Pharmacokinetic disposition and clinical outcomes in infants and children receiving intravenous busulfan for allogeneic hematopoietic stem cell transplantation.

We conducted a retrospective pharmacokinetic analysis of i.v. busulfan in children undergoing hematopoietic stem cell transplantation (HSCT) and describe its relation to transplantation outcomes. Forty-five children (median age, 3 yr) underwent HSCT at The Hospital for Sick Children from April 2003 through January 2006 and received i.v. busulfan every 6 h as part of their conditioning regimen. Initial busulfan doses were based on actual patient weight: <9 kg, 0.95 mg/kg per dose; 9-16 kg, 1.2 mg/kg per dose; 16-23 kg, 1.1 mg/kg per dose; 24-34 kg, 0.95 mg/kg per dose; >34 kg, 0.8 mg/kg per dose. Plasma busulfan concentrations were obtained after the first dose. The fourth and subsequent busulfan doses were adjusted to achieve an area under the concentration versus time curve (AUC) of 900-1500 microM.min. Development of hepatic venous occlusive disease (HVOD; modified Baltimore criteria) and engraftment (absolute neutrophil count >or=0.5 x 10(9)/L) were evaluated. Busulfan pharmacokinetic parameters were calculated using 1-compartment methods. Mean busulfan pharmacokinetic parameters were maximum concentration (C(max); 4.7 +/- 0.75 microM), volume of distribution at steady state (0.68 +/- 0.17 L/kg), elimination rate constant (0.0051 +/- 0.0010 min(-1)), total body clearance (3.5 +/- 1.23 mL/[min.kg]), and AUC (1271 +/- 280 microM.min). Mean volume of distribution at steady state was larger in children <1 yr of age (0.77 +/- 0.24 vs 0.64 +/- 0.11 L/kg; P = .040) and children <4 yr of age (0.73 +/- 0.18 vs 0.60 +/- 0.11 L/kg; P = .001) than in older children. Compared with older children, mean weight-adjusted total body clearance was higher in children <4 yr of age (3.8 +/- 1.40 versus 3.0 +/- 0.76 mL/[min.kg]). HVOD was diagnosed in 8 children (18%), including 4 children <1 yr of age. Children who developed HVOD achieved a lower C(max) than did those without HVOD (4.2 +/- 0.68 versus 4.8 +/- 0.73 microM; P = .035). Other than C(max), no association was observed between busulfan disposition and development of HVOD in children for whom i.v. busulfan doses were adjusted to achieve a target AUC. The influence of factors other than busulfan disposition on transplantation outcomes, such as genetic polymorphisms, should be evaluated.     

Cyclophosphamide following targeted oral busulfan as conditioning for hematopoietic cell transplantation: pharmacokinetics, liver toxicity, and mortality.

The pharmacokinetics of cyclophosphamide (CY) and its metabolites hydroxycyclophosphamide and carboxyethylphosphoramide mustard were determined in 75 patients receiving targeted oral busulfan followed by i.v. CY ((T)BU/CY) and in 147 patients receiving i.v. CY followed by total body irradiation (CY/TBI) in preparation for hematopoietic cell transplantation (HCT). In the (T)BU/CY patients only, the association of the pharmacokinetic data with liver toxicity, relapse, and survival was evaluated. CY was infused at 60 mg/kg/day over 1 or 2 hours on 2 consecutive days; the majority of patients had BU levels targeted to a steady state plasma concentration (Css) of 800-900 ng/mL. Systemic exposure (i.e., area under the concentration-time curve [AUC]) of CY, hydroxycyclophosphamide, and carboxyethylphosphoramide mustard was measured. Liver toxicity was assessed as the development of hepatic sinusoidal obstruction syndrome (SOS). CY metabolism was highly variable and age dependent. (T)BU/CY-treated patients had lower AUC(CY) (P < .0001), higher AUC(HCY) (P < .0001), and higher AUC(CEPM) (P = .15) than CY/TBI-conditioned patients. Among patients receiving (T)BU/CY, 17 (23%) developed SOS, and there were no statistically significant associations between the AUC of CY or its metabolites and SOS, nonrelapse mortality, relapse, or survival (all P >.15). In conclusion, CY exhibits conditioning-regimen dependent pharmacokinetics and pharmacodynamics, suggesting that lowering CY doses is unlikely to improve outcomes to (T)BU/CY. Alternative strategies, such as administering i.v. busulfan or CY before BU, should be explored.     

Evaluation of safety and pharmacokinetics of administering intravenous busulfan in a twice-daily or daily schedule to patients with advanced hematologic malignant disease undergoing stem cell transplantation.

