Outcomes from hematopoietic stem cell transplantation following treosulfan-based conditioning: A clinical and pharmacokinetic analysis.

BACKGROUND: The aims of this study are to report our experience with treosulfan-based conditioning regimens for patients with non-malignant hematologic conditions, correlating clinical outcomes at different time points post-transplant with treosulfan exposure (AUC). METHODS: This study was a single-center observational study investigating overall survival (OS), disease-free survival (DFS), and event-free survival (EFS) end-points post-transplant. The consequences of treosulfan AUC with respect to toxicity, correction of underlying disease, and long-term chimerism were also explored using pharmacokinetic analysis. RESULTS: Forty-six patients received 49 transplants with treosulfan and fludarabine-based conditioning between 2005 and 2023. Twenty-four patients also received thiotepa. Donor chimerism was assessed on either whole blood or sorted cell lines at different time points post-transplant. Thirty-nine patients received treosulfan pharmacokinetic assessment to evaluate cumulative AUC, with five infants receiving real-time assessment to facilitate daily dose adjustment. OS, DFS, and EFS were 87%, 81%, and 69%, respectively. Median follow-up was 32.1 months (range 0.82-160 months) following transplant. Lower EFS was associated with patient age (<1 year; p = .057) and lower cumulative treosulfan dose (<42 g/m2; p = .003). Stable donor chimerism in B-cell, NK-cell, and granulocyte lineages at 1-year post-transplant were more prevalent in patients receiving thiotepa conditioning. Two infants required daily dose adjustment to treosulfan to avoid high AUC. CONCLUSIONS: Excellent clinical outcomes and stable chimerism were observed in this patient series. The addition of thiotepa conferred no significant toxicity and trended toward sustained ongoing donor engraftment. Correlating treosulfan AUC with long-term patient outcomes is required.

Maximum a posteriori Bayesian methods out-perform non-compartmental analysis for busulfan precision dosing.

Dose personalization improves patient outcomes for many drugs with a narrow therapeutic index and high inter-individuality variability, including busulfan. Non-compartmental analysis (NCA) and model-based methods like maximum a posteriori Bayesian (MAP) approaches are two methods routinely used for dose optimization. These approaches vary in how they estimate patient-specific pharmacokinetic parameters to inform a dose and the impact of these differences is not well-understood. Using busulfan as an example application and area under the concentration-time curve (AUC) as a target exposure metric, these estimation methods were compared using retrospective patient data (N = 246) and simulated precision dosing treatment courses. NCA was performed with or without peak extension, and MAP Bayesian estimation was performed using either the one-compartment Shukla model or the two-compartment McCune model. All methods showed good agreement on real-world data (correlation coefficients of 0.945-0.998) as assessed by Bland-Altman plots, although agreement between NCA and MAP methods was higher during the first dosing interval (0.982-0.994) compared to subsequent dosing intervals (0.918-0.938). In dose adjustment simulations, both NCA and MAP estimated high target attainment (> 98%) although true simulated target attainment was lower for NCA (63-66%) versus MAP (91-93%). The largest differences in AUC estimation were due to different assumptions for the shape of the concentration curve during the infusion phase, followed by how the methods considered time-dependent clearance and concentration-time points collected in earlier intervals. In conclusion, although AUC estimates between the two methods showed good correlation, in a simulated study, MAP lead to higher target attainment. When changing from one method to another, or changing infusion duration and other factors, optimum estimated exposure targets may require adjusting to maintain a consistent exposure.

Temozolomide nano-in-nanofiber delivery system with sustained release and enhanced cellular uptake by U87MG cells.

