Dose Modification Protocol Using Intravenous

Home , Busulfan

Biology of Blood and Marrow Transplantation 10:614-623 (2004) 2004 American Society for Blood and Marrow Transplantation 1083-8791/04/1009-0004$30.00/0 doi:10.1016/j.bbmt.2004.05.010

Dose Modiﬁcation Protocol Using Intravenous Busulfan (Busulfex) and Cyclophosphamide Followed by Autologous or Allogeneic Peripheral Blood Stem Cell Transplantation in Patients with Hematologic Malignancies

Casey B. Williams,1 Suzanne D. Day,1 Michael D. Reed,2 Edward A. Copelan,3 Thomas Bechtel,3 Helen L. Leather,4 John R. Wingard,5 Brian L. Abbott,1 Sunil Abhyankar,1 Joseph P. McGuirk1

1Blood and Marrow Transplant Program of the Kansas City Cancer Centers and the Cancer Institute at Saint Luke’s Hospital, Kansas City, Missouri; 2Pharmacology Division, Case Western Reserve University, Cleveland, Ohio; 3Division of Hematology and Oncology, Ohio State University, Columbus, Ohio; 4Department of Pharmacy, University of Florida, Gainesville, Florida; 5Department of Medicine, University of Florida, Gainesville, Florida

Correspondence and reprint requests: Casey Williams, Pharm D, BCOP, Kansas City Blood and Marrow Transplant Program, 4320 Wornall, Suite 220, Kansas City, MO 64111 (e-mail: [email protected]).

Received October 10, 2003; accepted May 10, 2004 ABSTRACT 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 ␮mol/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. © 2004 American Society for Blood and Marrow Transplantation

KEY WORDS Busulfan ● Once-daily ● Bone marrow transplant ● Cyclophosphamide

INTRODUCTION alternative Bu administration schedules other than the 4-times-daily dosing schedule often used. Studies in The availability of an intravenous (IV) formulation patients undergoing BMT for hematologic malignan- of busulfan (Bu) combined with the desire to shift care cies suggest that IV Bu (IV Busulfex; ESP Pharma, to the outpatient setting led to the investigation of Edison, NJ) is associated with similar outcomes and

614 Dose-Modification Protocol for Hematologic Malignancies toxicities when used instead of oral Bu as a compo- creatinine of Ͼ2.0 mg/dL, (2) a serum bilirubin nent of the preparative regimen [1-8]. In addition, Ͼ1.5 ϫ the upper limit of normal, (3) evidence of available information suggests that the incidence of hepatitis or cirrhosis, (4) abnormal pulmonary func- hepatic veno-occlusive disease (VOD) may be lower in tion, (5) a cardiac left ventricular ejection fraction patients receiving IV Bu as compared with oral Bu Ͻ40%, and (6) human immunodeficiency virus sero- [5-8]. positivity. Patients receiving autologous transplants ϩ Bu, a bifunctional alkylating agent, is often com- must have collected a minimum of 2.5 ϫ 106 CD34 bined with cyclophosphamide (Cy) for conditioning of cells per kilogram during peripheral blood stem cell patients undergoing allogeneic or autologous hema- mobilization. Patients undergoing allogeneic trans- topoietic stem cell transplantation [1-3,5-15]. The plantation were required to have granulocyte colony- standard oral BuCy2 regimen includes the administra- stimulating factor–mobilized peripheral blood pro- tion of Bu at a dose and schedule of 1.0 mg/kg every genitor cells or bone marrow from an HLA-matched 6 hours for 16 doses and Cy 60 mg/kg daily for 2 related donor available. The study protocol was ap- doses. proved by the Institutional Review Board for Human Attempts at developing an IV preparation of Bu Subject Investigation from each of the participating were initially limited because of the drug’s poor aque- study sites, and written, informed consent was ob- ous solubility; however, several formulations have tained from each patient. been investigated, including a formulation developed by Andersson et al. [16] that uses dimethyl acetamide Conditioning Regimen and polyethylene glycol (IV Busulfex); it became com- Patients were hospitalized during IV Bu adminis- mercially available in 1999. Data from the phase I trial tration to facilitate observation of toxicities and PK of Andersson et al. determined that an IV Bu dose of monitoring. Patients were consecutively assigned to 0.8 mg/kg provided systemic exposure similar to the dose cohorts 1 through 5. IV Bu was given according systemic exposure obtained after a standard oral dose to the designated cohort schedule and infusion rate of 1 mg/kg [17]. Pharmacokinetic (PK) data from a beginning on day Ϫ7. Cy 60 mg/kg was given IV over phase II trial [8] in which patients with advanced 2 hours for 2 consecutive days beginning on day Ϫ3, hematologic malignancies were treated with 16 doses no sooner than 6 hours after the last IV Bu dose. of IV Bu 0.8 mg/kg followed by 2 daily IV doses of Cy Doses for both Bu and Cy were based on the lesser of 60 mg/kg showed that the regimen was well tolerated actual or adjusted ideal body weight [18]. and demonstrated a more consistent PK profile than that reported with oral Bu. Dose-Modification Schedule The purpose of this investigation was to evaluate the safety and tolerability of a modified dosing regi- Each cohort was to consist of 4 patients. All pa- men of IV Bu combined with high-dose IV Cy. tients within a cohort were monitored for a minimum Through a dose-modification strategy involving 5 of 30 days after stem cell infusion to assess safety and unique Bu dose cohorts, we investigated the potential initial efficacy. The last patient within a cohort must to administer IV Bu once daily for 4 days (cohort 5) in have completed the monitoring period of 30 days after combination with Cy as the preparative regimen be- stem cell infusion before proceeding to the next co- fore bone marrow transplantation for hematologic hort. In the event that 1 of the following dose-limiting malignancies. PK profiles associated with each dosing toxicities occurred within a cohort during the moni- schedule are reported. toring period, an additional 2 patients were added to the specified cohort before advancing to the next cohort: (1) seizures considered related to Bu; (2) severe PATIENTS AND METHODS VOD, as defined by death due to VOD or lack of resolution or improvement of VOD by day 30; (3) Eligibility Criteria grade 4 gastrointestinal toxicity related to Bu; (4) Patients with hematologic malignancies who were delayed neutrophil engraftment related to Bu, defined 16 to 60 years old and without a previous stem cell by lack of achievement of absolute neutrophil count transplantation were eligible if they were in complete Ͼ500 by day 28; and (5) an unexpected grade 4 or remission but had a high risk of relapse or if they had life-threatening toxicity related to Bu. If no dose- relapsed or refractory disease. Patients older than 60 limiting toxicity occurred in the 2 additional patients, years of age with a good performance status and min- we advanced to the next Bu dose cohort. If 2 or more imal comorbidities were considered for enrollment on dose limiting toxicities occurred within a Bu dose an individual basis. Patients were required to have a cohort, then subsequent patients were enrolled in the life expectancy longer than 12 weeks and could not be previous cohort. The maximally tolerated IV Bu dos- severely limited by concomitant illness. Patients were ing schedule was then defined as the cohort dose excluded if they had any of the following: (1) a serum schedule below the cohort in which 2 or more dose

BB&MT 615 C. B. Williams et al.