Intravenous busulfan (i.v. BU) has demonstrated safety when administered at 0.8 mg/kg per dose i.v. every 6 hours x 16 doses. We evaluated the safety and pharmacokinetics (PK) of giving the same total daily i.v. BU dose (3.2 mg/kg) either divided as a twice-daily infusion or as a single infusion to patients undergoing hematopoietic stem cell transplantation (HSCT). Twelve patients with hematologic malignant disease were treated; 7 patients had non-Hodgkin's lymphoma, 4 patients had acute myeloid leukemia, and 1 patient had chronic myelogenous leukemia. The first cohort (group A) received, on the basis of actual body weight, i.v. BU at 1.6 mg/kg per dose over 4 hours every 12 hours for 4 days (day -7 to day -4). The second cohort (group B) received 3.2 mg/kg per dose of i.v. BU (same total dose as group A) as a single infusion over 4 hours daily for 4 days. In both groups the i.v. BU was followed by cyclophosphamide 60 mg/kg daily for 2 days (day -3 and day -2). Blood specimens were collected on the first, fifth, and seventh doses for group A and on the first and fourth doses for group B to determine the disposition of i.v. BU. Peripheral blood stem cells (autologous in 7 cases and HLA-matched allogeneic in 5 cases) were given 2 days after completion of cyclophosphamide administration (day 0), and granulocyte colony-stimulating factor 5 microg/kg was started on the same day. GVHD prophylaxis consisted of tacrolimus plus methotrexate for recipients of allogeneic stem cells. One patient developed presumed fungal pneumonia and died of multisystem organ dysfunction on day +21 before hematologic reconstitution could be evaluated. Another was reported to have sudden death of undetermined cause at home on day 40. The remaining patients had engraftment (absolute neutrophil count >500/microL) at a median of 11 days and sustained platelet counts >20,000/microL at a median of 14 days. Significant regimen-related toxicity (grade III-IV) was limited to hepatic toxicity (2 cases) catheter infection (2 cases), epistaxis (3 cases), diarrhea (1 case), anorexia (1 case), mucositis (1 case), hyperglycemia (1 case), pneumonia (1 case), and sepsis (1). In group B there was 1 case of mild venoocclusive disease, which resolved without sequelae. No central nervous system or pulmonary toxicity was noted. Pharmacokinetic parameters, including clearance, half-life, maximum concentration, and area under the curve, demonstrated that the first dose profile was highly predictive of later dose PK profiles. No accumulation of the drug was noted. The change in dosing schedule did not increase toxicity or end-organ damage despite higher plasma concentration-times. Although further study for long-term efficacy is warranted, i.v. BU can be given safely with reproducible results on a twice-daily divided or single-daily dosing schedule to patients undergoing HSCT.     

Busulfan Pharmacokinetics and Precision Dosing: Are Patients with Fanconi Anemia Different?

It is well known that pharmacokinetics (PK)-guided busulfan (BU) dosing increases engraftment rates and lowers hepatotoxicity in patients undergoing hematopoietic cell transplantation (HCT). However, there are no published PK data in patients with Fanconi anemia (FA), who are known to have baseline DNA repair defect and related inherent sensitivity to chemotherapy. In our prospective, multi-institutional study of alternative donor HCT for FA using chemotherapy-only conditioning, we replaced the single dose of total-body irradiation with BU at initial doses of 0.8 to 1.0 mg/kg and 0.6 to 0.8 mg/kg given i.v. every 12 hours for 4 doses. Patients received the first dose of i.v. busulfan on day –8, and blood levels for PK were obtained. PK samples were drawn following completion of infusion. BU PK levels were collected at 2 hours, 2 hours and 15 minutes, and 4, 5, 6, and 8 hours from the start of infusion. The remaining 3 doses of BU were given on days –7 and –6. Thirty-seven patients with available BU PK data with a median age of 9.2 years (range, 4.3 to 44 years) are included in the final analyses. The overall BU PK profile in patients with FA is similar to non-FA patients after considering their body weight. In our cohort, a strong correlation between BU clearance and weight supports current practice of per kilogram dosing. However, not surprisingly, we show that the disease (ie, host) sensitivity related to FA is the main determinant of total dose of BU that can be safely administered to patients in this high-risk population. On the basis of our results, we propose an optimal BU concentration at steady-state level of ≤350 ng/mL (equivalent to total cumulative exposure of 16.4 mg*h/L for 4 doses over 2 days) for patients with FA undergoing HCT. To our knowledge, this is the first and largest report of prospective BU PK in patients with FA undergoing HCT, providing an optimal BU target cutoff to achieve stable donor engraftment while avoiding excessive toxicity.     

Dose modification protocol using intravenous busulfan (Busulfex) and cyclophosphamide followed by autologous or allogeneic peripheral blood stem cell transplantation in patients with hematologic malignancies.

