses of CD4⁺ and CD8⁺ T cell doses were not possible given our small sample size.     

Effect of Conditioning Regimen Dose Reduction in Obese Patients Undergoing Autologous Hematopoietic Cell Transplantation

Data are limited on whether to adjust high-dose chemotherapy before autologous hematopoietic cell transplant (autoHCT) in obese patients. This study explores the effects of dose adjustment on the outcomes of obese patients, defined as body mass index (BMI) ≥ 30 kg/m². Dose adjustment was defined as a reduction in standard dosing ≥20%, based on ideal, reported dosing and actual weights. We included 2 groups of US patients who had received autoHCT between 2008 and 2014. Specifically, we included patients with multiple myeloma (MM, n?=?1696) treated with high-dose melphalan and patients with Hodgkin or non-Hodgkin lymphomas (n?=?781) who received carmustine, etoposide, cytarabine, and melphalan conditioning. Chemotherapy dose was adjusted in 1324 patients (78%) with MM and 608 patients (78%) with lymphoma. Age, sex, BMI, race, performance score, comorbidity index, and disease features (stage at diagnosis, disease status, and time to transplant) were similar between dose groups. In multivariate analyses for MM, adjusting for melphalan dose and for center effect had no impact on overall survival (P?=?.894) and treatment-related mortality (TRM) (P?=?.62), progression (P?=?.12), and progression-free survival (PFS; P?=?.178). In multivariate analyses for lymphoma, adjusting chemotherapy doses did not affect survival (P?=?.176), TRM (P?=?.802), relapse (P?=?.633), or PFS (P?=?.812). No center effect was observed in lymphoma. This study demonstrates that adjusting chemotherapy dose before autoHCT in obese patients with MM and lymphoma does not influence mortality. These results do not support adjusting chemotherapy dose in this population.     

Outcome of Fludarabine-Based Conditioning in High-Risk Aplastic Anemia Patients Undergoing Matched Related Donor Transplantation: A Single-Center Study from Pakistan

Despite excellent transplant outcomes of aplastic anemia (AA) in developed countries, management in developing countries is challenging because of delay in the diagnosis, use of family donors for transfusions, and higher infection risk pretransplant. These factors can lead to allo-immunization, increased risk of graft failure, graft-versus-host disease (GVHD), and transplant-related mortality, leading to unfavorable outcomes. Conventional cyclophosphamide (Cy) and antithymocyte globulin (ATG) are associated with inferior overall survival in such high-risk patients. We conducted single-center retrospective analysis of high-risk AA patients (N = 147) enrolled consecutively and undergoing matched related donor transplant from March 2002 through October 2018. We included high-risk AA patients receiving fludarabine (Flu)-based conditioning. Median patient age was 20 years (range, 3 to 52). The median time from diagnosis to transplant was 11 months (range, 3 to 63). High-risk features included age ≥ 20 years in 55.8% of patients (n = 82), disease duration more than 3 months in 95 % (n = 140), RBC concentrates transfusions > 20 in 79.6% (n = 117), random donor platelet transfusion > 50 in 64.6% of patients (n = 95), and second hematopoietic stem cell transplant (HSCT) in 7.4% (11). We divided patients into 2 groups based on different conditioning regimens. Flu group 1 (Flu1) received Flu 120 to 150 mg/m², Cy 120 to 200 mg/kg, and ATG 20 mg/kg, and Flu group 2 (Flu2) was given Flu 150 mg/m², Cy 300 mg/m², and ATG 20 mg/kg. Bone marrow stem cells were used as graft source in 97% of patients (n = 144) (alone in 52% and with peripheral blood stem cells in 45%). Cyclosporine alone was used for GVHD prophylaxis in 75% (n = 110) and cyclosporine plus methotrexate in 25% (n = 37). Median total nucleated cell dose was 5 × 10⁸/kg. Median days for neutrophil engraftment was 13 (range, 10 to 20) and platelet engraftment 20 (range, 14 to 43). Day 100 mortality was 7.5% (n = 11). Sustained successful engraftment was achieved in 87.8% of patients (n = 129). Most graft failures (40%) occurred in Flu2 conditioning (P = .000) and in patients with >2 risk factors (P = .000). Overall incidence of acute and chronic GVHD was 11.6% (n = 17) and 12.9% (n = 19), respectively, in Flu1 and Flu2 groups. Overall survival (OS), disease-free survival (DFS), and GVHD-free relapse-free survival (GRFS) was 83.7%, 78.2%, and 70.7%, respectively. A trend toward improved OS was observed in patients receiving Flu1 conditioning but was statistically nonsignificant (P = .256), whereas DFS and GRFS were significantly better in Flu1 versus Flu2 (P = .004 and .001, respectively). When stratified per number of risk factors (age > 20, RBC concentrate > 20 or platelet > 50 random, duration > 3 months, previous HSCT), OS and DFS decreased significantly with increasing number of risk factors (P = .000 and .001, respectively). Patients are able to tolerate Flu-based conditioning well with lower rates of rejection and excellent long-term survival in high-risk AA patients. Cyclosporine alone as GVHD prophylaxis and marrow source stem cells as graft source are preferable options. Use of Flu plus low-dose Cy conditioning is associated with inferior survival outcomes. A randomized trial of Flu-based versus conventional Cy-containing conditioning would be helpful in establishing a standard of care conditioning regimen in high-risk AA patients.     

