Pharmacology of dimethanesulfonate alkylating agents: busulfan and treosulfan

Impact of fludarabine and treosulfan on ovarian tumor cells and mesothelin chimeric antigen receptor T cells

In addition to their immunosuppressive effect, cytostatics conditioning prior to adoptive therapy such as chimeric antigen receptor (CAR) T cells may play a role in debulking and remodeling the tumor microenvironment. We investigated in vitro the killing efficacy and impact of treosulfan and fludarabine on ovarian cancer cells expressing mesothelin (MSLN) and effect on MSLN-targeting CAR T cells. Treosulfan and fludarabine had a synergetic effect on killing of SKOV3 and OVCAR4 cells. Sensitivity to the combination of treosulfan and fludarabine was increased when SKOV3 cells expressed MSLN and when OVCAR4 cells were tested in hypoxia, while MSLN cells surface expression by SKOV3 and OVCAR4 cells was not altered after treosulfan or fludarabine exposure. Exposure to treosulfan or fludarabine (10 µM) neither impacted MSLN-CAR T cells degranulation, cytokines production upon challenge with MSLN + OVCAR3 cells, nor induced mitochondrial defects. Combination of treosulfan and fludarabine decreased MSLN-CAR T cells anti-tumor killing in normoxia but not hypoxia. In conclusion, treosulfan and fludarabine killed MSLN + ovarian cancer cells without altering MSLN-CAR T cells functions (at low cytostatics concentration) even in hypoxic conditions, and our data support the use of treosulfan and fludarabine as conditioning drugs prior to MSLN-CAR T cell therapy.

Safety and Efficacy of High-Dose Chemotherapy with TreoMel 200 vs. TreoMel 140 in Acute Myeloid Leukemia Patients Undergoing Autologous Stem Cell Transplantation

(1) Background: Treosulfan and melphalan (TreoMel)-based high-dose chemotherapy (HDCT) has shown promising safety and efficacy as a conditioning regimen for acute myeloid leukemia (AML) patients undergoing autologous stem cell transplantation (ASCT). However, despite intensive first-line induction treatment and upfront consolidation with HDCT and ASCT, AML relapse rates are still high, and further efforts are needed to improve patient outcomes. The aim of this study was to compare two melphalan dose schedules in regard to the safety of TreoMel HDCT and patient outcomes. (2) Methods: We retrospectively analyzed the safety and efficacy of two melphalan dose schedules combined with standard-dose treosulfan in AML patients undergoing HDCT and ASCT at the University Hospital of Bern, Switzerland, between August 2019 and August 2023. Patients received treosulfan 42 g/m2 combined with either melphalan 140 mg/m2 (TreoMel 140) or melphalan 200 mg/m2 (TreoMel 200). Co-primary endpoints were progression-free survival (PFS), overall survival (OS), as well as safety profile. (3) Results: We included a total of 51 AML patients: 31 (60.8%) received TreoMel 140 and 20 (39.2%) TreoMel 200. The patients' basal characteristics were comparable between both cohorts. No significant differences in the duration of hospitalization or the adverse event profile were identified. There were no statistically significant differences in relapse (0.45 vs. 0.30, p = 0.381) and mortality rates (0.42 vs. 0.15, p = 0.064) between the melphalan 140 mg/m2 and 200 mg/m2 cohorts, nor for PFS (HR: 0.81, 95% CI: 0.29-2.28, p = 0.70) or OS (HR: 0.70, 95% CI: 0.19-2.57, p = 0.59) for the TreoMel 140 vs. TreoMel 200 cohort. (4) Conclusions: A higher dose of melphalan (TreoMel 200) was well tolerated overall. No statistically significant differences for patient outcomes could be observed, possibly due to the relatively small patient cohort and the short follow-up. A longer follow-up and prospective randomized studies would be required to confirm the safety profile and clinical benefit.

Characterization and enrichment of spermatogonial stem cells of common carp (Cyprinus carpio)

Spermatogenesis is a systematically organized process that ensures uninterrupted sperm production in which the spermatogonial stem cells (SSCs) play a crucial role. However, the existing absence of teleost-specific molecular markers for SSCs presents a notable challenge. Herein we characterized phenotypically the spermatogonial stem cells using specific molecular markers and transmission electron microscopy. Moreover, we also describe a simple method to suppress common carp spermatogenesis using the combination of Busulfan and thermo-chemical treatment, and finally, we isolate and enrich the undifferentiated spermatogonial fraction. Our results showed that C-kit, GFRα1, and POU2 proteins were expressed by germ cells, meanwhile, undifferentiated spermatogonial populations preferentially expressed GFRα1 and POU2. Moreover, the combination of high temperature (35 °C) and Busulfan (40 mg/kg/BW) effectively suppressed the spermatogenesis of common carp males. Additionally, the amh expression analysis showed differences between the control (26 °C) when compared to 35 °C with a single or two Busulfan doses, confirming that the testes were depleted by the association of Busulfan at high temperatures. In an attempt to isolate the undifferentiated spermatogonial fraction, we used the Percoll discontinuous density gradient. Thus, we successfully dissociated the carp whole testes in different cellular fractions; subsequently, we isolated and enriched the undifferentiated spermatogonial population. Therefore, our results suggest that probably both GFRα-1 and POU2 are highly conserved factors expressed in common carp germinative epithelium and that these molecules were well conserved along the evolutionary process. Furthermore, the enriched undifferentiated spermatogonial population developed here can be used in further germ cell transplantation experiments to preserve and propagate valued and endangered fish species.

Fertility Protection, A Novel Concept: Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Protect against Chemotherapy-Induced Testicular Cytotoxicity

Currently, there is no viable option for fertility preservation in prepubertal boys. Experimentally, controlled vitrification of testicular tissue has been evaluated and found to cause potential structural damage to the spermatogonial stem cell (SSC) niche during cryopreservation. In this report, we leveraged the regenerative effect of human umbilical cord-derived Mesenchymal stem cell exosomes (h-UCMSC-Exo) to protect against testicular damage from the cytotoxic effects of polychemotherapy (CTX). A chemotherapy-induced testicular dysfunctional model was established by CTX treatment with cyclophosphamide and Busulfan in vitro (human Sertoli cells) and in prepubescent mice. We assessed the effects of the exosomes by analyzing cell proliferation assays, molecular analysis, immunohistochemistry, body weight change, serum hormone levels, and fertility rate. Our data indicates the protective effect of h-UCMSC-Exo by preserving the SSC niche and preventing testicular damage in mice. Interestingly, mice that received multiple injections of h-UCMSC-Exo showed significantly higher fertility rates and serum testosterone levels (p < 0.01). Our study demonstrates that h-UCMSC-Exo can potentially be a novel fertility protection approach in prepubertal boys triaged for chemotherapy treatment.

Population Pharmacokinetic Modeling for Twice-Daily Intravenous Busulfan in a Large Cohort of Pediatric Patients Undergoing Hematopoietic Stem Cell Transplantation-A 10-Year Single-Center Experience

Reaching target exposure of busulfan-based conditioning prior to hematopoietic stem cell transplantation is vital for favorable therapy outcomes. Yet, a wide inter-patient and inter-occasion variability in busulfan exposure has been reported, especially in children. We aimed to identify factors associated with the variability of busulfan pharmacokinetics in 124 consecutive patients transplanted at the University Children's Hospital Zurich between October 2010 and February 2020. Clinical data and busulfan plasma levels after twice-daily intravenous administration were analyzed retrospectively by population pharmacokinetic modeling. The volume of distribution correlated with total body water. The elimination rate constant followed an age-dependent maturation function, as previously suggested, and correlated with the levels of serum albumin. Acute lymphoblastic leukemia reduced busulfan clearance by 20%. Clearance significantly decreased by 17% on average from the start to the third day of busulfan administration, in agreement with other studies. An average reduction of 31% was found in patients with hemophagocytic lymphohistiocytosis and X-linked lymphoproliferative disease. In conclusion, we demonstrate that in addition to known factors, underlying disease and serum albumin significantly impact busulfan pharmacokinetics in pediatric patients; yet, substantial unexplained variability in some patients remained. Thus, we consider repeated pharmacokinetic assessment essential to achieve the desired target exposure in twice-daily busulfan administration.

