The effect of administration order of BU and CY on toxicity in hematopoietic SCT in humans

Veno-occlusive Disease in HSCT Patients: Consensus-based Recommendations for Risk Assessment, Diagnosis, and Management by the GITMO Group

Variation in clinical practice affects veno-occlusive disease management, mainly in patients who undergo allogeneic hematopoietic stem cell transplantation. Disputes about diagnostic criteria, treatment, and prophylaxis, due to the lack of high-quality data, are at the base of this variability. With the aim of limiting inconsistency in clinical care, thus improving both patient outcomes and data collection reliability, the Italian Society of Stem cell transplant (Gruppo Italiano Trapianto Midollo Osseo e Terapia Cellulare) launched a collaborative effort to formulate recommendations based on integration of available evidence and expert's consensus. A systematic method, according to US National Institute of Health guidelines and Italian National System for Guidelines, was used. Twenty-nine recommendations were approved with a strong (20) or weak (9) level of agreement, while 26 were rejected. In particular, the panel pointed out the need to achieve an early diagnosis, encouraging the adoption of European Society for Blood and Marrow Transplantation criteria and the prompt use of ultrasonography. Moreover, our experts strongly recommended in favor of prophylactic use of ursodeoxycholic acid. As soon as a veno-occlusive disease diagnosis is established, treatment with defibrotide should be started for at least 21 days. A number of areas of uncertainty, particularly concerning risk stratification and use of diagnostic tools such as elastography has been identified and discussed.

Evaluation of Reversed Administration Order of Busulfan (BU) and Cyclophosphamide (CY) as Conditioning on Liver Toxicity in Allogenic Hematopoietic Stem Cell Transplantation (ALL-HSCT)

Background: Busulfan (BU) in combination with cyclophosphamide (CY) is used as an effective conditioning regimen in hematopoietic SCT. Busulfan, depletes glutathione level in liver and causes elevated levels of CY metabolites. Cyclophosphamide metabolites are highly toxic for sinusoidal endothelial cells and cause VOD/ SOS with high mortality rate.

Materials and Methods: Between September 2013 and September 2015, all adult patients with acute leukemia who were candidates for myeloablative allogenic SCT and were admitted to Stem Cell Transplantation center were enrolled in this prospective randomized clinical trial. We tested the hypothesis that reverse administration from BU-CY (n=28) to CY-BU group (n=27) would reduce liver toxicity.

Results: Liver function tests were significantly higher in the BU-CY group between day -1 and +4 (p<0.05), but VOD/SOS was not diagnosed in both groups. The incidence and severity of acute GVHD was higher in the BU-CY group, but not statistically significant. Engraftment and mortality rate were not different.

Conclusion: These data support the concept that CY-BU is associated with less liver toxicity, suggesting CY-BU is superior to BU-CY as conditioning.

Clarifying busulfan metabolism and drug interactions to support new therapeutic drug monitoring strategies: a comprehensive review

INTRODUCTION

Busulfan (Bu) is an alkylating agent with a limited therapeutic margin and exhibits inter-patient variability in pharmacokinetics (PK). Despite decades of use, mechanisms of Bu PK-based drug-drug interactions (DDIs), as well as the negative downstream effects of these DDIs, have not been fully characterized. Areas covered: This article provides an overview of Bu PK, with a primary focus on how known and potentially unknown drug metabolism pathways influence Bu-associated DDIs. In addition, pharmacogenomics of Bu chemotherapy and Bu-related DDIs observed in the stem cell transplant clinic (SCT) are summarized. Finally the increasing importance of Bu therapeutic drug monitoring is highlighted. Expert opinion: Mechanistic studies of Bu metabolism have shown that in addition to GST isoenzymes, other oxidative enzymes (CYP, FMO) and ABC/MDR drug transporters likely contribute to the overall clearance of Bu. Despite many insights, results from clinical studies, especially in polypharmacy settings and between pediatric and adult patients, remain conflicting. Further basic science and clinical investigative efforts are required to fully understand the key factors determining Bu PK characteristics and its effects on complications after SCT. Improved TDM strategies are promising components to further investigate, for instance DDI mechanisms and patient outcomes, in the highly complex SCT treatment setting.

Effect of the duration between total body irradiation and stem cell infusion on the outcome of allogeneic transplantation with myeloablative conditioning

OBJECTIVES

Limited data are available on the effect of how cyclophosphamide (CY) and total body irradiation (TBI) are administered. We analyzed the effect of the interval from TBI to hematopoietic stem cell transplantation (HSCT) on the outcome of HSCT.

METHODS

Adult patients who underwent HSCT using myeloablative conditioning consisting of TBI and CY were retrospectively analyzed. They were divided into three groups according to the duration between the start of TBI and HSCT (Group A: 2-4 days, Group B: 5-8 days, Group C: 9-10 days).