Standard Antithymocyte Globulin Dosing Results in Poorer Outcomes in Overexposed Patients after Ex Vivo CD34+ Selected Allogeneic Hematopoietic Cell Transplantation

Antithymocyte globulin (ATG) use mitigates the risk of graft rejection and graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT), but ATG overexposure in the setting of lymphopenia negatively affects immune recovery. We hypothesized that standard empiric weight-based dosing of ATG, used to prevent graft rejection in ex vivo CD34-selected allo-HCT, may lead to serious adverse consequences on outcomes in certain patients. We evaluated 304 patients undergoing myeloablative-conditioned ex vivo CD34-selected allo-HCT with HLA-matched donors for the treatment of hematologic malignancies. Patients received rabbit ATG at a dose of 2.5 mg/kg/day i.v. on days -3 and/or -2. An ATG dosing cutoff of 450 mg was used for statistical analyses to assess the relationship between ATG and overall survival (OS). Among all patients, median total ATG dose was 360 mg (range, 130 to 510 mg); 279 (92%) received a total dose of ATG ≤450 mg, and 25 (8%) received a total dose >450 mg. On the first day of ATG administration (day -3), the median absolute lymphocyte count was .0 K/µL. For patients who received a total dose of ATG >450 mg or ≤450 mg, the incidences of acute and late-acute GVHD grade II-IV were statistically similar. At 3 years post-HCT, for patients who received a total dose of ATG >450 mg or ≤450 mg, nonrelapse mortality (NRM) rates were 35% and 18%, respectively (P = .029), disease-free survival (DFS) rates were 37% and 61%, respectively (P = .003), and OS rates were 40% and 67%, respectively (P = .001). Among all patient and HCT characteristics in multivariable analyses, receipt of a total dose of ATG >450 mg was associated with an increased risk of NRM (hazard ratio [HR], 2.9; P = .01), shorter DFS (HR, 2.0; P = .03), and inferior OS (HR, 2.1; P = .01). In summary, the use of weight-based ATG at a time of relative lymphopenia before ex vivo CD34-selected allo-HCT results in overdosing in heavier patients, leading to higher NRM and lower DFS and OS. Further pharmacokinetic investigation in this setting is critical to determining the optimal dosing strategy for ATG.     