We evaluated the safety and toxicity through a 5-cohort dose-modification model of once-daily administration of IV busulfan (Bu) in combination with high-dose cyclophosphamide (Cy) as preparative therapy for stem cell transplantation. Twenty-one adult patients with hematologic malignancies were evaluated. Eleven patients underwent autologous and 10 patients underwent HLA-matched sibling allogeneic transplantation. Patients were sequentially enrolled into 5 cohorts. Cohort 1 received intravenous (IV) Bu 1.6 mg/kg every 12 hours for 2 doses and then 0.8 mg/kg every 6 hours for 12 doses; cohort 2 received IV Bu 1.6 mg/kg every 12 hours for 4 doses and then 0.8 mg/kg every 6 hours for 8 doses; cohort 3 received IV Bu 3.2 mg/kg for 1 dose and then 1.6 mg/kg every 12 hours for 2 doses and 0.8 mg/kg every 6 hours for 8 doses; cohort 4 received IV Bu 3.2 mg/kg every 24 hours for 2 doses and then 0.8 mg/kg every 6 hours for 8 doses; and cohort 5 received IV Bu 3.2 mg/kg every 24 hours for 4 doses. In all groups, Bu was administered on day -7 through day -4 and was followed at least 6 hours after the last Bu dose by Cy 60 mg/kg daily for 2 doses on days -3 and -2. Blood samples were collected for pharmacokinetic analysis on the first and last day of IV Bu administration. All patients were alive and had engrafted at day 30. Five patients developed grade 3 or 4 toxicities. Four patients developed hepatic abnormalities, and 3 exhibited evidence of veno-occlusive disease. Two of 3 patients in cohort 5 with a Bu area under the curve >6000 micromol/min developed autopsy-confirmed veno-occlusive disease. Interpatient variability in AUCs was observed in patients within and between cohorts, but no statistically significant interpatient differences were observed in Bu half-life, volume of distribution, clearance, or dose-adjusted area under the curve. Further, minimal variability in Bu pharmacokinetics was observed between the 2 evaluations performed in each patient, thus reflecting the stability of Bu disposition within individual patients. On the basis of the dosing guidelines and schedule outlined in this study, our data suggest that administration of IV Bu 3.2 mg/kg IV every 24 hours for 4 doses in combination with Cy may result in excessive toxicity.     

Highly variable pharmacokinetics of once-daily intravenous busulfan when combined with fludarabine in pediatric patients: phase I clinical study for determination of optimal once-daily busulfan dose using pharmacokinetic modeling

Busulfan has a narrow therapeutic range, and in children, pharmacokinetic variability has been found to be high even after the use of intravenous (i.v.) busulfan. Recently, a reduced toxicity myeloablative regimen showed promising results, but the data of busulfan pharmacokinetics in hematopoietic stem cell transplantation (HSCT) using a targeted busulfan/fludarabine regimen in children has not yet been reported. We performed therapeutic drug monitoring (TDM) after once-daily i.v. busulfan combined with fludarabine and analyzed the outcomes. Busulfan (i.v.) was administered once daily for 4 consecutive days. The daily target area under the curve (AUC) was 18,125-20,000 μg*h/L/day (4415-4872 μmol*min/L/day), which was reduced to 18,000-19,000 μg*h/L/day (4384-4628 μmol*min/L/day) after a high incidence of toxicity was observed. A total of 24 patients were enrolled. After infusion of busulfan on the first day, patients showed AUC that ranged from 12,079 to 31,660 μg*h/L (2942 to 7712 μmol*min/L) (median 16,824 μg*h/L, percent coefficient of variation (%CV) = 26.5%), with clearance of 1.74-6.94 mL/min/kg (median 4.03 mL/min/kg). We performed daily TDM in 20 patients, and during the daily TDM, the actual AUC ranged from 73% to 146% of the target AUC, showing high intraindividual variability. The %CV of busulfan clearance of each individual ranged from 7.7% to 38.7%. The total dose of busulfan administered for 4 days ranged from 287.3 mg/m(2) to 689.3 mg/m(2). Graft failure occurred in 3 patients with total AUC less than 74,000 μg*h/L (18,026 μmol*min/L), and 2 patients with relatively high total AUC experienced veno-occlusive disease. Busulfan pharmacokinetics showed high inter- and intraindividual variability in HSCT using a targeted busulfan/fludarabine regimen, which indicates the need for intensive monitoring and dose adjustment to improve the outcome of HSCT. Currently, we are performing a newly designed phase II study to decrease regimen-related toxicities and reduce graft failure by setting an optimal target AUC based on this study.     

Adult recipients of matched related donor blood cell transplants given myeloablative regimens including pretransplant antithymocyte globulin have lower mortality related to graft-versus-host disease: a matched pair analysis.

Because pretransplantation anti-thymocyte globulin (ATG) seems to reduce graft-versus-host-disease (GVHD) and treatment-related mortality (TRM) after unrelated donor bone marrow transplantation (BMT), we investigated this agent in matched related donor (MRD) blood cell transplantation (BCT). Fifty-four adults receiving rabbit ATG, cyclosporine A, and methotrexate with myeloablative conditioning and undergoing first MRD BCT were matched for disease and stage with 54 patients not given ATG. Most ATG-treated patients had fludarabine with oral (7) or i.v. busulfan (46) with total body irradiation (TBI) in 10. Control patients largely received TBI with VP16 (28) or oral busulfan with cyclophosphamide (15) or fludarabine (7). The ATG was given at a total dose of 4.5 mg/kg over 3 d, finishing on day 0. Rates of acute GVHD (aGVHD) grade II-IV, aGVHD grade III-IV, and chronic GVHD (cGVHD) were 19 +/- 5% versus 32 +/- 6% (P = .1), 6 +/- 3% versus 13 +/- 5% (P = NS), and 55 +/- 8% versus 96 +/- 3% (P = .002) in the ATG and control groups, respectively. Patients given ATG had fewer sites involved by cGVHD compared with the control group (mean 2.1 +/- 0.2 versus 2.8 +/- 0.2, P = .04). Non-relapse mortality (NRM) with and without ATG, respectively, was 4 +/- 3% versus 17 +/- 5% at 100 d and 9 +/- 4% versus 34 +/- 7% at 4 yr (P = .002). Deaths were GVHD related in 3 ATG-treated patients versus 14 controls (P = .007). Despite a trend to more relapse with ATG (43 +/- 7% versus 22 +/- 7% at 4 yr, P = 0.05), survival was 66 +/- 7% in the patients given ATG versus 50 +/- 7% in the controls (P = 0.046). This study indicates that myeloablative regimens incorporating fludarabine and oral or i.v. busulfan with pretransplantation ATG given to recipients undergoing MRD BCT may result in less cGVHD, lower TRM, and probably improved quality of life in survivors compared with previous protocols.     

