The Addition of 400 cGY Total Body Irradiation to a Regimen Incorporating Once-Daily Intravenous Busulfan, Fludarabine, and Antithymocyte Globulin Reduces Relapse Without Affecting Nonrelapse Mortality in Acute Myelogenous Leukemia

High dose total marrow irradiation (TMI) does not increase long-term toxicity of myeloablative fludarabine/busulfan (FluBu4) conditioning regimen in allogeneic hematopoietic stem cell transplantation (HSCT)

OBJECTIVES

Based on a previous phase 1 study, total marrow irradiation (TMI) at 9Gy was added to a myeloablative FluBu4 conditioning regimen in allogeneic hematopoietic stem cell transplantation (HSCT) for myeloid malignancies. Here, we report on the long-term toxicity of TMI combined with FluBu4 and compare it to patients who received only FluBu4.

METHODS

We retrospectively analyzed 38 consecutive patients conditioned with FluBu4/TMI (n = 15) or FluBu4 (n = 23, control group) who had at least 1 year follow-up post-transplant. The rate of long-term adverse events that have been previously associated with total body irradiation (TBI) was analyzed in the two groups.

RESULTS

The baseline characteristics did not differ between the two groups. The control group had a longer median follow-up (71.2 mo) than the TMI group (38.5 mo) (p = .004). The most common adverse events were xerostomia, dental complications, cataracts, or osteopenia and did not differ between the two groups. Cognitive dysfunction or noninfectious pneumonitis, often detected after high dose TBI, were also not different in the two groups (p = .12 and p = .7, respectively). There was no grade 4 adverse event.

CONCLUSION

Our results suggest that a conditioning regimen with TMI 9Gy and FluBu4 does not increase long-term adverse events after allogeneic HSCT.

Rituximab Toxicity after Preemptive or Therapeutic Administration for Post-Transplant Lymphoproliferative Disorder

Rituximab is commonly used as prevention, preemption, or therapeutically for post-transplant lymphoproliferative disorder (PTLD) after hematopoietic cell transplantation (HCT). Although it is generally assumed that rituximab toxicity (ie, infections resulting from hypogammaglobulinemia and neutropenia) is negligible in relation to mortality due to PTLD, limited evidence supports the validity of this assumption. We sought to determine the impact of rituximab on immunoglobulin levels, neutrophil count, infection density, and mortality outcomes. This study retrospectively analyzed 349 HCT recipients, 289 of whom did not receive rituximab and 60 of whom received rituximab preemptively or therapeutically at a median of 55 days post-transplantation. IgM, IgG, and IgA levels at 6 months and 12 months post-transplantation were lower in patients who received rituximab compared with those who did not (significant at P < .05 for IgM and IgA at 6 months and for IgM and IgG at 12 months). Rituximab recipients also had a higher incidence of severe neutropenia (<.5/nl) between 3 and 24 months (subhazard ratio [SHR], 2.3; P = .020). Regarding non-Epstein-Barr viral infections/PTLD, the rituximab group had a higher infection density between 3 and 24 months compared with the no-rituximab group (3.8 versus 1.6 infections per 365 days at risk; incidence rate ratio, 2.2; P < .001). The rituximab group also had a higher incidence of fatal infections (SHR, 3.1; P = .026), higher nonrelapse mortality (SHR, 2.4; P = .006), and higher overall mortality (hazard ratio, 1.7; P = .033). There were no significant between-group differences in the incidence of clinically significant graft-versus-host disease, graft failure, or relapse. Based on this study, rituximab given for PTLD is associated with substantial morbidity and mortality. Whether the benefit of preemptive rituximab outweighs the risk remains to be determined. © 2022 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Outcomes of Busulfan, Fludarabine, and 400 cGy Total Body Irradiation Compared With Busulfan and Fludarabine Reduced-Intensity Conditioning Regimens for Allogeneic Stem Cell Transplantation in Adult Patients With Hematologic Diseases: A Single-Center Experience

BACKGROUND

Reduced intensity conditioning (RIC) regimens decrease the risk for nonrelapse mortality (NRM) in adult patients undergoing allogeneic hematopoietic stem cell transplantation for hematologic malignancies but increase the risk for relapse. The aim of this study was to compare the outcomes of fludarabine-total body irradiation (TBI) with fludarabine among patients with hematologic diseases.

PATIENTS AND METHODS

This retrospective study of 137 patients with different hematologic malignancies compared the outcomes of 63 patients who received a conventional RIC regimen with 2 days of IV busulfan (3.2 mg/kg/d × 2 days) and fludarabine with 74 patients who received the same regimen plus 400 cGy of fludarabine and busulfan (FB)-TBI divided in 2 doses over 1 day (200 cGy BID). Median follow-up was 4.62 years.

RESULTS

The donors were either HLA-matched siblings (36%) or HLA-matched unrelated donors (64%). The FB-TBI showed trends toward improvement in progression-free survival (PFS) and overall survival (OS) over FB (5-year PFS rates 50% vs 34%, P = .06, and 5-year OS rate 53% vs 39%, P = .13). Acute graft-vs-host disease (aGVHD), relapse, and NRM were similar between the 2 groups. The 5-year cumulative incidence of chronic GVHD (cGVHD) was lower in the FB-TBI group compared with the FB group (29% vs 52%, P = .003). Multivariable analysis revealed that grade III-IV aGVHD was the only independent risk factor for worse OS (P = .001) in both groups. A high disease risk index was possibly associated with inferior OS (P = .07) in both groups.

CONCLUSIONS

The FB-TBI is a safe and effective intensified RIC regimen for adult patients with hematologic malignancies. It predicted a lower risk for cGVHD and showed possibly improved PFS and OS compared with FB.

Incomplete chimerism following myeloablative and anti-thymocyte globulin-conditioned hematopoietic cell transplantation is a risk factor for relapse and chronic graft-versus-host disease

BACKGROUND AIMS

The value of routine chimerism determination after myeloablative hematopoietic cell transplantation (HCT) is unclear, particularly in the setting of anti-thymocyte globulin (ATG)-based graft-versus-host disease (GVHD) prophylaxis.

METHODS

Blood samples were collected at 3 months post-HCT from 558 patients who received myeloablative conditioning and ATG-based GVHD prophylaxis. Chimerism was assessed using multiplex polymerase chain reaction of short tandem repeats in sorted T cells (CD3+) and leukemia lineage cells (CD13+CD33+ for myeloid malignancies and CD19+ for B-lymphoid malignancies). ATG exposure was determined using a flow cytometry-based assay. The primary outcomes of interest were relapse and chronic GVHD (cGVHD).