Table 1. Dosing Schedules* dose 11 for cohort 1, dose 9 for cohort 2, dose 8 for cohort 3, dose 7 for cohort 4, and dose 4 for cohort 5. Cohort 1 The PK parameter estimates for Bu were deter- Day ؊7 1.6 mg/kg IV (over 4 h) q12h ؋ 2 doses Day ؊6 0.8 mg/kg IV (over 2 h) q6h ؋ 4 doses mined by using standard noncompartmental methods ,.Day ؊5 0.8 mg/kg IV (over 2 h) q6h ؋ 4 doses [21] with Kinetica version 4.1 (Innaphase Corp Day ؊4 0.8 mg/kg IV (over 2 h) q6h ؋ 4 doses Champs-sur-Marne, France). For each patient, plasma Cohort 2 Bu concentrations were plotted against time on a -Day ؊7 1.6 mg/kg IV (over 2 h) q12h ؋ 2 doses semilogarithmic scale. The peak Bu plasma concen Day ؊6 1.6 mg/kg IV (over 4 h) q12h ؋ 2 doses -Day ؊5 0.8 mg/kg IV (over 2 h) q6h ؋ 4 doses tration and time to peak concentration were deter Day ؊4 0.8 mg/kg IV (over 2 h) q6h ؋ 4 doses mined directly from the plasma concentration/time Cohort 3 curves. The area under the curve (AUC) was obtained Day ؊7 3.2 mg/kg IV (over 4 h) q24h ؋ 1 dose by using the linear trapezoidal rule up to the final -Day ؊6 1.6 mg/kg IV (over 2 h) q12h ؋ 2 doses measured concentration and was extrapolated to in ␤ Day ؊5 0.8 mg/kg IV (over 2 h) q6h ؋ 4 doses Day ؊4 0.8 mg/kg IV (over 2 h) q6h ؋ 4 doses finity by using after the first dose and to the end of Cohort 4 the dosing interval (t) under multidose conditions. Day ؊7 3.2 mg/kg IV (over 4 h) q24h ؋ 1 dose The elimination half-life (t1⁄2) was determined from Day ؊6 3.2 mg/kg IV (over 4 h) q24h ؋ 1 dose the postdistributive terminal portion of the plasma .Day ؊5 0.8 mg/kg IV (over 2 h) q6h ؋ 4 doses concentration/time curve Day ؊4 0.8 mg/kg IV (over 2 h) q6h ؋ 4 doses Cohort 5 Total body clearance (Cl) was determined with the Day ؊7 3.2 mg/kg IV (over 4 h) q24h ؋ 1 dose formula dose/AUC0-infinity after the first dose and .Day ؊6 3.2 mg/kg IV (over 4 h) q24h ؋ 1 dose dose/AUC0-t under multidose conditions Day ؊5 3.2 mg/kg IV (over 4 h) q24h ؋ 1 dose The apparent steady-state volume of distribution Day ؊4 3.2 mg/kg IV (over 4 h) q24h ؋ 1 dose (Vdss) was determined with the following equation: 12h indicates every 12 hours. ϭ 2 Ϫ *Doses are based on the lesser of actual or adjusted body weight. Vdss [(dose)(AUMC)]/AUC [(dose)(T)/(AUC)(2)] Ideal body weight [18]: male (kg), 56.2 ϩ (1.41 ϫ No. inches where AUMC is the area under the first moment of over 60); female (kg) 53.1 ϩ (1.36 ϫ No. inches over 60). Adjusted body weight: 0.25 (total body weight Ϫ ideal body the concentration/time curve and T is the infusion weight) ϩ ideal body weight. duration.

Sample Preparation limiting toxicities occurred with at least 6 patients A 0.2-mL plasma sample was added to a borosili- studied. cate glass tube containing 0.04 mL of internal standard and vortexed; 0.5 mL of methanol was added and Supportive Care vortexed again for 10 seconds. The samples were de- rivatized by using a modification of the method of Phenytoin was administered as seizure prophylaxis Rifai et al. [22] by adding 0.15 mL of 5% diethyldi- before and during Bu treatment in all patients. Mesna, thiocarbamate and vortexing for 10 seconds. To this antiemetics, blood products, and other supportive care sample, 0.5 mL of ultrapure water was added and measures were used according to institutional guide- vortexed for 10 seconds, after which 2 mL of ethyl lines and at the discretion of the attending physician as acetate was added. The tube was covered with alumi- deemed necessary by a patient’s disease history and num foil and capped, vortexed for 1 minute, and cen- risk factors. For patients undergoing allogeneic trans- trifuged at 4000 rpm for 2 minutes. The supernatant plantation, cyclosporine and short-course mini-meth- was transferred to a clean borosilicate tube with the otrexate were used as graft-versus-host disease pro- contents dried under nitrogen at 40°C by using a phylaxis [19,20]. Zymark Turbo Vap Evaporator (Zymark, Hopkinton, MA), resuspended in 0.05 mL of butanol, and trans- PK Analysis ferred to a clean vial. Subsequently 1 ␮L was injected Multiple timed blood samples (5 mL) for Bu PK into a Varian 3400 gas chromatograph (Varian, Wal- analysis were obtained from each patient. The time nut Creek, CA) equipped with a thermionic specific and quantity of samples obtained were dependent on detector (nitrogen/phosphorous detector) and an 8100 which Bu dose cohort each patient was participating autosampler. A Varian 1077 split/splitless injector at in. The IV Bu dose regimen for each of the 5 dose 270°C and a Restek Cyclosplitter inlet sleeve (Restek, cohorts is outlined in Table 1. In all cohorts, samples Bellefonte, PA) were used; the injector was operated were collected on day Ϫ7 and day Ϫ4. On day Ϫ7, in the splitless mode. Analysis was performed with a samples were collected around dose 1, regardless of J&W Scientific capillary DB5 mass spectrometry col- cohort. On day Ϫ4, samples were collected around Bu umn (30 m ϫ 0.25 mm) with a film thickness of 0.25