Once-daily intravenous busulfan given with fludarabine as conditioning for allogeneic stem cell transplantation: study of pharmacokinetics and early clinical outcomes.

The availability of an i.v. form of busulfan (Bu) has prompted investigation of administration schedules other than the 4-times-daily dosage commonly used with oral Bu. We have studied an allogeneic stem cell transplantation (SCT) preparative regimen comprising fludarabine (FLU) 50 mg/m2 on days -6 to -2 plus i.v. Bu 3.2 mg/kg daily in a 3-hour infusion on days -5 to -2. The regimen was given to 70 patients aged 15 to 64 years (median, 41 years) with hematologic malignancy. Thirty-six patients (51%) had high-risk malignancy, 28 (40%) had unrelated or genotypically mismatched related donors (alternate donors [AD]) and 29 (41%) received bone marrow rather than blood as stem cell source. Acute GVHD prevention comprised antithymocyte globulin 4.5 mg/kg over 3 days pretransplantation, cyclosporin A, and short-course methotrexate with folinic acid. Hepatic toxicity was transient and there was no clinically diagnosed veno-occlusive disease. Grade II stomatitis occurred in 49 patients (70%) and hemorrhagic cystitis in 9 patients (13%). One patient with subtherapeutic phenytoin levels had a convulsion 8 hours after the third i.v. Bu dose, but no other neurotoxicity was apparent. Incidence of acute GVHD grades II to IV was 8% and incidence of grade III-IV was 3%, with no deaths from this cause. Actuarial incidence of chronic GVHD at 2 years is 38%. There were 2 cases of graft failure in unrelated donor BMT recipients, 1 of which was reversed by asecond transplantation. With a median follow-up of 16 months (range, 6-27 months), transplantation-related mortality at 100 days and 2 years was 2% and 5% for matched related donor (MRD) SCT and 8% and 19% for AD SCT, respectively (P = not significant). Relapse rates were 21% for 34 patients with acute myeloid leukemia (AML) in complete remission or chronic myeloid leukemia in chronic phase (low-risk), 66% for 19 patients with high-risk AML, and 18% for 17 patients with other active malignancy. Projected disease-free and overall survival rates at 2 years were 74% and 88% for low-risk disease, 26% and 37% for advanced AML, and 65% and 71% for other high-risk disease, respectively. Pharmacokinetic studies were done using 11 samples with the first and fourth doses of Bu. Kinetics were linear, and for the first and fourth doses, the half-lives were 2.60 +/- 0.44 and 2.57 +/- 0.36 hours, respectively. Clearances were 106.77 +/- 16.68 and 106.86 +/- 21.57 mL/min per m2, peak concentrations (Cmax) were 3.92 +/- 0.31 and 3.96 +/- 0.28 mcg/mL, and Bu areas under the plasma concentration versus time curve (AUC) were 4866.51 +/- 771.42 and 4980 +/- 882.80 microM x min, respectively. Bu was completely cleared within 24 hours and the day 4 pharmacokinetic values were very similar to those on day 1 for every patient. The cumulative AUC was comparable to the target range established for p.o. Bu. This regimen incorporating once-daily i.v. Bu is convenient to give, is relatively well tolerated, gives predictable blood levels, and deserves further study in circumstances in which cytoreduction as well as immune suppression is needed.     

Costs and Outcomes with Once-Daily versus Every-6-Hour Intravenous Busulfan in Allogeneic Hematopoietic Cell Transplantation

The high cost of healthcare in the United States has not been consistently associated with improved health outcomes or quality of care, necessitating a focus on value-based care. We identified busulfan dosing frequency during allogeneic hematopoietic cell transplantation (HCT) conditioning as a potential target for optimization. To improve patient convenience and to decrease the cost of busulfan-based conditioning regimens, our institution changed busulfan dose frequency from every 6 hours (q6h) to once-daily (q24h). We compared costs and patient outcomes between these 2 dosing schedules. In June 2017, our institution transitioned from q6h to q24h busulfan dosing. We compared patients who received busulfan/cyclophosphamide conditioning regimens (BU/CY) for allogeneic HCT in the year before the dosing change (q6h cohort) and those who did so in the year after the dosing change (q24h cohort). The primary outcomes were differences in cost, day +90 mortality, and day +90 relapse. Between June 1, 2016, and June 1, 2018, 104 patients (median age 49 years; range, 20 to 63 years) received BU/CY before allogeneic HCT. Fifty-nine patients (57%) received q6h busulfan and 45 (43%) received q24h busulfan. There were fewer men in the q24h busulfan cohort compared with the q6h busulfan cohort (42% versus 64%; P = .024), but there were no other significant differences between the groups. There was an average annual cost savings of $19,990 per patient with q24h busulfan compared with q6h busulfan, and an annual busulfan cost savings of $899,550. There was a significantly lower day +90 mortality in the q24h busulfan cohort compared to the q6h busulfan cohort (0% versus 10%; P = .028). There were no significant differences in relapse at day +90 or in hospital length of stay. Our data indicate that i.v. busulfan dosing for allogeneic HCT conditioning is a target for improved value-based care. At our institution, patients who received q24h busulfan dosing had similar or superior outcomes compared with those receiving q6h dosing, with an average annual cost reduction of $19,990 per patient and an overall annual reduction in busulfan cost of approximately $900,000. These data support the adoption of q24h i.v. busulfan dosing as a standard of care to improve value-based care in allogeneic HCT.     

