Improved Outcomes in Intermediate- and High-Risk Aggressive Non-Hodgkin Lymphoma after Autologous Hematopoietic Stem Cell Transplantation Substituting Intravenous for Oral Busulfan in a Busulfan, Cyclophosphamide, and Etoposide Preparative Regimen

Toxicity analysis of busulfan pharmacokinetic therapeutic dose monitoring

Busulfan-based conditioning regimens are associated with serious toxicities and literature reports increased risk of toxicities when daily area under the curve concentrations exceed 6000 µM-minute. We implemented real time pharmacokinetic-guided therapeutic drug monitoring of busulfan for myeloablative conditioning regimens. The objective was to compare toxicity of intravenous busulfan before and after therapeutic drug monitoring implementation. The primary endpoint was incidence of hepatotoxicity. Medical records were retrospectively reviewed with weight-based dose Busulfan/Cyclophosphamide (BuCy) conditioning from August 2017 through March 2018 (N = 14) and therapeutic drug monitoring from April 2018 through December 2018 (N = 22). Recipients of busulfan therapeutic drug monitoring were younger than those receiving weight-based dose (median: 45 vs. 58 years, p = 0.008). No other baseline differences were observed. There was no difference in hepatotoxicity between therapeutic drug monitoring and weight-based dose (median 1 vs. 0 days, p = 0.40). In the therapeutic drug monitoring group, 45% of patients had increases and 41% had decreases in busulfan dose after Bu1. Repeat pharmacokinetic after Bu2 were required in 32% of patients. A pharmacokinetic dose monitoring program for myeloablative conditioning intravenous busulfan regimens may be considered a safe practice in stem cell transplant recipients. The majority of patients receiving pharmacokinetic-guided therapeutic drug monitoring required dose changes and therapeutic drug monitoring patients had no significant difference in toxicity compared to those receiving weight-based dose.

Decreased Systemic Busulfan Exposure After Oral Dosing With Concomitant Levetiracetam Compared With Phenytoin

BACKGROUND

Busulfan (Bu) conditioning used in hematopoietic stem cell transplantation may induce seizures, and prophylactic antiepileptic treatment is recommended. Following updated guidelines, in August 2019, the adult hematopoietic stem cell transplantation department of the Rambam Health Care Campus (Haifa, Israel) switched the antiepileptic prophylaxis protocol from phenytoin to oral levetiracetam during oral Bu conditioning. The aim of this study was to compare the pharmacokinetic parameters of Bu after oral dosing between patients receiving phenytoin and those receiving levetiracetam prophylaxis.

METHODS

This study was a retrospective cohort study in adults undergoing myoablative conditioning with oral Bu between August 2018 and August 2020. Bu pharmacokinetic parameters (AUC0-6, C0, Cmax, and Tmax) were compared in patients treated with phenytoin comedication (during the year before the change in policy) and levetiracetam comedication (during the year after the change). Potential confounders were accounted for including age, azole comedication, and body weight.

RESULTS

There were no significant differences in demographic and clinical parameters or weight-corrected Bu dose between the phenytoin group (n = 28) and the levetiracetam group (n = 25). There was no difference in the rate of voriconazole comedication, but fluconazole was more common in the phenytoin group (P = 0.026). The median AUC0-6 was significantly lower in the levetiracetam group (949 μM*min; IQR = 806 to 1101 μM*min) than in the phenytoin group (1208 μM*min; IQR = 1087 to 1389 μM*min; P < 0.001). This is a clinically significant difference of 258 μM*min (21%). Azole use was not associated with Bu exposure.

CONCLUSIONS

The findings suggest that, after treatment with oral Bu, oral levetiracetam comedication is associated with reduced systemic exposure compared with phenytoin comedication, possibly because of decreased bioavailability.

Phase II study of safety and efficacy of BEB (bendamustine, etoposide, and busulfan) conditioning regimen for autologous stem cell transplantation in non-Hodgkin lymphoma

Autologous stem cell transplant (ASCT) is an effective treatment for non-Hodgkin lymphoma (NHL). However, recent supply issues and toxicity of carmustine have necessitated a new conditioning regimen. We conducted a multicenter, phase II study of BEB (busulfan, etoposide, and bendamustine) conditioning regimen for ASCT in patients with NHL. Thirty-one patients were enrolled and underwent ASCT with the BEB conditioning regimen. The most common subtype was diffuse large B-cell lymphoma (n = 23, 74.2%). Nine patients (29.0%) had a history of relapse, and 18 patients (58.1%) received more than 2 lines of chemotherapy before ASCT. A median number of 6.05 × 10⁶/kg CD34 cells were infused, and all patients engrafted after a median period of 11 days. Thirteen patients (41.9%) experienced neutropenic fever, and 16 patients (51.6%) had grade 3 or 4 toxicities during ASCT. No one had a documented infection, veno-occlusive disease, or treatment-related death. Three-month complete remission rate was 81.8%. Median follow-up period of 15 months showed 6 patients (19.4%) relapsed or progressed and 3 patients died. The estimated 2-year progression-free survival and overall survival rate were 73.0% and 89.8%, respectively. Our results show that BEB conditioning regimens for ASCT are feasible with tolerable toxicity in patients with NHL.