Synergistic cytotoxicity of fludarabine, clofarabine, busulfan, vorinostat and olaparib in AML cells

Combinations of nucleoside analog(s) and DNA alkylating agent(s) are used for cancer treatment as components of pre-transplant regimens used in hematopoietic stem cell transplantation. Their efficacies are enhanced by combining drugs with different mechanisms of action, which also allows a reduction in the individual drug dosages and thus potentially in toxicity to the patient. We hypothesized that addition of SAHA and olaparib, an HDAC- and a PARP-inhibitor, respectively, to the established combination of fludarabine, clofarabine and busulfan would enhance AML cell cytotoxicity. Exposure of the AML cell lines KBM3/Bu2506, MV4-11, MOLM14 and OCI-AML3 to the 5-drug combination resulted in synergistic cytotoxicity with combination indexes < 1. Increased protein acetylation and decreased poly(ADP-ribosyl)ation were observed, as expected. Activation of apoptosis was suggested by cleavage of Caspase 3 and PARP1, DNA fragmentation, increased reactive oxygen species, and decreased mitochondrial membrane potential. The reduction in poly(ADP-ribosyl)ation was independent of caspase activation. Several proteins involved in DNA damage response and repair were downregulated, which may be contributing factors for the observed synergism. The increased phosphorylation of DNAPKcs suggests inhibition of its kinase activity and diminution of its role in DNA repair. A similar synergism was observed in patient-derived cell samples. These findings will be important in designing clinical trials using these drug combinations as pre-transplant conditioning regimens for AML patients.

Metformin pretreatment ameliorates busulfan-induced liver endothelial toxicity during haematopoietic stem cell transplantation

The success of Haematopoietic cell transplantation (HCT) is often limited by regimen-related toxicity (RRT) caused by conditioning regimen drugs. Among different conditioning drugs, busulfan (Bu) and treosulfan (Treo), although widely used in HCT, exhibit different toxicity profiles, the mechanism of which is still unclear. Here we investigated the effects of Bu and Treo in endothelial cells. While both Bu and Treo induced DNA damage in endothelial cells, we observed Bu alone to induce oxidative stress and sustained activation of phospho-ERK1/2, leading to apoptosis. However, Treo-treated cells exhibited no oxidative stress/apoptosis of endothelial cells. Screening of pharmacological inhibitors of both ROS and p-ERK revealed that metformin effectively ameliorates Bu-mediated toxicity in endothelial cells. In Balb/c mice, we observed a significant reduction in bone marrow endothelial cells in Bu-treated mice compared to Treo-treated mice. Further, liver sinusoidal endothelial cells (LSEC) was damaged by Bu, which is implicated in liver vasculature and their functional capacity to uptake FITC-albumin. However, Treo-treated mice liver vasculature was morphologically and functionally normal. When mice were pretreated with metformin followed by Bu, LSECs damage was ameliorated morphologically and functionally. Bone marrow transplants done on these mice did not affect the engraftment of donor cells.

Sitagliptin ameliorates busulfan-induced pulmonary and testicular injury in rats through antioxidant, anti-inflammatory, antifibrotic, and antiapoptotic effects

Busulfan (BUS) is an anticancer agent with serious adverse effects on various body organs, including the lung and testis. Sitagliptin was proven to have antioxidant, anti-inflammatory, antifibrotic, and antiapoptotic effects. This study aims to evaluate whether sitagliptin, a DPP4I, ameliorates BUS-induced pulmonary and testicular injury in rats. Male Wistar rats were split into control, sitagliptin (10 mg/kg), BUS (30 mg/kg), and sitagliptin + BUS groups. Weight change, lung and testis indices, serum testosterone, sperm parameters, markers of oxidative stress [malondialdehyde (MDA) and reduced glutathione (GSH)], inflammation [tumor necrosis factor-alpha (TNF-α)], and relative expression of sirtuin1 (SIRT1) and forkhead box protein type O1 (FOXO1) genes were estimated. Histopathological examination of lung and testicular tissues was done to detect architectural changes [Hematoxylin & Eosin (H&E)], fibrosis (Masson's trichrome), and apoptosis (caspase-3). Sitagliptin treatment reduced body weight loss, lung index, lung and testis MDA, serum TNF-α and sperm abnormal morphology, and increased testis index, lung and testis GSH, serum testosterone, sperm count, viability and motility. SIRT1/FOXO1 balance was restored. Also, sitagliptin attenuated fibrosis and apoptosis in lung and testicular tissues via reducing collagen deposition and caspase-3 expression. Accordingly, sitagliptin ameliorated BUS-induced pulmonary and testicular damage in rats via attenuating oxidative stress, inflammation, fibrosis, and apoptosis.

Evaluation of treosulfan cumulative exposure in paediatric patients through population pharmacokinetics and dosing simulations

AIM

To investigate the pharmacokinetics (PK) of intravenous treosulfan in paediatric patients undergoing haematopoietic stem cell transplantation (HSCT) for a broad range of diseases and to explore the impact of different dosing regimens on treosulfan exposure (area under the concentration-time curve, AUC_0→∞ ) through dosing simulations.

METHODS

A prospective multicentre PK study was conducted using treosulfan concentration data (n = 423) collected from 53 children (median age 3.5, range 0.2-17.0 years) receiving three daily age-guided doses (10-14 g/m² ). Population PK modelling was performed using NONMEM software, utilising a stepwise forward selection backward elimination method and likelihood-ratio test for screening covariates to describe PK variability. Monte Carlo simulation was used to generate patient PK data for 10 000 virtual paediatric patients and cumulative AUC_0→∞ values were evaluated using age, body surface area (BSA) and model-based dosing regimens, targeting 4800 mg*h/L.

RESULTS

Treosulfan concentration data were described using a one-compartment PK model with first-order elimination. Population mean (95% CI) estimates for clearance (CL) and volume of distribution (V) were 16.3 (14.9-18.1) L/h and 41.9 (38.8-45.1) L, respectively. Allometrically scaled body weight was the best covariate descriptor for CL and V, and maturational age further explained variability in CL. Dosing simulations indicated that in young patient groups (<2 years), a model-based dosing regimen more accurately achieved the target AUC_0→∞ (58.3%) over the age (42.6%) and BSA-based (51.3%) regimens.

CONCLUSION

Treosulfan disposition was described through allometric body weight and maturational age descriptors. Model-informed dosing is recommended for patients under 2 years. Treosulfan PK parameters and AUC_0→∞ were not influenced by patient disease.

Busulfan or Treosulfan Conditioning Platform for Allogeneic Stem Cell Transplantation in Patients Aged >60 Y With Acute Myeloid Leukemia/Myelodysplastic Syndrome: A Subanalysis of the GITMO AlloEld Study

The conditioning regimens with different alkylators at different doses can influence the outcome of allogeneic stem cell transplantation (SCT), but conclusive data are missing.

Methods

With the aim to analyze real-life allogeneic SCTs performed in Italy between 2006 and 2017 in elderly patients (aged >60 y) with acute myeloid leukemia or myelodysplastic syndrome, we collected 780 first transplants data. For analysis purposes, patients were grouped according to the type of alkylator included in the conditioning (busulfan [BU]-based; n = 618; 79%; treosulfan [TREO]-based; n=162; 21%).

Results

No significant differences were observed in nonrelapse mortality, cumulative incidence of relapse, and overall survival, although in the TREO-based group, we observed a greater proportion of elderly patients (P < 0.001); more active diseases at the time of SCT (P < 0.001); a higher prevalence of patients with either hematopoietic cell transplantation-comorbidity index ≥3 (P < 0.001) or a good Karnofsky performance status (P = 0.025); increased use of peripheral blood stem cells as graft sources (P < 0.001); and greater use of reduced intensity conditioning regimens (P = 0.013) and of haploidentical donors (P < 0.001). Moreover, the 2-y cumulative incidence of relapse with myeloablative doses of BU was significantly lower than that registered with reduced intensity conditioning (21% versus 31%; P = 0.0003). This was not observed in the TREO-based group.

Conclusions

Despite a higher number of risk factors in the TREO group, no significant differences were observed in nonrelapse mortality, cumulative incidence of relapse, and overall survival according to the type of alkylator, suggesting that TREO has no advantage over BU in terms of efficacy and toxicity in acute myeloid leukemia and myelodysplastic syndrome.

Impact of Glutathione S-Transferase Polymorphisms on Busulfan Pharmacokinetics and Outcomes of Hematopoietic Stem Cell Transplantation

BACKGROUND

Busulfan (Bu) is an alkylating drug used in many preparative regimens before hematopoietic stem cell transplantation (HSCT). It is conjugated in the liver mainly by glutathione S-transferase isoenzyme A1-1 ( GSTA1 ). Genetic polymorphisms in these isoenzymes may affect the pharmacokinetics of Bu and the clinical outcomes of HSCT. This study aimed to assess the impact of glutathione S-transferase ( GST ) genetic polymorphisms on the clearance of Bu and the clinical outcomes of patients undergoing HSCT.