OBJECTIVE: The study was aimed at formulating temozolomide (TMZ) loaded gelatin nanoparticles (GNPs) encapsulated into polyvinyl alcohol (PVA) nanofibers (TMZ-GNPs-PVA NFs) as the nano-in-nanofiber delivery system. The secondary objective was to explore the sustained releasing ability of this system and to assess its enhanced cellular uptake against U87MG glioma cells in vitro. SIGNIFICANCE: Nano-in-nanofibers are the emerging drug delivery systems for treating a wide range of diseases including cancers as they overcome the challenges experienced by nanoparticles and nanofibers alone. METHODS: The drug-loaded GNPs were formulated by one-step desolvation method. The Design of Experiments (DoE) was used to optimize nanoparticle size and entrapment efficiency. The optimized drug-loaded nanoparticles were then encapsulated within nanofibers using blend electrospinning technique. The U87MG glioma cells were used to investigate the uptake of the formulation. RESULTS: A 32 factorial design was used to optimize the mean particle size (145.7 nm) and entrapment efficiency (87.6%) of the TMZ-loaded GNPs which were subsequently ingrained into PVA nanofibers by electrospinning technique. The delivery system achieved a sustained drug release for up to seven days (in vitro). The SEM results ensured that the expected nano-in-nanofiber delivery system was achieved. The uptake of TMZ-GNPs-PVA NFs by cells was increased by a factor of 1.964 compared to that of the pure drug. CONCLUSION: The nano-in-nanofiber drug delivery system is a potentially useful therapeutic strategy for the management of glioblastoma multiforme.

Determinants of Interpatient Variability in Treosulfan Pharmacokinetics in AML Patients Undergoing Autologous Stem Cell Transplantation.

Limited data on treosulfan pharmacokinetics in adults, particularly regarding autologous stem cell transplantation (ASCT) in acute myeloid leukemia (AML), is available to date. Furthermore, correlations between treosulfan exposure, toxicity, and clinical outcome remain understudied. In this single-center retrospective study, we analyzed data from 55 AML patients who underwent HDCT with treosulfan (14 g/m2) and melphalan (140 mg/m2 or 200 mg/m2) (TreoMel) between August 2019 and November 2023 at the University Hospital of Bern. We assessed treosulfan pharmacokinetics and correlations with several physiological parameters with potential impact on its interpatient variability. We further analyzed how treosulfan exposure correlates with toxicity and clinical outcomes. Women above 55 years showed higher area under the curve (AUC) levels (median: 946 mg*h/L, range: 776-1370 mg*h/L), as compared to women under 55 (median: 758 mg*h/L, range: 459-1214 mg*h/L, p = 0.0487). Additionally, women above 55 showed higher peak levels (median: 387 mg/L, range: 308-468 mg/L), as compared to men of the same age range (median: 326 mg/L, range: 264-395 mg/L, p = 0.0159). Treosulfan levels varied significantly with body temperature, liver enzymes, hemoglobin/hematocrit., and treosulfan exposure correlated with diarrhea severity in women over 55 (p = 0.0076). Our study revealed age- and gender-related variability in treosulfan pharmacokinetics, with higher plasma levels observed in female patients above 55. Moreover, our data suggest that treosulfan plasma levels may vary with several physiological parameters and that higher treosulfan exposure may impact toxicity. Our study underlines the need for further research on treosulfan pharmacokinetics, especially in older patients undergoing HDCT in the ASCT setting.

Association study of candidate DNA-repair gene variants and acute graft versus host disease in pediatric patients receiving allogeneic hematopoietic stem-cell transplantation.

Acute Graft versus Host Disease (aGvHD) grades 2-4 occurs in 15-60% of pediatric patients undergoing allogeneic haematopoietic stem-cell transplantation (allo-HSCT). The collateral damage to normal tissue by conditioning regimens administered prior to allo-HSCT serve as an initial trigger for aGvHD. DNA-repair mechanisms may play an important role in mitigating this initial damage, and so the variants in corresponding DNA-repair protein-coding genes via affecting their quantity and/or function. We explored 51 variants within 17 DNA-repair genes for their association with aGvHD grades 2-4 in 60 pediatric patients. The cumulative incidence of aGvHD 2-4 was 12% (n = 7) in the exploratory cohort. MGMT rs10764881 (G>A) and EXO rs9350 (c.2270C>T) variants were associated with aGvHD 2-4 [Odds ratios = 14.8 (0 events out of 40 in rs10764881 GG group) and 11.5 (95% CI: 2.3-191.8), respectively, multiple testing corrected p ≤ 0.001]. Upon evaluation in an extended cohort (n = 182) with an incidence of aGvHD 2-4 of 22% (n = 40), only MGMT rs10764881 (G>A) remained significant (adjusted HR = 2.05 [95% CI: 1.06-3.94]; p = 0.03) in the presence of other clinical risk factors. Higher MGMT expression was seen in GG carriers for rs10764881 and was associated with higher IC50 of Busulfan in lymphoblastoid cells. MGMT rs10764881 carrier status could predict aGvHD occurrence in pediatric patients undergoing allo-HSCT.