616 Dose-Modiﬁcation Protocol for Hematologic Malignancies

␮m (J&W Scientific, Folsom, CA). UHP helium RESULTS (Matheson Gas Products, Parsippany, NJ) was used as Patient Characteristics carrier gas at a flow rate of 4.3 mL/min. The thermionic specific detector was set at 280°C with flow rates Clinical data are presented on 21 patients with of 4.6 mL/min for hydrogen and 169 mL/min for air. hematologic malignancies treated at 3 institutions be- The initial oven temperature was maintained at 150°C tween August 2000 and September 2002. Patient char- for 1.5 minutes and was then increased 25°C/min to acteristics are listed in Table 2. The median age was 260°C with a hold time of 2.6 minutes, followed by a 47 years (range, 26-66 years), and there were 12 men second increase of 25°C/min to 280°C with a hold and 9 women. Eleven patients underwent autologous time of 10.3 minutes. Standards were prepared from a transplantation: 8 for non-Hodgkin lymphoma, 1 each stock solution, 2 mg Bu per milliliter of acetone, that for acute myelogenous leukemia (AML), Hodgkin dis- was immediately diluted 10:1 in methanol. Bu and ease, and multiple myeloma. Ten patients underwent sodium diethyldithiocarbamate trihydrate were ob- allogeneic transplantation: 3 for non-Hodgkin lym- tained from Aldrich Chemical Company (St. Louis, phoma, 3 for chronic myelogenous leukemia (CML), MO). Internal standard—1,6-bis-(methane sulfonly- 2 for myelodysplastic syndrome (MDS), 1 for AML, oxy) hexane—was synthesized by a modification of and 1 for myeloproliferative disease. Five patients the method of Rifai et al. [22]. Ethyl acetate, metha- were in complete remission at the time of transplan- nol, n-butyl alcohol, and acetone were obtained from tation. Fifteen patients (71%) had received at least 2 Honeywell Burdick and Jackson (Muskegon, MI), and therapies before transplantation, and 9 patients had all were high-performance liquid chromatography relapsed or refractory disease at the time of transplan- grade. Internal standard (0.05 mg Bu per milliliter tation. The 3 CML patients were in chronic phase, methanol) was prepared by the addition of 3.8 mL of and 2 patients were newly diagnosed with MDS and methanol to 200 ␮L of stock solution. A 5% diethyl- myeloproliferative disease. The patient with multiple dithiocarbamate solution was prepared daily in ultra- myeloma had stable disease. pure water. Bu analysis in plasma was linear to 5.0 All patients were alive at day 30. Neutrophil Ͼ ␮ ␮g/mL. The within-day mean coefficient of variation engraftment (absolute neutrophil count 500/ L) was 1.41%, and the mean SD was 0.017 (n ϭ 24). For occurred at a median of 14 days (14 days for autol- the between-day variance, triplicate plasma standard ogous and 15 days for allogeneic transplantations). curves yielded mean correlation coefficients of 0.9991, The median time to a sustained platelet count of Ͼ ␮ 0.9993, and 0.9996. The between-day mean coeffi- 20000/ L was 19 days (20 days for autologous and cient of variation was 2.43%, and the mean SD was 19 days for allogeneic transplantations). Three pa- 0.045 (n ϭ 24). tients received granulocyte colony-stimulating factor to speed up neutrophil engraftment. One patient Statistical Analysis with chronic phase CML initially engrafted plate- lets on day 0 (platelet nadir Ͼ30000), on the basis of PK parameter estimates and demographic data the International Bone Marrow Transplant Registry were examined univariately and graphically to deter- definition of engraftment [25], but later the platelet mine distributional characteristics. Bu AUC and peak count decreased, and the patient was transfusion plasma concentration were normalized for each sub- dependent starting on day 25. The patient later died ject by dividing the parameter by the Bu dose per from complications related to the development of kilogram administered. The effect of cohort and time VOD. on these parameters, as well as Cl corrected for weight, was tested by using a mixed model approach Busulfan Pharmacokinetics that allows for a possible within-subject correlation The results of the Bu PK evaluation are shown across time. An interaction term of time and cohort in Table 3. Interpatient variability in Bu disposition was also added to the model. If the AUCs were pro- was observed for the Bu PK parameter estimates t1⁄2, portional to the dose, then one would not expect to see volume of distribution, Cl, and dose-adjusted AUC. a cohort effect with this analysis. Differences between This variability in Bu disposition parameters was first-dose and multidose Bu PK parameter estimates observed between patients within the same dose were tested as post hoc contrasts in the mixed model. cohort as well as between patients in each of the 5 dose cohorts. However, no statistically significant Hepatic VOD Diagnosis and Evaluation differences in Bu t1⁄2, volume of distribution, Cl, or A clinical diagnosis of VOD was made by the treat- dose-adjusted AUC were observed between dose ing physician after clinical examination and laboratory cohorts. Although a large degree of interpatient findings were analyzed. Diagnosis was based on the cri- variability was observed in Bu disposition, intrapa- teria of Jones et al. [23] and assigned a severity grade tient Bu PK remained relatively constant between based on the criteria of Bearman et al. [24]. the first and second PK analysis for individual pa-

BB&MT 617 C. B. Williams et al.