RESULTS

Incomplete (<95%) T-cell chimerism and leukemia lineage chimerism were present in 17% and 4% of patients, respectively. Patients with incomplete T-cell chimerism had a significantly greater incidence of relapse (36% versus 22%, subhazard ratio [SHR] = 2.03, P = 0.001) and lower incidence of cGVHD (8% versus 25%, SHR = 0.29, P < 0.001) compared with patients with complete chimerism. In multivariate modeling, patients with high post-transplant ATG area under the curve and any cytomegalovirus (CMV) serostatus other than donor/recipient seropositivity (non-D+R+) had an increased likelihood of incomplete T-cell chimerism. Patients with incomplete leukemia lineage chimerism had a significantly greater incidence of relapse (50% versus 23%, SHR = 2.70, P = 0.011) and, surprisingly, a greater incidence of cGVHD (45% versus 20%, SHR = 2.64, P = 0.003).

CONCLUSIONS

High post-transplant ATG exposure and non-D+R+ CMV serostatus predispose patients to incomplete T-cell chimerism, which is associated with an increased risk of relapse. The increased risk of cGVHD with incomplete B-cell/myeloid chimerism is a novel finding that suggests an important role for recipient antigen-presenting cells in cGVHD pathogenesis.

Cumulative incidence of subsequent malignancy after allo-HCT conditioned with or without low-dose total body irradiation

Subsequent malignancies (SMs) present a significant burden of morbidity and are a common cause of late mortality in survivors of allogeneic hematopoietic cell transplant (allo-HCT). Previous studies have described total body irradiation (TBI) as a risk factor for the development of SMs in allo-HCT survivors. However, most studies of the association between TBI and SM have examined high-dose TBI regimens (typically ≥600 cGy), and thus little is known about the association between low-dose TBI regimens and risk of SMs. Our goal, therefore, was to compare the cumulative incidence of SMs in patients of Alberta, Canada, who received busulfan/fludarabine alone vs busulfan/fludarabine plus 400 cGy TBI. Of the 674 included patients, 49 developed a total of 56 malignancies at a median of 5.9 years' posttransplant. The cumulative incidence of SMs at 15 years' post-HCT in the entire cohort was 11.5% (95% confidence interval [CI], 8.5-15.6): 13.4% (95% CI, 9.1-19.3) in the no-TBI group and 10.8% (95% CI, 6.6-17.4) in the TBI group. In the multivariable model, TBI was not associated with SMs, whereas there was an association with number of pre-HCT cycles of chemotherapy. The standardized incidence ratio for the entire cohort, compared with the age-, sex-, and calendar year-matched general population, was 1.75. allo-HCT conditioning that includes low-dose TBI does not seem to increase risk of SMs compared with chemotherapy-alone conditioning.

Impact of FLT3 internal tandem duplication and NPM1 mutations in acute myeloid leukemia treated with allogeneic hematopoietic cell transplantation

BACKGROUND AIMS

The internal tandem duplication of FLT3 (FLT3^ITD) and NPM1 mutations (NPM1^mut) are well-established prognostic factors in cytogenetically intermediate-risk acute myeloid leukemia (AML) when treated with chemotherapy alone. However, their prognostic value in the setting of allogeneic hematopoietic cell transplantation (HCT) is controversial.

METHODS

FLT3 and NPM1 mutational status was determined at diagnosis using single-gene polymerase chain reaction or next-generation sequencing in 247 adult patients with cytogenetically intermediate-risk AML who underwent myeloablative HCT. Multivariate Fine-Gray and Cox regression was used to analyze the cumulative incidence of relapse (CIR), relapse-free survival (RFS) and overall survival (OS).

RESULTS

FLT3^ITD and NPM1^mut were present in 74 of 247 (30%) and 79 of 247 (32%) patients, respectively. There was no significant difference between patients without a FLT3^ITD or NPM1^mut (FLT3^NONITD/NPM1^WT) and patients with a FLT3^ITD mutation alone (FLT3^ITD/NPM1^WT) with regard to CIR (P = 0.60), RFS (P = 0.91) or OS (P = 0.66). Similarly, there was no significant difference between FLT3^NONITD/NPM1^WT and FLT3^NONITD/NPM1^mut patients with regard to CIR (P = 0.70), RFS (P = 0.75) or OS (P = 0.95). The presence of a concurrent mutation in NPM1 did not appear to modify the impact of having a FLT3^ITD mutation.

CONCLUSIONS

In contrast to chemotherapy-only treatment, FLT3 and NPM1 mutational status does not appear to predict outcomes in patients with cytogenetically intermediate-risk AML following HCT. These results suggest that HCT may ameliorate the poor prognostic effect of FLT3^ITD mutation and that HCT should be considered over chemotherapy-only treatment in FLT3^ITD-mutated AML.

Fludarabine/busulfan versus busulfan/cyclophosphamide as myeloablative conditioning for myelodysplastic syndrome: a propensity score-matched analysis

Myeloablative conditioning with fludarabine/busulfan (Flu/Bu4) prior to allogeneic hematopoietic stem cell transplantation (allo-HSCT) is effective for acute myeloid leukemia. However, the effectiveness of Flu/Bu4 for myelodysplastic syndrome (MDS) remains poorly understood. Therefore, we retrospectively analyzed nationwide registry data in Japan from 2006 to 2018 and compared transplant outcomes of adult MDS patients receiving Flu/Bu4 and busulfan/cyclophosphamide (Bu4/Cy) using propensity score (PS) matching. The primary endpoint was overall survival (OS). Among 2,482 MDS patients, 153 patients were assigned each to the Flu/Bu4 and Bu4/Cy groups. The 3-year OS rates were 52.7% (95% confidence interval [CI], 43.8-60.8%) and 49.5% (95% CI, 40.8-57.6%) in the Flu/Bu4 and Bu4/Cy group, respectively (P = 0.548). The 3-year progression-free survival (P = 0.858), the cumulative incidence of relapse (P = 0.536), and cumulative incidence of non-relapse mortality (P = 0.684) were not significantly different between the two groups. According to the findings of subgroup analyses, no patient had a favorable OS when using either of the two regimens. In conclusion, although our PS-matched cohort mainly comprised older patients who had a low hematopoietic cell transplantation-comorbidity index and low-risk disease status, Flu/Bu4 could be an alternative to Bu4/Cy for MDS patients prior to allo-HSCT.