Phase I clinical trial of temozolomide and methoxyamine (TRC-102), an inhibitor of base excision repair, in patients with advanced solid tumors.

Temozolomide (TMZ) generates DNA adducts that are repaired by direct DNA and base excision repair mechanisms. Methoxyamine (MX, TRC-102) potentiates TMZ activity by binding to apurinic and apyrimidinic (AP) sites after removal of N3-methyladenine and N7-methylguanine, inhibiting site recognition of AP endonuclease. We conducted a phase I trial to determine the maximum tolerated dose and dose-limiting toxicities (DLTs) of intravenous MX when given with oral TMZ. Patients with advanced solid tumors and progression on standard treatment were enrolled to a standard 3 + 3 dose escalation trial assessing escalating doses of TMZ and MX. Tumor response was assessed per RECIST and adverse events (AEs) by CTCAEv3. Pharmacokinetics (PK) of MX and COMET assays on peripheral blood mononuclear cells were performed. 38 patients were enrolled-median age 59.5 years (38-76), mean number of cycles 2.9 [1-13]. No DLTs were observed. Cycle 1 grade 3 AEs included fatigue, lymphopenia, anemia, INR, leukopenia, neutropenia, allergic reaction, constipation, psychosis and paranoia. Cycle 2-13 grade 4 AEs included thrombocytopenia and confusion. A partial response was seen in 1 patient with a pancreatic neuroendocrine tumor (PNET) and six additional patients, each with different tumor types, demonstrated prolonged stable disease. MX PK was linear with dose and was not affected by concomitant TMZ. TMZ 200 mg/m2 daily × 5 may be safely administered with MX 150 mg/m2 intravenously once on day 1 with minimal toxicity. Further studies assessing this drug combination in select tumor types where temozolomide has activity may be warranted.

Dual Encapsulated Dacarbazine and Zinc Phthalocyanine Polymeric Nanoparticle for Photodynamic Therapy of Melanoma.

PURPOSE: Melanoma is an invasive and very aggressive skin cancer due to its multi-drug resistance that results in poor patient survival. There is a need to test new treatment approaches to improve therapeutic efficacy and reduce side effects of conventional treatments. METHODS: PLA/PVA nanoparticles carrying both Dacarbazine and zinc phthalocyanine was produced by double emulsion technique. The characterization was performed by dynamic light scattering and atomic force microscopy. In vitro photodynamic therapy test assay using MV3 melanoma cells as a model has been performed. In vitro cell viability (MTT) was performed to measure cell toxicity of of nanoparticles with and without drugs using human endothelial cells as a model. The in vivo assay (biodistribution/tissue deposition) has been performed using radiolabeled PLA/PVA NPs. RESULTS: The nanoparticles produced showed a mean diameter of about 259 nm with a spherical shape. The in-vitro photodynamic therapy tests demonstrated that the combination is critical to enhance the therapeutic efficacy and it is dose dependent. The in vitro cell toxicity assay using endothelial cells demonstrated that the drug encapsulated into nanoparticles had no significant toxicity compared to control samples. In-vivo results demonstrated that the drug loading affects the biodistribution of the nanoparticle formulations (NPs). Low accumulation of the NPs into the stomach, heart, brain, and kidneys suggested that common side effects of Dacarbazine could be reduced. CONCLUSION: This work reports a robust nanoparticle formulation with the objective to leveraging the synergistic effects of chemo and photodynamic therapies to potentially suppressing the drug resistance and reducing side effects associated with Dacarbazine. The data corroborates that the dual encapsulated NPs showed better in-vitro efficacy when compared with the both compounds alone. The results support the need to have a dual modality NP formulation for melanoma therapy by combining chemotherapy and photodynamic therapy.