Cyclophosphamide followed by Intravenous Targeted Busulfan for Allogeneic Hematopoietic Cell Transplantation: Pharmacokinetics and Clinical Outcomes

Targeted busulfan (^TBU) and cyclophosphamide (CY) for allogeneic hematopoietic cell transplantation carries a high risk of sinusoidal obstruction syndrome (SOS) in patients undergoing transplantation for myelofibrosis. We tested the hypothesis that reversing the sequence of administration (from ^TBU/CY to CY/^TBU) would reduce SOS and day +100 nonrelapse mortality. We enrolled 51 patients with myelofibrosis (n = 20), acute myelogenous leukemia (n = 20), or myelodysplastic syndrome (n = 11) in a prospective trial of CY/^TBU conditioning for allogeneic hematopoietic cell transplantation. CY 60 mg/kg/day i.v. for 2 days was followed by daily i.v. BU for 4 days, targeted to a concentration at steady state (Css) of 800-900 ng/mL. Compared with ^TBU/CY-conditioned patients, CY/^TBU-conditioned patients had greater exposure to CY (P < .0001) and less exposure to 4-hydroxycyclophosphamide (P < .0001). Clinical outcomes were compared between cases and controls (n = 271) conditioned with ^TBU/CY for the same indications. In patients with myelofibrosis, CY/^TBU conditioning was associated with a significantly reduced incidence of SOS (0% versus 30% after ^TBU/CY; P = .006), whereas the incidence of SOS was low in both cohorts with acute myelogenous leukemia/myelodysplastic syndrome. Day +100 mortality was significantly lower in the CY/^TBU cohort (2% versus 13%; P = .01). CY/^TBU conditioning had a marked affect on the pharmacokinetics of CY and was associated with significantly lower incidence of SOS and day +100 mortality, suggesting that CY/^TBU is superior to ^TBU/CY as conditioning for patients with myelofibrosis.     

Pharmacokinetics and individualized dose adjustment of intravenous busulfan in children with advanced hematologic malignancies undergoing allogeneic stem cell transplantation.

We investigated the pharmacokinetics (PK) of a recently approved intravenous busulfan (IVBU) formulation as a part of the preparative regimen in 20 children with advanced hematologic malignancies undergoing allogeneic hematopoietic stem cell transplantation. Seventeen patients received a thiotepa, IVBU, and cyclophosphamide-based regimen, and 3 patients received an IVBU and cyclophosphamide-based regimen. All patients received IVBU 0.8 mg/kg for the first 2 doses; thereafter, the IVBU dose was modified, if required, to achieve a final area under the concentration-time curve (AUC) at steady state of 1150 micromol/L/min per dose (range, 1000-1300 micromol/L/min per dose; SD +/-13%) based on the first-dose PK determination. PK studies were repeated on subsequent doses to verify the final AUC. Initial mean IVBU clearance and half-life were 3.96 mL/min/kg and 1.98 hours, respectively. Sixteen (80%) of the 20 patients received dose adjustments: 14 patients required dose escalations, and 2 required dose reductions. Overall, thirteen (72%) of 18 available sample sets at final follow-up PK analysis showed the IVBU exposure to be within the targeted range. IVBU PK was linear, and interpatient variability was much lower than that observed with oral busulfan. IVBU was well tolerated, and no case of hepatic veno-occlusive disease was encountered. Mild and transient hyperbilirubinemia was observed in 7 patients. Thirteen of the 20 patients were alive at a median follow-up of 651 days (range, 386-1555 days). We conclude that a standardized IVBU dose of 0.8 mg/kg in children does not always result in an AUC within the reference range defined in this study. Therapeutic drug monitoring with dose adjustment based on first-dose PK can optimize the systemic busulfan exposure for children undergoing allogeneic hematopoietic stem cell transplantation.     

Randomized trial of sequential administration of G-CSF and GM-CSF vs. G-CSF alone following peripheral blood progenitor cell autograft in solid tumors.