METHODS

This single-center retrospective study included patients who received IV Bu before HSCT at Sultan Qaboos University Hospital (SQUH), Oman from January 2003 to October 2016. Genotyping for polymorphisms was performed for GSTM1 , GSTT1 , GSTA1 , and GSTP1 . Each GST polymorphism was analyzed for its impact on Bu clearance and HSCT outcomes.

RESULTS

A total of 135 patients were included. The mean Bu clearance was 3.7 ± 0.98 mL/min/kg. Patients with GSTA1 A-513G heterozygosity (AG) were found to have a higher incidence of graft loss ( P = 0.006). Homozygous double null of GSTM1 and GSTT1 was associated with a higher incidence of acute graft versus host disease ( P = 0.04). Double non-null GSTM1 and GSTT1 and non-null GSTM1 increased the risk of mortality ( P = 0.034 and 0.021, respectively).

CONCLUSIONS

GST genotyping before HSCT may predict HSCT outcomes. The results of this preliminary retrospective study need to be confirmed in a larger prospective study.

Biosynthesized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) as biocompatible microcapsules with extended release for busulfan and montelukast

An extended release dosage form based on encapsulating the challenging drug busulfan within microspheres of the biodegradable, biocompatible and biosynthesized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) polyester was achieved. The used (PHBV) polymer was biosynthesized by the halophilic archaeon Haloferax mediterranei from date waste biomass as feed-stock. PHBV microspheres of 1.2-2.1 μm diameter were successfully fabricated and loaded with busulfan with an encapsulation efficiency of 29.2 ± 0.2%. In addition, PHBV microspheres of 1.5-3.5 μm diameter and loaded with montelukast sodium (MK) drug were also fabricated with an encapsulation efficiency of 16.0 ± 0.4%. The double-emulsion solvent evaporation method was used to fabricate the drug-loaded microspheres. The drug-loaded microspheres have been characterized by XRD, FTIR and SEM, and confirmed to be successfully fabricated. The drugs in vitro release profiles have shown extended release for up to 3 days in case of busulfan and 8 h in case of montelukast sodium. The in vitro release profiles for busulfan and montelukast suggest that these drug-loaded microcapsules can be efficiently used as new dosage forms to solve the current issues of busulfan administration protocols, and to introduce a new dosage form for montelukast with extended release performance.

Intratesticular versus intraperitoneal injection of Busulfan for the induction of azoospermia in a rat model

BACKGROUND

Administration of antineoplastic drugs may cause azoospermia driving to subfertility. Production of animal azoospermia models is essential for evaluating new treatment methods before therapeutic interventions in human setup. This study aimed to investigate the toxic effects of Busulfan (an anticancer drug) on some vital organs and describe the best method and appropriate dose of Busulfan to induce an animal azoospermia model.

METHODS

Rats were randomly assigned into four groups, treatment groups received 10 mg/kg, 40 mg/kg Busulfan intraperitoneally (IP), 5 mg/kg Busulfan intratesticular (IT), and control group. Blood, bone marrow, liver, renal, and testes samples were collected for histological (H&E staining), biochemical (serum levels of ALT, AST, ALP, creatinine, and urea), and hematological analyses.

RESULTS

Results revealed severe anemia and leukopenia in rats that received Busulfan via IP. By contrast, injection of 5 mg/kg Busulfan via IT did not cause anemia except with a mild decrease in RBC count. Non-significant differences in the M/E ratio were observed in all groups. The administration of 40 mg/kg of Busulfan led to evacuation and destruction in the spermatogenesis process with thin-walled seminiferous epithelium in most tubules, but in rats treated with 10 mg/kg of Busulfan, the normal spermatogenesis process was notified. IT injection of Busulfan contributed to the complete degradation of spermatogenesis in which all spermatogenic cells degenerated. In the renal tissue, hyperemia, extensive tubular necrosis degeneration, and hyaline casts were found after IP injection of Busulfan. In hepatic tissue, focal hemorrhagic, chronic cholangitis, and hepatocyte degeneration, and swelling were noticed. Biochemical analysis revealed apparent Busulfan toxicity of both hepatic and renal tissues in IP Busulfan-treated rats.

CONCLUSIONS

In summary, we found that the intratesticular injection of low doses of Busulfan (5 mg/kg) is a relatively non-invasive and safe method for producing the rat azoospermia model causing the least toxicity on vital organs.

Delivery strategies in treatments of leukemia

Leukemia is a hematological malignancy associated with the uncontrolled proliferation of mutant progenitors, suppressing the production of normal blood cells. Current treatments, including chemotherapy, radiotherapy, and immunotherapy, still lead to unsatisfactory results with a 5 year survival rate of only 30-50%. The poor prognosis is related to both disease relapse and treatment-associated toxicity. Delivery strategies can improve the in vivo pharmacokinetics of drugs, navigating the therapeutics to target cells or the tumor microenvironment and reversing drug resistance, which maximizes tumor elimination and alleviates systematic adverse effects. This review discusses available FDA-approved anti-leukemia drugs and therapies with a focus on the advances in the development of anti-leukemia drug delivery systems. Additionally, challenges in clinical translation of the delivery strategies and future research opportunities in leukemia treatment are also included.

ABT199/venetoclax potentiates the cytotoxicity of alkylating agents and fludarabine in acute myeloid leukemia cells

The antineoplastic activity of pre-transplant regimens in hematopoietic stem cell transplantation (HSCT) is a critical factor for acute myeloid leukemia (AML) patients. There is an urgent need to identify novel approaches without jeopardizing patient safety. We hypothesized that combination of drugs with different mechanisms of action would provide better cytotoxicity. We, therefore, determined the synergistic cytotoxicity of various combinations of the alkylating agents busulfan (Bu) and 4-hydroperoxycyclophosphamide (4HC), the nucleoside analog fludarabine (Flu) and the BCL2 inhibitor ABT199/venetoclax in AML cells. [Bu+4HC] and [Bu+Flu] inhibited cell proliferation and activated apoptosis; addition of ABT199 to either combinations significantly increased these effects with combination indexes < 1. Apoptosis is suggested by cleavages of PARP1 and CASPASE 3, DNA fragmentation, increased reactive oxygen species, decreased mitochondrial membrane potential, and increased pro-apoptotic proteins in the cytoplasm. A similar enhancement of apoptosis was observed in patient-derived cell samples. ABT199/venetocalx upregulated anti-apoptotic MCL1 as a compensatory mechanism but addition of [Bu+4HC] or [Bu+Flu] negated this effect by CASPASE 3-mediated cleavage of MEK1/2 and its substrate MCL1. CASPASE 3 caused cleavage of pro-survival β-CATENIN, which likely contributed to the activation of stress signaling pathways involving SAPK/JNK and AMPK. The observed synergistic cytotoxicity was associated with an inhibition of pro-survival pathways involving STAT1, STAT5 and PI3K. These findings will be useful in designing clinical trials using these drug combinations as pre-transplant conditioning regimens for AML patients.

Can First-Dose Therapeutic Drug Monitoring Predict the Steady State Area Under the Blood Concentration-Time Curve of Busulfan in Pediatric Patients Undergoing Hematopoietic Stem Cell Transplantation?

Busulfan has high intra-individual variability and possible time-dependent changes in clearance, which complicates therapeutic drug monitoring (TDM), as first dose sampling may not predict the steady state concentrations. In this study, we aimed to use Bayesian pharmacokinetic parameters estimated from the first dose to predict the steady state AUC for busulfan. This observational study was conducted among pediatric patients at King Abdullah Specialist Children's Hospital. From each patient, we collected six blood samples (2, 2.25, 2.5, 3, 4, and 6 h after the start of IV infusion of the first dose). A subset of patients were also sampled at the steady state. First, we modeled the data using only the first dose. The model was used to estimate the empirical Bayesian estimates of clearance for each individual patient, then we used the empirical Bayesian estimates of clearance to predict the AUC_0-tau at steady state (i.e., predicted AUC_0-tau). Steady state AUC_0-tau was also calculated for patients sampled at steady state using the trapezoidal method using raw time concentration data; this was considered the reference AUC_0-tau.. Then, we compared the AUC_0-tau predicted using the Bayesian approach with the reference AUC_0-tau values. We calculated bias and precision to assess predictability. In total we had 33 patients sampled after first dose and at steady state. Using the Bayesian approach to predict the AUC_0-tau, bias was -2.8% and precision was 33%. This indicates that first dose concentrations cannot accurately predict steady state busulfan concentrations; therefore, follow-up TDM may be required for optimal dosing.

Does Chemotherapy-Induced Gastrointestinal Mucositis Affect the Bioavailability and Efficacy of Anti-Infective Drugs?