Pharmacokinetics, safety, and activity of trabectedin as first-line treatment in elderly patients who are affected by advanced sarcoma and are unfit to receive standard chemotherapy: A phase 2 study (TR1US study) from the Italian Sarcoma Group.

BACKGROUND: Although elderly patients (≥70 years) represent 30% of new diagnoses of soft tissue sarcoma (STS), they are underrepresented in clinical trials and are often unfit to receive standard anthracycline-based chemotherapy. Trabectedin is registered as a second-line treatment for advanced STS and is characterized by a favorable safety profile. METHODS: The aim of this single-arm, phase 2 study was to investigate trabectedin (scheduled dose, 1.3-1.5 mg/m2 ) as a first-line treatment in elderly patients with advanced stage STS who are inoperable and are unfit to receive standard anthracycline-based chemotherapy. The coprimary endpoints were progression-free survival at 3 months (PFS3) and the rate of clinically limiting toxicities (CLTs). We also conducted an ancillary study on pharmacokinetics. RESULTS: Twenty-four patients (12 men and 12 women) with a median age of 79 years (interquartile range [IQR], 74-83 years) were enrolled. The histological subtype was leiomyosarcoma in 46%, liposarcoma in 33%, and other histotypes in 21%. The median number of trabectedin courses was 4 (IQR, 3-6), with 7 patients (29%) receiving ≥6 cycles. Eight patients (33%) required dose reductions. The most frequent grade 3/4 adverse events were neutropenia in 9 patients (38%), fatigue in 5 patients (21%), and aminotransferase elevation in 5 patients (21%). PFS3, median PFS, and overall survival were 71% (80% CI, 57%-81%), 4 months, and 12 months, respectively. Ten patients (42% [80% CI, 28%-57%]) experienced CLTs. Trabectedin Cmax , half-life, clearance, and distribution volume were 1.28 ng/mL (standard deviation [SD], 0.58 ng/mL), 26.70 hours (SD, 9.09 hours), 39.98 L/h/m2 (SD, 14.08 L/h/m2 ), and 1460 L/m2 (SD, 561 L/m2 ), respectively. CONCLUSION: Trabectedin can be administered safely to elderly patients with STS who are unfit to receive anthracyclines. Pharmacokinetics in the elderly population was superimposable to historical data.

Site-Specific Conjugation of the Indolinobenzodiazepine DGN549 to Antibodies Affords Antibody-Drug Conjugates with an Improved Therapeutic Index as Compared with Lysine Conjugation.

Antibody-drug conjugates have elicited great interest recently as targeted chemotherapies for cancer. Recent preclinical and clinical data have continued to raise questions about optimizing the design of these complex therapeutics. Biochemical methods for site-specific antibody conjugation have been a design feature of recent clinical ADCs, and preclinical reports suggest that site-specifically conjugated ADCs generically offer improved therapeutic indices (i.e., the fold difference between efficacious and maximum tolerated doses). Here we present the results of a systematic preclinical comparison of ADCs embodying the DNA-alkylating linker-payload DGN549 generated with both heterogeneous lysine-directed and site-specific cysteine-directed conjugation chemistries. Importantly, the catabolites generated by each ADC are the same regardless of the conjugation format. In two different model systems evaluated, the site-specific ADC showed a therapeutic index benefit. However, the therapeutic index benefit is different in each case: both show evidence of improved tolerability, though with different magnitudes, and in one case significant efficacy improvement is also observed. These results support our contention that conjugation chemistry of ADCs is best evaluated in the context of a particular antibody, target, and linker-payload, and ideally across multiple disease models.

Reduced Toxicity of Liposomal Nitrogen Mustard Prodrug Formulation Activated by an Intracellular ROS Feedback Mechanism in Hematological Neoplasm Models.