Therapeutic Dose Monitoring of Busulfan Is Associated with Reduced Risk of Relapse in Non-Hodgkin Lymphoma Patients Undergoing Autologous Stem Cell Transplantation

Optimal administration of busulfan (Bu) is hampered by variable and unpredictable drug metabolism in individual patients. At our institution, Bu was previously administered with fixed weight-based dosing (WBD) in combination with cyclophosphamide (Cy) and etoposide (E) for patients with non-Hodgkin lymphoma (NHL) undergoing autologous stem cell transplantation (ASCT). In 2014, we adopted real-time pharmacokinetic (PK)-guided therapeutic drug monitoring (TDM) of Bu for all NHL patients undergoing Bu-containing ASCT. Here we compare outcomes of NHL patients who underwent ASCT with Bu/Cy/E using WBD and those who did so using TDM of Bu. We studied 336 consecutive adult NHL patients who underwent ASCT with Bu/Cy/E using WBD from January 2007 to December 2013 (n = 258) or TDM from May 2014 to December 2017 (n = 78), excluding patients with mantle cell lymphoma. Clinical outcomes, including relapse, nonrelapse mortality (NRM), progression-free survival (PFS), and overall survival (OS), hepatotoxicity and pulmonary toxicity were compared in the 2 groups. To adjust for differences in baseline characteristics between the groups, propensity-matched cohorts of WBD and TDM patients were also studied. After the first dose of Bu, the dose was increased in 36% of the patients and decreased in 41%. Changes in pulmonary and liver function from baseline to transplantation were not different between the 2 groups, although these changes showed significantly less variability with TDM than with WBD. Relapse was significantly lower and PFS was improved with TDM; 2-year estimates were 19% for TDM and 38% for WBD for relapse (P = .004) and 69% and 55%, respectively, for PFS (P = .038). No significant between-group differences in NRM or OS were seen. In multivariable analysis, TDM remained prognostic for lower risk of relapse (hazard ratio [HR], .52; 95% confidence interval [CI], .30 to .89; P = .018), but did not remain prognostic for PFS (HR, .74; 95% CI, .48 to 1.16; P = .19). Propensity-matched cohorts displayed similar patterns of outcomes. In subset analysis based on disease status at ASCT, TDM was associated with less relapse and better PFS than WBD for patients who underwent transplantation in less than complete remission (CR) compared with those who underwent transplantation in CR. Compared with WBD, PK-directed TDM of Bu reduces the incidence of relapse when used in combination with Cy and E for patients with NHL undergoing ASCT, particularly for patients in less than CR. These data support the continued use of personalized PK-guided dosing for all NHL patients undergoing ASCT with Bu-containing preparative regimens.

The effectiveness of busulfan-based conditioning regimens for stem cell transplantation against lymphomas in children, adolescents, and young adults in Japan

Conditioning regimens for stem cell transplantation (SCT) involving total body irradiation (TBI) are generally preferred over busulfan (BU)-based ones for lymphoid malignancies. However, reports of favorable results using BU against lymphomas have recently emerged. This study sought to compare the effectiveness of BU and TBI regimens for SCT against lymphomas. We retrospectively analyzed 893 lymphoma patients who underwent primary SCT in Japan between 1980 and 2015. The median age of all patients was 18 years (range, 0-30 years) with 589 males, 303 females, and 1 patient whose sex was unknown. Overall survival (OS) was not different between those receiving BU and TBI (P = 0.672). OS in patients receiving autologous SCT was significantly better with BU over TBI regimens (P = 0.038), particularly in children (0-15 years) (P = 0.024). Conversely, OS in adolescents and young adults (AYAs; 16-30 years) receiving allogeneic SCT was significantly worse with BU over TBI regimens (P = 0.035). Overall, BU regiments had comparable effectiveness to TBI conditioning regimens, and, although less effective for AYAs with allogeneic SCT, were particularly more effective than TBI regimens for children who received autologous SCT.

Pharmacokinetic and clinical outcomes when ideal body weight is used to dose busulfan in obese hematopoietic stem cell transplant recipients

Weight-based dosing of intravenous busulfan is widely used in hematopoietic cell transplantation. However, a variety of dosing weights have been described. The objective of this retrospective study was to determine the pharmacokinetic impact of using ideal body weight as the initial dosing weight in obese as compared to non-obese transplant recipients. The secondary objectives were to describe the use of alternative dosing weights, the impact on survival, and the rates of toxicities. The mean steady-state concentration was 779.3 ng/mL (n = 82) in the non-obese cohort and 673.7 ng/mL (n = 63) in the obese cohort (p < 0.001). A smaller proportion of concentrations were below goal in the non-obese cohort (10% vs. 41%, p < 0.001). Ideal body weight and adjusted body weights with a 25 and 40% correction factor are appropriate in non-obese patients; adjusted body weights with a 25 and 40% correction factor are appropriate in obese patients. There was no difference in overall survival (p = 0.18); there was a difference in median progression-free survival (1078 vs. 500 days, p = 0.045) in the non-obese compared to obese cohorts. The use of ideal body weight to dose busulfan resulted in lower steady-state concentrations, a larger proportion of subtherapeutic concentrations, and worse progression-free survival in obese patients.