Table 2. Patient Characteristics

Patient No. Age (y) Disease Pre-BMT Status Type of BMT

Cohort 1 01-001 26 NHL Primary refractory Auto PBSCT 01-002 40 AML CR1 Auto PBSCT 01-103 52 MDS CMML Allo PBSCT 02-104 66 NHL First relapse Auto PBSCT Cohort 2 02-201 45 MM Stable disease Auto PBSCT 01-202 59 NHL CR1 Auto PBSCT 03-203 55 AML Primary refractory Allo PBSCT 01-204 30 HD Second relapse Auto PBSCT Cohort 3 01-301 29 NHL CR1 Auto PBSCT 03-302 61 NHL CR3 Auto PBSCT 02-303 49 NHL CR2 Allo PBSCT 02-304 46 CML First chronic phase Allo PBSCT Cohort 4 01-401 39 MPD New diagnosis Allo PBSCT 03-402 64 NHL Primary refractory Auto PBSCT 03-403 51 NHL CR2 Auto PBSCT 02-404 59 NHL Relapsed refractory Allo PBSCT 02-405 48 CML First chronic phase Allo PBSCT 02-406 46 NHL Primary refractory Allo PBSCT Cohort 5 02-501 46 MDS New diagnosis Allo PBSCT 02-502 33 CML First chronic phase Allo PBSCT 01-503 52 NHL Relapsed refractory Auto PBSCT

AML indicates acute myelogenous leukemia; Allo, allogeneic; Auto, autologous; CML, chronic myelogenous leukemia; CR1, first complete remission; CR2, second complete remission; CR3, third complete remission; HD, Hodgkin disease; MDS, myelodysplastic syndrome; MM, multiple myeloma; MPD, myeloproliferative disease; NHL, non-Hodgkin lymphoma; PBSCT, peripheral blood stem cell transplantation; Allo, allogeneic; Auto, autologous; CMML, chronic myelomonocytic leukemia; BMT, bone marrow transplantation. tients (data not shown). With the exception of AUC developed moderate clinical VOD on day 18 (max- in cohort 5, no relationship was observed between imum total bilirubin, 18 mg/dL; maximum Bu Bu PK parameter estimates and patient toxicity. As AUC, 2062 ␮mol/min), which resolved without expected, and reflecting the dose administered, the treatment. The remaining 2 cases of VOD occurred 3 patients enrolled in cohort 5 had the greatest Bu in patients enrolled in cohort 5. One patient (max- AUC. In cohorts 3, 4, and 5, a total of 7 patients had imum Bu AUC, 6380 ␮mol/min) with VOD—based Bu AUC Ͼ5000 ␮mol/min, and 5 patients exhibited on a maximum total bilirubin of 32.7 mg/dL, jaun- no significant toxicities. dice, ascites, weight gain, and right upper quadrant pain—was diagnosed with VOD on day 40 and died Toxicity on day 51. Autopsy and liver biopsy results con- Most toxicities were grade 1 and 2, including firmed the diagnosis of VOD. The other cohort 5 nausea, vomiting, diarrhea, fatigue, and mucositis. patient (maximum Bu AUC, 6198 Mol-min) was Five patients developed grade 3 or greater toxicities, diagnosed as having moderate VOD on day 17. This 3 of which resulted in death. One patient had a was further defined as severe VOD because of a lack seizure assumed to be from herpetic encephalitis of resolution by day 30. The same patient also and subsequently developed complications relating experienced a grade 3 paralytic ileus and later died. to toxic epidermal necrolysis; this patient died on Five patients had a measured Bu AUC Ͼ6000 day 40. Four patients developed hepatic abnormal- ␮mol/min. Three of the patients were in cohorts 3 ities, and 3 exhibited evidence of VOD. Of these 4 and 4, in which the AUC was the highest after day 1 patients, the only patient in the group who was not of Bu. The remaining 2 patients were in cohort 5, in diagnosed with VOD was enrolled in cohort 4. This which the AUC was highest on day 4 of Bu. Both patient (maximum Bu AUC, 6272 ␮mol/min) devel- patients in cohort 5 developed VOD, whereas the oped biopsy-confirmed drug-induced hepatitis on other 3 patients did not. In contrast, the patient in day 22, which resulted in a maximum aspartate cohort 5 who did not develop VOD had Bu AUCs of aminotransferase level of 1332 U/L. Of the 3 pa- 4573 ␮mol/min on day 1 and 5391 ␮mol/min on day tients with VOD, 1 patient enrolled in cohort 2 4 (Table 4).

618 Dose-Modiﬁcation Protocol for Hematologic Malignancies

DISCUSSION

0) Although the standard oral BuCy2 regimen is ef- 3)

-fective, it is often not well tolerated. Oral Bu is avail ؍ (1678-1989.6) (5391.1-6380.4) able in the United States only as a 2-mg tablet. This 1932.3 6197.9 requires patients to ingest large numbers of pills with each dose. Administration can be eased by repackag-

6) ing the tablets, but ingestion remains difficult, partic- ularly if the patient is nauseated or has difficulty swal- (1423.3-1686.8) (4572.9-5410.4) lowing. The PK profile of orally administered Bu 1599 5127.5 demonstrates wide interpatient and intrapatient variability due to age-related differences, alterations in absorption, circadian variations, drug-drug and drug- 6) Dose Cohort 5 (n

food interactions, and patient-speciﬁc parameters [26- ؍ pharmacokinetic parameter corrected for dose administered; (997.4-2343.2) (801.1-1869)

ϭ 31]. PK studies with oral Bu demonstrate variations as 1407 1125.6 high as 50% in calculated PK parameter estimates and may not be calculable in up to 20% of patients because of slow absorption, delayed elimination, or both [26- 28]. Although the practice of ﬁrst-dose Bu PK analysis (941-2071.7) (2999-6634.4) directing subsequent dosing for an individual treat- 1453.9 4650.2 ment course is routine at many centers, common problems with sampling and monitoring of oral Bu underscore the need for alternate methods of drug 4) Dose Cohort 4 (n

delivery that provide more consistent and reliable Bu ؍ sample 2. (1355.9-1722.3) (1076.8-1373.7)

maximal plasma busulfan concentration; cor disposition and systemic exposure. ϭ 1701.6 1360.1 ϭ Initial BuCy regimens required Bu to be adminis- max tered 4 times daily. Similar to the oral Bu dosing strategies, initial IV Bu studies used the same dosing sample 1; T2

ϭ strategy (ie, every-6-hour dosing) and have demon- (1492-1882.1) (4767.4-6027.1) strated predictable and consistent PK proﬁles with 1550.4 4947.1 acceptable toxicity [1-3,5-8,17]. The data presented here with IV Bu dosing across the range studied con- busulfan body clearance; C