Antimicrobial prophylaxis is increasingly being used in patients with hematological malignancies receiving high-dose chemotherapy and hematopoietic stem cell transplantation (HSCT). However, few studies have focused on the potential impact of gastrointestinal mucositis (GI-M), a frequently observed side effect of chemotherapy in patients with cancer that affects the gastrointestinal microenvironment, on drug absorption. In this review, we discuss how chemotherapy leads to an overall loss of mucosal surface area and consequently to uncontrolled transport across the barrier. The barrier function is depending on intestinal luminal pH, intestinal motility, and diet. Another factor contributing to drug absorption is the gut microbiota, as it modulates the bioavailability of orally administrated drugs by altering the gastrointestinal properties. To better understand the complex interplay of factors in GI-M and drug absorption we suggest: (i) the longitudinal characterization of the impact of GI-M severity on drug exposure in patients, (ii) the development of tools to predict drug absorption, and (iii) strategies that allow the support of the gut microbiota. These studies will provide relevant data to better design strategies to reduce the severity and impact of GI-M in patients with cancer.

Treosulfan-Based Conditioning Regimen Prior to Allogeneic Stem Cell Transplantation: Long-Term Results From a Phase 2 Clinical Trial

Introduction

Reducing toxicities while preserving efficacy in allogeneic stem cell transplant (allo-HCT) remains a particularly challenging problem. Different strategies to enhance the antitumor activity without increasing early and late adverse toxicities of the conditioning regimens have been investigated.

Methods

The aim of “AlloTreo” prospective phase 2 clinical trial was to evaluate the efficacy and safety of a conditioning regimen based on Treosulfan (42 g/m²) and fludarabine (https://clinicaltrials.gov/ct2/show/NCT00598624). We enrolled 108 patients with hematological diseases who received a first allo-HCT between June 2005 and January 2011, inside the frame of this trial at our center. Median age at allo-HCT was 49 (21–69) years. Disease Risk Index was low in 14 (13%) patients, intermediate in 73 (67.7%), high in 17 (15.7%), and very high in 4 (3.7%). Donors were human leukocyte antigen (HLA)-matched related in 50 cases, 10/10-matched unrelated in 36, and 9/10-mismatched unrelated in 22. Graft-versus-host disease (GvHD) prophylaxis consisted of cyclosporine-A and methotrexate. Anti-T-lymphocyte globulin (ATLG) was administered in patients receiving unrelated allo-HCT. Stem cell source was mainly peripheral blood stem cells (95%).

Results

Conditioning regimen was well tolerated. Full donor chimerism was documented for most patients (88%) at day +30. At 12 years, overall survival (OS) was 41.7% (32.2%–50.9%), progression-free survival (PFS) was 31.7% (23%–40.7%), GvHD-free/relapse-free survival was 20.9% (13.7%–29.1%), cumulative incidence (CI) of relapse was 44.5% (34.9%–53.6%), and transplant-related mortality (TRM) was 22.5% (15.1%–30.9%). CI of acute GvHD grades II–IV was 27.8% (19.7%–36.5%) at 100 days; 12-year CI of chronic GvHD was 40.7% (31.3%–49.9%). Relevant long-term adverse effects were 10 secondary malignancy, 3 fatal cardiovascular events, and 1 late-onset transplant-associated thrombotic microangiopathy. Ten successful pregnancies were reported after allo-HCT. In multivariate analysis, older age (≥60 years) at transplant [hazard ratio (HR), 2.157; p = 0.004] and a high/very high disease risk index (HR, 1.913; p = 0.026) were significantly associated with a lower OS.

Conclusions

Overall, our data confirmed the myeloablative potential and safe toxicity profile of full dose Treo (42 g/m²) especially for the younger population.

Busulfan impairs blood-testis barrier and spermatogenesis by increasing noncollagenous 1 domain peptide via matrix metalloproteinase 9

BACKGROUNDS

Sterility induced by anti-cancer treatments has caused significant concern, yet the mechanism and treatment exploration are little for male infertility after cancer therapy. Busulfan, the antineoplastic that was widely applied before bone marrow transplantation, was known to induce male reproductive disorder.

OBJECTIVES

To investigate the effect of busulfan on blood-testis barrier function in adult rats and determine whether noncollagenous 1 domain peptide, the biologically active fragment proteolyzed from the collagen α3 chain (IV) by matrix metalloproteinase 9, was involved during this process.

MATERIALS AND METHODS

Adult male rats were treated with one-dose or double-dose of busulfan (10 mg/kg) before euthanized at day 35. Blood-testis barrier integrity assay, HE staining, immunofluorescence, and Western blot were used to validate the effect of busulfan on blood-testis barrier permeability and spermatogenesis. JNJ0966 was applied to specifically inhibit the matrix metalloproteinase 9 activity. The polymerization activity of F-actin/G-actin and microtubule/tubulin in the testis were assessed by using commercial kits.

RESULTS

A noteworthy blood-testis barrier injury and significant up-regulation of matrix metalloproteinase 9 activity and noncollagenous 1 level after a single-dose busulfan (10 mg/kg) treatment in adult rat testis were revealed. The application of JNJ0966 was found to decrease noncollagenous 1 level and rescue the busulfan-induced blood-testis barrier injury including the mis-localization of junction proteins across the seminiferous epithelium, by recovering the organization and polymerization of both F-actin and microtubule. The busulfan-induced spermatogenesis impairment was also improved by JNJ0966.

CONCLUSION

These findings thus demonstrate that the elevation in matrix metalloproteinase 9 and noncollagenous 1 might participate in busulfan-induced blood-testis barrier disruption in adult male rats. As such, busulfan-induced male infertility could possibly be managed through interventions on noncollagenous 1 production.

Treosulfan in platinum-resistant ovarian cancer

OBJECTIVES

Treosulfan is offered as last-line treatment in patients with end-stage ovarian cancer. This retrospective study aimed to evaluate the response rates, overall survival, and adverse events of treosulfan in this patient population.

METHODS

The study included patients with end-stage platinum-resistant ovarian cancer treated with treosulfan from October 2015 to October 2020 at the Department of Oncology, Lillebaelt Hospital, University Hospital of Southern Denmark, Vejle, Denmark. Patients were included for treatment if their cancer had progressed and if other treatment options were limited. Patients receiving treosulfan as first-line treatment were excluded from the study. Response rates were evaluated according to the combined criteria of CA125 and Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Kaplan-Meier survival analyses were used to illustrate progression-free and overall survival. Adverse events were graded 1-5 according to the Common Terminology Criteria for Adverse Events version 5.0.

RESULTS

Sixty-seven patients with a median age of 72 years (range 33-92) were identified. Sixty-three (94%) patients were diagnosed with serous adenocarcinoma. Fifty-seven (85%) patients were Federation of International Gynecology and Obstetrics (FIGO) stage III or IV at the time of diagnosis. The median number of treatments prior to treosulfan treatment was 3 (range 1-8). One patient had a complete response (2%), eight patients had a partial response (13%), and 22 patients (35%) had stable disease as the best response. The median duration of response (complete or partial) was 239 days (range 43-572). Median progression-free survival was 63 days (95% CI 41 to 77). The most common adverse events were anemia (83%), fatigue (83%), anorexia (62%), nausea (57%), and constipation (41%).

CONCLUSIONS

Treosulfan is an alternative for the treatment of relapsed ovarian cancer when other treatment options are limited, with response rates of approximately 15%. In general, the treatment was well tolerated. Taking the mild adverse events and the response rates into account, palliative treosulfan mainly seems beneficial for patients with performance status 0-1.

Amniotic fluid-derived exosomes improved spermatogenesis in a rat model of azoospermia

AIMS

This study aimed to explore the therapeutic effects of amniotic fluid-derived extracellular vesicles including exosomes (AF-Exos) on the recovery of sperm production capacity in a rat model of azoospermia.

MAIN METHODS

The non-obstructive azoospermia (NOA) was induced in rats using intratesticular administration of Busulfan. Azoospermia was confirmed by testis histology. AF-Exos samples containing 10 or 40 μg exosomal proteins were injected into testicular tissue of NOA rats. After two months, the recovery of spermatogenesis was monitored via histopathological staining, spermiogram, and hormonal analysis. Immunohistochemistry staining for OCT-3/4 was used to identify of spermatogonial progenitors. The expression of DAZL and VASA, was also measured.