Bendamustine-based conditioning prior to autologous stem cell transplantation (ASCT): Results of a French multicenter study of 474 patients from LYmphoma Study Association (LYSA) centers

Carmustine shortage has led to an increase use of alternative conditioning regimens prior to autologous stem cell transplantation for the treatment of lymphoma, including Bendamustine-based (BeEAM). The aim of this study was to evaluate the safety of the BeEAM regimen in a large cohort of patients. A total of 474 patients with a median age of 56 years were analyzed. The majority of patients had diffuse large B-cell lymphoma (43.5%). Bendamustine was administered at a median dose of 197 mg/m² /day (50-250) on days-7 and -6. The observed grade 1-4 toxicities included mucositis (83.5%), gastroenteritis (53%), skin toxicity (34%), colitis (29%), liver toxicity (19%), pneumonitis (5%), and cardiac rhythm disorders (4%). Nonrelapse mortality (NRM) was reported in 3.3% of patients. Acute renal failure (ARF) was reported in 132 cases (27.9%) (G ≥2; 12.3%). Organ toxicities and death were more frequent in patients with post conditioning renal failure. In a multivariate analysis, pretransplant chronic renal failure, bendamustine dose >160 mg/m² and age were independent prognostic factors for ARF. Pretransplant chronic renal failure, hyperhydration volume, duration of hyperhydration, and etoposide dose were predictive factors of NRM. A simple, four-point scoring system can stratify patients by levels of risk for ARF and may allow for a reduction in the bendamustine dose to avoid toxicity. Drugs shortage may have dangerous consequences. Prospective, comparative studies are needed to confirm the toxicity/efficacy extents from this conditioning regimen compared to other types of high dose therapy.

Personalizing Busulfan-Based Conditioning: Considerations from the American Society for Blood and Marrow Transplantation Practice Guidelines Committee

The Practice Guidelines Committee of the American Society of Blood or Marrow Transplantation (ASBMT) sought to develop an evidence-based review about personalizing busulfan-based conditioning. The Committee sought to grade the relevant published studies (June 1, 2008 through March 31, 2016) according to criteria set forth by the Steering Committee for Evidence Based Reviews from ASBMT. Unfortunately, the published literature was too heterogeneous and lacked adequately powered and sufficiently controlled studies for this to be feasible. Despite this observation, the continued interest in this topic led the Practice Guidelines Committee to develop a list of most frequently asked questions (FAQs) regarding personalized busulfan dosing. This "Considerations" document is a list of these FAQs and their responses, addressing topics of practical relevance to hematopoietic cell transplantation clinicians.

Efficacy of Pharmacokinetics-Directed Busulfan, Cyclophosphamide, and Etoposide Conditioning and Autologous Stem Cell Transplantation for Lymphoma: Comparison of a Multicenter Phase II Study and CIBMTR Outcomes

Busulfan, cyclophosphamide, and etoposide (BuCyE) is a commonly used conditioning regimen for autologous stem cell transplantation (ASCT). This multicenter, phase II study examined the safety and efficacy of BuCyE with individually adjusted busulfan based on preconditioning pharmacokinetics. The study initially enrolled Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) patients ages 18 to 80 years but was amended due to high early treatment-related mortality (TRM) in patients > 65 years. BuCyE outcomes were compared with contemporaneous recipients of carmustine, etoposide, cytarabine, and melphalan (BEAM) from the Center for International Blood and Marrow Transplant Research. Two hundred seven subjects with HL (n = 66) or NHL (n = 141) were enrolled from 32 centers in North America, and 203 underwent ASCT. Day 100 TRM for all subjects (n = 203), patients > 65 years (n = 17), and patients ≤ 65 years (n = 186) were 4.5%, 23.5%, and 2.7%, respectively. The estimated rates of 2-year progression-free survival (PFS) were 33% for HL and 58%, 77%, and 43% for diffuse large B cell lymphoma (DLBCL; n = 63), mantle cell lymphoma (MCL; n = 29), and follicular lymphoma (FL; n = 23), respectively. The estimated rates of 2-year overall survival (OS) were 76% for HL and 65%, 89%, and 89% for DLBCL, MCL, and FL, respectively. In the matched analysis rates of 2-year TRM were 3.3% for BuCyE and 3.9% for BEAM, and there were no differences in outcomes for NHL. Patients with HL had lower rates of 2-year PFS with BuCyE, 33% (95% CI, 21% to 46%), than with BEAM, 59% (95% CI, 52% to 66%), with no differences in TRM or OS. BuCyE provided adequate disease control and safety in B cell NHL patients ≤ 65 years but produced worse PFS in HL patients when compared with BEAM.