RESULTS

Seventy-five adult patients were included. The 3-year overall survival rate was 56, 47, and 77% in Groups A, B, and C, respectively (P = 0.14). Similarly, there was no significant difference among the three groups with respect to progression-free survival (57, 47, and 72%, P = 0.17), relapse rate (32, 37, and 16%, P = 0.29), or non-relapse mortality (8, 14, and 12%, P = 0.81). In addition, we observed no significant difference among the three groups with respect to the incidence of grade II-IV acute graft-versus-host disease (GVHD) (31, 47, and 32%, respectively, P = 0.56) and that of chronic GVHD (23, 23, and 22%, respectively, P = 0.97).

DISCUSSION AND CONCLUSION

Although recipient immune system at HSCT might be affected by the timing of TBI, the duration between the start of TBI and HSCT did not influence the outcome of HSCT using myeloablative conditioning with TBI and CY.

A modified busulfan and cyclophosphamide preparative regimen for allogeneic transplantation in myeloid malignancies

BACKGROUND

Busulfan/cyclophosphamide (Bu/Cy) is commonly used as a standard conditioning regimen without total body irradiation for patients with hematological myeloid malignancies undergoing hematopoietic stem cell transplantation (HSCT).

OBJECTIVE

To develop a new myeloablative conditioning regimen incorporating fludarabine (Flu) and cytarabine (Ara-c).

SETTING

A tertiary blood disease hospital in Tianjin, China.

METHODS

A Bu/Cy preparative regimen was used, modified by Flu 90 mg/m(2) and Ara-c 6 g/m(2) in 57 unselected patients (median age 37 years) with hematological myeloid malignancies. The patients were to receive allogeneic hematopoietic stem cell transplantation (allo-HSCT). Thirteen patients had high-risk leukemia, fifty patients had HLA matched sibling donors while seven patients had HLA mismatched sibling donors. Cy was given 50 mg/kg/day for 2 days while Bu was given 3.2 mg/kg/day intravenously for 3 days.

MAIN OUTCOME MEASURE

Post-transplant donor chimerism, relapse tendency and minimal residual disease.

RESULTS

Extramedullar toxicity was relatively limited; the incidence of treatment-related mortality (TRM) within 100 days was 3.5 %. The incidence of grade II-IV, grade III-IV acute graft versus host disease (GVHD) and chronic GVHD of the evaluable patients were 21.1, 8.8 and 36.4 %, respectively. With a median follow up of 59 (13-96.5) months, TRM and relapse rate (RR) at eight years were 24.1 ± 5.8 and 14.7 ± 4.8 %, respectively. Disease free survival at eight years was 67.9 ± 6.2 % for the entire group, 60.0 ± 8.9 % for patients with AML, 77.3 ± 8.9 % for patients with CML, 70.0 ± 6.5 and 42.9 ± 18.7 % or matched sibling and mismatched sibling HSCT respectively.

CONCLUSION

The new regimen was associated with a low relapse rate, low incidence and severity of graft versus host disease and satisfactory survival for patients with myeloid malignancies.

Cyclophosphamide followed by intravenous targeted busulfan for allogeneic hematopoietic cell transplantation: pharmacokinetics and clinical outcomes

Targeted busulfan ((T)BU) 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 (T)BU/CY to CY/(T)BU) 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/(T)BU 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 (T)BU/CY-conditioned patients, CY/(T)BU-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 (T)BU/CY for the same indications. In patients with myelofibrosis, CY/(T)BU conditioning was associated with a significantly reduced incidence of SOS (0% versus 30% after (T)BU/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/(T)BU cohort (2% versus 13%; P = .01). CY/(T)BU 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/(T)BU is superior to (T)BU/CY as conditioning for patients with myelofibrosis.

Role of pharmacogenetics in busulfan/cyclophosphamide conditioning therapy prior to hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is a curative treatment for several malignant and nonmalignant disorders. Busulfan (Bu) and cyclophosphamide (Cy) are the most commonly used alkylators in high-dose pretransplant conditioning for HSCT; a treatment that is correlated with drug-related toxicity and relapse. Pharmacogenetic investigations have shown that CYP450, as well as aldehyde dehydrogenase, are clearly involved with Cy metabolism and are associated with altered treatment response, Cy metabolism and the unique stem-cell sparing capacity. Moreover, glutathione-S-transferase isoenzymes have been associated with cellular outward transport of various alkylating agents, including Cy metabolites, melphalan, Bu and chlorambucil. A shift from genetic-based studies to whole-genome-based investigations of Cy- and Bu-associated markers may contribute to personalizing the conditioning therapy and enhancing the clinical outcome of HSCT.