Effect of altering administration order of busulphan and cyclophosphamide on the myeloablative and immunosuppressive properties of the conditioning regimen in mice

Romiplostim addition to conditioning prior to HSCT allows chemotherapy reduction while maintaining engraftment levels

Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) offers are curative treatment approach for certain benign and malignant hematologic diseases. The actual HSCT is preceded by a conditioning therapy that reduces host-versus HSCT graft rejection and creates niche space for transplanted Hematopoietic Stem and Progenitor Cells (HSPCs). Conditioning consists of chemotherapy with or without irradiation and is a major cause of side-effects in HSCT. However, reduction of the intensity of cytotoxic conditioning leads to higher rates of engrafment failure and increased rates of relapse. In the present study, we investigated in how far sensitization of HSPCs to chemotherapy allows a reduction of the dose of drugs used as conditioning regimen in an HSCT mouse model. The thrombopoietin receptor agonist Romiplostim was shown to induce cell cycling activity in Hematopoietic Stem Cells (HSCs). We thus tested if the addition of Romiplostim to the clinically applied conditioning chemotherapy regimen cyclophosphamide and busulfan leads to increased efficacy of the chemotherapeutic regimen. We found that Romiplostim not only sensitizes HSCs to chemotherapy but also enables a reduction of the main chemotherapeutic component Busulfan by half, while HSC engraftment levels are maintained in long-term, serial transplantation assays.

Antioxidant and anti-inflammatory protective effects of rutin and kolaviron against busulfan-induced testicular injuries in rats

There are few treatment options, including the use of natural phenolics-based combination therapy for mitigating male infertility conditions associated with chemotherapy. Busulfan is an anti-cancer drug that leads to testicular problems in humans. Here, we studied the effect of co-treatment of rutin and kolaviron against busulfan-induced testis damage. Young adult male Wistar rats were intraperitoneally injected busulfan (4 mg/kg b.w), and then orally administered rutin (30 mg/kg b.w), and kolaviron (50 mg/kg b.w) alone and combined for 60 days. Results revealed that rutin and kolaviron alone or in combination reversed busulfan-induced increase in oxidative stress along with sperm quality of treated animals. However, kolaviron and rutin separately improved the concentrations of MDA and GSH and sperm quality more than when they were combined. Similarly, rutin and kolaviron separately or in combination preserved spermatogenesis and relieved busulfan-induced increase in nitric oxide concentration, myeloperoxidase and 3β-hydroxysteroid dehydrogenase activities. Co-supplementation with kolaviron but not rutin nor when rutin was combined with kolaviron also improved the testicular level of tumor necrosis-alpha. Finally, the histological features in the testes caused by busulfan were reversed by rutin, whereas treatment with kolaviron alone or in combination with rutin partially protected the testis from busulfan-induced injury as demonstrated by the appearance of few germ cells, damaged tubules, loss of round spermatids and defoliation of the seminiferous epithelium. Thus, the combined treatment regimen of rutin and kolaviron sparingly prevented busulfan-induced testicular injuries in rats.Abbreviations: CAT: Catalase; GSH: Glutathione; 3β-HSD: 3β- hydroxysteroid Dehydrogenase; MDA: Malondialdehyde; TNF-α: Tumor necrosis-alpha; BUS: Busulfan; RUT: Rutin; KV: Kolaviron; TBARS: Thiobarbituric Acid Reactive Substances; MPO: Myeloperoxidase; ELISA: Enzyme-Linked Immunoassay; NAD: Nicotinamide Adenine Dinucleotide (oxidized); ROS: Reactive Oxygen Species.

Busulfan-cyclophosphamide versus cyclophosphamide-busulfan as conditioning regimen before allogeneic hematopoietic cell transplantation: a prospective randomized trial

Busulfan and cyclophosphamide (BuCy) is a frequently used myeloablative conditioning regimen for allogeneic hematopoietic cell transplantation (allo-HCT). Theoretical considerations and pharmacological data indicate that application of busulfan prior to subsequent cyclophosphamide (BuCy) may trigger liver toxicity. Reversing the order of application to cyclophosphamide-busulfan (CyBu) might be preferable, a hypothesis supported by animal data and retrospective studies. We performed a prospective randomized trial to determine impact of order of application of Bu and Cy before allo-HCT in 70 patients with hematological malignancy, 33 patients received BuCy and 37 CyBu for conditioning. In the short term, there were minimal differences in liver toxicity favoring CyBu over BuCy, significant only for alanine amino transferase at day 30 (p = 0.03). With longer follow-up at 4 years, non-relapse mortality (6% versus 27%, p = 0.05) was lower and survival (63% versus 43%, p = 0.06) was higher with CyBu compared to BuCy. Other outcomes, such as engraftment (p = 0.21), acute and chronic graft-versus-host disease (p = 0.40; 0.36), and relapse (p = 0.79), were similar in both groups. We prospectively show evidence that the order of application of Cy and Bu in myeloablative conditioning in allo-HCT patients has impact on outcome.