Daily Weight-Based Busulfan with Cyclophosphamide and Etoposide Produces Comparable Outcomes to Four-Times-Daily Busulfan Dosing for Lymphoma Patients Undergoing Autologous Stem Cell Transplantation

High-dose busulfan (Bu) is an integral component of commonly used preparative regimens for both allogeneic and autologous transplantation. There is significant interest in comparing the efficacy and toxicity of administering Bu every 6 (Bu6) or every 24 hours (daily Bu). To facilitate a therapeutic dose-monitoring protocol, we transitioned from Bu6 to daily Bu dosing for patients with Hodgkin and non-Hodgkin lymphoma undergoing autologous stem cell transplantation (ASCT). Here, we retrospectively review outcomes of 400 consecutive eligible lymphoma patients who underwent ASCT from 2007 to 2013 with high-dose busulfan (Bu), cyclophosphamide (Cy), and etoposide (E). Bu was given at a fixed dose of either .8 mg/kg every 6 hours for 14 doses for 307 patients or a fixed dose of 2.8 mg/kg every 24 hours for 4 doses (days -9 through -6) for 93 patients who underwent transplantation after the transition from Bu6 to daily Bu was made. Toxicity was assessed using pulmonary and liver function tests (LFT) at specified time points before and after ASCT. Baseline patient and disease characteristics of patients dosed with Bu6 and daily Bu were similar. There was no significant difference in forced expiratory volume in 1 second or diffusing capacity of the lungs for carbon monoxide before and after transplantation in the Bu6 versus daily Bu cohorts. Changes in LFTs with daily Bu were not significantly different than those with Bu6. There were no differences in relapse, nonrelapse mortality, progression-free survival, or overall survival between Bu6 and Bu 24 administration schedules in univariable or multivariable analysis (P ≥ .34). For a subset of 23 patients who had first-dose Bu levels measured, we observed significant variation in an median estimated cumulative area under the curve (AUC) of 17,568 µM-minute (range, 12,104 µM-23,084 µM-minute). In conclusion, daily Bu with Cy/E is more convenient than Bu6, has equivalent outcomes, and results in no increase in either hepatic or pulmonary toxicity. Consistent with previous reports, there is a significant range of Bu AUC levels, with a standard deviation of 13%. These data provide rationale for our prospective clinical trial of real-time therapeutic dose monitoring of Bu.

Thiotepa-based high-dose therapy for autologous stem cell transplantation in lymphoma: a retrospective study from the EBMT

Clinical information about thiotepa-based autologous stem cell transplantation (auto-SCT) outside the primary central nervous system lymphoma (PCNSL) field is sparse. In this registry-based retrospective study, we evaluated potential risks and benefits of thiotepa-based preparative regimens compared with BEAM (carmustine, etoposide, cytarabine, melphalan) in auto-SCT for diffuse large B-cell lymphoma (DLBCL, excluding PCNSL), follicular lymphoma (FL) or Hodgkin lymphoma (HL). A total of 14 544 patients (589 thiotepa and 13 955 BEAM) met the eligibility criteria, and 535 thiotepa- and 1031 BEAM-treated patients were matched in a 1:2 ratio for final comparison. No significant differences between thiotepa and BEAM groups for any survival end point were identified in the whole sample or disease entity subsets. For a more detailed analysis, 47 TEAM (thiotepa, etoposide, cytarabine, melphalan)-treated patients were compared with 75 matched BEAM patients with additional collection of toxicity data. Again, there were no significant differences between the two groups for any survival end point. In addition, the frequency of common infectious and non-infectious complications including secondary malignancies was comparable between TEAM and BEAM. These results indicate that thiotepa-based high-dose therapy might be a valuable alternative to BEAM in DLBCL, HL and FL. Further evaluation by prospective clinical trials is warranted.

Economic and clinical aspects of intravenous versus oral busulfan in adult patients for conditioning prior to HSCT

PURPOSE

Busulfan (BU) used as cytoreductive conditioning prior to hematopoietic stem cell transplantation (HSCT) is available as intravenous (IV) and oral (O) preparation. IV-BU has clinical advantages associated with relevant incremental costs. The aim was to determine the economic impact of IV-BU versus O-BU in adult HSCT recipients from a German health care providers' perspective.

METHODS

A budget-impact model (BIM) including costs and risks for oral mucositis (OM), infection with OM, and hepatic sinusoidal obstruction syndrome (SOS) was developed. Model inputs are literature data comparing clinical effects of IV-BU versus O-BU and German cost data (conditioning therapy, treatment of OM, infections, SOS without/with multiorgan failure) from literature and tariff lists.

RESULTS

Base case calculations resulted the following: total costs of adverse events were €86,434 with O-BU and €44,376 with IV-BU for ten patients each. Considering costs of adverse events and drugs, about €5840 for ten patients receiving IV-BU are saved. Sensitivity analyses were conducted in several ways. Cost savings range between €4910 and €12,640 per ten patients for all adverse events and €2070 or €1140 per ten patients considering SOS only. Drug treatment of SOS and treatment of multiorgan failure during severe SOS are major cost drivers. Worst case scenario calculations (assuming -25% risk of all adverse events for O-BU and +25% for IV-BU) yield up to €27,570 per ten patients with IV-BU.