Impact of HLA Disparity in Haploidentical Bone Marrow Transplantation Followed by High-Dose Cyclophosphamide

We studied the impact of HLA mismatching on the outcome of 318 consecutive patients who received an unmanipulated haploidentical bone marrow transplant, followed by post-transplant cyclophosphamide (PTCy). The number of HLA-mismatched antigens was tested for its impact on overall survival (OS) and nonrelapse mortality (NRM), whereas HLA mismatches in the graft-versus-host (GVH) direction were tested for prediction of graft-versus-host disease (GVHD and relapse. Finally, we studied whether graft rejection correlated with the number of HLA mismatched antigens in host-versus-graft (HVG) direction. Two hundred thirty-one donor–recipient pairs (72%) had 4/8 mismatches at the -A, -B, -C, -DRB1 HLA loci. HLA mismatches did not predict the 2-year OS (hazard ratio, .83; P?=?.58) and NRM (subhazard ratio, 1.08; P?=?.93). The cumulative incidence of acute GVHD (P?=?.13), 1-year chronic GVHD (P?=?.84), and relapse rate (P?=?.26) did not correlate with univectorial GVH mismatches. Similarly, no correlation was observed between the amount of HLA mismatch in the HVG direction and graft rejection. In multivariate analysis advanced disease at transplant was the strongest predictor of survival, NRM, relapse, and graft rejection. In conclusion, the degree of HLA mismatching should not be used as a criterion to select family haploidentical donors when using bone marrow as stem cell source and PTCy for GVHD prophylaxis.     

Superior Survival of Black Versus White Patients Following Post-Transplant Cyclophosphamide-Based Haploidentical Transplantation for Adults with Hematologic Malignancy

Available evidence from large registry studies has shown inferior survival for black adult patients following both unrelated donor and cord blood transplantation. Post-transplant cyclophosphamide (PTCy)–based haploidentical donor transplantation (HIDT) is being increasingly used in ethnic minorities. However, no studies of the impact of race on outcomes following HIDT have been reported. We analyzed 203 consecutive patients (123 white, 80 black) who underwent first HIDT using PTCy for hematologic malignancy at a single institution. Median recipient age was 53 (range, 19-75) years. Peripheral blood stem cells (PBSCs) were used as the stem cell source in 66% of patients, and conditioning intensity was myeloablative (MA) in 41%. After a median follow-up of 36 months, the estimated 3-year overall survival (OS), disease-free survival (DFS), and cumulative incidence of relapse (CIR) were significantly better in black patients, compared with white patients (72% [95% confidence interval (CI), 60% to 81%], 65% [95% CI, 52% to 75%], and 25% [95% CI, 16% to 35] versus 50% [95% CI, 40% to 59%], 45% [95% CI, 36% to 54%], and 39% [95% CI, 31% to 47%], respectively; P?<?.001 for OS and DFS, P?=?.015 for CIR). In contrast, 3-year nonrelapse mortality was similar between black (11%) and white (16%) patients, as were the incidences of acute graft-versus-host disease (GVHD) and moderate-to-severe chronic GVHD. Improved survival was noted in all subgroups of black patients—younger versus older, male versus female, lower versus higher disease risk index, MA versus non-MA conditioning, or PBSC versus marrow stem cell source. In multivariate analysis, black race was independently associated with better OS (hazard ratio [HR], .47; P?=?.003), DFS (HR, .49; P?=?.003), and relapse (HR, .49; P?=?.01). Black patients achieve superior outcomes to their white counterparts following PTCy-based HIDT due to a decreased incidence of disease relapse.     

Thiotepa,Busulfan, and Fludarabine Conditioning Regimen in T Cell-Replete HLA-Haploidentical Hematopoietic Stem Cell Transplantation