KEY FINDINGS

AF-Exos exhibited sphere-shaped morphology with the mean diameter and zeta potential of 50 ± 7.521 nm and -7.16 mV. Immunoblots revealed that isolated nanoparticles were CD63, CD9, and CD81 positive. Histopathological evaluation revealed that spermatogenesis was improved significantly in NOA rats after AF-Exos injection. Data showed that the sperm parameters and spermatogenesis index were significantly improved after AF-Exos injection compared to azoospermic groups. OCT-3/4⁺ cells were increased in NOA rats after AF-Exos injection, showing the restoration of spermatogenesis. In the present study, both doses of exosome (10 and 40 μg) restored the testicular function of NOA rats. DAZL and VASA were increased significantly in animals who received 40 μg exosomal protein compared to azoospermic rats. Except in a high dose of AF-Exos (40 μg) for Testosterone and FSH, no statistically significant differences were found regarding hormones post-exosome injection.

SIGNIFICANCE

Our study demonstrated that AF-Exos regenerated spermatogenesis and improved sperm quality in NOA rats.

Effects of GSTT1 Genotype on the Detoxification of 1,3-Butadiene Derived Diepoxide and Formation of Promutagenic DNA-DNA Cross-Links in Human Hapmap Cell Lines

Smoking is a leading cause of lung cancer, accounting for 81% of lung cancer cases. Tobacco smoke contains over 5000 compounds, of which more than 70 have been classified as human carcinogens. Of the many tobacco smoke constituents, 1,3-butadiene (BD) has a high cancer risk index due to its tumorigenic potency and its abundance in cigarette smoke. The carcinogenicity of BD has been attributed to the formation of several epoxide metabolites, of which 1,2,3,4-diepoxybutane (DEB) is the most toxic and mutagenic. DEB is formed by two oxidation reactions carried out by cytochrome P450 monooxygenases, mainly CYP2E1. Glutathione-S-transferase theta 1 (GSTT1) facilitates the conjugation of DEB to glutathione as the first step of its detoxification and subsequent elimination via the mercapturic acid pathway. Human biomonitoring studies have revealed a strong association between GSTT1 copy number and urinary concentrations of BD-mercapturic acids, suggesting that it plays an important role in the metabolism of BD. To determine the extent that GSTT1 genotype affects the susceptibility of individuals to the toxic and genotoxic properties of DEB, GSTT1 negative and GSTT1 positive HapMap lymphoblastoid cell lines were treated with DEB, and the extent of apoptosis and micronuclei (MN) formation was assessed. These toxicological end points were compared to the formation of DEB-GSH conjugates and 1,4-bis-(guan-7-yl)-2,3-butanediol (bis-N7G-BD) DNA-DNA cross-links. GSTT1 negative cell lines were more sensitive to DEB-induced apoptosis as compared to GSTT1 positive cell lines. Consistent with the protective effect of GSH conjugation against DEB-derived apoptosis, GSTT1 positive cell lines formed significantly more DEB-GSH conjugate than GSTT1 negative cell lines. However, GSTT1 genotype did not affect formation of MN or bis-N7G-BD cross-links. These results indicate that GSTT1 genotype significantly influences BD metabolism and acute toxicity.

Protective effect of curcumin on busulfan-induced renal toxicity in male rats

AIM

The aim of this study was to evaluate the effects of curcumin in an experimental model of busulfan-induced renal toxicity with emphasis on importance of histological alterations.

METHODS

In this study, we utilized 32 adult male Wistar rats (250 ± 10 g). All the animals were divided into four experimental groups randomly: (I) Control; (II) Busulfan (40 mg/kg); (III) Olive oil; and (IV) Curcumin (80 mg/kg/day). Finally, the rats were euthanized and kidney tissues were taken for histopathology experiments, serum BUN, and creatinine level, reactive oxygen species (ROS) production and glutathione disulfide (GSH) activity.

RESULTS

Our result showed that the reduction in body weight and kidney weight in busulfan groups in comparison with the control and curcumin groups. The result in this study also showed that the reduction in BUN, creatinine, and ROS production in curcumin groups in comparison with the busulfan group together with an increasing of GSH activity compared to busulfan induced rats.

CONCLUSION

Our results of this study indicated that that the reduction in body weight, kidney weight, total volume of kidney, total length of nephron tubules, and numerical density of glomeruli and nephron tubules in busulfan groups in comparison with the control and curcumin groups However, curcumin can be an alternative choice for therapeutically and research purposes in the disturbing kidney after treatment with busulfan.

Effect of Gosha-Jinki-Gan on Levels of Specific mRNA Transcripts in Mouse Testes after Busulfan Treatment

With the increase in survival rates of cancer patients in recent years, infertility caused by anticancer treatments has become a significant concern for cancer survivors. Some studies have suggested that Sertoli cells play a key role in mediating testicular immunology in busulfan-induced aspermatogenesis. We recently demonstrated that Gosha-jinki-gan (TJ107), a traditional Japanese medicine, can completely recover injured spermatogenesis in mice 60 days after busulfan injection. In the present study, we sought to examine the levels of mRNA transcripts encoding markers of 25 Sertoli cell-specific products and 10 markers of germ cell differentiation. Our results demonstrated that only supplementation of TJ107 at day 60 after busulfan injection could significantly recover the increase in five mRNA species (Amh, Clu, Shbg, Testin, and Il1a) and the decrease in four mRNA species (Aqp8, CST9, Wnt5a, and Tjp1) in response to Busulfan (BSF) at day 120, with the increase of all examined spermatogenic markers.

Co-Administration of the Traditional Medicines Hachimi-Jio-Gan and Hochu-Ekki-To Can Reverse Busulfan-Induced Aspermatogenesis

Busulfan is used as a chemotherapeutic drug to treat childhood and adult chronic myelogenous leukemia, and as an immunosuppressive agent before bone marrow transplantation. A key side effect of busulfan is the alteration of male reproductive function. Infertility caused by anti-cancer treatments has become a significant concern, but there are currently limited treatments for this condition. Recently, we demonstrated that Gosha-jinki-gan, a traditional Japanese medicine, completely reversed the spermatogenesis defects caused by cancer treatment in mice. Hochu-ekki-to and Hachimi-jio-gan are commonly used to treat male infertility, and Hachimi-jio-gan shares herbal ingredients with Gosha-jinki-gan. Therefore, in the present study, we administered Hachimi-jio-gan and Hochu-ekki-to alone or in combination to mice with severe aspermatogenesis caused by busulfan treatment. We performed testis weight measurements, quantitative histological assessments of the testes and the epididymis, and evaluated sperm counts and morphology. We also assessed the expression of immune mediators and macrophage markers. Treatment with a combination of both the medicines significantly reduced busulfan-induced testicular toxicity when compared to the lone treatment with either medicine. We demonstrated that treatment efficacy was related to a differential impact on testicular inflammation, and that the synergistic effect of co-administration completely reversed the busulfan-induced damage to the reproductive functions.

Synthesis of new N,N′-Pd(Pt) complexes based on sulfanyl pyrazoles, and investigation of their in vitro anticancer activity

The synthesis of new N,N′-mononuclear bi-ligand Pd(ii) and tri-ligand Pt(ii)complexes bearing sulfanyl(phenyl, benzyl, cyclohexyl, 4-hydroxyphenyl)3,5-dimethyl-1H-pyrazole ligands has been carried out. The obtained compounds were studied for apoptosis-inducing activity and effect on the cell cycle for Jurkat, K562, and U937 neoplastic cell cultures and conditionally normal human embryonic kidney HEK293 cells. The cells showed the highest sensitivity to platinum and palladium complexes in comparison with ligands and cisplatin. The cytotoxic properties are enhanced for compounds with cyclohexyl substituents at the S-atom in sulfanyl pyrazoles and complexes.

Efficient cytostatics against Jurkat, K562 and U937 neoplastic cell lines were found among the synthesized new Pd(ii) and Pt(ii)complexes (six examples) with sulfanyl-1H-pyrazole ligands using in vitro assay.

A simplified method for detection of N-terminal valine adducts in patients receiving treosulfan

RATIONALE

Treosulfan is a substance that is being studied as part of the conditioning regimen given prior to allogeneic stem cell transplantation in patients with hematological malignancies. It is known to decompose into 1,2:3,4-diepoxybutane (DEB) under physiologic conditions. In this study, we investigate whether N-terminal valine adducts can be utilized to monitor differences in DEB formation of patients receiving treosulfan as part of the conditioning regimen for transplantation.

METHODS

Blood samples were collected from a group of 14 transplant recipients and analyzed for N,N-(2,3-dihydroxy-1,4-butadiyl)valine (pyr-Val) and 2,3,4-trihydroxybutylvaline (THB-Val) adducts as biomarkers for drug uptake and metabolism before treosulfan treatment and 6 days after treatment.