CONCLUSIONS

Considering costs of adverse events and drugs, IV-BU is the dominant alternative from a German providers' perspective. For more comprehensive economic evaluations, additional epidemiological data, evidence on clinical outcomes, patient-reported outcomes, and treatment patterns are needed.

Outcomes after autologous SCT in lymphoma patients grouped by weight

Obesity continues to be an increasing global health issue contributing to the complexity of chemotherapy dosing in the field of SCT. Investigation into the optimal dosing weight used to calculate chemotherapy doses in obese patients undergoing SCT is limited and inconclusive. Our single-center, retrospective study compared safety and efficacy outcomes by body mass index (BMI) for 476 adult lymphoma patients who underwent auto-SCT with a myeloablative chemotherapeutic regimen of BU, CY and etoposide dosed using adjusted body weight. Three weight groups categorized based on BMI were defined: normal/underweight ⩽24.9 kg/m(2), overweight 25-29.9 kg/m(2) and obese ⩾30 kg/m(2). Severity of mucositis, incidence of secondary malignancy, incidence of bacteremia and median hospital length of stay did not differ among the groups. The median times to absolute neutrophil count and platelet recovery were 10 days (P=0.75) and 14 days (P=0.17), respectively. Obese patients had a lower 100-day mortality compared with other weight groups, although this did not translate into an OS benefit. OS and disease relapse were similar among the groups. Our study demonstrates that use of adjusted body weight to calculate chemotherapy doses does not negatively have an impact on outcomes in obese patients undergoing auto-SCT with BU, CY and etoposide.

Conditioning regimens in acute myeloid leukemia

Current intensive consolidation chemotherapy for patients with acute myeloid leukemia (AML) produces median remission duration of 12-18 months, with less than 30% of patients surviving 5 years free of disease. Post-remission therapy is necessary to prevent relapse in most patients with AML; therefore, the aim of post-remission treatment is to eradicate the minimal residual disease. Nevertheless, the optimal form of treatment is still under debate. The choice among the possible approaches (intensive chemotherapy, autologous or allogeneic hematopoietic stem cell transplantation) relies on two main factors: the expected risk of relapse, as determined by biological features, and expected morbidity and mortality associated with a specific option. In this review, we focus on the different preparative regimens before autologous and allogeneic hematopoietic stem cell transplantation in patients with AML, stressing the importance of an adequate conditioning regimen as a mandatory element of a successful AML therapy, in both the allogeneic and the autologous transplant setting.

Busulfan-containing conditioning regimens are optimal preparative regimens for autologous stem cell transplant in patients with diffuse large B-cell lymphoma

We retrospectively examined the outcomes of 56 patients with diffuse large B-cell lymphoma (DLBCL) who underwent autologous stem cell transplant (ASCT) with BEAM/BEAC (carmustine, etoposide, cytarabine, melphalan/cyclophosphamide) or busulfan (Bu)-containing conditioning regimens. The Bu group had lower disease-related mortality and more frequent achievement of complete remission (CR) after ASCT from partial remission (PR) or refractory status before ASCT compared with the BEAM/BEAC group. The estimated 2-year EFS (59.3% vs. 15.0%) and overall survival (OS) (70.2% vs. 42.0%) in pre-ASCT rituximab-exposed patients with DLBCL were higher in the Bu group. In patients with high-risk DLBCL exposed to rituximab with first remission, the Bu group had better EFS (p = 0.004) and OS (p = 0.053) rates, while survival rates for relapsed/refractory patients did not differ between groups. Bu regimens are highly effective for preparing patients with DLBCL with previous exposure to rituximab for ASCT, especially in high-risk patients who achieved a first remission.

Comparison of intravenous with oral busulfan in allogeneic hematopoietic stem cell transplantation with myeloablative conditioning regimens for pediatric acute leukemia

Recent reports revealed that intravenous (iv) busulfan (BU) may not only reduce early nonrelapse mortality (NRM) but also improve overall survival (OS) probability in adults. Therefore, we retrospectively compared outcomes for 460 children with acute leukemia who underwent hematopoietic stem cell transplantation with either iv-BU (n = 198) or oral busulfan (oral-BU) (n = 262) myeloablative conditioning. OS at 3 years was 53.4% ± 3.7% with iv-BU and 55.1% ± 3.1% with oral-BU; the difference was not statistically significant (P = .77). OS at 3 years in 241 acute lymphoblastic leukemia and 219 acute myeloid leukemia patients was 56.4% ± 5.5% with iv-BU and 54.6% ± 4.1 with oral-BU (P = .51) and 51.0% ± 5.0% with iv-BU and 55.8% ± 4.8% with oral-BU (P = .83), respectively. Cumulative incidence of relapse at 3 years with iv-BU was similar to that with oral-BU (39.0% ± 3.6% and 36.4% ± 3.1%, respectively; P = .67). Cumulative incidence of NRM at 3 years was 16.6% ± 2.7% with iv-BU and 18.3% ± 2.5% with oral-BU (P = .51). Furthermore, multivariate analysis showed no significant survival advantage with iv-BU. In conclusion, iv-BU failed to show a significant survival advantage in children with acute leukemia.