We report the outcomes of 51 patients who underwent unmanipulated haploidentical hematopoietic stem cell transplantation (haplo-HSCT) with post-transplantation cyclophosphamide (PT-Cy) and antithymocyte globulin (ATG), from peripheral blood stem cells (PBSCs) or bone marrow, after receipt of a TBF (thiotepa, busulfan, and fludarabine) conditioning regimen. Their median age was 55 years (range, 16 to 72 years). Hematologic diagnoses included acute leukemias (n = 31), lymphoid neoplasm (n = 12), myeloproliferative neoplasm (n = 5), and myelodysplastic syndromes (n = 3). Thirty-seven patients (73%) were in complete remission. Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and mycophenolate for all patients, associated with ATG in 39 patients (76.5%). The median time to neutrophil engraftment was 17 days (range, 12 to 34 days). The cumulative incidences of grade II-IV and grade III-IV acute GVHD were 27.5% and 14%, respectively. In patients receiving a PBSC graft and ATG prophylaxis, grade II-IV aGVHD occurred in 16% of patients. The use of ATG and a lower thiotepa dose (5 mg/kg versus 10 mg/kg) were associated with a reduced cumulative incidence of grade II-IV acute GVHD (P = .03 and .005, respectively). The 2-year cumulative incidence of chronic GVHD was 29% and was significantly reduced to 13% with the lower thiotepa dose (P = .002). After a median follow-up of 25 months (range, 12 to 62 months), the cumulative incidences of nonrelapse mortality, relapse, overall survival (OS), disease-free survival (DFS), and GVHD-free, relapse-free survival (GFRFS) were 20%, 22.5%, 67%, 58%, and 51%, respectively. Pretransplantation disease status (complete remission versus others) was the main factor associated with OS, DFS, and GFRFS. In conclusion, the TBF conditioning regimen is an appealing platform in the haplo-HSCT setting with PT-Cy in terms of engraftment rate, toxicity, and disease control. We found no benefit of a thiotepa dose of 10 mg/kg compared with a dose of 5 mg/kg. ATG reduced the risk of acute GVHD without comprising outcomes.     

Comparison of Two Doses of Antithymocyte Globulin in Patients Undergoing Matched Unrelated Donor Allogeneic Stem Cell Transplantation

Antithymocyte globulin (ATG) as part of conditioning regimens is known to reduce the incidence and severity of acute and chronic graft-versus-host disease (aGVHD, cGVHD). The influence of ATG on transplant-related mortality (TRM) and disease-free survival (DFS) is controversial, and may depend on the dose and timing of ATG. We retrospectively compared 2 doses of ATG-Fresenius (ATG-F) in patients undergoing matched unrelated donor allogeneic hematopoetic stem cell transplantation (HSCT) for hematologic malignancies. A dose of 60 mg/kg body weight has previously been recommended for ATG-F. All patients received cyclosporine A and short course methotrexate. ATG-F was administered at a dose of 30 mg/kg on day –1 (ATG-30 group, n = 34) or 20 mg/kg/day on days –3 to –1 (ATG-60 group, n = 49). There was no difference in time to leukocyte and platelet engraftment in the 2 groups. The incidence of aGVHD grade II-IV (50% versus 53%, P = .83) and grade III-IV (27 versus 20%, P = .60) was similar in the ATG-30 versus ATG-60 groups, respectively. There was a trend to a higher incidence of cGVHD in the ATG-30 group (59% versus 40%, P = .14). The estimated 3-year incidence of relapse was similar in the ATG-30 and ATG-60 groups (15% versus 16%, P = .84) whereas the 2-year TRM was lower for the ATG-30 group (12% versus 33%, P = 0.02), mainly because of a higher incidence of fatal infections in the ATG-60 group. This resulted in a better DFS (73% versus 51%, P = .07) for the ATG-30 group. ATG-F (30 mg/kg) administered as a single dose on day –1 may lead to better outcome in patients undergoing unrelated donor allogeneic HSCT compared to 60 mg/kg given in 3 equivalent doses. A prospective randomized study comparing these 2 doses of ATG-F is warranted.     