Nitrogen mustard (NM) is among the earliest drugs used to treat malignant tumors and it kills tumor cells by cross-linking DNA. Unfortunately, because of the short half-life and unfavorable selectivity, NM causes significant damage to normal tissues. As NM can increase the levels of reactive oxygen species (ROS) in tumor cells, a ROS-activated nitrogen mustard prodrug (NM-Pro) was synthesized and mixed with NM at a specific ratio to obtain an "NM-ROS-NM-Pro-NM" positive feedback system, which ultimately achieves a specific lethal effect on hematological neoplasms. The further encapsulation of NM/NM-Pro in liposomes allows the sustained release of the drug and prolongs the residence time in vivo. Here, we prepared stable liposomes with a uniform particle size of 170.6 ± 2.2 nm. The optimal ratio of NM to NM-Pro in this study was 2:1. The active drug NM in the NM/NM-Pro system continuously stimulated ROS production by the cells, which in turn further activated the NM-Pro to continuously generate NM. The positive feedback pathway between the NM and NM-Pro resulted in the specific death of tumor cells. Furthermore, the K562 hematological neoplasm model was utilized to evaluate the therapeutic effect of NM/NM-Pro liposomes in vivo. After encapsulation in liposomes, the targeting of tumor cells was increased approximately two times compared with that of normal cells, and NM/NM-Pro liposomes exhibited reduced toxicity, without an increase in drug activity compared to the NM/NM-Pro combination. The NM/NM-Pro delivery system exerts a positive feedback effect on ROS production in tumor cells and displays good potential for the specific killing of hematoma cells.

Thymoquinone-Loaded Soluplus®-Solutol® HS15 Mixed Micelles: Preparation, In Vitro Characterization, and Effect on the SH-SY5Y Cell Migration.

Thymoquinone (TQ) is the main active ingredient of Nigella sativa essential oil, with remarkable anti-neoplastic activities with anti-invasive and anti-migratory abilities on a variety of cancer cell lines. However, its poor water solubility, high instability in aqueous solution and pharmacokinetic drawbacks limits its use in therapy. Soluplus® and Solutol® HS15 were employed as amphiphilic polymers for developing polymeric micelles (SSM). Chemical and physical characterization studies of micelles are reported, in terms of size, homogeneity, zeta potential, critical micelle concentration (CMC), cloud point, encapsulation efficiency (EE%), load capacity (DL), in vitro release, and stability. This study reports for the first time the anti-migratory activity of TQ and TQ loaded in SSM (TQ-SSM) in the SH-SY5Y human neuroblastoma cell line. The inhibitory effect was assessed by the wound-healing assay and compared with that of the unformulated TQ. The optimal TQ-SSM were provided with small size (56.71 ± 1.41 nm) and spherical shape at ratio of 1:4 (Soluplus:Solutol HS15), thus increasing the solubility of about 10-fold in water. The entrapment efficiency and drug loading were 92.4 ± 1.6% and 4.68 ± 0.12, respectively, and the colloidal dispersion are stable during storage for a period of 40 days. The TQ-SSM were also lyophilized to obtain a more workable product and with increased stability. In vitro release study indicated a prolonged release of TQ. In conclusion, the formulation of TQ into SSM allows a bio-enhancement of TQ anti-migration activity, suggesting that TQ-SSM is a better candidate than unformulated TQ to inhibit human SH-SY5Y neuroblastoma cell migration.

Kinetics of Cyclophosphamide Metabolism in Humans, Dogs, Cats, and Mice and Relationship to Cytotoxic Activity and Pharmacokinetics.