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.

Pharmacokinetic-directed high-dose busulfan combined with cyclophosphamide and etoposide results in predictable drug levels and durable long-term survival in lymphoma patients undergoing autologous stem cell transplantation

The clinical advantage of pharmacokinetic (PK)-directed-based dosing on intravenous (i.v.) versus oral busulfan-related toxicity and survival remains unclear. We performed a retrospective cohort study of sequential cohorts of patients comparing PK-directed oral and i.v. busulfan-based conditioning regimens in lymphoma patients undergoing autologous hematopoietic cell transplantation (ASCT). Patients received oral (n = 95), every 6 hours i.v. (IV16, n = 113), or once-daily i.v. (IV4, n = 86) busulfan, cyclophosphamide, and etoposide. PK-directed dosing was performed to achieve a predefined target area under the curve (AUC) of 20,000 μM-min (range: 18,400-21,600 μM-min). PK-directed dose adjustments markedly reduced the number of patients in the oral group with total AUC higher than the targeted AUC range, and reduced the variations of total AUC values in all patient groups. One hundred-day mortality was 2.1%, 3.6%, and 3.5% for oral, IV16, and IV4 cohorts, respectively. Five-year overall survival (OS) was 57% (95% confidence interval [CI] 45%-66%) and 64% (95% CI 53%-73%) for patients who received oral and i.v. busulfan, respectively. Both multivariable and instrumental variable analyses indicated the route of delivery had no significant impact on OS, whereas refractory disease and age ≥55 were significantly associated with poorer OS. In lymphoma patients undergoing ASCT, PK-directed i.v. or oral busulfan-based conditioning regimens have comparable toxicity and OS.

BeEAM (bendamustine, etoposide, cytarabine, melphalan) before autologous stem cell transplantation is safe and effective for resistant/relapsed lymphoma patients

We designed a phase 1-2 study to evaluate the safety and the efficacy of increasing doses of bendamustine (160 mg/m², 180 mg/m², and 200 mg/m² given on days -7 and -6) coupled with fixed doses of etoposide, cytarabine, and melphalan (BeEAM regimen) as the conditioning regimen to autologous stem cell transplantation for resistant/relapsed lymphoma patients. Forty-three patients (median age, 47 years) with non-Hodgkin (n = 28) or Hodgkin (n = 15) lymphoma were consecutively treated. Nine patients entered the phase 1 study; no patients experienced a dose-limiting toxicity. Thirty-four additional patients were then treated in the phase 2. A median number of 6 × 10⁶ CD34(+) cells/kg (range, 2.4-15.5) were reinfused. All patients engrafted, with a median time to absolute neutrophil count > 0.5 × 10⁹/L of 10 days. The 100-day transplantation-related mortality was 0%. After a median follow-up of 18 months, 35 of 43 patients (81%) are in complete remission, whereas 6 of 43 relapsed and 2 of 43 did not respond. Disease type (non-Hodgkin lymphomas vs Hodgkin disease) and disease status at transplantation (chemosensitive vs chemoresistant) significantly influenced DFS (P = .01; P = .007). Remarkably, 4 of 43 (9%) patients achieved the first complete remission after receiving the high-dose therapy with autologous stem cell transplantation. In conclusion, the new BeEAM regimen is safe and effective for heavily pretreated lymphoma patients. The study was registered at European Medicines Agency (EudraCT number 2008-002736-15).

The role of cytotoxic therapy with hematopoietic stem cell transplantation in the treatment of adult acute lymphoblastic leukemia: update of the 2006 evidence-based review

Clinical research published since the first evidence-based review on the role of hematopoietic stem cell transplantation (SCT) in the treatment of acute lymphoblastic leukemia (ALL) in adults is presented and critically evaluated in this update. Treatment recommendations changed or modified based on new evidence include: (1) myeloablative allogeneic SCT is an appropriate treatment for adult (<35 years) ALL in first complete remission for all disease risk groups; and (2) reduced-intensity conditioning may produce similar outcomes to myeloablative regimens. Treatment recommendations unchanged or strengthened by new evidence include: (1) allogeneic SCT is recommended over chemotherapy for ALL in second complete remission or greater; (2) allogeneic is superior to autologous SCT; and (3) there are similar survival outcomes after related and unrelated allogeneic SCT. New treatment recommendations based on new evidence include: (1) in the absence of a suitable allogeneic donor, autologous SCT may be an appropriate therapy, but results in a high relapse rate; (2) it is appropriate to consider cord blood transplantation for patients with no HLA well-matched donor; and (3) imatinib therapy before and/or after SCT (for Ph+ ALL) yields significantly superior survival outcomes. Areas of needed research in the treatment of adult ALL with SCT were identified and presented in the review.