Influence of Donor Type (Sibling versus Matched Unrelated Donor versus Haploidentical Donor) on Outcomes after Clofarabine-Based Reduced-Intensity Conditioning Allograft for Myeloid Malignancies

Clofarabine-based reduced-intensity conditioning (RIC) regimens are well-established schedules for allograft in patients with myeloid malignancies. A retrospective study was conducted including all adults allografted in our department with such a regimen and disease with the aim to assess whether or not the donor type (matched sibling [MSD], matched unrelated [MUD], or haploidentical [haplo]) impacted outcomes. Between October 2009 and February 2018, 118 patients met the inclusion criteria. Thirty-six, 55, and 27 patients received a graft from an MSD, MUD, or haplo donor, respectively. Peripheral blood stem cells (PBSCs) were the source of graft for all patients. The median age of the entire cohort was 62 years (range, 20 to 73), and the median follow-up was 31 months (range, 4.5 to 106). All patients engrafted except 1 haplo recipient. Neutrophils (>.5 × 10⁹/L) and platelets (50 × 10⁹/L) recoveries were significantly delayed in the haplo group (P = .0003 and P < .0001) compared with MSD and MUD. Acute grades II to IV or III to IV graft-versus-host disease (GVHD) incidences were similar between the 3 groups as well as the incidence of moderate or severe chronic GVHD. Also, similar 2-year overall survival (OS; 64.7% versus 73.9% versus 60.2%, P = .39), disease-free survival (DFS; 57.7% versus 70.9% versus and 53.6%, P = .1), and GVHD relapse-free survival (37.9% versus 54.3% versus 38.9%, P = .23) were observed between MSD versus MUD versus haplo groups. The same was true when considering only acute myeloid leukemia (AML) cases. In multivariate analysis the type of donor remained independent of outcomes in this series, whereas myelodysplastic syndrome (versus AML), high disease risk index, and older donor (≥50 years) were associated with lower OS and DFS. These data suggest that haplo donors are an acceptable alternative for patients receiving a clofarabine-based RIC PBSC allograft for myeloid malignancies who lack an MSD or a MUD.     

Allele-Level HLA Matching Impacts Key Outcomes Following Umbilical Cord Blood Transplantation for Inherited Metabolic Disorders

Allogeneic hematopoietic stem cell transplantation has demonstrated efficacy for numerous inherited metabolic disorders (IMDs). Umbilical cord blood transplant (UCBT) is increasingly used as a graft source in IMDs, but little is known of the impact of cord blood unit (CBU)/recipient HLA allelic disparity on key outcomes following UCBT for IMD. We reviewed outcomes of 106 consecutive first, single UCBTs for IMD at the University of Minnesota with regard to CBU/recipient HLA allelic matching (HLA-A, -B, -C, and -DRB1). The median age at UCBT was 1 year, and 87 patients (82%) received myeloablative conditioning. Primary diagnoses were Hurler syndrome (41%), cerebral adrenoleukodystrophy (35%), metachromatic leukodystrophy/globoid cell leukodystrophy (9%), and other (16%). The 5-year overall survival (OS) for the entire cohort was 70% (95% confidence interval, 59% to 79%). Rates of severe acute and chronic graft-versus-host disease were low (6% for each). CBU/recipient HLA conventional matching was based on antigen-level matching at HLA-A and -B, and on allele-level matching at HLA-DRB1. Of 46 conventional matched UCBTs, 20 (43%) were mismatched at?1 or more alleles. Of 49 conventional 5/6 UCBTs, 30 (61%) were mismatched at?≥2 alleles and 19 (39%) were mismatched at?≥3 alleles. Within the 6/6 conventional match stratum, comparisons of key outcomes between allele-matched and allele-mismatched UCBT were as follows: 5-year OS, 88% versus 42% (P?<?.01); 1-year engrafted survival (ES) with ≥90% donor chimerism, 73% versus 60% (P?=?.33); graft failure, 8% versus 30% (P?=?.05); and transplantation-related mortality (TRM), 8% versus 30% (P?=?.04). For patients undergoing conventional 5/6 HLA-matched UCBT, better allelic matching was associated with similar outcomes: 5-year OS, 77% versus 74% (P?=?.72); 1-year ES, 73% versus 47% (P?=?.06); graft failure, 17% versus 42% (P?=?.05); and TRM, 10% versus 16% (P?=?.54). On multivariable analyses, fewer allele-level mismatches within each conventional match stratum continued to predict more favorable outcomes following UCBT. These data provide evidence that allele-level HLA matching considerations within a conventional HLA match stratum may better predict outcomes of interest after UCBT for IMD. Larger studies are warranted to confirm these findings and explore other allele-level HLA match dynamics.     