A trial was conducted to investigate whether the sequential administration of recombinant human granulocyte colony-stimulating factor (G-CSF) and recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) could accelerate reconstitution of hematopoiesis, compared with G-CSF alone following high-dose chemotherapy (HDCT). A group of 34 consecutive patients with solid tumors undergoing HDCT and autologous peripheral blood progenitor cell (PBPC) transplantation was studied. Conditioning regimen included carboplatin, etoposide, mitoxantrone, and melphalan for breast cancer and cyclophosphamide or ifosfamide, carboplatin, and etoposide for the other tumors. HDCT was delivered from day -3 to day -1. PBPC were infused on day 0, and on the same day growth factors were administered subcutaneously (s.c.) 5 microg/kg each. Seventeen patients were randomized to receive G-CSF from day 0 to day 13 after HDCT (arm A), and 17 patients received G-CSF from day 0 to day 6 and GM-CSF from day 7 to day 13 (arm B). Patients were stratified, and their characteristics were homogeneous in both arms for age, performance status, and number of previous chemotherapy courses and CD34+ infused. The median time to absolute neutrophil count (ANC) >500/microl was 10 days in arm A and 9 days in arm B (p = 0.96). Days to platelet (PLT) count >20,000 were not different in the two treatment arms (p = 0.1), but patients randomized to arm A had a lower platelet count compared with patients in arm B. One month after PBPC transplantation, a statistically significant difference in PLT count was observed (arm A median 150x10(3)/microl (90-310), arm B median 254x10(3)/microl (117-387),p = 0.0013). The days patients had fever >38 degrees C were 39 in arm A and 26 in arm B (p = 0.18). The difference in the length of hospital stay was not statistically significant between the groups (Mann-Whitney sum rank test). After a median follow-up of 30 months, 21 patients were alive and 20 were disease free. These data show that the two growth factors are associated with different patterns of hematopoietic recovery, and larger randomized trials in groups of more homogeneous patients will be needed to define the effects and benefits of combination growth factor therapies.     

Pharmacokinetics of once-daily IV busulfan as part of pretransplantation preparative regimens: a comparison with an every 6-hour dosing schedule.

In pretransplantation therapy busulfan is typically given every 6 hours. We infused busulfan once daily at 130 mg/m2 for 4 days, performing pharmacokinetic analyses on plasma concentration-time data (n = 60 patients) on days 1, 3, and/or 4. Mean (percent coefficient of variation) maximum concentration, volume of distribution, half-life, and clearance were 3.6 microg/mL (13.8%), 22.6 L/m2 (20.2%), 2.73 hours (27.5%), and 109 mL/min/m2 (26%), respectively. The mean (percent coefficient of variation) and median daily areas under the curve were 4873 (21.8%) and 4871 microM x minute. Intrapatient variability in day-to-day estimated clearance was <20%, without day-to-day drug accumulation. The pharmokinetic parameters were compared with those from 47 patients given intravenous busulfan at approximately 0.8 mg/kg (approximately 32 mg/m2) every 6 hours. We conclude that there is (1) a dose proportionality based on mean and median areas under the curve, (2) unchanged estimated clearance with a 4-fold increase in dose and a 2.5-fold difference in dosing rate, (3) negligible variability in dose-to-dose pharmacokinetics and negligible interdose accumulation with once-daily administration, and (4) no change in pharmokinetic parameter(s) with concomitant use of imidazole antifungals, oral contraceptives, or phenytoin. In summary, intravenous busulfan has highly predictable, linear pharmacokinetics from 32 mg/m2 (approximately 0.8 mg/kg) to 130 mg/m2 (approximately 3.2 mg/kg). Further, once-daily intravenous busulfan dosing is convenient, favoring its more widespread application.     

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.

Forty-nine patients with intermediate- and high-risk aggressive non-Hodgkin lymphoma underwent autologous hematopoietic stem cell transplantation (autoHSCT) using the regimen of busulfan (Bu), cyclophosphamide (Cy), and etoposide (E) that was originally developed for allogeneic HSCT. Eighteen patients treated before 1999 received Cy 2.5 g/m2 on days -3 to -2 and E 1800 mg/m2 on day -3 after oral (PO) administration of Bu 1 mg/kg every 6 hours x 4 days for a total of 16 doses beginning on day -7. After April 1999, 31 patients similar in all pretransplantation risk assessments received the same regimen except that intravenous (IV) Bu was substituted for PO Bu and pharmacokinetic-directed (PKD) dosing was attempted to achieve an area under the concentration time curve of 1000-1500 micromol/min for each dose. Nonrelapse mortality was 28% for PO Bu patients versus 3% for the IV PKD group (P = .01, chi-square test). Actuarial 5-year overall survivals were 28% for patients who received the PO Bu regimen and 58% for patients who received the IV Bu regimen (P = .010, log-rank test), and progression-free survivals were 17% and 50%, respectively (P = .008, log-rank test). After substitution of PKD IV Bu in the BuCyE regimen, we observed lower nonrelapse mortality with increased overall and progression-free survivals in patients with intermediate- and high-risk aggressive non-Hodgkin lymphoma who underwent autoHSCT.     

Busulfan- or Thiotepa-Based Conditioning in Myelofibrosis: A Phase II Multicenter Randomized Study from the GITMO Group

We report a randomized study comparing fludarabine in combination with busulfan (FB) or thiotepa (FT), as conditioning regimen for hematopoietic stem cell transplantation (HSCT) in patients with myelofibrosis. The primary study endpoint was progression-free survival (PFS).Sixty patients were enrolled with a median age of 56 years and an intermediate-2 or high-risk score in 65%, according to the Dynamic International Prognostic Staging System (DIPSS). Donors were HLA-identical sibling (n = 25), matched unrelated (n = 25) or single allele mismatched unrelated (n = 10). With a median follow-up of 22 months (range, 1 to 68 months), outcomes at 2 years after HSCT in the FB arm versus the FT arm were as follows: PFS, 43% versus 55% (P = .28); overall survival (OS), 54% versus 70% (P = .17); relapse/progression, 36% versus 24% (P = .24); nonrelapse mortality (NRM), 21% in both arms (P = .99); and graft failure, 14% versus 10% (P = .96). A better PFS was observed in patients with intermediate-1 DIPSS score (P = .03). Both neutrophil engraftment and platelet engraftment were significantly influenced by previous splenectomy (hazard ratio [HR], 2.28; 95% confidence interval [CI], 1.16 to 4.51; P = .02) and splenomegaly at transplantation (HR, 0.51; 95% CI, 0.27 to 0.94; P = .03). In conclusion, the clinical outcome after HSCT was comparable when using either a busulfan or thiotepa based conditioning regimen.     