Cyclophosphamide (CP), a prodrug that is enzymatically converted to the cytotoxic 4-hydroxycyclophosphamide (4OHCP) by hepatic enzymes, is commonly used in both human and veterinary medicine to treat cancers and modulate the immune system. We investigated the metabolism of CP in humans, dogs, cats, and mice using liver microsomes; apparent K M, V max, and intrinsic clearance (V max/K M) parameters were estimated. The interspecies and intraspecies variations in kinetics were vast. Dog microsomes were, on average, 55-fold more efficient than human microsomes, 2.8-fold more efficient than cat microsomes, and 1.2-fold more efficient than mouse microsomes at catalyzing CP bioactivation. These differences translated to cell-based systems. Breast cancer cells exposed to 4OHCP via CP bioactivation by microsomes resulted in a stratification of cytotoxicity that was dependent on the species of microsomes measured by IC50: dog (31.65 µM), mouse (44.95 µM), cat (272.6 µM), and human (1857 µM). The contributions of cytochrome P450s, specifically, CYP2B, CYP2C, and CYP3A, to CP bioactivation were examined: CYP3A inhibition resulted in no change in 4OHCP formation; CYP2B inhibition slightly reduced 4OHCP in humans, cats, and mice; and CYP2C inhibition drastically reduced 4OHCP formation in each species. Semiphysiologic modeling of CP metabolism using scaled metabolic parameters resulted in simulated data that closely matched published pharmacokinetic profiles, determined by noncompartmental analysis. The results highlight differential CP metabolism delineated by species and demonstrate the importance of metabolism on CP clearance.

The importance of both CYP2C19 and CYP2B6 germline variations in cyclophosphamide pharmacokinetics and clinical outcomes.

Cyclophosphamide is an alkylating agent used in the treatment of solid and haematological malignancies and as an immunosuppressive agent. As a prodrug, it is dependent on bioactivation to the active phosphoramide mustard metabolite to elicit its therapeutic effect. This focused review will highlight the evidence for the role of germline pharmacogenetic variation in both plasma pharmacokinetics and clinical outcomes. There is a substantial indication from 13 pharmacokinetic and 17 therapeutic outcome studies, in contexts as diverse as haematological malignancy, breast cancer, systemic lupus erythematosus and myeloablation, that pharmacogenetic variation in both CYP2C19 and CYP2B6 influence the bioactivation of cyclophosphamide. An additional role for pharmacogenetic variation in ALDH1A1 has also been reported. Future studies should comprehensively assess these 3 pharmacogenes and undertake appropriate statistical analysis of gene-gene interactions to confirm these findings and may allow personalised treatment regimens.

Population pharmacokinetics of treosulfan in paediatric patients undergoing hematopoietic stem cell transplantation.

AIMS: Treosulfan is an alkylating agent increasingly used prior to haematopoietic stem cell transplantation. The aim of this study was to develop a population pharmacokinetic (PK) model of treosulfan in paediatric haematopoietic stem cell transplantation recipients and to explore the effect of potential covariates on treosulfan PK. Also, a limited sampling model (LSM) will be developed to accurately predict treosulfan exposure suitable for a therapeutic drug monitoring setting. METHODS: In this multicentre study, 91 patients, receiving a total dose of 30, 36 or 42 g/m2 treosulfan, administered over 3 consecutive days, were enrolled. A population PK model was developed and demographic factors, as well as laboratory parameters, were included as potential covariates. In addition, a LSM was developed using data from 28 patients. RESULTS: A 2-compartment model with first order elimination best described the data. Bodyweight with allometric scaling and maturation function were identified as significant predictors of treosulfan clearance. Treosulfan clearance reaches 90% of adult values at 4 postnatal years. A model-based dosing table is presented to target an exposure of 1650 mg*h/L (population median) for different weight and age groups. Samples taken at 1.5, 4 and 7 hours after start of infusion resulted in the best limited sampling strategy. CONCLUSIONS: This study provides a treosulfan population PK model in children and captures the developmental changes in clearance. A 3-point LSM allows for accurate and precise estimation of treosulfan exposure.

Galactosylated chitosan triptolide nanoparticles for overcoming hepatocellular carcinoma: Enhanced therapeutic efficacy, low toxicity, and validated network regulatory mechanisms.