Risk Factors for the Incidence of and the Mortality due to Post-Transplant Lymphoproliferative Disorder after Hematopoietic Cell Transplantation

Post-transplant lymphoproliferative disorder (PTLD) is a potentially serious complication that occurs following hematopoietic cell transplantation (HCT), in which B cells transformed by Epstein-Barr virus (EBV) proliferate uncontrollably. It is unknown whether risk factors for the incidence of PTLD are identical to those for mortality due to PTLD, a clinically more important outcome. We sought to determine the risk factors influencing the incidence of PTLD and those influencing mortality due to PTLD in a cohort of 1184 allogenic HCT recipients. All patients were predisposed to PTLD, because their graft-versus-host disease (GVHD) prophylaxis included antithymocyte globulin. The overall PTLD incidence was 9.0%, and mortality due to PTLD was 1.1%. In multivariate analysis, risk factors for PTLD incidence include donor+/recipient- (D+/R-) EBV serostatus (subhazard ratio [SHR], 3.3; P = .002), use of a donor other than an HLA-matched sibling donor (non-MSD) (SHR, 1.7; P = .029), receipt of total body irradiation (TBI; SHR, 3.3; P = .008), and the absence of GVHD (SHR, 3.3; P < .001). The sole risk factor for mortality due to PTLD among all patients was D+/R- serostatus (SHR, 5.8; P = .022). Risk factors for mortality due to PTLD among patients who developed PTLD were use of a bone marrow (BM) graft (compared with peripheral blood stem cells [PBSCs]; SHR, 22.8; P < .001) and extralymphatic involvement (SHR, 14.6; P < .001). Interestingly, whereas the absence of GVHD was a risk factor for PTLD incidence, there was a trend toward the presence of GVHD as a risk factor for PTLD mortality (SHR, 4.2; P = .093). Likewise, whereas use of a BM graft was a risk factor for PTLD mortality, there was a trend toward use of a PBSC graft as a risk factor for PTLD incidence (SHR, 0.44; P = .179). Some risk factors for the incidence of PTLD are identical to the risk factors for mortality due to PTLD (ie, D+/R- serostatus), whereas other risk factors are disparate. Specifically, TBI was identified as a risk factor for PTLD incidence but not for PTLD mortality; the absence of GVHD was a risk factor for PTLD incidence, whereas the presence of GVHD was possibly a risk factor for PTLD mortality; and receipt of a PBSC graft was possibly a risk factor for PTLD incidence, whereas receipt of a BM graft was a risk factor for PTLD mortality.

A biomarker-guided, prospective, phase 2 trial of pre-emptive graft-versus-host disease therapy using anti-thymocyte globulin

BACKGROUND AIMS

Intensified immunosuppressive prophylaxis for graft-versus-host disease (GVHD) may be toxic and therefore warranted only in patients at high risk of developing GVHD. In patients who underwent allogeneic hematopoietic cell transplant at the authors' center, high serum soluble IL-2 receptor alpha (sIL-2Rα) and low IL-15 levels on day 7 post-transplant were found to predict a high risk of developing clinically significant GVHD (sGVHD), defined as grade 2-4 acute GVHD or moderate to severe chronic GVHD.

METHODS

This was a prospective, phase 2 trial in which high-risk patients (serum sIL-2Rα >4500 ng/L or IL-15 <31 ng/L) received rabbit anti-thymocyte globulin (ATG) 3 mg/kg on day 8 post-transplant. Controls consisted of patients who had their sIL-2Rα/IL-15 levels measured but did not participate in the trial. A total of 68 trial patients and 143 controls were accrued to this study. The primary endpoint was incidence of sGVHD.

RESULTS

There was a reduction in sGVHD in high-risk trial patients (received day 8 ATG) compared with high-risk controls (did not receive day 8 ATG) (sub-hazard ratio [SHR] = 0.48, P < 0.05). There was no significant difference between the groups in overall survival or relapse; however, there was a greater incidence of non-GVHD-associated non-relapse mortality in high-risk trial patients (SHR = 3.73, P < 0.05), mostly related to infections. This may be due in part to the biomarkers ineffectively stratifying GVHD risk.

CONCLUSIONS

Pre-emptive ATG therapy is both feasible and effective at reducing sGVHD without increasing relapse. Further mitigation strategies are needed to reduce the risk of infection associated with intensified GVHD prophylaxis. This study was registered at ClinicalTrials.gov (NCT01994824).

Reduced-toxicity conditioning regimen with busulfan, fludarabine, rATG, and 400 cGy TBI in pediatric patients undergoing hematopoietic stem cell transplant for high-risk hematologic malignancies

Myeloablative conditioning regimens decrease the risk of relapse in pediatric patients undergoing allogeneic hematopoietic stem cell transplant (HCT) for hematologic malignancies, but cause significant toxicities PROCEDURE: This prospective study evaluated the use of a reduced-toxicity, myeloablative regimen with dose-adjusted busulfan, fludarabine, antithymocyte globulin and 400 cGy of total body irradiation in 40 patients < 21 years of age undergoing HCT for high-risk leukemias. Busulfan pharmacokinetics were measured to target 4000 μmol*min/day in the first 30 patients; this was increased to 5000 μmol*min/day in the subsequent 10 in efforts to further decrease relapse risk RESULTS: Overall survival at two- and five-years post-HCT was 67% and 51%, respectively. Relapse occurred in 11 patients (28%) at a median of seven months and was the leading cause of death. Transplant-related mortality was 8% and 13% at 100 days and one-year post-HCT, respectively. Trends toward improved survival were seen in patients transplanted for myeloid disease using bone marrow as stem cell source who achieved a busulfan AUC > 4000 μmol*min/day with two-year relapse-free survival approaching 80% CONCLUSIONS: This conditioning regimen is safe and effective in patients with high-risk leukemias, particularly myeloid disease. Larger studies are needed to compare its safety and efficacy to other myeloablative regimens in this population.

Outcomes of Fludarabine, Melphalan and Total Body Irradiation as a Reduced Intensity Conditioning Regimen in Matched Donor Allogeneic Peripheral Blood Stem Cell Transplantation

Fludarabine 30 mg/m²/d × 5 and melphalan 140 mg/m² × 1 (Flu-Mel140) is a commonly used reduced-intensity conditioning regimen. We hypothesized that addition of 200cGy total body irradiation (TBI) to Flu-Mel140 may improve antitumor activity and transplant outcomes. Primary objectives was overall survival (OS) at 3 years. Secondary objectives were to assess the cumulative incidences of acute and chronic GVHD, relapse-free survival (RFS), relapse rate, and nonrelapse mortality (NRM). We retrospectively evaluated outcomes of patients receiving Flu-Mel140-TBI followed by HLA-matched donor allogeneic hematopoietic stem cell transplantation (alloSCT) using peripheral blood stem cells. Eighty-one patients (median age, 58 years) underwent alloSCT between January 2008 and December 2018. Thirty-one percent of patients had a prior transplant, 32% had high or very-high disease risk index, and the donor was unrelated in 70% of patients. Grade 3 to 4 regimen-related toxicities were mucositis (37%), cardiac toxicity (17%), and renal toxicity (10%). The cumulative incidence of grade III to IV acute GVHD at day +100 was 24.7% and chronic GVHD at 1 year was 51.3%. Median follow-up for survival was 6.1 years. At 3 years, OS was 39.81%, RFS was 31.47%, and relapse rate was 30.5%. One-year NRM was 29.9%. Patients undergoing first transplantation experienced improved OS compared with second or beyond (63.08% versus 42.31%, P = .02). After adjusting for disease subtypes, age (≤55 versus 55), comorbidity index (CI), number of transplant and GVHD prophylaxis, multivariable analysis did not demonstrate any survival difference among disease subtypes. High CI (≥3) was predictive of adverse OS and NRM, whereas older age (>55 years) was associated with high NRM. Our study shows that Flu-Mel140-TBI seems feasible and provides durable disease control. Addition of TBI did not appear to improve outcomes compared to previously published reports of Flu-Mel140. Considerable NRM could result from the inclusion of patients with older age and prior transplants.