ϭ ﬁrm the overall intrapatient consistency and predict-

4) Dose Cohort 3 (n ability of IV Bu PK. Once-daily IV Bu dosing would seem to be more convenient for the patient, possibly ؍ (1187.1-1424.4) (955.5-1144.5) volume of distribution; T1 ϭ 1387.8 1121.6 allowing for outpatient transplantations, and could be d equally effective if overall Bu exposure were compa- rable to standard oral Bu dosing regimens. The primary objective of this study was to assess the safety, by using a dose-modiﬁcation cohort sched- (1281.1-1518.4) (2062.2-2421.3) ule, of once-daily IV Bu in combination with high- 1417.3 2261.7 elimination half-life; V dose IV Cy as the preparative regimen for patients ϭ 2 ⁄ 1 undergoing autologous or allogeneic stem cell transplantation. We found that once-daily administration 4) Dose Cohort 2 (n

-of high-dose IV Bu in combination with Cy was as ؍ (1123.8-3153.5) (881.1-2522.8) sociated with an increased risk of liver toxicity and the 1507.7 1209.6 development of VOD. Patients in cohorts that used 22 021conventional 17 693 every-6-hour IV Bu 20 685dosing after the in- 19 736 20 147 vestigational portion of the dosing regimen tolerated Dose Cohort 1 (n T1 T2 T1 T2the preparative T1 regimen T2 better. However, T1 on T2 the basis T1 T2 (1010.6-1996) (1626.3-3193.5) of our study protocol and the apparently dispropor- 3.5 (3.4-3.8)2.7 (1.9-3.6) 2.0 (1.5-2.1) 3.1 (2.3-4.4) 2.0 (1.6-2.1) 2.9 (2.7-3) 2.1 (2-2.1) 2.8 (2.4-2.9) 4.0 (3.9-4.0) 3.0 (2.6-3.5) 2.0 (1.5-2.2) 2.3 (2.0-3.3) 3.9 (3.7-4.1) 3.3 (2.5-4.3) 2.0 (1.7-2.5) 2.9 (1.8-4.1) 4.1 (4.1-4.2) 3.0 (2.6-3.1) 3.9 (3.3-4.0) 2.9 (2.3-3.6) 1335.3 0.66 (0.47-0.67) 0.6 (0.51-0.73) 0.59 (0.49-0.61) 0.6 (0.43-0.68) 0.54 (0.49-0.55) 0.45 (0.35-0.63) 0.66 (0.49-0.79) 0.5 (0.4-0.74) 0.4 (0.36-0. 0.9 (0.8-1.3) 1.1 (1.0-3.0) 1.1 (1.04-1.3) 1.5 (1.4-1.7) 1.03 (1.5-2.1) 1.8 (1.5-2.1) 0.87 (0.7-1.2) 1.9 (1.2-2.5) 1.0 (0.8-1.1) 0.9 (0.8-1.2) 1.5 (1.3-2) 1.3 (0.95-2.2) 1.7 (1.7-2.1) 1.2 (1.1-1.4) 3.3 (2.8-3.5) 1.4 (1.2-1.7) 2.8 (2.1-3.8) 1.5 (1.0-2.0) 3.3 (2.7-3.5) 2.9 (2.7-3.9) 2142.5 tionate increase in observed adverse effects (VOD) for cohort 5 patients, we believed it prudent and appro-

time to maximal plasma busulfan concentration; t priate after enrolling 3 patients to discontinue enroll- Pharmacokinetic Proﬁle of Intravenous Busulfan g/mL) ␮ ϭ ( g/mL) ment. ␮ ( max (h) cor mol/min) m/min) Estimate T Parameter ␮ ␮ (h) (L/kg) Data from PK evaluations after oral Bu given ( ( 2 max maxcor max d ⁄ 1 Pharmacokinetic t V Table 3. Cl (mL/min/kg)AUC 2.5 (2.1-4) 2.3 (1.4-3.7) 2.5 (1.9-2.7) 2.6 (1.8-3) 2.0 (1.8-2.5) 1.9 (1.7-3.0) 2.2 (1.3-3.7) 2.5 (1.1-3.7) 2.2 (1.9-2.3) 1.8 (1.6-2. T C C AUC ratioTotal mean AUC 1.8 (1.3-1.9) 2.1 (1.97-2.2) 4.0 (3.5-4.7) 4.0 (3.6-4.6) 0.9 (0.8-0.9) Data are presented as the median (range). AUC indicates area under the busulfan concentration curve; CI AUC every 6 hours indicated that increased Bu exposure

BB&MT 619 C. B. Williams et al.

Table 4. Treatment-Related Risk Factors for the Development of VOD

Time Interval between Last Dose of Bu and Patent No. Pre-BMT Treatment(s) First Dose of Cy

Cohort 1 ABVD ؋ 8 cycles, ESHAP ؋ 2 cycles 9h 01-001 01-002 3-drug induction and Cy/VP/G-CSF mobilization 8 h 01-103 No prior treatment 9h CHOP ؋ 8 cycles, MINE ؋ 3 cycles 8h 02-104 Cohort 2 VAD ؋ 4 cycles, Cy/G-CSF mobilization 8 h 02-201 CHOP ؋ 6 cycles 8h 01-202 Ida/ARA-C induction and high-dose ARA-C consolidation ؋ 110h 03-203 ABVD ؋ 10 cycles, ESHAP ؋ 2 cycles, Cy/GCSF mobilization, XRT to spine and mediastinum 8 h 01-204 Cohort 3 CHOP ؋ 4 cycles, RICE ؋ 2 cycles 8h 01-301 M-BACOD ؋ 10 cycles, CHOP ؋ 10 cycles 7 h 03-302 CHOP ؋ 4 cycles, MINE ؋ 6 cycles, rituximab ؋ 4 cycles, XRT to abdomen and pelvis 8.5 h 02-303 02-304 No prior treatment 8h Cohort 4 01-401 Local XRT 8h Left nephrectomy and adrenalectomy, splenectomy, CHOP ؋ 4 cycles, ESHAP ؋ 2 cycles, 4.5 h 03-402 rituximab ؋ 5 cycles, Cy/VP mobilization CVP ؋ 10 cycles, rituximab ؋ 8 cycles, FNP ؋ 2 cycles 5 h 03-403 CVP ؋ 4 cycles, ﬂudarabine ؋ 12 cycles, DHAP ؋ 2 cycles, rituximab ؋ 5 cycles, 8h 02-404 CHOP ؋ 3 cycles Hydroxyurea ؋ 2mo 8h 02-405 R-CHOP ؋ 7 cycles, ESHAP ؋ 2 cycles, XRT to spine 8 h 02-406 Cohort 5 Mitomycin/5-FU ؋ 2 cycles, XRT to pelvis, abdominal surgery 23.5 h 02-501 Imatinib ؋ 2mo 20 h 02-502 R-CHOP ؋ 8 cycles and Cy/VP/G-CSF mobilization 20 h 01-503