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.

Myeloid Conditioning with c-kit-Targeted CAR-T Cells Enables Donor Stem Cell Engraftment

We report a novel approach to bone marrow (BM) conditioning using c-kit-targeted chimeric antigen receptor T (c-kit CAR-T) cells in mice. Previous reports using anti-c-kit or anti-CD45 antibody linked to a toxin such as saporin have been promising. We developed a distinctly different approach using c-kit CAR-T cells. Initial studies demonstrated in vitro killing of hematopoietic stem cells by c-kit CAR-T cells but poor expansion in vivo and poor migration of CAR-T cells into BM. Pre-treatment of recipient mice with low-dose cyclophosphamide (125 mg/kg) together with CXCR4 transduction in the CAR-T cells enhanced trafficking to and expansion in BM (<1%-13.1%). This resulted in significant depletion of the BM c-kit⁺ population (9.0%-0.1%). Because congenic Thy1.1 CAR-T cells were used in the Thy1.2-recipient mice, anti-Thy1.1 antibody could be used to deplete CAR-T cells in vivo before donor BM transplant. This achieved 20%-40% multilineage engraftment. We applied this conditioning to achieve an average of 28% correction of chronic granulomatous disease mice by wild-type BM transplant. Our findings provide a proof of concept that c-kit CAR-T cells can achieve effective BM conditioning without chemo-/radiotherapy. Our work also demonstrates that co-expression of a trafficking receptor can enhance targeting of CAR-T cells to a designated tissue.

Bone Marrow Cell Transplant From Donors With Cardiovascular Risk Factors Increases the Pro-atherosclerotic Phenotype in the Recipients

Improvement of long-term survival after hematopoietic stem cell transplantation has revealed that these patients have an increased appearance of de novo cardiovascular risk factors. Even though in these clinical studies no relation to transplant-related factors has been found, no attention has been paid to the influence of cardiovascular risk factors affecting the bone marrow donors on the cardiovascular risk of the recipients. Thus, the aim of this study was to analyze, using an animal model, whether transplantation of bone marrow from donors with cardiovascular risk factors increases cardiovascular risk in healthy recipients. Results from transplantation experiments have shown that bone marrow from donors with cardiovascular risk factors induced pro-atherogenic modifications in the cholesterol profile of healthy recipients, increasing the low-density lipoprotein cholesterol fraction in comparison to those transplanted with control bone marrow. Moreover, bone marrow from donors with cardiovascular risk factors induced significant alterations in liver pro-inflammatory state and lipid metabolism-related gene expression that could contribute to alter cholesterol homeostasis. Altogether, these results suggest that cardiovascular risk factors in the donor confer a cardiometabolic alteration to their bone marrow cells that is transferred to noncardiovascular disease transplant recipients, affecting their liver function and increasing their cardiovascular risk.

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.

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.

Once-daily intravenous busulfan for 47 pediatric patients undergoing autologous hematopoietic stem cell transplantation: a single center study

We report our results using once-daily intravenous (IV) busulfan (Bu)-based conditioning adjusted by weight without drug monitoring as myeloablative conditioning in 47 pediatric patients undergoing first autologous hematopoietic transplantation from 2006 to 2010. Median age was 4 years (range, 1 to 22 y). There were 35 boys and 12 girls. Conditioning was Bu-based in all patients. In medulloblastoma patients (n=12), IV thiotepa at 5 mg/kg/d×2 days was associated with Bu. In solid tumors other than medulloblastoma, IV melphalan was used at 140 mg/m/d×1 day. In lymphoma patients (n=9), IV cyclophosphamide was used at 60 mg/kg/d×2 days. Median number of CD34 cells infused was 4.65×10/kg (range, 1.7 to 58.7×10/kg). Median times to neutrophil and platelet recovery (>20×10/L) were 11 days (range, 8 to 16 d) and 12 days (range, 7 to 135 d), respectively. Median hospitalization time was 14 days (range, 9 to 92 d). Sixteen patients developed grades III and IV mucositis. Only 1 patient developed mild sinusoidal obstruction syndrome. No patient developed seizures or severe neurological complications. With a median follow-up of 18 months, probability of transplantation-related mortality and disease-free survival were 0% and 70%±8%, respectively. In conclusion, in our experience, once-daily IV Bu-based conditioning without drug monitoring for autologous hematopoietic transplantation in pediatric patients is a safe and effective regimen with no mortality.