Comparison of myeloablative and reduced intensity conditioning unrelated donor allogeneic peripheral blood stem cell transplant outcomes for AML using thymoglobulin for GVHD prophylaxis

A head-to-head comparison of outcomes of unrelated donor allogeneic peripheral blood stem cell transplantation for AML between reduced intensity conditioning (RIC) and myeloablative conditioning (MAC) regimens using thymoglobulin for GVHD prophylaxis is limited. We evaluated outcomes of 122 AML patients who received either busulfan (Bu)/fludarabine (Flu)/low-dose total body irradiation (TBI) as RIC (n = 64, 52%) or Bu/Flu as MAC (n = 58, 48%), and thymoglobulin 4.5 mg/kg total dose between day - 3 to - 1 for GVHD prophylaxis. Grades III-IV acute GVHD (aGVHD) was lower with Bu/Flu/TBI compared with Bu/Flu (6.2% vs 26.1%, p = 0.009). At 1 year, Bu/Flu/TBI was associated with similar chronic GVHD (41.2% vs 44.8%, p = 0.75), OS (61.9% vs 56.9%, p = 0.69), relapse rate (29.9% vs 20.7%, p = 0.24), relapse-free survival (52.8% vs 50%, p = 0.80), non-relapse mortality (17.4% vs 29.3%, p = 0.41), and GVHD-free relapse-free survival (24.2% vs 27.5%, p = 0.80) compared with Bu/Flu. Multivariable analysis did not reveal any difference in outcomes between both regimens. In summary, thymoglobulin at 4.5 mg/kg did not have any adverse impact on survival when used with RIC regimen. Both Bu/Flu/TBI and Bu/Flu conditioning regimens yielded similar survival.

Hematopoietic cell transplant outcomes after myeloablative conditioning with fludarabine, busulfan, low-dose total body irradiation, and rabbit antithymocyte globulin

Optimal conditioning and graft-vs-host disease (GVHD) prophylaxis for hematopoietic cell transplantation (HCT) are unknown. Here, we report on outcomes after low toxicity, myeloablative conditioning consisting of fludarabine, busulfan, and 4 Gy total body irradiation, in combination with thymoglobulin and post-transplant methotrexate and cyclosporine. We retrospectively studied 700 patients with hematologic malignancies who received blood stem cells from 7 to 8/8 HLA-matched unrelated or related donors. Median follow-up of surviving patients was 5 years. At 5 years, overall survival (OS), relapse-free survival (RFS), and chronic GVHD/relapse-free survival (cGRFS) were 58%, 55%, and 40%. Risk factors for poor OS, RFS, and cGRFS were (1). high to very high disease risk index (DRI), (2). high recipient age, and (3). cytomegalovirus (CMV)-seropositive recipient with seronegative donor (D-R+). The latter risk factor applied particularly to patients with lymphoid malignancies. Neither donor other than HLA-matched sibling (7-8/8 unrelated) nor one HLA allele mismatch was risk factors for poor OS, RFS, or cGRFS. In conclusion, the above regimen results in excellent long-term outcomes. The outcomes are negatively impacted by older age, high or very high DRI, and CMV D-R+ serostatus, but not by donor unrelatedness or one HLA allele mismatch.

Antirelapse effect of pretransplant exposure to rabbit antithymocyte globulin

It remains unknown why rabbit antithymocyte globulin (ATG; Thymoglobulin) has not affected relapse after hematopoietic cell transplantation (HCT) in randomized studies. We hypothesized that high pre-HCT ATG area under the curve (AUC) would be associated with a low incidence of relapse, whereas high post-HCT AUC would be associated with a high incidence of relapse. We measured serum levels of ATG capable of binding to mononuclear cells (MNCs), lymphocytes, T cells, CD4 T cells, or CD33 cells. We estimated pre- and post-HCT AUCs in 152 adult recipients of myeloablative conditioning and blood stem cells. High pre-HCT AUCs of MNC- and CD33 cell-binding ATG were associated with a low incidence of relapse and high relapse-free survival (RFS). There was a trend toward an association of high post-HCT AUC of lymphocyte-binding ATG with a high incidence of relapse and low RFS. High pre-HCT AUCs were also associated with faster engraftment and had no impact on graft-versus-host disease (GVHD) or fatal infections. High post-HCT AUCs were associated with a low risk of GVHD, seemed associated with an increased risk of fatal infections, and had no impact on engraftment. In conclusion, pre-HCT AUC seems to have a positive, whereas post-HCT AUC seems to have a negative, impact on relapse.

Haploidentical stem cell transplant with post-transplantation cyclophosphamide and mini-dose methotrexate in children

BACKGROUND

Haploidentical stem cell transplantation (haplo-SCT) is an option for patients without human leukocyte antigen-matched related or unrelated donor. Post-transplantation cyclophosphamide (PTCy) is an effective method of graft versus host disease (GVHD) prophylaxis and permits the use of T-cell replete grafts in settings were ex vivo manipulation is not feasible.

METHODS

A retrospective study among patients younger than 18 years, with a history of hematologic malignancies who underwent haplo-SCT between 2012 and 2016. All patients received a preparative regimen of fludarabine, busulfan, and 400 cGy total body irradiation or melphalan. Post-transplant GvHD prophylaxis consisted either of PTCy (50 mg/kg on Days + 3 and + 4) and cyclosporine (CSA) plus mycophenolate (MMF) (15 mg/kg/dose, thrice daily, per os), or mini-dose methotrexate (MTX; 5 mg/m² dose) on Days + 5, +7, +10, and + 15.