G-CSF indicates granulocyte colony-stimulating factor; XRT, radiotherapy; 5-FU, 5-fluorouracil; BMT, bone marrow transplantation; ABVD, doxorubicin, bleomycin, vinblastine, dacarbazine; ESHAP, etoposide, methylprednisolone, cytarabine, cisplatin; Cy/VP/G-CSF, cyclophosphamide, etoposide, G-CSF; R-CHOP, cyclophosphamide, doxorubicin, vincristine, prednisone, rituximab; MINE, mesna, ifosfamide, mitoxantrone, etoposide; VAD, vincristine, doxorubicin, dexamethasone; M-BACOD, methotrexate, bleomycin, doxorubicin, cyclophosphamide, vincristine, dexamethasone; RICE, rituximab, ifosfamide, carboplatin, etoposide; Ida/ARA-C, idarubicin, cytarabine; ARA-C, cytarabine; CVP, cyclophosphamide, vincristine, prednisone; FNP, fludarabine, mitoxantrone, prednisone; DHAP, dexamethasone, cytarabine, cisplatin. was associated with an increased risk for VOD and tent with conventional Bu dosing. The observed inci- also with other regimen-related toxicities [30-35]. dence of VOD and other toxicities in these first 4 dose Copelan et al. [30,36] demonstrated that patients who cohorts was similar to what has been previously pub- had received more extensive chemotherapy before lished [5-8,17]. In contrast, 2 of 3 patients enrolled in transplant were at greater risk for the development of the cohort receiving 4 once-daily doses of IV Bu VOD as a result of having higher Bu AUC. Patients developed severe VOD and died from regimen-re- receiving antileukemic therapy (induction/consolida- lated toxicity. In cohort 5, exposure to high Bu plasma tion) before allogeneic bone marrow transplantation concentrations was prolonged, as demonstrated by the also showed a greater chance of developing severe increased AUC concentrations on day Ϫ4 (dose 4) as VOD than patients without therapy before transplan- compared with day Ϫ7 (dose 1). However, total Bu tation [37]. This study was not designed to examine or exposure between cohorts was not significantly dif- correlate pretransplantation treatment and risk of de- ferent. veloping VOD. However, patients who developed he- A series of recently published articles [4-7] pre- patic abnormalities, VOD, or both had at least 1 risk sented the clinical and pharmacologic experience of factor (heavy pretreatment; induction/consolidation IV Bu administered in combination with either Cy or for leukemia), as reported previously [30-37]. fludarabine. Studies by Russell et al. [4] and Fernandez Excessive systemic exposure to Bu has been asso- et al. [6] reported results with once-daily IV Bu. The ciated with higher morbidity and mortality [36]. In first study reported the results observed in 70 patients this study, dose cohorts 1 through 4 received higher treated concurrently with once-daily IV Bu and flu- initial doses of IV Bu; subsequent doses were consis- darabine. Patients were dosed on the basis of ideal

620 Dose-Modification Protocol for Hematologic Malignancies body weight, and the IV Bu infusion was given over 3 pletion of glutathione-S-transferase by Bu negatively hours. The investigators performed a detailed PK influences the PKs of Cy and ultimately leads to in- analysis in 12 patients; results showed remarkable con- creased toxicity. sistency among patients, with no significant differ- In this study, all patients were required to receive ences in PK parameters between the first and fourth at least a 6-hour interval between the last dose of Bu doses. No patient developed VOD, but 62 (88%) of 70 and the first dose of Cy, depending on the cohort. patients had transient bilirubin increases. Overall, the Two patients received the first dose of Cy without combination of IV Bu and fludarabine seemed to be waiting the entire 6 hours. This coincided with drug- well tolerated. induced hepatitis in 1 patient. This patient received An article by de Lima et al. [38] describes the the first dose of Cy 4.5 hours after the last dose of Bu. results of using once-daily IV Bu in combination with In cohort 5, in which 2 of 3 patients died as a result fludarabine in 96 patients with either AML or MDS. of complications related to VOD, all 3 patients re- Only 2 cases of reversible VOD are reported. PK ceived the first dose of Cy without waiting a full 24 analysis showed that the once-daily IV Bu was cleared hours. in less than 24 hours without drug accumulation, A third possible explanation is that pretransplan- which is supported by our results. tation therapy significantly influenced outcomes in Fernandez et al. [6] reported the results of 12 heavily pretreated patients. No patient received me- patients treated with the combination of IV Bu and Cy droxyprogesterone acetate or gemtuzumab ozogami- as preparative therapy. Six patients received twice- cin, which have both previously been documented to daily IV Bu 1.6 mg/kg per dose for 8 doses, and the increase the risk of developing hepatic VOD [6,41]. other 6 patients received once-daily IV Bu 3.2 mg/kg Fifteen (71%) of 21 patients were moderately to per dose for 4 doses. All doses were infused over 4 heavily treated before transplantation. Four patients hours and were based on actual body weight, with the (19%) received 4 or more prior therapies. Of the 5 exception of 2 patients who received reduced doses patients who developed grade 3 or greater toxicities, 3 because of obesity. Hepatic abnormalities were seen in were considered heavily pretreated. 2 patients; 1 of these patients developed VOD on day Multiple factors likely influenced the observed 23. The development of VOD in this patient was outcomes in this study, most notably treatment before attributed to the administration of medroxyprogester- transplantation and the dosing interval between Bu one acetate; the VOD resolved by day 43 after discon- and Cy. All of the patients who developed grade 3 or tinuation of the drug. PK analysis demonstrated greater toxicities were either pretreated, received Cy highly consistent and reproducible Bu PK parameters earlier than directed after the final dose of Bu, or both. in both cohorts. Our data suggest that the administration of IV Bu The inconsistency between our outcomes and the 3.2 mg/kg every 24 hours for 4 doses in combination outcomes reported by Russell et al. [4], de Lima et al. with Cy may result in excessive toxicity, presumably [38], and Fernandez et al. [6] may be explained by because of increased Bu exposure. It seems probable several factors. One possible explanation is a loss of that the observed intolerance was augmented by the linear Bu elimination in the patients receiving once- administration of Cy, but the current data do not daily dosing, with resulting increased Bu exposure and permit such analysis. In contrast, it seems that the toxicity. Patients in cohort 5 seemed to show de- once-daily administration of IV Bu in combination creased Bu Cl and drug accumulation from the first with fludarabine is well tolerated [4,38]. dose to the fourth dose. However, when AUC is The combination of once-daily IV Bu and Cy as corrected for dose administered and allowing for usual preparative therapy for transplantation should be done interpatient variability, no statistically significant con- with caution and is not recommended unless it is part clusions can be made. of a clinical trial. Future studies examining once-daily Another possible explanation is the potential ad- IV Bu dosing in combination with Cy should evaluate ditive toxicity from the combination of Bu and Cy. Cy increasing the dosing interval between Bu and Cy to at is already known to cause VOD [23,39], and the risk of least 24 hours and potentially targeting lower Bu VOD is of particular concern when Bu is used in AUCs to improve outcomes and patient tolerability. combination. McDonald et al. [39] found a strong correlation between blood levels of various Cy metab- olites and VOD. ACKNOWLEDGMENTS Hassan et al. [40] showed that the metabolism of The authors thank Jami Niehus, RN, Marcia Ja- Cy when used in combination with oral Bu greatly cobson, RN, Diane Scholl, RN, Becky Whittaker, influenced toxicity and outcome. When doses of Cy RN, Renee Boyette, RN, Stephanie Picken, RN, and were given within 24 hours of the last dose of oral Bu, Patty Gerken, RN, FNP, for their outstanding con- prolonged exposure and decreased Cl of Cy were tributions to our research efforts. We also thank observed. The authors concluded that the hepatic de- Teresa Maag for exemplary administrative support. IV