Randomized comparison of granulocyte colony-stimulating factor versus granulocyte-macrophage colony-stimulating factor plus intensive chemotherapy for peripheral blood stem cell mobilization and autologous transplantation in multiple myeloma.

Autologous peripheral blood stem cell transplantation for multiple myeloma offers higher response rates and improved survival compared with conventional chemotherapy. However, successful autografting requires effective cytoreduction and rapid hematologic reconstitution. We conducted a prospective randomized clinical trial to assess the efficacy of 2 cycles of priming chemotherapy with either granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) for peripheral blood stem cell mobilization followed by autologous transplantation. The major study end points were the comparative utility of G-CSF versus GM-CSF, the percentage of patients achieving complete response after transplantation, and overall and progression-free survival. Priming chemotherapy included cyclophosphamide (4 g/m2), mitoxantrone (8 g/m2 every day for 2 days), and dexamethasone (20 mg/m2 every 12 hours for 2 days) followed by randomization to either G-CSF or GM-CSF daily until completion of leukapheresis. Conditioning for transplantation included cyclophosphamide (75 mg/kg every day for 2 days) plus total body irradiation (165 cGy twice daily for 3 days), and patients received maintenance immunotherapy with interferon alpha. Seventy-two patients were randomized, and 64 underwent autologous transplantation. The median age at transplantation was 52 years, and the median time from diagnosis to transplantation was 10 months; 58% of the patients had received >4 cycles of pretransplantation chemotherapy. The median number of CD34+ cells obtained after mobilization was 16.4 x 10(6)/kg in the G-CSF arm versus 12.8 x 10(6)/kg in the GM-CSF arm (P = .8). Neutrophil recovery was faster in the G-CSF group after both cycle 1 (median, 13 days with G-CSF and 16 days with GM-CSF; P < .01) and cycle 2 (median, 13 days versus 17 days in the 2 groups, respectively; P = .03). Although platelet recovery was similar after cycle 1, platelet recovery to >100000/microL was notably faster in the G-CSF group both after cycle 2 and after transplantation (P = .03). Response and overall and disease-free survival were similar in both cohorts. Overall, 23% of the patients achieved a complete response after priming chemotherapy, which improved to 33% after transplantation. An additional 47% attained a partial response after transplantation, for a total response rate of 80%. With a median follow-up of 2 years (range, 0.7-8 years), the overall survival was 88% (95% confidence interval [CI], 80%-96%) at 1 year and 65% (95% CI, 51%-79%) at 3 years. Progression-free survival was 73% (95% CI, 62%-84%) at 1 year and 40% (95% CI, 26%-54%) at 3 years. Relapse or progressive disease was the most common cause of death (25 [83%] of 30 deaths). We conclude that mobilization with chemotherapy plus G-CSF versus GM-CSF results in similar CD34+ progenitor collections, even in patients exposed to multiple cycles of alkylator-based chemotherapy. Earlier neutrophil and platelet recovery was seen with G-CSF priming. Two cycles of priming chemotherapy plus autologous transplantation yields survival rates similar to those in published reports, including those using tandem transplantation.     

Cardiac allograft acceptance after localized bone marrow transplantation by isolated limb perfusion in nonmyeloablated recipients

Donor-specific tolerance to cardiac grafts may be induced by hematopoietic chimerism. This study evaluates the potential of localized bone marrow transplantation (BMT) performed by isolated limb (IL) perfusion to induce tolerance to secondary cardiac grafts without myeloablative conditioning. BALB/c recipients (H2d) preconditioned with lethal and sublethal doses of busulfan were injected i.v. and IL with 10(7) whole bone marrow cells (wBMCs) from B10 donors (H2(b)). Two hours after IL infusion of PKH-labeled wBMCs into myeloablated hosts, there were few labeled cells in the host peripheral blood (p < 0.001 versus i.v.) and femurs of the infused limb contained 57% +/- 7% PKH-labeled blasts (p < 0.001 versus 8% +/- 0.6% after i.v.). Femurs of the noninfused limbs contained 60-70 PKH-labeled blasts (p < 0.001 versus i.v.-BMT) after 2 days and 47% +/- 5% of 0.32 x 10(7) donor cells (p < 0.001 versus 78% +/- 4% of 1.2 x 10(7) donor cells in infused femurs) after 4 weeks. The survival rates of myeloablated hosts were 90% and 80% after i.v. and IL infusion, respectively, and the chimeras had 78%-84% donor peripheral blood cells. In recipients conditioned with 35 mg/g busulfan, the levels of donor chimerism in peripheral blood were 33% +/- 4% and 21% +/- 4% at 3 weeks after i.v.- and IL-BMT, respectively. Transplantation of donor-matched (H2(b)) secondary vascularized hearts in these chimeras after 3 weeks resulted in graft survival for periods exceeding 8 weeks, while third-party (H2(k)) allografts were acutely rejected (p < 0.001 versus H2(b)). These data indicate that IL perfusion is a reliable alternative procedure for establishment of hematopoietic chimerism and donor-specific tolerance without myeloablative conditioning.     