Peripheral Blood Eosinophilia Has a Favorable Prognostic Impact on Transplant Outcomes after Allogeneic Peripheral Blood Stem Cell Transplantation

Peripheral eosinophilia after allogeneic stem cell transplant (ASCT) may reflect the activation of the Th2 cytokine pathway. A retrospective analysis was performed to evaluate the impact of early- (before day 100: EEo) or late-onset (beyond day 100: LEo) eosinophilia (≥0.5 × 10⁹/L in peripheral blood) on transplant outcomes after peripheral blood SCT (PBSCT) in 237 patients. The incidence of EEo and LEo was 43% at day 100 and 62% at 2 years, respectively. Compared with patients without LEo, improved transplant outcomes were observed in patients with LEo: better overall survival (OS; 86% versus 41%, P = 5 × 10⁻¹¹), lower nonrelapse mortality (NRM; 10% versus 37%, P = 3 × 10⁻⁶), lower relapse incidence (11% versus 31%, P = 3 × 10⁻⁵), and higher GVHD-specific survival (GSS; 90% versus 64%, P = 1 × 10⁻⁶) were observed. In addition, similar finding was observed when transplant outcomes were analyzed according to the occurrence of eosinophilia at the onset of cGVHD. The multivariate analyses confirmed a favorable implication of LEo on OS, NRM, and GSS. LEo was associated with: (1) less severe chronic GVHD (cGVHD), (2) higher prevalence of autoantibodies, and (3) rapid lymphocyte count recovery after ASCT. In summary, the development of eosinophila after allogeneic PBSCT seemed to be a prognostic marker for improving transplant outcome.     

Impact of Single-Dose Plerixafor as an Adjunct to Granulocyte Colony-Stimulating Factor–Based Peripheral Blood Stem Cell Mobilization on the Graft Composition and Outcome for T Cell–Replete Haploidentical Peripheral Blood Stem Cell Transplantation with Post-Transplantation Cyclophosphamide: A Comparative Study

We conducted a prospective study on T and natural killer (NK) cell subset composition of graft and transplant outcomes in T cell–replete haploidentical transplantation with a single dose of subcutaneous plerixafor (Px) added to granulocyte colony-stimulating factor (G-CSF)-based mobilization in allogeneic donors to collect 10?×?10⁶/kg CD34⁺ hematopoietic stem cells (HSCs) at single apheresis. Twnety-six donors received G-CSF?+?Px and 25 G-CSF alone for mobilization. Despite significantly lower peripheral blood (PB) CD34⁺ HSCs on day 4 in the G-CSF?+?Px group (33 [range, 6-47] cells/µL versus 81 [range, 50-168] cells/µL in the G-CSF group; P?=?.0001), PB CD34⁺ HSC count (median 136 versus 139 cells/µL) on day 5 as well as that in the graft (2.7 versus 2.3?×?10⁶/mL, P?=?.1) were comparable between the 2 groups. The total nucleated cell count was higher (3.4 versus 3.1?×?10⁸/mL, P?=?.05), but CD4⁺ T cells (2.3 versus 2.7?×?10⁷/mL, P?=?.09) were lower in the G-CSF group with mobilization of regulatory T cells being similar. NK cells were skewed toward the CD56⁺/16^? subset in both groups, varying significantly from the steady-state NK subset ratio in PB. The time to engraftment, incidences of acute and chronic graft-versus-host disease, nonrelapse mortality, and overall survival were also similar. Addition of single-dose Px to G-CSF mobilization improves CD34 recovery and does not significantly alter the T and NK cell composition of the graft, including regulatory T cells, with no adverse impact on transplant outcomes.     