RESULTS

A total of 52 children were included, whose median age was 9 years (interquartile range, 4.9-14; range, 1.2-17 years), and 63% were males. The most common complications were cytomegalovirus reactivation (57%) and hemorrhagic cystitis (36%). The acute GVHD prophylaxis was PTCy, CSA, and mini-dose MTX in 42 (81%) patients, and 10 (19%) patients received PTCy, CSA, and MMF. The cumulative incidence of acute GvHD II-IV, acute GvHD III-IV, and chronic GvHD were 42%, 8.5%, and 19%, respectively. Grades I-IV acute GvHD occurred in 100% of the patients who received prophylaxis with CSA and MMF, and 62% who received CSA and mini-dose MTX (p = .055). The transplant-related mortality at 100 days was 18%. The 5-year overall and event-free survival were 59% and 57%, respectively.

CONCLUSIONS

Haplo-SCT with PT/Cy can be an available, safe, and feasible option for children with hematologic malignancies; meanwhile, the use of mini-dose of MTX was associated with lower rates of acute GVHD. However, our results require further support from prospective randomized studies to improve the efficacy of this prophylactic strategy.

Standardized flattening filter free volumetric modulated arc therapy plans based on anteroposterior width for total body irradiation

In this work, the feasibility of using flattening filter free (FFF) beams in volumetric modulated arc therapy (VMAT) total body irradiation (TBI) treatment planning to decrease protracted beam‐on times for these treatments was investigated. In addition, a methodology was developed to generate standardized VMAT TBI treatment plans based on patient physical dimensions to eliminate plan optimization time. A planning study cohort of 47 TBI patients previously treated with optimized VMAT ARC 6 MV beams was retrospectively examined. These patients were sorted into six categories depending on height and anteroposterior (AP) width at the umbilicus. Using Varian Eclipse, clinical 40 cm × 10 cm open field arcs were substituted with 6 MV FFF. Mid‐plane lateral dose profiles in conjunction with relative arc output factors (RAOF) yielded how far a given multileaf collimator (MLC) leaf must move in order to achieve a mid‐plane 100% isodose for a specific control point. Linear interpolation gave the dynamic MLC aperture for the entire arc for each patient AP width category, which was subsequently applied through Python scripting. All FFF VMAT TBI plans were then evaluated by two radiation oncologists and deemed clinically acceptable. The FFF and clinical VMAT TBI plans had similar Body–5 mm D98% distributions, but overall the FFF plans had statistically significantly increased or broader Body–5 mm D2% and mean lung dose distributions. These differences are not considered clinically significant. Median beam‐on times for the FFF and clinical VMAT TBI plans were 11.07 and 18.06 min, respectively, and planning time for the FFF VMAT TBI plans was reduced by 34.1 min. In conclusion, use of FFF beams in VMAT TBI treatment planning resulted in dose homogeneity similar to our current VMAT TBI technique. Clinical dosimetric criteria were achieved for a majority of patients while planning and calculated beam‐on times were reduced, offering the possibility of improved patient experience.

High incidence of Pneumocystis jirovecii pneumonia in allogeneic hematopoietic cell transplant recipients in the modern era

BACKGROUND

International guidelines for Pneumocystis jirovecii pneumonia (PJP) prevention recommend prophylaxis for ≥6 months following allogeneic hematopoietic cell transplantation, and longer in patients with graft-versus-host disease (GVHD) or on immunosuppressive therapy (IST). These recommendations are based on cohorts of patients who did not routinely receive anti-thymocyte globulin (ATG) for GVHD prophylaxis.

METHODS

We performed a retrospective chart review of 649 patients, all of whom received ATG as part of GVHD prophylaxis.

RESULTS

The cumulative incidence of definite PJP was 3.52% at both 3 and 5 years (median follow up, 1648 days for survivors). PJP occurred in 13 non-GVHD patients between days 207 and 508, due in part to low CD4 T-cell counts (<200 CD4 T cells/µL). PJP occurred in eight GVHD patients between days 389 and 792, due in part to non-adherence to PJP prophylaxis guidelines (discontinuation of PJP prophylaxis at <3 months after discontinuation of IST). Breakthrough PJP infection was not observed in patients receiving prophylaxis with cotrimoxazole, dapsone or atovaquone, whereas three cases were observed with inhaled pentamidine.

DISCUSSION

In conclusion, for non-GVHD patients receiving ATG-containing GVHD prophylaxis, 6 months of PJP prophylaxis is inadequate, particularly if the CD4 T-cell count is <200 cells/µL or if there is a high incidence of PJP in the community. For patients with GVHD receiving ATG-containing GVHD prophylaxis, continuing PJP prophylaxis until ≥3 months post-discontinuation of IST is important. Cotrimoxazole, dapsone and atovaquone are preferred over inhaled pentamidine.

National survey on total-body irradiation prior to reduced-intensity stem cell transplantation in Japan: The Japanese Radiation Oncology Study Group

Reduced-intensity stem cell transplantation (RIST) minimizes the adverse effects of traditional hematopoietic stem cell transplantation, and low-dose total-body irradiation (TBI) is administered over a short period prior to RIST (TBI-RIST). Different institutes adopt different approaches for the administration of TBI-RIST, and since no study had previously investigated this issue, a survey of the TBI schedules in Japan was conducted. In October 2015, the Japanese Radiation Oncology Study Group initiated a national survey of TBI-RIST procedures conducted between 2010 and 2014. Of 186 institutions performing TBI, 90 (48%) responded to the survey, 78 of which performed TBI-RIST. Of 2488 patients who underwent TBI for malignant disease at these institutions, 1412 (56.8%) patients were treated for leukemia, 477 (19.2%) for malignant lymphoma, 453 (18.2) for myelodysplastic syndrome, 44 (1.8%) for multiple myeloma, and 102 (4.1%) for other malignant diseases. Further, 206 (52.0%) of 396 patients (a high proportion of patients) who underwent TBI for benign disease had aplastic anemia. The TBI-RIST equipment and treatment methods were similar to those used for myeloablative regimens. Routinely shielded organs included the lungs (43.6%), eyes (50.0%) and kidneys (10.2%). The ovaries (14.1%), thyroid (6.4%) and testicles (16.7%) were also frequently shielded, possibly reflecting an emphasis on shielding reproductive organs in children. TBI-RIST was performed more frequently than myeloablative conditioning in patients with benign disease. Genital and thyroid shielding were applied more frequently in patients treated with TBI-RIST than in patients treated with myeloablative conditioning. In conclusion, this study indicates the status of TBI-RIST in Japan and can assist future efforts to standardize TBI-RIST treatment methods and to design a future multicenter collaborative research study.

Clinical Outcomes of Fludarabine and Melphalan With an 800 cGy Total Body Irradiation Conditioning Regimen in Patients With Refractory or Relapsed Aggressive Non-Hodgkin Lymphoma Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

INTRODUCTION

Allogeneic hematopoietic stem cell transplant with reduced-intensity conditioning is an effective therapeutic option for patients with refractory or relapsed aggressive non-Hodgkin lymphoma (NHL).