Prospective Randomized Study Comparing Myeloablative Unrelated Umbilical Cord Blood Transplantation versus HLA-Haploidentical Related Stem Cell Transplantation for Adults with Hematologic Malignancies

In this prospective randomized study, we compared the outcomes of single-unit umbilical cord blood transplantation (UCBT) and unmanipulated haploidentical stem cell transplantation (haplo-SCT) with post-transplantation cyclophosphamide (PTCy) in adults with hematologic malignancies. All patients received a myeloablative conditioning (MAC) regimen consisting of thiotepa, busulfan, and fludarabine, with antithymocyte globulin (ATG) added for UCBT recipients. Nineteen patients were randomized to UCBT and the other 26 to haplo-HSCT. Four patients (15%) allocated to the haplo-HSCT arm lacked a suitable donor and were crossed over to the UCBT arm. Finally, 23 underwent UCBT and 22 underwent haplo-HSCT. The cumulative incidence of neutrophil recovery was 87% at a median of 19 days (range, 13 to 24 days) in the UCBT arm versus 100% at a median of 17 days (range, 13 to 25 days) in the haplo-SCT arm (P = .04). Platelet recovery was 70% at a median of 40 days (range, 18 to 129 days) in the UCBT arm versus 86% at a median of 24 days (range, 12 to 127 days) in the haplo-HCT arm (P = .02). Rates of acute graft-versus-host disease (GVHD) grade II-IV or grade III-IV, overall chronic GVHD, and extensive chronic GVHD in the UCBT and Haplo-SCT arms were 43% versus 36% (P = .8), 9% versus 9% (P = 1), 66% versus 43% (P = .04), and 41% versus 23% (P = .2), respectively. Two-year nonrelapse mortality and relapse in the 2 arms were 52% versus 23% (P = .06) and 17% versus 23% (P = .5), respectively. Two-year disease-free survival, overall survival, and GVHD/relapse-free survival in the 2 arms were 30% versus 54% (P = .2), 35% versus 59% (P = .1), and 17% versus 40% (P = .04), respectively. Our data show that in the context of an MAC regimen, haplo-SCT with PTCy provides improved outcomes compared with ATG-containing single-unit UCBT.     

Quantification of busulfan in plasma by liquid chromatography-ion spray mass spectrometry. Application to pharmacokinetic studies in children.

Optimisation of busulfan dosage in patients undergoing bone marrow transplantation is recommended in order to reduce toxic effects associated with high drug exposure. A new method was developed coupling liquid chromatography with mass spectrometry (LC-MS) and was validated for the determination of busulfan concentrations in plasma. Recovery was 86.7%, the limit of detection was 2.5 ng/ml and linearity ranged from 5 to 2500 ng/ml. The correlation between the busulfan concentrations measured by our previously published HPLC-UV method and the new HPLC-MS method was highly significant (P<0.0001). Sample volume was reduced and the method was rapid, sensitive and less expensive than the methods previously used in our laboratory. This method was used to determine the pharmacokinetic parameters of busulfan after the first administration of 1 mg/kg orally, in 13 children receiving the drug as part of the preparative regimen for bone marrow transplantation. Our results were similar to previously reported data. They showed that the apparent oral clearance of busulfan was 0.299+/-0.08 l/h/kg, and that it was significantly higher (P=0.02) in patients below the age of 5 years than in older children.     

Dose Intensification of Busulfan in the Preparative Regimen is Associated with Improved Survival: A Phase I/II Controlled,Randomized Study

Dose intensity is important for disease control in patients undergoing allogeneic stem cell transplantation. We conducted a phase I/II controlled, adoptive, randomized study to determine the optimal dosing schedule of i.v. busulfan. Patients aged ≤75 years with advanced hematologic malignancies with human leukocyte antigen–compatible donor were eligible. All patients received fludarabine at 30 mg/m²/d for 4 days, and busulfan was administered in different doses in oral or i.v. formulations. As determined by the phase I trial, i.v. busulfan at a dose of 11.2 mg/kg/d was used for the phase II expansion cohort. Altogether, 80 patients with a median age of 56 years were enrolled. Forty percent had active disease at the time of transplantation. Engraftment occurred in 91%, and a complete response was achieved in 79% of patients posttransplantation. At a median follow-up of 91 months in the surviving patients, the outcomes for i.v. busulfan dose of 11.2 mg/kg/d versus other doses were as follows: nonrelapse mortality, 34% versus 23% (P = .4); cumulative incidence of relapse, 43% versus 68% (P = .02); relapse-free survival, 25% versus 9% (P = .017); and overall survival, 27% versus 9% (P = .02). We conclude that optimizing i.v. busulfan dose intensity in the preparative regimen may overcome disease-associated poor prognostic factors.