Linearity and stability of intravenous busulfan pharmacokinetics and the role of glutathione in busulfan elimination

High-dose busulfan (Bu) is frequently used in preparative myeloablative conditioning (MAC) regimens for patients undergoing hematopoietic stem cell transplantation (HSCT). MAC and reduced-intensity conditioning (RIC) protocols for i.v. Bu infusion have been developed to achieve reliable systemic exposure while minimizing toxicity and treatment failure (relapse). The objectives of the present study were to (1) compare the pharmacokinetics (PK) of i.v. Bu in different dosing protocols, (2) compare intrasubject variability of Bu PK over repeated administrations; (3) examine the effect of concomitant administration of fludarabine on Bu PK, and (4) examine the effect of plasma concentrations of glutathione (GSH), the cosubstrate in Bu metabolism, on Bu clearance. We studied Bu PK twice in each of 46 HSCT patients (after the first and then after the middle dose of the treatment cycle) receiving one of 4 dosing protocols, 2 MAC (cumulative dose, 12.8 mg/kg) and 2 RIC (cumulative dose, 6.4 mg/kg), with daily doses administered either as an individual infusion (3.2 mg/kg) or as 4 infusions of 0.8 mg/kg each. Blood samples were obtained for 6-24 hours after dosing for measurement of Bu plasma concentrations. PK parameters were estimated using compartmental analyses. In a subgroup of patients (n = 14), GSH blood concentrations were determined before Bu administration. Dose- and weight-corrected Bu PK parameters (clearance, 0.173 ± 0.051 L/hour · kg; volume of distribution, 0.71 ± 0.17 L/kg; half-life time, 3.0 ± 0.7 hours) did not differ among treatment protocols (all P >.14) and remained stable between the first and mid-cycle doses. Fludarabine did not affect Bu PK. Blood GSH concentrations before Bu dosing were positively correlated with Bu clearance (adjusted R(2) = 0.45; P = .009). Our data indicate that Bu PK parameters are linear, stable, and predictable in different i.v. protocols and are unaffected by coadministration of fludarabine. Differences in whole blood GSH might contribute to variability in Bu clearance.

Pediatric immunohematopoietic stem cell transplantation at a tertiary care center in Cape Town

INTRODUCTION AND STUDY DESIGN: We conducted a retrospective analysis of consecutive referrals of patients under 18 years of age undergoing immunohematopoietic stem cell transplantation to assess the influence of age, diagnosis, graft type and gender on survival. We also contrasted program activity and outcome to that reported from a state hospital in the same geographical area over a comparable period.

METHODS

Conditioning employed either a sequential combination of fractionated 12Gy whole body and 6Gy total nodal irradiation separated by 120mg/kg of cyclophosphamide in patients over 15 years of age. Alternatively, the latter agent was combined initially with oral busulphan and later the intravenous equivalent. Neuroblastoma cases were prepared using a different regimen. In allografts the harvested product underwent ex vivo T-cell depletion with the humanized version of anti-CD 52 monoclonal antibody designated Campath 1H. No additional immunosuppression was given except where matched unrelated volunteer donors were employed.

RESULTS

Sixty-eight procedures were carried out in 61 patients over a 6-year period. Of 11 with acute myeloid leukemia, 8 are alive and well whereas 8 of the 14 with the lymphoblastic variant have died. Of the remaining 12 with hematologic malignancy, all but 2 are alive. Ten of the 17 with aplasia are alive as are all with thalassemia or sickle cell disease. None of the four variables tested affected survival.

CONCLUSION

Our analysis indicates that the standardized preparative regimen, coupled with a now well-established immunosuppressive regimen, is as effective in patients under 18 years of age as in adults. Our analysis also indicates that in a resource-scarce or developing country, it is mandatory to limit high-risk and relatively expensive procedures to active teams that enjoy international accreditation, whether these be in the state or private sector.

Busulfan in hematopoietic stem cell transplant setting

This paper focuses primarily on the data published in the last decade about the pharmacokinetics and pharmacodynamics of oral and intravenous (i.v.) busulfan, therapeutic drug monitoring and clinical outcome in hematopoietic stem cell transplant (HCT) patients. Busulfan is commonly used in HCT as it is toxic to the marrow. Busulfan is available as oral or i.v. formulation. The most common significant toxicity of busulfan is sinusoidal obstruction syndrome. Even with the introduction of i.v. busulfan, variability in the systemic concentrations of busulfan after weight-based dosing and the association between busulfan plasma exposure and outcome in HCT patients have led to the continued use of therapeutic drug monitoring of busulfan. New strategies for personalizing busulfan dosing are being studied to maximize the use of busulfan for optimal disease control with the least toxicity to HCT patients. One such strategy currently being evaluated is if busulfan clearance can be accurately predicted by genetic polymorphism of glutathione S-transferase (GST), with the currently available data suggesting that GST polymorphisms cannot be used to personalize busulfan dosing.