PATIENTS AND METHODS

We retrospectively evaluated survival outcomes and the efficacy of our fludarabine/melphalan/total body irradiation (TBI) (FMT) regimen. A total of 89 patients had received the FMT regimen from 2007 to 2017.

RESULTS

The majority of patients (n = 81; 91%) belonged to the histologic subtype of aggressive NHL. The estimated 3-year overall survival and disease-free survival for the entire cohort during a median follow-up of 31 months were 47.1% (95% confidence interval, 36%-57%) and 45.4% (95% confidence interval, 35%-56%), respectively. The cumulative incidence rates of relapse and non-relapse mortality at 3 years were 33.1% and 13.8%, respectively. In analyses of risk factors affecting survival outcomes, chemosensitive disease status at transplant (hazard ratio [HR], 2.45; P = .010), delayed relapse after first-line chemotherapy (HR, 2.101; P = .009), no grade III to IV acute graft-versus-host disease (HR, 11.212; P < .001), and mild chronic graft-versus-host disease (HR, 0.448; P = .016) were independent significant predictors of favorable overall survival. Also, similar parameters were related to favorable disease-free survival. All non-hematologic toxicities occurred within 50 days after allogeneic hematopoietic stem cell transplant, and most of the adverse events were tolerable and manageable with a < 30% incidence.

CONCLUSION

Our FMT regimen shows favorable transplant outcomes with relatively low-risk toxicities, so it may be a promising strategy for patients with relapsed or refractory aggressive NHL.

Clinical significance of low-dose total body irradiation in HLA-mismatched reduced-intensity stem cell transplantation

The significance of low-dose total body irradiation (TBI) in HLA-mismatched reduced-intensity conditioning stem cell transplantation (RICT) remains unknown. We, retrospectively, evaluated the impact of low-dose TBI in patients with hematological malignancies who received first RICT from ≥1 antigen-mismatched donors between 2004 and 2014. Of the 575 patients, 361 patients received low-dose TBI (2 or 4 Gy). There were no significant differences in neutrophil engraftment or platelet recovery between TBI and non-TBI groups. The benefit of low-dose TBI on neutrophil engraftment was not observed in any subgroups. Low-dose TBI was not associated with decreased secondary graft failure. Suppressed mixed chimerism and autologous hematopoiesis by low-dose TBI was observed. There were no significant differences in cumulative incidences of acute GVHD or nonrelapse mortality rates in either group; however, low-dose TBI improved overall survival (OS), especially in patients with high-risk disease, multi-HLA mismatch, and fludarabine/busulfan conditioning. Multivariate analysis demonstrated that low-dose TBI was an independent prognostic factor for OS. Compared with the non-TBI group, 4 Gy TBI, but not 2 Gy TBI, was associated with increased acute GVHD and reduced relapse. These findings suggest that low-dose TBI may be beneficial for patients at high risk for relapse in HLA-mismatched RICT.

Rabbit Antithymocyte Globulin Serum Levels: Factors Impacting the Levels and Clinical Outcomes Impacted by the Levels

Antithymocyte globulin (ATG) levels and clearance vary significantly among patients receiving the same weight-based dose of ATG. To date, ATG area under the curve (AUC), its determinants, and its impact on clinical outcomes have been examined in pediatric hematopoietic cell transplant (HCT) and adult nonmyeloablative HCT. Here we set out to examine ATG AUC in 219 uniformly treated adults undergoing myeloablative allogeneic HCT at our institution. Sera were collected for the determination of pre- or post-HCT ATG AUC. The lowest quintiles of pre- and post-HCT AUC were associated with inferior chronic graft-versus-host disease (GVHD) and relapse-free survival (cGRFS) and a higher risk of acute GVHD, respectively. The highest pre- or post-HCT ATG AUC quintiles were not associated with risk of death, nonrelapse mortality, or relapse. Factors most strongly associated with AUC were day -2 recipient absolute lymphocyte count, body mass index (BMI), and graft lymphocyte content. To achieve ideal pre-HCT AUC (avoiding low AUC to maximize cGRFS) in this HCT setting, ATG dosing will need to take into consideration recipient weight, BMI, and blood and graft lymphocyte counts. Further studies are required to develop a modern ATG dosing schema and to demonstrate that adjusting ATG dose to target a particular AUC is feasible and leads to improved outcomes.

Patient eligibility for hematopoietic stem cell transplantation: a review of patient-associated variables

Assessing patient eligibility for hematopoietic stem cell transplantation (HSCT) remains a complex, multifaceted challenge. Among these challenges, the paucity of comprehensive clinical data to guide decision making remains problematic coupled with unclear trade-offs between patient, disease and local HSCT center factors. Moreover, it is unclear that the modification of poor patient characteristics will improve post-HSCT outcomes. However, the use of Comorbidity Indices and Comprehensive Geriatric Assessments helps meet this challenge, but may be limited by overlapping patient characteristics. The increasing consideration for pre-HSCT psychosocial assessments and interventions remains to be studied. Ultimately, the decision to proceed with a HSCT remains interdisciplinary while considering the available evidence discussed in this review.

Current practice in total-body irradiation: results of a Canada-wide survey

BACKGROUND

Total-body irradiation (tbi) is used to condition patients before bone marrow transplant. A variety of tbi treatment strategies have been described and implemented, but no consensus on best practice has been reached. We report on the results of a survey created to assess the current state of tbi delivery in Canada.

RESULTS

A 19-question survey was distributed to 49 radiation oncology programs in Canada. Responses were received from 20 centres, including 12 centres that perform tbi. A variety of tbi dose prescriptions was reported, although 12 Gy in 6 fractions was used in 11 of the 12 centres performing tbi. Half of the centres also reported using a dose prescription unique to their facility. Most centres use an extended-distance parallel-opposed-pair technique, with the patient standing or lying on a stretcher against a wall. Others translate the patient under the beam, sweep the beam over the patient, or use a more complicated multi-field technique. All but 1 centre indicated that they attenuate the lung dose; only 3 centres indicated attenuating the dose for other organs at risk. The survey also highlighted the considerable resources used for tbi, including extra staff, prolonged planning and treatment times, and use of locally developed hardware or software.

CONCLUSIONS

At transplant centres, tbi is commonly used, but there is no commonly accepted approach to planning and treatment delivery. The important discrepancies in practice between centres in Canada creates an opportunity to prompt more discussion and collaboration between centres, improving consistency and uniformity of practice.