RESULTS

A new direct injection liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed and validated prior to clinical analysis. The assay precision was determined by 3 replicate analyses on 3 individual days using control globin spiked with known amounts of pyr-Val and THB-Val. The intra- and inter-day precision coefficients of variance (CVs) and accuracy were < 10% and 15%, respectively. In clinical specimens, the means ± SD of pyr-Val and THB-Val background were 0.29 ± 0.10 pmol/g HB and 5.17 ± 1.7 pmol/g HB, respectively.

CONCLUSIONS

These values are similar to those found previously. Treosulfan treatment leads to a significant increase in pyr-Val and THB-Val adducts in each patient (Student's t-test p <0.0001). The mean ± SD amounts of adduct formed were 245.3 ± 89.6 and 210 ± 78.5 pmol/g globin for pyr-Val and THB-Val, respectively. Importantly, these results show that this direct injection method can quantitate both background and treosulfan-induced pyr-Val and THB-Val N-terminal valine globin adducts in humans.

Treosulfan Pharmacokinetics and its Variability in Pediatric and Adult Patients Undergoing Conditioning Prior to Hematopoietic Stem Cell Transplantation: Current State of the Art, In-Depth Analysis, and Perspectives

Treosulfan is a prodrug that undergoes a highly pH- and temperature-dependent nonenzymatic conversion to the monoepoxide {(2S,3S)-1,2-epoxy-3,4-butanediol 4-methanesulfonate [S,S-EBDM]} and diepoxide {(2S,3S)-1,2:3,4-diepoxybutane [S,S-DEB]}. Currently, treosulfan is tested in clinical trials as an alternative to busulfan in conditioning prior to hematopoietic stem cell transplantation (HSCT). Of note, the optimal dosing of the prodrug is still unresolved, especially in infants. In this paper, the pharmacokinetics of treosulfan, together with its biologically active epoxides, is comprehensively reviewed for the first time, with the focus on conditioning prior to HSCT. Most of the insightful data presented in this review comes from studies that have been conducted in the last 3 years. The article widely discusses the volume of distribution and total clearance of treosulfan. In particular, the interindividual variability of these key parameters in infants, children above 1 year of age, and adults is analyzed, including possible covariates. A clinically important aspect of the formation rate-limited elimination of S,S-EBDM and S,S-DEB is described, including the correlation between the exposure of the prodrug and S,S-EBDM in children. The significance of the elimination half-life of treosulfan and its epoxides for successful conditioning prior to HSCT is also raised. Furthermore, the organ disposition of treosulfan and S,S-EBDM in rats is discussed in the context of the clinical toxicity and myeloablative activity of treosulfan versus busulfan. Moreover, perspectives for future therapeutic drug monitoring of treosulfan are presented. The review is intended to be helpful to pharmacists and doctors in the comprehension of the clinical pharmacokinetics of treosulfan.

Kinetics of in Vitro Guanine- N7-Alkylation in Calf Thymus DNA by (2 S,3 S)-1,2-Epoxybutane-3,4-diol 4-methanesulfonate and (2 S,3 S)-1,2:3,4-Diepoxybutane: Revision of the Mechanism of DNA Cross-Linking by the Prodrug Treosulfan

Prodrug treosulfan, originally registered for treatment of ovarian cancer, has gained a use in conditioning prior to hematopoietic stem cell transplantation. Treosulfan converts nonenzymatically to the monoepoxide intermediate (EBDM), and then to (2 S,3 S)-1,2:3,4-diepoxybutane (DEB). The latter alkylates DNA forming mainly (2' S,3' S)- N-7-(2',3',4'-trihydroxybut-1'-yl)guanine (THBG) and (2 S,3 S)-1,4-bis(guan-7'-yl)butane-2,3-diol cross-link (bis-N7G-BD) via the intermediate epoxide adduct (EHBG). It is believed that DNA cross-linking by DEB is a primary mechanism for the anticancer and myeloablative properties of treosulfan, but clear evidence is lacking. Recently, we have proved that EBDM alkylates DNA producing (2' S,3' S)- N-7-(2',3'-dihydroxy-4'-methylsulfonyloxybut-1'-yl)-guanine (HMSBG) and that free HMSBG converts to EHBG. In this paper, we investigated the kinetics of HMSBG, bis-N7G-BD, and THBG in DNA in vitro to elucidate the contribution of EBDM and DEB to treosulfan-dependent DNA-DNA cross-linking. Calf thymus DNA was exposed to ( A) 100 μM treosulfan, ( B) 200 μM treosulfan, and ( C) DEB at a concentration 100 μM, exceeding that produced by 200 μM treosulfan. Following mild acid thermal hydrolysis of DNA, ultrafiltration, and off-line HPLC purification, the guanine adducts were quantified by LC-MS/MS. Both bis-N7G-BD and THBG reached highest concentrations in the DNA in experiment B. Ratios of the maximal concentration of bis-N7G-BD and THBG to DEB (adduct C_max/DEB C_max) in experiments A and B were 1.7-3.0-times greater than in experiment C. EHBG converted to the bis-N7G-BD cross-link at a much higher rate constant (0.20 h^-1) than EBDM and DEB initially alkylated the DNA (1.8-3.4 × 10^-5 h^-1), giving rise to HMSBG and EHBG, respectively. HMSBG decayed unexpectedly slowly (0.022 h^-1) compared with the previously reported behavior of the free adduct (0.14 h^-1), which revealed the inhibitory effect of the DNA environment on the adduct epoxidation to EHBG. A kinetic simulation based on the obtained results and the literature pharmacokinetic parameters of treosulfan, EBDM, and DEB suggested that in patients treated with the prodrug, EBDM could produce the vast majority of EHBG and bis-N7G-BD via HMSBG. In conclusion, EBDM can produce DNA-DNA lesions independently of DEB, and likely plays a greater role in DNA cross-linking after in vivo administration of treosulfan than DEB. These findings compel revision of the previously proposed mechanism of the pharmacological action of treosulfan and contribute to better understanding of the importance of EBDM for biological effects.

Plausible biochemical mechanisms of chemotherapy-induced cognitive impairment ("chemobrain"), a condition that significantly impairs the quality of life of many cancer survivors

Increasing numbers of cancer patients survive and live longer than five years after therapy, but very often side effects of cancer treatment arise at same time. One of the side effects, chemotherapy-induced cognitive impairment (CICI), also called "chemobrain" or "chemofog" by patients, brings enormous challenges to cancer survivors following successful chemotherapeutic treatment. Decreased abilities of learning, memory, attention, executive function and processing speed in cancer survivors with CICI, are some of the challenges that greatly impair survivors' quality of life. The molecular mechanisms of CICI involve very complicated processes, which have been the subject of investigation over the past decades. Many mechanistic candidates have been studied including disruption of the blood-brain barrier (BBB), DNA damage, telomere shortening, oxidative stress and associated inflammatory response, gene polymorphism of neural repair, altered neurotransmission, and hormone changes. Oxidative stress is considered as a vital mechanism, since over 50% of FDA-approved anti-cancer drugs can generate reactive oxygen species (ROS) or reactive nitrogen species (RNS), which lead to neuronal death. In this review paper, we discuss these important candidate mechanisms, in particular oxidative stress and the cytokine, TNF-alpha and their potential roles in CICI.

Effects of Chemotherapy and Radiotherapy on Spermatogenesis: The Role of Testicular Immunology

Substantial improvements in cancer treatment have resulted in longer survival and increased quality of life in cancer survivors with minimized long-term toxicity. However, infertility and gonadal dysfunction continue to be recognized as adverse effects of anticancer therapy. In particular, alkylating agents and irradiation induce testicular damage that results in prolonged azoospermia. Although damage to and recovery of spermatogenesis after cancer treatment have been extensively studied, there is little information regarding the role of differences in testicular immunology in cancer treatment-induced male infertility. In this review, we briefly summarize available rodent and human data on immunological differences in chemotherapy or radiotherapy.