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide. Current therapies present significant limitations. Triptolide (TP) is highly effective against multiple cancers including HCC. However, high toxicity, low water solubility, and unknown therapeutic targets limit its clinical application. Herein, we designed galactosylated-chitosan-TP-nanoparticles (GC-TP-NPs) with high drug loading capacities for targeted delivery to HCC. In addition to a sustained release pattern, an efficient asialoglycoprotein receptor mediated cellular uptake in vitro, and high liver tumor accumulation in vivo, GC-TP-NPs showed lower systemic and male reproductive toxicities than free TP. Importantly, GC-TP-NPs retained the anti-cancer activities of the free TP, exerting the same pro-apoptotic and anti-proliferative effects on HCC cells in vitro, and displayed higher efficacies in reducing tumor sizes in vivo. Further investigation revealed that GC-TP-NPs induced cancer cell apoptosis via blocking TNF/NF-κB/BCL2 signaling. Collectively, GC-TP-NP represents a promising candidate in halting liver cancer progression while minimizing systemic toxicity.

Bendamustine-PAMAM Conjugates for Improved Apoptosis, Efficacy, and in Vivo Pharmacokinetics: A Sustainable Delivery Tactic.

Successful delivery of a chemotherapeutic agent like bendamustine still remains a challenge in clinical conditions like chronic lymphatic leukemia (CLL), non-Hodgkin lymphoma (NHL), and multiple myeloma. We have conjugated bendamustine to polyamidoamine (PAMAM) dendrimers after conjugating with N-(hydroxyethyl)maleimide (spacer) via an ester bond. The particle size of PAMAM-bendamustine conjugate was 49.8 ± 2.5 nm. In vitro drug release resulted in sustained release with improved solution stability of drug up to 72 h. In a 24 h cytotoxicity study by MTT assay against human monoblastic leukemia cells (THP-1), the IC50 value for PAMAM-bendamustine was 32.1 ± 4.8 µM compared to 50.42 ± 3.4 µM and 2303 ± 106.5 µM for bendamustine and PAMAM dendrimer, respectively. Significantly higher cell uptake and apoptosis were observed in THP-1 cells by PAMAM-bendamustine conjugate which was confirmed by flow cytometry and confocal laser scanning microscopy. Preliminary in vivo studies undertaken included pharmacokinetics studies, organ distribution studies, and tumor inhibition studies. In healthy Wistar rat model (1CBM IV push model), the pharmacokinetic studies revealed that bioavailability and t1/2 increased significantly, i.e., almost 8.5-fold (193.8 ± 1.116 vs 22.8 ± 0.158 µg mL-1/h) and 5.1-fold (0.75 ± 0.005 vs 3.85 ± 0.015 h), respectively, for PAMAM-bendamustine conjugate compared to pure bendamustine ( p < 0.05), however, clearance and volume of distribution were found to be decreased compared to those of free drug. The study suggests that PAMAM-bendamustine conjugate was not only stable for the longer period but also least toxic and highly taken up by THP-1 cells to exert an anticancer effect at the reduced dose. Tumor inhibition and biodistribution studies in tumor-bearing BALB/c mice revealed that PAMAM-bendamustine conjugate was more effective than the pure drug and showed higher accumulation in the tumor.

Role of Temozolomide in the Treatment of Cancers Involving the Central Nervous System.

Temozolomide has been available to oncologists for over 30 years. During this time, it has become an integral part of standard therapy in patients with high-grade gliomas. Given its ability to traverse the blood-brain barrier, temozolomide has also been evaluated in other cancers that involve the central nervous system (CNS). We review its role in the management of patients with primary brain tumors, brain metastases, leptomeningeal carcinomatosis, and other selected CNS cancers. There is strong evidence that temozolomide is effective in patients with high-grade astrocytomas and oligodendrogliomas. Modest evidence supports its activity in primary CNS lymphomas and aggressive pituitary adenomas. Temozolomide, however, has minimal efficacy in a wide variety of systemic cancers. Given that concentrations of temozolomide in the CNS are only 20% of those in the blood, it is not surprising that it is generally inactive in patients with CNS metastases from solid tumors.

Population pharmacokinetics of treosulfan and development of a limited sampling strategy in children prior to hematopoietic stem cell transplantation.