Zoster prophylaxis after allogeneic hematopoietic cell transplantation using acyclovir/valacyclovir followed by vaccination

Varicella zoster virus (VZV) disease (usually cutaneous zoster) occurs frequently after hematopoietic cell transplantation (HCT), and postherpetic neuralgia (PHN) results in poor quality of life. The optimal prophylaxis of VZV disease/PHN has not been established. At our center, before 2008, VZV prophylaxis consisted of ∼1 year of post-HCT acyclovir/valacyclovir ("old strategy"), whereas post-2008 prophylaxis consisted of 2 years of acyclovir/valacyclovir followed by immunization using varicella vaccine ("new strategy"). We performed a retrospective study comparing the cumulative incidence of VZV disease and PHN among patients who completed the old strategy (n = 153) vs the new strategy (n = 125). Patients who completed the old strategy had a significantly higher cumulative incidence of VZV disease (33% vs 17% at 5 years, P ≤ .01) and PHN (8% vs 0% at 5 years, P = .02). In conclusion, VZV prophylaxis with 2 years of acyclovir/valacyclovir followed by vaccination appears to result in a low incidence of VZV disease and may eliminate PHN.

A Novel Reduced-Toxicity Myeloablative Conditioning Regimen Using Full-Dose Busulfan, Fludarabine, and Melphalan for Single Cord Blood Transplantation Provides Durable Engraftment and Remission in Nonremission Myeloid Malignancies

A pilot study of a novel, reduced-toxicity, myeloablative conditioning regimen using intravenous busulfan 12.8 mg/kg, fludarabine 180 mg/m(2), and melphalan 80 mg/m(2) for single cord blood transplantation (CBT) was conducted at our institution. Fifty-one patients with myeloid malignancies not in remission were included in this study. Their median age was 59 years (range, 19 to 70 years), with a median hematopoietic cell transplantation-specific comorbidity index score of 3. With a median observation period of 39.6 months (range, 24.3 to 90.8 months) among the survivors, overall survival and progression-free survival at 2 years were both 54.9%. Forty-six of 51 achieved neutrophil engraftment at a median of 19.5 days (range, 13 to 38 days) after transplantation, with a cumulative incidence of 90.2%. No patient developed graft rejection in this study. All patients who achieved engraftment showed hematological complete remission with complete donor chimerism. Eleven patients relapsed at a median of 4.9 months (range, .5 to 26.7 months). Cumulative incidences of nonrelapse mortality (NRM) at 100 days and 2 years were 11.8% and 25.5%, respectively. In conclusion, the present results show that the novel conditioning regimen for single CBT provided durable engraftment and remission with acceptable NRM leading to excellent survival, even for a relatively older population with myeloid malignancies not in remission.

Genetic network profiles associated with established resistance to ionizing radiation in acute promyelocytic leukemia cells and their extracellular vesicles

Radiation-resistant acute promyelocytic leukemia (APL) cells present challenges to treatment, and the acquisition of resistance to ionizing radiation (IR) is a matter of clinical concern. However, little information is available on the behavior of radio-resistant APL in terms of gene expression profiles and intercellular communication. In this study, cDNA microarray and RT-PCR were used to analyze the intracellular genetic network and extracellular vesicles (EVs), respectively, in the established radio-resistant HL60 (Res-HL60) cell line. Significant changes in the expression of 7,309 known mRNAs were observed in Res-HL60 relative to control. In addition, 7 mRNAs were determined as targets because significant changes in the expression were observed using Ingenuity analysis software, confirming the quantitative RT-PCR. However, EVs from Res-HL60 cells did not include these target molecules. These results suggest that radio-resistant APL is regulated by the expression and suppression of specific molecules, and these molecules are not transferred between cells by EVs.

Older recipient age is paradoxically associated with a lower incidence of chronic GVHD in thymoglobulin recipients: a retrospective study exploring risk factors for GVHD in allogeneic transplantation with thymoglobulin GVHD prophylaxis

Thymoglobulin (TG) given with conditioning for allogeneic haematopoietic SCT (alloHSCT) is effective in reducing the risk of acute and chronic GVHD (cGVHD). Whether conventional risk factors for GVHD apply to TG-conditioned alloHSCT is unknown. We retrospectively studied 356 adults from three centres who received TG 4.5 mg/kg prior to alloHSCT for haematologic malignancy. Donors were unrelated in 64%. At 3 years, OS was 61% (95% confidence interval (CI) 55-67%), cumulative incidence of relapse was 28% (95% CI 23-33%) and non-relapse mortality was 19% (14-24%). The cumulative incidences of grade 2-4, and grade 3-4 acute GVHD were 23% (95% CI 19-28%) and 10% (95% CI 6-13%), respectively. The cumulative incidence of cGVHD requiring systemic immunosuppression (cGVHD-IS) at 3 years was 32% (95% CI 27-37%). On multivariate analysis, counterintuitively, recipient age over 40 was associated with a significantly decreased risk of cGVHD-IS (P=0.001). We report for the first time a paradoxical association of older age with reduced cGVHD in TG recipients, and conclude that traditional risk factors for GVHD may behave differently in the context of pre-transplant TG.

Allogeneic hematopoietic cell transplantation for myelofibrosis using fludarabine-, intravenous busulfan- and low-dose TBI-based conditioning

Graft failure is one of the major barriers to the success of allogeneic hematopoietic cell transplantation (HCT) in myelofibrosis (MF). We report our institutional experience with 27 MF patients who underwent HCT using fludarabine-, intravenous BU- and low-dose total body irradiation (FBT)-based reduced-intensity (n=20) or full-intensity (n=7) conditioning regimens. Eight patients had prior exposure to JAK1/2 inhibitor therapy; six patients received JAK1/2 inhibitors leading on to HCT and two patients received transplant at the failure of JAK1/2 inhibitor therapy. No adverse impact of JAK1/2 inhibitor therapy was observed on early post-transplant outcomes. All evaluable patients had neutrophil recovery, and no primary graft failure was observed. Cumulative incidence of grades II-IV acute GVHD at day 100 was 48% (95% confidence interval (CI), 29-67%) and chronic GVHD at 2 years was 66% (95% CI, 49-84%). Cumulative incidences of nonrelapse mortality (NRM), relapse and probability of OS at 2 years were: 43% (95% CI, 12-74%), 10% (95% CI, 0-39%) and 56% (95% CI, 28-77%), respectively. FBT-based conditioning regimen has a favorable impact on engraftment; however, further efforts are required to reduce NRM.

Reduced-intensity allogeneic stem cell transplantation for co-emergence of chemotherapy-refractory follicular lymphoma and therapy-related myelodysplastic syndrome

A 54-year-old male was diagnosed with follicular lymphoma in September 2003. Despite multiple chemotherapies, including autologous hematopoietic stem cell transplantation (HSCT) with high-dose chemotherapy, the disease eventually relapsed. Additionally, bone marrow analysis revealed the co-emergence of therapy-related myelodysplastic syndrome (t-MDS) in February 2012. In March 2012, we performed related allogeneic HSCT for the treatment of both malignancies. This strategy was successful and the patient has remained free from both malignancies for 23 months. Allogeneic HSCT is a potent curative therapeutic option for both t-MDS and refractory follicular lymphoma.