T Cell-Replete Haploidentical Transplantation with Post-Transplantation Cyclophosphamide for Hodgkin Lymphoma Relapsed after Autologous Transplantation: Reduced Incidence of Relapse and of Chronic Graft-versus-Host Disease Compared with HLA-Identical Related Donors

Allogeneic hematopoietic stem cell transplantation (SCT) represents a potential curative strategy for patients with Hodgkin lymphoma (HL) relapsing after autologous SCT (ASCT), but the incidence of disease relapse is still high. We performed a retrospective study on 64 patients with HL relapsing after ASCT to compare outcomes after HLA-identical SCT (HLAid-SCT; n?=?34) and haploidentical SCT with post-transplantation cyclophosphamide (PT-Cy) (Haplo-SCT; n?=?30). All patients engrafted, with a significantly shorter median time for neutrophil and platelet engraftment after HLAid compared with Haplo-SCT (14 days versus 19 days and 11 days versus 23 days, respectively; P?<?.005). With a median follow-up of 47 months, 3-year overall survival (OS), 3 -year progression-free survival (PFS), and 1-year nonrelapse mortality (NRM) were 53%, 44% and 17%, respectively. Recipients of Haplo-SCT were less likely to experience disease relapse (3-year cumulative incidence of relapse, 13% versus 62%; P?=?.0001) and chronic graft- versus-host disease (GVHD; 3% versus 32%; P?=?.003), resulting in improved PFS (60% versus 29%; P?=?.04) and GVHD-free/relapse-free survival (47% versus 17%; P?=?.06). The 3-year OS did not differ between the 2 groups (56% versus 54%; P?not significant), and NRM was higher after Haplo-SCT, but the difference did not reach statistical significance (26% versus 9%; P?=?.09). On multivariate Cox regression analysis, receipt of Haplo-SCT (hazard ratio [HR], .17; P?=?.02) and achieving optimal disease control (complete remission before SCT: HR, .6; P?<?.0001) were the only independent variables associated with a reduced risk of disease relapse. Haplo-SCT is a valid option for patients with HL relapsing after ASCT, with a reduced incidence of relapse compared with HLAid SCT.     

Preconditioning Absolute Lymphocyte Count and Transplantation Outcomes in Matched Related Donor Allogeneic Hematopoietic Stem Cell Transplantation Recipients with Reduced-Intensity Conditioning and Antithymocyte Globulin Treatment

The integration of antithymocyte globulin (ATG) into therapy has significantly reduced the incidence of graft-versus-host disease (GVHD) and is being actively used in allogeneic hematopoietic stem cell transplantation (allo-HSCT). The ATG dosage is determined by the recipient's body weight, but some insist that this approach does not reflect the actual target of ATG. In this respect, weight-based dosing may lead to ATG overdose, particularly in recipients with a relatively low absolute lymphocyte count (ALC). We retrospectively analyzed 84 patients with acute leukemia or myelodysplastic syndrome who underwent matched related donor (MRD) allo-HSCT with reduced-intensity conditioning (RIC) at a single institution. Patients were dichotomized according to the ALC measured on the first day of conditioning (day -7) to investigate the associations of the ALC with GVHD and survival outcomes. The median duration of follow-up was 29 months. The preconditioning ALC was closely correlated with the ALC at the first ATG administration (day -3). The cumulative incidences of both acute GVHD and chronic GVHD were significantly lower in the preconditioning ALC <500/μL group compared with the ALC ≥500/μL group. There was no significant difference in disease relapse incidence between the 2 groups; however, mortality was significantly higher in the ALC <500/μL group. Multivariate analysis including disease status, modified European Blood and Marrow Transplantation score, and preconditioning ALC (≥500/μL versus <500/μL) identified disease status and ALC as being independently associated with overall survival (OS). In particular, infection was the most common cause of death in the ALC <500/μL group. Our data suggest that uniform weight-based ATG dosing in MRD allo-HSCT with RIC is associated with an increase in nonrelapse mortality and a relatively inferior OS in patients with a significantly low preconditioning ALC. Therefore, alternative strategies for the integration of ATG should be considered in allo-HSCT, at least for patients with a substantially low preconditioning ALC.