BB&MT 621 C. B. Williams et al.

Busulfex was provided and the investigation was sup- Hodgkin’s lymphoma. Bone Marrow Transplant. 1998;21:383- ported in part by an unrestricted grant from Orphan 389. Medical. 13. Ringden O, Labopin M, Tura S, et al. A comparison of busulfan versus total body irradiation combined with cyclophosphamide as conditioning for autograft or allograft bone marrow transplantation in patients with acute leukemia. Acute leukemia working party of the European Group for Blood and Marrow REFERENCES Transplantation (EBMT). Br J Haematol. 1996;93:637-645. 1. Andersson BS, McWilliams K, Tran H, et al. IV busulfan, 14. Devergie A, Blaise D, Attal M, et al. Allogeneic bone marrow cyclophosphamide (BuCy) and allogeneic hematopoietic stem transplantation for chronic myeloid leukemia in first chronic cells (BMT) for chronic myeloid leukemia (CML). Blood. 1998; phase: a randomized trial of busulfan-cytoxan versus cytoxan- 92(suppl 1): (abstr. 1168). total body irradiation as preparative regimen—a report from 2. Kashyap A, Forman S, Cagnoni P, et al. Intravenous busulfan the French Society of Bone Marrow Graft (SFGM). Blood. (Busulfex)/Cytoxan (Cy) preparative regimen for allogeneic 1995;85:2263-2268. (allo) and autologous (auto) hematopoietic stem cell transplan- 15. Blume KG, Kopecky KJ, Henslee-Downey JP, et al. A prospec- tation (BMT) is well tolerated by patients over 50 years of age. tive randomized comparison of total body irradiation-etoposide Blood. 1998;92(suppl 1):.(abstr. 515) versus busulfan/cyclophosphamide as preparative regimens for 3. Vaughan WP, Cagnoni P, Fernandez H, et al. Decreased inci- bone marrow transplant in patients with leukemia who were not dence of and risk factors for hepatic veno-occlusive disease with in first remission: a Southwest Oncology Group study. Blood. an IV busulfan (bu) containing preparative regimen for hema- 1993;81:2187-2193. topoietic stem cell transplantation (HSCT). Blood. 1998; 16. Andersson BS, Bhagwatar H, Chow D. Parenteral busulfan for 92(suppl 1): (abstr. 2121). treatment of malignant disease. US patents 5,430,057 (1995) 4. Russell J, Tran H, Quinlan D, et al. Once-daily intravenous and 5,559,148 (1996). busulfan given with fludarabine as conditioning for allogeneic 17. Andersson BS, Madden T, Tran HT, et al. Acute safety and stem cell transplantation: study of pharmacokinetics and early pharmacokinetics of intravenous busulfan when used with oral clinical outcomes. Biol Blood Marrow Transplant. 2002;9:468- busulfan and cyclophosphamide as pre-transplantation condi- 476. tioning therapy: a phase I study. Biol Blood Marrow Transplant. 5. Andersson B, Thall P, Madden T, et al. Busulfan systemic 2000;6:548-554. exposure relative to regimen-related toxicity and acute graft- 18. Miller DR. Determining Ideal Body Weight and Mass. Am J versus-host disease: defining a therapeutic window for IV Hosp Pharm. 1983;40:1622. [letter] BuCy2 in chronic myelogenous leukemia. Biol Blood Marrow 19. Storb R, Deeg HJ, Whitehead J, et al. Methotrexate and cy- Transplant. 2002;9:477-485. closporine compared with cyclosporine alone for prophylaxis of 6. Fernandez H, Tran H, Albrecht F, et al. Evaluation of safety acute graft versus host disease after marrow transplantation for and pharmacokinetics of administering intravenous busulfan in leukemia. N Engl J Med. 1986;314:729-735. a twice-daily or daily schedule in patients with advanced hema- 20. Przepiorka D, Khouri I, Ippoliti C, et al. Tacrolimus and tologic malignant disease undergoing stem cell transplantation. minidose methotrexate for prevention of acute graft-versus- Biol Blood Marrow Transplant. 2002;9:486-492. host disease after HLA-mismatched marrow or blood stem cell 7. Kashyap A, Wingard J, Cagnoni P, et al. Intravenous versus transplantation. Bone Marrow Transplant. 1999;24:763-768. oral busulfan as part of a busulfan/cyclophosphamide prepara- 21. Gibaldi M, Perrier D. Pharmacokinetics. Second Edition. New tive regimen for allogeneic hematopoietic stem cell transplan- York 409-417: Marcel Dekker; 1982. tation: decreased incidence of hepatic veno-occlusive disease 22. Rifai N, Sakanoto M, Lafi M, Guinan E. Measurement of (HVOD), HVOD-related mortality, and overall 100-day mor- plasma busulfan concentration by high-performance liquid tality. Biol Blood Marrow Transplant. 2002;9:493-500. chromatography with ultraviolet detection. Ther Drug Monit. 8. Andersson BS, Ashwin K, Gian V, et al. Conditioning therapy 1997;19:169-174. with intravenous busulfan and cyclophosphamide (IV BuCy2) 23. Jones RJ, Lee KS, Beschorner WE, et al. Venoocclusive disease for hematological malignancy prior to allogeneic stem cell of the liver following bone marrow transplantation. Transplan- transplantation: a phase II study. Biol Blood Marrow Transplant. tation. 1987;44:778-783. 2002;8:145-154. 24. Bearman SI, Anderson GL, Mori M, et al. Venoocclusive dis- 9. Santos GW, Tutschka PJ, Brookmeyer R, et al. Marrow trans- ease of the liver: development of a model for predicting fatal plantation for acute nonlymphocytic leukemia after treatment outcomes after marrow transplantation. J Clin Oncol. 1993;9: with busulfan and cyclophosphamide. N Engl J Med. 1983;309: 1729-1736. 1347-1353. 25. IBMTR Registration Manual. International Bone Marrow 10. Tutschka PJ, Copelan EA, Klein JP. Bone marrow transplan- Transplant Registry, 2001. tation for leukemia following a new busulfan and cyclophos- 26. Hassan M, Ehrsson H, Ljungman P. Aspects concerning busul- phamide Regimen. Blood. 1987;70:1382-1388. fan pharmacokinetics and bioavailability. Leuk Lymphoma. 1996; 11. Geller RB, Saral R, Piantadosi S, et al. Allogeneic bone marrow 22:395-407. transplantation after high-dose busulfan and cyclophosphamide 27. Hassan M, Oberg G, Ehrsson H, et al. Pharmacokinetics and in patients with acute nonlymphocytic leukemia. Blood. 1989; metabolic studies of high-dose busulphan in adults. Eur J Clin 73:2209-2218. Pharmacol. 1989;36:525-530. 12. Weaver CH, Schwartzberg L, Rhinehart S, et al. High-dose 28. Hassan M, Oberg G, Bekassy AN, et al. Pharmacokinetics of chemotherapy with BuCY or BEAC and unpurged peripheral high-dose busulphan in relation to age and chronopharmacol- blood stem cell infusion in patients with low-grade non- ogy. Cancer Chemother Pharmacol. 1991;28:130-134.