Busulfan and cyclophosphamide (Bu/Cy) as a preparative regimen for autologous stem cell transplantation in patients with non-Hodgkin lymphoma: a single-institution experience

High-dose chemotherapy with autologous stem cell transplantation (ASCT) has been established as a standard form of therapy for patients with non-Hodgkin lymphoma (NHL). While many high-dose chemotherapy combinations are used, no single regimen has proved superior over another. Here, we report our single center's experience in patients with NHL undergoing ASCT with the combination of busulfan and cyclophosphamide (Bu/Cy). This study is a retrospective analysis of 78 consecutive patients with NHL who underwent ASCT with Bu/Cy at Massachusetts General Hospital Cancer Center. Data were collected through review of electronic medical records. A total of 78 patients with NHL underwent ASCT with Bu/Cy preparative therapy between 1996 and 2006. Median follow-up for survivors was 5.0 years (range, 6 months to 12 years). Significant transplantation-associated complications included 9 documented bacterial infections, 4 cases of engraftment syndrome, 3 cases of hepatic veno-occlusive disease (VOD), 6 cases of cardiac complications, and 2 cases of pulmonary fibrosis. The 100-day treatment-related mortality (TRM) was 1%. At 3 years, progression-free survival (PFS) was 48% (95% confidence interval [CI]=37% to 59%) and overall survival (OS) was 65% (95% CI=53% to 74%). Our data indicate that in patients with NHL undergoing ASCT, Bu/Cy has efficacy and toxicity comparable to that of other reported regimens.

Busulfan in hematopoietic stem cell transplantation

The development of intravenous busulfan (Bu) and its incorporation in the preparative regimens for allogeneic stem cell transplantation has changed transplantation for myelogenous malignancies. Bypassing the oral route to achieve 100% bioavailability translated into improved control over drug administration, with increased safety and reliability of generating therapeutic Bu levels, maximizing antileukemic efficacy. Bu-nucleoside analog-based conditioning chemotherapy, thus far represented by fludarabine (Flu), is becoming the conditioning chemotherapy regimen of choice for patients with acute myelogenous leukemia (AML) at many transplant centers. The use of busulfan Bu-based conditioning is extending rapidly also to hematopoietic stem cell transplantation (HSCT) for lymphoid malignancies, genetic diseases, and umbilical cord blood transplantation.

Once-daily intravenous busulfan with therapeutic drug monitoring compared to conventional oral busulfan improves survival and engraftment in children undergoing allogeneic stem cell transplantation

Because of intra- and interindividual variability, bioavailability, and pharmacokinetics of busulfan (Bu) in children, oral busulfan without therapeutic drug monitoring (TDM) is assumed to be associated with higher graft failure rates as well as higher toxicity (eg, veno-occlusive disease [VOD]). This study compares the outcome of hematopoietic stem cell transplantation (HSCT) of 2 groups: 1) 30 patients who received myeloablation with once-daily intravenous (i.v.) dose-targeted busulfan (BUdtIV) based on TDM and 2) 30 patients who received the current practice of untargeted oral busulfan (BUPO). Patients received a 3-hour infusion of Bu at a first dose of 120 mg/m(2) (age >or=1 year) or 80 mg/m(2) (<1 year), or BUPO 1 mg/kg 4 times daily. Both regimens were continued for 4 days. The target area under the curve (AUC) was defined as 17,500 microg *h/l. BUdtIV resulted in higher event-free survival (EFS) and survival rates compared to BUPO (EFS: 30% versus 83%, P < .001, survival: 53% versus 83%, P = .016). BUdtIV was associated with more cases of VOD. TDM was feasible in routine clinical practice. The results show that i.v. Bu using TDM is preferable over oral Bu in children undergoing allogeneic stem cell transplantation, especially in those at high risk for graft failure/relapse.

Multicenter study of intravenous busulfan, cyclophosphamide, and etoposide (i.v. Bu/Cy/E) as conditioning regimen for autologous stem cell transplantation in patients with non-Hodgkin's lymphoma

The current study aimed to evaluate the efficacy and toxicity of a combination of intravenous busulfan, cyclophosphamide and etoposide (i.v. Bu/Cy/E) as a conditioning regimen prior to autologous hematopoietic stem cell transplantation in patients with non-Hodgkin's lymphoma (NHL). Sixty-four patients with relapsed/refractory (n=36) or high-risk (n=28) lymphoma were enrolled. The high-dose chemotherapy consisted of i.v. Bu (0.8 mg kg(-1) i.v. q 6 h from day -7 to day -5), Cy (50 mg kg(-1) i.v. on day -3 and day -2) and E (400 mg m(-2) i.v. on day -5 and day -4). The median age was 43 (range 18-65) years, and 39 patients were male. Diffuse large B-cell lymphoma (40.6%) was the most common histological subtype. All evaluable patients achieved an engraftment of neutrophils (median, day 12) and platelets (median, day 13). Hepatic veno-occlusive disease was observed in four patients (three mild, one moderate grade), and two patients (3.1%) died from treatment-related complications. At a median follow-up of 16.4 months, 15 patients (23.4%) exhibited a relapse or progression, while 13 patients (20.3%) had died of disease. The estimated 3-year overall and progression-free survival for all patients was 72.1 and 70.1%, respectively. In conclusion, the conditioning regimen of i.v. Bu/Cy/E was well tolerated and seemed to be effective in patients with aggressive NHL.