Liquid chromatography-tandem mass spectrometry method for simultaneous determination of three N-7-guanine adducts of the active epoxides of prodrug treosulfan in DNA in vitro

Prodrug treosulfan undergoes a pH and temperature-dependent activation to the monoepoxide intermediate (EBDM) and (2S,3S)-1,2:3,4-diepoxybutane (DEB). The latter DNA cross-linker is presently believed to mainly account for the pharmacological action of treosulfan. However, neither respective monoadducts nor cross-links have been isolated from treosulfan-treated DNA, and the exact alkylation mechanism of the treosulfan epoxides is unclear. In this paper, liquid chromatography method with tandem mass spectrometry detection (LC-MS/MS) for simultaneous determination of the N-7-guanine adducts of EBDM and DEB - (2'S,3'S)-N-7-(2'3'-dihydroxy-4'-methylsulfonyloxybut-1'-yl)guanine (HMSBG), N-7-(2',3',4'-trihydroxybut-1'-yl)guanine (THBG), and 1,4-bis(N-7-guanyl)butane-2,3-diol cross-link (bis-N7G-BD) - in calf-thymus DNA has been developed and validated for the first time. The mixture of drug-free nucleic acid with the analytes and ¹⁵N-isotope labeled internal standards underwent a mild acid thermal hydrolysis and ultrafiltration (cut-off 10 kDa). Following offline LC purification, the analytes and internal standards were determined in the LC-MS/MS system with an electrospray interface. Complete resolution of THBG, HMSBG, and bis-N7G-BD was accomplished on a Zorbax Eclipse C18 column using gradient elution with a mobile phase composed of 0.1% formic acid and acetonitrile. Calibration curves were linear in the ranges: THBG 0.2-200 pmol, HMSBG 0.2-20 pmol, and bis-N7G-BD 0.4-40 pmol. The limits of quantitation allowed to determine the adducts at concentration of 330 or 660 per 10⁹ DNA nucleotides. The LC-MS/MS method was adequately precise (coefficient of variation ≤ 16.7%) and accurate (relative error ≤ 17.7%). Calibration standards were stable for 14 days at -25 °C. The validated method enabled determination of THBG, HMSBG, and bis-N7G-BD in calf thymus DNA treated with treosulfan at pH 7.2 and 37 °C, which constitutes a novel bioanalytical application. To the authors' best knowledge, the quantification of THBG and bis-N7G-BD in one analytical run is also reported for the first time.

Decane-1,2-diol derivatives as potential antitumor agents for the treatment of glioblastoma

Glioblastoma remains the most common and aggressive type of malignant brain tumor among adults thus, considerable attention has been given to discovery of novel anti-tumor drugs for its treatment. This study reports the synthesis of a series of twelve novel decane-1,2-diol derivatives and evaluation of its anti-tumor activity in mammalian glioblastoma cell lines, U87 and LN229. Starting from decane-1,2-diol, several derivatives were prepared using a diversity oriented synthesis approach through which a small library composed of esters, silyl ethers, sulfonates, sulfites, sulfates, ketals, and phosphonates was built. The decane-1,2-diol ditosylated derivative, DBT, found to have higher cytotoxicity than the standard drug cisplatin, has IC₅₀ value of 52 µM in U87 and 270 µM in LN229. Migration analysis of U87 cell line treated with the DBT indicated its ability to effectively suppress proliferation during initial hours of treatment and decrease anti-proliferative property over time. Additionally, DBT was assessed for its role in apoptosis, oxidative stress and caspase 3/7 activation in U87. Interestingly, our experiments indicated that its cytotoxicity is independent of Reactive oxygen species induced caspase 3/7 activity. The compound also exhibited caspase independent apoptosis activity in U87. DBT treatment led to G1/S cell cycle arrest and apoptosis induction of glioma cell lines. In addition, we identified 1533 genes with significant changes at the transcriptional level, in response to DBT. A molecular docking study accounting for the interaction of DBT with NMDA receptor disclosed several hydrogen bonds and charged residue interactions with 17 amino acids, which might be the basis of the DBT cytotoxicity observed. We conclude that this molecule exerts its cytotoxicity via caspase 3/7 independent pathways in glioblastoma cells. Concisely, simple decane-1,2-diol derivatives might serve as scaffolds for the development of effective anti-glioblastoma agents.

Busulfan administration produces toxic effects on epididymal morphology and inhibits the expression of ZO-1 and vimentin in the mouse epididymis

Busulfan is an alkane sulphonate currently used as an anticancer drug and to prepare azoospermic animal models, because it selectively destroys differentiated spermatogonia in the testes. However, few studies have focussed on the exact effects of busulfan treatment on the epididymis currently. The present study assessed the effect of busulfan on epididymal morphology and the blood-epididymis barrier in mice. We treated mice with a single injection of busulfan and detected the effect at different time points. We showed that busulfan was toxic to the morphological structure and function of the epididymis. Furthermore, busulfan treatment down-regulated the epididymal expression of vimentin and zonula occludens-1 (ZO-1) at the mRNA and protein levels. In addition, there was an increase in total androgen receptor (AR) levels, whereas the estrogen receptor-α (ER-α) levels were reduced, both in the caput and cauda regions after busulfan treatment, which may be secondary to the testicular damage. In conclusion, our study describes the effects of busulfan administration on the mouse epididymis and also provides a potential understanding of male infertility arising from chemotherapy-related defects in the epididymis.

Disposition of treosulfan and its active monoepoxide in a bone marrow, liver, lungs, brain, and muscle: Studies in a rat model with clinical relevance

For the recent years, the application of treosulfan (TREO)-based conditioning prior to hematopoietic stem cell transplantation (HSCT) has been increasing as an alternative to busulfan-based therapy, especially for patients presenting high risk of developing hepato-, pulmo-, and neurotoxicity. So far, the penetration of TREO and its epoxy-derivatives into central nervous system and aqueous humor of the eye has been investigated. However, lacking knowledge on the compounds distribution into the other key tissues precludes comprehensive understanding and assessment of TREO clinical efficacy and toxicity. In this paper, the disposition of TREO and its active monoepoxide (S,S-EBDM) in a bone marrow, liver, lungs, brain, and quadriceps femoris was studied in an animal model. Male and female adult Wistar rats (n=48/48) received an intraperitoneal injection of TREO at the dose of 500mg/kg b.w. Concentrations of TREO and S,S-EBDM in tissues were determined with a validated HPLC-MS/MS method. Pharmacokinetic calculations were performed in WinNonlin using a noncompartmental analysis. Mean values of the maximal concentrations of TREO and S,S-EBDM in the organs were sex-independent and ranged from 61 to 1650μM and 25-105μM, respectively. No quantifiable levels of S,S-EBDM were found in the liver. Average tissue/plasma area under the curve (AUC) ratio for unbound TREO increased in the sequence: brain (0.10)<muscle (0.77)<bone marrow=lungs (0.82)<liver (0.96). The tissue/plasma AUC ratio for unbound S,S-EBDM changed as follows: brain (0.35)<lungs (0.50)<bone marrow (0.75)<muscle (1.14). Elimination half-lives of the compounds in plasma and the organs ranged from 0.7h to 2.1h. Scaling of the obtained AUCs of TREO and S,S-EBDM and the literature AUCs of busulfan to concentrations of the drugs in HSCT patients' plasma show that TREO reaches much higher levels in the organs than busulfan. Nonetheless, low S,S-EBDM exposure in a liver, lungs, and brain, even compared with busulfan, may contribute to relatively low organ toxicity of TREO-based conditioning regimens. Similarity of the scaled bone marrow AUCs of S,S-EBDM and busulfan corresponds to comparable myeloablative potency of TREO- and busulfan-based conditioning. The biological half-lives of TREO and S,S-EBDM in plasma and the studied organs indicate that 48h lag time following administration of the last dose of TREO to HSCT patients is sufficient to protect the transplanted stem cells from the compounds' exposure.

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.

Opening Marrow Niches in Patients Undergoing Autologous Hematopoietic Stem Cell Gene Therapy

Successful gene therapy for genetic disorders requires marrow niches to be opened to varying degrees to engraft gene-corrected hematopoietic stem cells (HSC). For example, in severe combined immunodeficiency, relatively limited chimerism is necessary for both T- and B-cell immune reconstitution, whereas for inborn errors of metabolism maximal donor chimerism is the goal. Currently, alkylating chemotherapy is used for this purpose. Significant pharmacokinetic variability exists in drug clearance in children less than 12 years old. Thus, pharmacokinetic monitoring is needed to achieve the targeted exposure goal for busulfan.

Increased Sat2 expression is associated with busulfan-induced testicular Sertoli cell injury

Busulfan is a chemotherapeutic agent used to treat chronic myelogenous leukemia and other myeloproliferative disorders. Increasing evidence has demonstrated that busulfan may induce testicular dysfunction by targeting genes that are expressed in the testis. Here, we showed that spermidine/spermine N1-acetyltransferase 2 (Sat2) was present in testicular Sertoli cells, and its expression was significantly increased by busulfan treatment. To investigate the implications of Sat2 upregulation for cell growth and function, a Sat2-overexpressing TM4 Sertoli cell model was established. Increased Sat2 expression led to inhibited cell proliferation and arrested cell cycle. Based on iTRAQ proteomics analysis, we revealed that Sat2 overexpression is detrimental to cell cycle progression and cell communication, and notably, Sat2 may disturb protein metabolic processes by altering translation regulation and protein complex subunit organization. In summary, the present study provides evidence that Sat2 upregulation induces alterations in the growth and function of Sertoli cells. In testis tissue subjected to busulfan, increased expression of Sat2 can cause cellular injury and subsequent organ damage, which could lead to male infertility. Therefore, Sat2 may be a novel molecular target for treating busulfan-induced testicular toxicity.