622 Dose-Modiﬁcation Protocol for Hematologic Malignancies

29. Grochow LB. Busulfan disposition: the role of therapeutic early transplantation, age, GVHD prevention regimen, and monitoring in bone marrow transplantation induction regi- other factors on outcome of allogeneic transplantation for mens. Semin Oncol. 1993;20(suppl 4):18-25. CML following BuCy. Bone Marrow Transplant. 2000;26:1037- 30. Copelan EA, Bechtel TP, Avalos BR, et al. Busulfan levels are 1043. influenced by prior treatment and are associated with hepatic 37. Copelan EA, Penza SL, Elder PJ, et al. Analysis of prognostic veno-occlusive disease and early mortality but not with delayed factors for allogeneic marrow transplantation following busul- complications following marrow transplantation. Bone Marrow fan and cyclophosphamide in myelodysplastic syndrome and Transplant. 2001;27:1121-1124. after leukemic transformation. Bone Marrow Transplant. 2000; 31. Dix SP, Wingard JR, Mullins RE, et al. Association of busulfan 25:1219-1222. area under the curve with veno-occlusive disease following 38. de Lima M, Couriel D, Thall PF, et al. Once daily intravenous BMT. Bone Marrow Transplant. 1996;17:225-230. busulfan and fludarabine: clinical and pharmacokinetic results 32. Grochow LB, Jones RJ, Brundett RB, et al. Pharmacokinetics of a myeloablative, reduced toxicity conditioning regimen for of high-dose busulfan: correlation with veno-occlusive disease allogeneic stem cell transplantation in AML and MDS. Blood. in patients undergoing bone marrow transplantation. Cancer In press. Chemother Pharmacol. 1989;25:55-61. 39. Hassan M, Ljungman P, Ringden O, et al. The effect of busul- 33. Slattery JT, Sanders JE, Buckner CD, et al. Graft-rejection and phan on the pharmacokinetics of cyclophosphamide and its toxicity following bone marrow transplantation in relation to 4-hydroxy metabolite: time interval influence on therapeutic busulfan pharmacokinetics. Bone Marrow Transplant. 1995;16: efficacy and therapy-related toxicity. Bone Marrow Transplant. 31-42. 2000;25:915-924. 34. Ljungman P, Hassan M, Bekassy AN, et al. High busulfan 40. McDonald GB, Slattery JT, Bouvier ME, et al. Cyclophos- concentrations are associated with increased transplant-related phamide metabolism, liver toxicity, and mortality following mortality in allogeneic bone marrow transplant patients. Bone hematopoietic stem cell transplantation. Blood. 2003;101:2043- Marrow Transplant. 1997;20:909-913. 2048. 35. Slattery JT, Clift RA, Buckner CD, et al. Marrow transplanta- 41. Wadleigh M, Richardson PG, Zahreih D, et al. Prior gemtu- tion for chronic myeloid leukemia: the influence of plasma zumab ozogamicin exposure significantly increases the risk of busulfan levels on the outcome of transplantation. Blood. 1997; veno-occlusive disease in patients who undergo myeloablative 89:3055-3060. allogeneic stem cell transplantation. Blood. 2003;102:1578- 36. Copelan EA, Penza SL, Theil KS, et al. The influence of 1582.

BB&MT 623