PURPOSE: There is an increasing interest in use of treosulfan (TREO), a structural analogue of busulfan, as an agent in conditioning regimens prior to hematopoietic stem cell transplantation (HSCT), both in pediatric and adult populations. The aim of this study was to develop a population pharmacokinetic model and to establish limited sampling strategies (LSSs) enabling accurate estimation of exposure to this drug. METHODS: The study included 15 pediatric patients with malignant and non-malignant diseases, undergoing conditioning regimens prior to HSCT including TREO administered as a 1 h or 2 h infusion at daily doses of 10, 12, or 14 g/m2. A population pharmacokinetic model was developed by means of non-linear mixed-effect modeling approach in Monolix® software. Multivariate regression analysis and Bayesian method were used to develop 2- and 3-point strategies for estimation of exposure to TREO. RESULTS: Pharmacokinetics of TREO was best described with a two-compartmental linear model with proportional residual error. Following sampling schedules allowed accurate estimation of exposure to TREO: 1 h and 6 h or 1 h, 2 h, and 6 h for a TREO dose 12 g/m2 in a 1 h infusion, or at 2 h and 6 h or 2 h, 4 h, and 8 h for a TREO dose of 12 g/m2 and 14 g/m2 in a 2 h infusion. CONCLUSIONS: A two-compartmental population pharmacokinetic model of TREO was developed and successfully used to establish 2- and 3-point LSSs for accurate and precise estimation of TREO AUC0→∞.

Association of CYP2C19*2 and ALDH1A1*1/*2 variants with disease outcome in breast cancer patients: results of a global screening array.

PURPOSE: Cyclophosphamide and doxorubicin (adjuvant chemotherapy) are commonly used to treat breast cancer patients. Variation in the genes involved in pharmacodynamics and pharmacokinetics of these drugs plays an important role in prediction of drug response and survival. The present study was carried out with an aim to evaluate the variation in all the genes involved in pharmacokinetic and pharmacodynamics pathways of cyclophosphamide and doxorubicin, and correlate specific variants with disease outcome in breast cancer patients from the Malwa region of Punjab. METHODS: A total of 250 confirmed breast cancer patients were involved in the study. Genotyping was performed on an Illumina Infinium HD assay platform using a Global Screening Array (GSA) microchip. GenomeStudio (Illumina, Inc.) was used for data preprocessing and a p value less than or equal to 5 × 10-8 was considered statistically significant. To rule out the influence of confounding risk factors, a step-wise multivariate regression analysis was carried out to evaluate the association of genotype with overall clinical outcome. RESULTS: Two gene variants, CYP2C19 (G681A) and ALDH1A1*2 (17 bp deletion), were found to be significantly associated with the disease outcome, including overall survival, recurrence and metastasis, in breast cancer patients on adjuvant therapy. Both these genes are involved in the pharmacokinetics of cyclophosphamide. However, none of the variants in the genes involved in pharmacokinetics and pharmacodynamics of doxorubicin were found to have any significant impact on disease outcome in the studied group. CONCLUSION: CYP2C19 (G681A) variant and ALDH1A1*2 emerged as two important biomarkers associated with bad outcome in breast cancer patients on adjuvant therapy.

Hybrid of DNA-targeting Chlorambucil with Pt(IV) Species to Reverse Drug Resistance.

Two hybrids of Pt(IV) species were designed and prepared by addition of a chlorambucil unit to the axial positions of the Pt(IV) complexes derived from DN603 and DN604. In vitro studies of two hybrids against two pairs of cisplatin sensitive and resistant cancer cell lines indicated that compound 5 had superior antitumor activity to cisplatin and chlorambucil via suppressing DNA damage repair to reverse drug resistance. Mechanistic investigation suggested that the potent antitumor activity of compound 5 arose from its major suppression of CK2-mediated MRE11-RAD50-NBS1(MRN) complex promotion of DNA double-strand break (DSB) repair. In nude mice with A549/CDDP xenografts, compound 5 exhibited higher anticancer efficacy than cisplatin and chlorambucil by reversing drug resistance, displayed improved effectiveness, and had no toxicity effects. Overall, compound 5 is a promising drug candidate, which could promote the anticancer activity and reverse drug resistance by attenuating CK2-induced MRN-dependent DSB repair.