Fludarabine and exposure-targeted busulfan compares favorably with busulfan/cyclophosphamide-based regimens in pediatric hematopoietic cell transplantation: maintaining efficacy with less toxicity

Busulfan (Bu) is used as a myeloablative agent in conditioning regimens before allogeneic hematopoietic cell transplantation (allo-HCT). In line with strategies explored in adults, patient outcomes may be optimized by replacing cyclophosphamide (Cy) with or without melphalan (Mel) with fludarabine (Flu). We compared outcomes in 2 consecutive cohorts of HCT recipients with a nonmalignant HCT indication, a myeloid malignancy, or a lymphoid malignancy with a contraindication for total body irradiation (TBI). Between 2009 and 2012, 64 children received Flu + Bu at a target dose of 80-95 mg·h/L, and between 2005 and 2008, 50 children received Bu targeted to 74-80 mg·h/L + Cy. In the latter group, Mel was added for patients with myeloid malignancy (n = 12). Possible confounding effects of calendar time were studied in 69 patients receiving a myeloablative dose of TBI between 2005 and 2012. Estimated 2-year survival and event-free survival were 82% and 78%, respectively, in the FluBu arm and 78% and 72%, respectively, in the BuCy (Mel) arm (P = not significant). Compared with the BuCy (Mel) arm, less toxicity was noted in the FluBu arm, with lower rates of acute (noninfectious) lung injury (16% versus 36%; P = .007), veno-occlusive disease (3% versus 28%; P = .003), chronic graft-versus-host disease (9% versus 26%; P = .047), adenovirus infection (3% versus 32%; P = .001), and human herpesvirus 6 infection reactivation (21% versus 44%; P = .005). Furthermore, the median duration of neutropenia was shorter in the FluBu arm (11 days versus 22 days; P < .001), and the patients in this arm required fewer transfusions. Our data indicate that Flu (160 mg/m(2)) with targeted myeloablative Bu (90 mg·h/L) is less toxic than and equally effective as BuCy (Mel) in patients with similar indications for allo-HCT.

Do different conditioning regimens really make a difference?

Over the past 15 years, the use of reduced-intensity/nonmyeloablative conditioning regimens before allogeneic hematopoietic stem cell transplantation has been increasing. Despite major disparities in the level of myeloablation, intensity of immunosuppression (including great diversity of in vivo T-cell depletion), and postgraft immunomodulation, the different approaches have contributed jointly to a modification of the stage of allogeneic stem cell transplantation: transplantation-related procedure mortality has been decreased dramatically, allowing allogeneic immunotherapy to be used in previously excluded populations, including elderly patients, young but clinically unsuitable patients, patients with lymphoid malignancies or solid tumors, and patients without an HLA-identical related or unrelated donor. Together, these diverse regimens have provided one of the biggest breakthroughs since the birth of allogeneic BM transplantation. However, consensus on how to reach the optimal goal of minimal transplantation-related mortality with maximum graft-versus-tumor effect is far from being reached, and further studies are needed to define optimal conditioning and immunomodulatory regimens that can be integrated to reach this goal. These developments, which will most likely vary according to different clinical situations, have to be compared continuously with advances achieved in traditional allogeneic transplantation and nontransplantation treatments. However, the lack of prospective comparative trials is and will continue to make this task challenging.

Pharmacology of dimethanesulfonate alkylating agents: busulfan and treosulfan

INTRODUCTION

Among the dimethanesulfonates, busulfan, in combination with other alkylating agents or nucleoside analogues, is the cornerstone of high-dose chemotherapy. It is used, and followed hematopoietic stem cell transplantation, for the treatment of various hematologic malignancies and immunodeficiencies. Treosulfan, which is a hydrophilic analogue of busulfan, was the first dimethanesufonate registered for the treatment of ovarian cancer. Recently, treosulfan has been investigated for the treatment of hematologic malignancies in combination with the same second agents before hematopoietic stem cell transplantation.

AREAS COVERED

This work reviews the pharmacological data of these two dimethanesulfonates alkylating agents. Specifically, the article looks at their chemistry, metabolism, anticancer activity, and their pharmacokinetics and pharmacodynamics.

EXPERT OPINION

Busulfan has been investigated widely for more than three decades leading to a large and precise handling of this agent with numerous studies on activity and pharmacokinetics and pharmacodynamics. In contrast, the behavior of treosulfan is still under investigation and not fully described. The complexity of treosulfan's metabolism and mechanism of action gives rise to the need of a deeper understanding of its pharmacological activity in a context of high-dose chemotherapy. Specifically, there is a great need to better understand its pharmacokinetics/pharmacodynamics relationship.

Two days of antithymocyte globulin are associated with a reduced incidence of acute and chronic graft-versus-host disease in reduced-intensity conditioning transplantation for hematologic diseases

BACKGROUND

The optimal combination of fludarabine, busulfan, and antithymocyte globulin (ATG) for reduced-intensity conditioning (RIC) transplantation has not been established. ATG plays a pivotal role in the prevention of graft-versus-host disease (GvHD), but it is associated with a higher relapse rate and an elevated incidence of infections when high doses are used.

METHODS

The authors retrospectively compared 2 different doses of ATG combined with fludarabine and busulfan in 229 adult patients who underwent transplantation at their institution. ATG was administered over 1 day (FBA1) or over 2 days (FBA2) at a daily dose of 2.5 mg/kg.

RESULTS

There were 124 patients in the FBA2 cohort and 105 patients in the FBA2 cohorts. Patients in the FBA2 cohort were older and more frequently underwent transplantation from an unrelated donor; 93% of patients in the FBA2 cohort received intravenous busulfan versus only 5% in the FBA1 cohort. The incidence of grade 2 through 4 acute GvHD was 23% in the FBA2 cohort versus 42% in the FBA1 cohort (P = .002); the incidence of grade 3 through 4 acute GvHD was 10% versus 23%, respectively (P = .006); and the incidence of chronic GvHD was 35% versus 69%, respectively (P < .0001). The 2-year rates of overall survival, nonrelapse mortality, and relapse/progression for the FBA1 and FBA2 cohorts were 65% versus 67%, respectively (P = .99), 20% versus 19%, respectively (P = .61), and 30% versus 19%, respectively (P = .09). The results were confirmed in multivariate analysis.

CONCLUSIONS

The use of ATG at a dose of 5 mg/kg was correlated significantly with reduced incidence and severity of GvHD without impairing disease control. Taken together, the current results suggest that this conditioning represents a step forward in the optimization of RIC.