Inventory of oral anticancer agents: Pharmaceutical formulation aspects with focus on the solid dispersion technique

Dissolution from the pharmaceutical formulation is a prerequisite for complete and consistent absorption of any orally administered drug, including anticancer agents (oncolytics). Poor dissolution of an oncolytic can result in low oral bioavailability, high variability in blood concentrations and with that suboptimal or even failing therapy. This review discusses pharmaceutical formulation aspects and absorption pharmacokinetics of currently licensed orally administered oncolytics. In nearly half of orally dosed oncolytics poor dissolution is likely to play a major role in low and unpredictable absorption. Dissolution-limited drug absorption can be improved with a solid dispersion which is a formulation method that induces super-saturated drug dissolution and with that it enhances in vivo absorption. This review discusses formulation principles with focus on the solid dispersion technology and how it works to enhance drug absorption. There are currently three licensed orally dosed oncolytics formulated as a solid dispersion (everolimus, vemurafenib and regorafenib) and these formulations result in remarkably improved dissolution and absorption compared to what can be achieved with conventional formulations of the respective oncolytics. Because of the successful implementation of these three solid dispersion formulations, we encourage the application of this formulation method for poorly soluble oral oncolytics.

Seminiferous epithelium damage after short period of busulphan treatment in adult rats and vitamin B12 efficacy in the recovery of spermatogonial germ cells

Several different strategies have been adopted in attempt to recover from chemotherapy-damaged spermatogenesis that is often seen in oncologic patients. In this study, we have evaluated the impact of short period of exposure to busulphan on the haemogram and seminiferous epithelium of adult rats, focusing on spermatogonial depletion and Sertoli cell (SC) integrity. We then examined whether vitamin B₁₂ supplementation improves the haematological parameters and spermatogonia number. The animals received 10 mg/kg of busulphan (BuG) or busulfan+vitamin B₁₂ (Bu/B₁₂ G) on the first and fourth days of treatment. In H.E.-stained testicular sections, the areas of the seminiferous tubule (ST) and seminiferous epithelium were measured. The number of spermatogonia in H.E-stained and PCNA-immunolabelled testicular sections was quantified. The frequency of tubules with abnormal SC nuclei or TUNEL-positive SC was evaluated. Vimentin immunofluorescence in ST was also evaluated. In BuG and Bu/B₁₂ G, the animals showed leukopenia and thrombocytopenia, but the body weight reduced only in BuG. The areas of ST and seminiferous epithelium decreased in Bu/B₁₂ G and BuG. In BuG, the number of H.E.-stained and PCNA-immunolabelled spermatogonia reduced significantly. The frequency of tubules containing abnormal SC nuclei and TUNEL-positive SC increased and the vimentin immunoexpression pattern changed. In Bu/B₁₂ G, the number of H.E.-stained or PCNA-immunolabelled spermatogonia increased fourfold in comparison with BuG. The structural changes in ST after 6 days of busulphan exposure may be associated with the potential effect of this anti-neoplastic agent on SC. The increased number of spermatogonia in the busulphan-treated animals receiving vitamin B₁₂ indicates that this vitamin can be an adjuvant therapy to improve the fertility in male cancer patients.

Use of an Oral Busulfan Test Dose in Patients Undergoing Hematopoietic Stem Cell Transplantation Treated With or Without Fludarabine

This study investigated the importance of an oral test dose for busulfan (BU) dose adjustment before a conditioning regimen for hematopoietic stem-cell transplantation (HSCT) and the effect of fludarabine (FLU) on the oral BU pharmacokinetics evaluated after the fifth treatment dose (first BU dose on day 2 of treatment). Twenty-eight patients treated with oral BU (1 mg/kg every 6 hours for 4 days) were divided into 2 groups according to the concomitant administration of FLU (n = 15; 30 mg/m² for 5 days) or subsequent administration of cyclophosphamide (CY) (n = 13; 60 mg/kg for 2 days). On the day prior to the beginning of the conditioning regimen, blood samples were collected (0-6 hours) after administration of an oral BU test dose of 0.25 mg/kg. Busulfan was quantified in plasma samples by LC-MS/MS, and the pharmacokinetic parameters were calculated using WinNonlin software. Blood samples were collected between the fifth and sixth treatment dose to confirm the mean plasma steady-state concentration (C_ss ) of BU. The AUC_0-6 and apparent clearance of BU did not differ (P < .05) between the groups receiving FLU and CY. In 81% of the patients who received BU doses adjusted based on the test dose (n = 21), the C_ss was within the target range of 600-900 ng/mL. No association was observed between BU AUC_0-6 and clinical outcome in the study group (n = 28). The results suggest that in concomitant administration of FLU and BU during conditioning regimens for HSCT, changes in BU dose should be considered only after the administration of the fifth BU dose.

Antineoplastic busulfan encapsulated in a metal organic framework nanocarrier: first in vivo results

Nanoparticles of a mesoporous iron(iii) trimesate MIL-100 nanocarrier encapsulating high amounts of the challenging antineoplastic busulfan were administered to rats and compared with the commercial Busilvex®.

Busulfan dosing algorithm and sampling strategy in stem cell transplantation patients

AIM

The aim of this investigation was to develop a model-based dosing algorithm for busulfan and identify an optimal sampling scheme for use in routine clinical practice.

METHODS

Clinical data from an ongoing study (n = 29) in stem cell transplantation patients were used for the purposes our analysis. A one compartment model was selected as basis for sampling optimization and subsequent evaluation of a suitable dosing algorithm. Internal and external model validation procedures were performed prior to the optimization steps using ED-optimality criteria. Using systemic exposure as parameter of interest, dosing algorithms were considered for individual patients with the scope of minimizing the deviation from target range as determined by AUC(0,6 h).

RESULTS

Busulfan exposure after oral administration was best predicted after the inclusion of adjusted ideal body weight and alanine transferase as covariates on clearance. Population parameter estimates were 3.98 h(-1), 48.8 l and 12.3 l h(-1) for the absorption rate constant, volume of distribution and oral clearance, respectively. Inter-occasion variability was used to describe the differences between test dose and treatment. Based on simulation scenarios, a dosing algorithm was identified, which ensures target exposure values are attained after a test dose. Moreover, our findings show that a sparse sampling scheme with five samples per patient is sufficient to characterize the pharmacokinetics of busulfan in individual patients.

CONCLUSION

The use of the proposed dosing algorithm in conjunction with a sparse sampling scheme may contribute to considerable improvement in the safety and efficacy profile of patients undergoing treatment for stem cell transplantation.

Busulfan as a myelosuppressive agent for generating stable high-level bone marrow chimerism in mice

Bone marrow transplantation (BMT) is often used to replace the bone marrow (BM) compartment of recipient mice with BM cells expressing a distinct biomarker isolated from donor mice. This technique allows for identification of donor-derived hematopoietic cells within the recipient mice, and can be used to isolate and characterize donor cells using various biochemical techniques. BMT typically relies on myeloablative conditioning with total body irradiation to generate niche space within the BM compartment of recipient mice for donor cell engraftment. The protocol we describe here uses myelosuppressive conditioning with the chemotherapeutic agent busulfan. Unlike irradiation, which requires the use of specialized facilities, busulfan conditioning is performed using intraperitoneal injections of 20 mg/kg busulfan until a total dose of 60-100 mg/kg has been administered. Moreover, myeloablative irradiation can have toxic side effects and requires successful engraftment of donor cells for survival of recipient mice. In contrast, busulfan conditioning using these doses is generally well tolerated and mice survive without donor cell support. Donor BM cells are isolated from the femurs and tibiae of mice ubiquitously expressing green fluorescent protein (GFP), and injected into the lateral tail vein of conditioned recipient mice. BM chimerism is estimated by quantifying the number of GFP+ cells within the peripheral blood following BMT. Levels of chimerism >80% are typically observed in the peripheral blood 3-4 weeks post-transplant and remain established for at least 1 year. As with irradiation, conditioning with busulfan and BMT allows for the accumulation of donor BM-derived cells within the central nervous system (CNS), particularly in mouse models of neurodegeneration. This busulfan-mediated CNS accumulation may be more physiological than total body irradiation, as the busulfan treatment is less toxic and CNS inflammation appears to be less extensive. We hypothesize that these cells can be genetically engineered to deliver therapeutics to the CNS.