Busulfan in hematopoietic stem cell transplant setting

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

Establishment and characterization of a new squamous cell carcinoma cell line, TMUU-08, derived from human bladder cancer

Human squamous cell carcinoma (SCC) of the bladder is a rare malignancy that represents less than 5% of bladder tumors. In contrast to non-bilharzial SCC, bilharzial SCC is a distinct pathological disease that is rarely encountered in Japan. The majority of patients with non-bilharzial SCC present with a poorly differentiated, muscle-invasive tumor with no previous episode of urothelial carcinoma (UC). Even in the absence of distant metastases, the prognosis of patients with non-bilharzial SCC of the bladder remains dismal because patients die of localized recurrence. This is in contrast to UC in which distant metastasis accounts for the great majority of recurrence. The 5-year survival rate of the patients treated for non-bilharzial SCC of the bladder was only about 10%. To date, large numbers of reports have examined the establishment of a human bladder cancer cell line with UC. However, few reports exist regarding the establishment of the human bladder cancer cell line with SCC. In the present study, we established a new cell line (TMUU-08) from the metastatic lymph node of a patient with SCC of the bladder. The TMUU-08 cell line of human bladder SCC was characterized. These results indicate that TMUU-08 cells might be useful in basic studies not only in the treatment but also etiology of human bladder SCC.

Myeloablative intravenous busulfan/fludarabine conditioning does not facilitate reliable engraftment of dual umbilical cord blood grafts in adult recipients

The efficacy of once-daily intravenous busulfan with fludarabine as a preparative regimen for partially matched umbilical cord blood transplantation has not been formally studied. We randomized 10 adult patients with myeloid malignancies to receive either concurrent or sequential administration of intravenous busulfan 130 mg/m(2) once daily x 4 days and fludarabine 40 mg/m(2) daily x 4 days, followed by dual umbilical cord blood transplantation. The median combined cryopreserved total nucleated cell dose was 3.6 x 10(7)/kg recipient body weight (range: 2.8-4.5 x 10(7)/kg). Graft-versus-host disease (GVHD) prophylaxis was provided by tacrolimus and mycophenolate mofetil (MMF). Donor-derived neutrophil recovery was observed in only 2 of 10 patients, resulting in premature closure of the study as per graft failure stopping rules. We conclude that the myeloablative conditioning regimen of once-daily intravenous busulfan with fludarabine provides insufficient immunosuppression to allow for engraftment of partially matched, dual umbilical cord blood grafts.

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.

The effect of administration order of BU and CY on engraftment and toxicity in HSCT mouse model

Conditioning regimens are an important issue determining the outcome of hematopoietic stem cell transplantation (HSCT). Less toxicity, early engraftment and no relapse are the aims of efficient conditioning. Our objective was to investigate the long-term effects of BU-CY and their administration order on the toxicity and chimerism in a mouse model of HSCT. Female BALB/c mice were treated with either BU (15 mg/kg/day x 4)-CY (100 mg/kg/day x 2) or CY-BU. Treated mice were transplanted with Sca-1+ cells from male BALB/c mice. Until 90 days after HSCT, the animals were monitored for body weight and analyzed for cellular phenotype of the thymus, spleen and BM, total chimerism, the spleen chimerism of DCs and T regulatory (Treg) cells, and hepatotoxicity. BU-CY and CY-BU treatments exerted comparable myeloablative and immunosuppressive effects. The long-term engraftment of donor cells in the BM and thymus regeneration showed the same features in both groups. However, the two regimens differed; in general, hepatotoxicity and chimerism of DC and Treg cells. In the long term, BU-CY, but not CY-BU caused a marked decrease in body weight and a significant increase in the activities of the liver enzymes, particularly aspartate amino transferase (AST). We conclude that the alteration of the administration order of BU-CY to CY-BU not only gives the same level of engraftment but also reduces the toxicity of the conditioning regimen that might be valuable specially in young patients who are undergoing HSCT.