UV spectroscopic method for estimation of temozolomide: Application in stability studies in simulated plasma pH, degradation rate kinetics, formulation design, and selection of dissolution media

Long acting tariquidar loaded stearic acid-modified hydroxyapatite enhances brain penetration and antitumor effect of temozolomide

Temozolomide (TMZ) is the first line chemotherapy for glioblastoma (GBM) treatment, but the P-glycoprotein (P-gp) expressed in blood-brain barrier (BBB) will pump out TMZ from the brain leading to decreased TMZ concentration. Tariquidar (TQD), a selective and potent P-gp inhibitor, may be suitable for combination therapy to increase concentration of TMZ in brain. Hydroxyapatite (HAP) is a biodegradable material with sustained release characteristics, and stearic acid surface-modified HAP (SA-HAP) can increase hydrophobicity to facilitate TQD loading. TQD-loaded stearic acid surface-modified HAP (SA-HAP-TQD) was prepared with optimal size and high TQD loading efficiency, and in vitro release and cellular uptake of SA-HAP-TQD showed that SA-HAP-TQD were taken up into lysosome and continuously released TQD from macrophages. In vivo studies have found that over 70 % of SA-HAP was degraded and 80 % of TQD was released from SA-HAP-TQD 28 days after administration. SA-HAP-TQD could increase brain penetration of TMZ, but it would not enhance adverse effects of TMZ in healthy mice. SA-HAP-TQD and TMZ combination had longer median survival than TMZ single therapy in GL261 orthotopic model. These results suggest that SA-HAP-TQD has sustained release characteristics and are potential for improving antitumor effect with TMZ treatment.

Unveiling the Influence of Tumor Microenvironment and Spatial Heterogeneity on Temozolomide Resistance in Glioblastoma Using an Advanced Human In Vitro Model of the Blood-Brain Barrier and Glioblastoma

Glioblastoma (GBM) is the most common primary malignant brain cancer in adults with a dismal prognosis. Temozolomide (TMZ) is the first-in-line chemotherapeutic; however, resistance is frequent and multifactorial. While many molecular and genetic factors have been linked to TMZ resistance, the role of the solid tumor morphology and the tumor microenvironment, particularly the blood-brain barrier (BBB), is unknown. Here, the authors investigate these using a complex in vitro model for GBM and its surrounding BBB. The model recapitulates important clinical features such as a dense tumor core with tumor cells that invade along the perivascular space; and a perfusable BBB with a physiological permeability and morphology that is altered in the presence of a tumor spheroid. It is demonstrated that TMZ sensitivity decreases with increasing cancer cell spatial organization, and that the BBB can contribute to TMZ resistance. Proteomic analysis with next-generation low volume sample workflows of these cultured microtissues revealed potential clinically relevant proteins involved in tumor aggressiveness and TMZ resistance, demonstrating the utility of complex in vitro models for interrogating the tumor microenvironment and therapy validation.

A Multicenter Randomized Bioequivalence Study of a Novel Ready-to-Use Temozolomide Oral Suspension vs. Temozolomide Capsules

BACKGROUND

Temozolomide (TMZ) oral suspension (Ped-TMZ, KIZFIZO®) is being developed for the treatment of relapsed or refractory neuroblastoma, a rare cancer affecting infants and young children. The study assessed the safety and the bioequivalence of this novel pediatric formulation with existing TMZ oral capsules.

METHODS

In vitro dissolution profiles and the bioequivalence were evaluated following the European Medicines Agency "Guidelines on the investigation of Bioequivalence". The phase I, multicenter, randomized, open-label, crossover, single-dose bioequivalence study enrolled 36 adult patients with glioblastoma multiforme or lower-grade glioma. Each patient received 200 mg/m2 Ped-TMZ suspension and TMZ capsules (Temodal®) on 2 consecutive days, with the order being randomly assigned. Fourteen blood samples were collected up to 10 h post-dosing. Bioequivalence was assessed by comparing the 90% confidence interval for the ratio of the geometric means of maximum TMZ plasma concentration (Cmax) and the area under the curve (AUCt). Other endpoints included further pharmacokinetic parameters and safety.

RESULTS

Both formulations exhibited a fast in vitro dissolution profile with more than 85% of TMZ dissolved within 15 min. For the bioequivalence study, thirty patients completed the trial as per the protocol. The ratio of Ped-TMZ/TMZ capsule geometric means (90% CI) for AUCt and Cmax were 97.18% (95.05-99.35%) and 107.62% (98.07-118.09%), respectively, i.e., within the 80-125% bioequivalence limits. No buccal toxicity was associated with Ped-TMZ liquid formulation.

CONCLUSIONS

This study showed that Ped-TMZ oral suspension and TMZ oral capsule treatment are immediate release and bioequivalent medicines. There were also no unexpected safety signals or local toxicity (funded by ORPHELIA Pharma; ClinicalTrials.gov number, NCT04467346).

Exploring temozolomide encapsulated PEGylated liposomes and lyotropic liquid crystals for effective treatment of glioblastoma: in-vitro, cell line, and pharmacokinetic studies

Temozolomide (TMZ) is one of the best choices for treating glioblastoma. However, due to the short plasma half-life, only 20-30 % brain bioavailability can be achieved using traditional formulations. In the present study, PEGylated liposomes and lyotropic liquid crystals (LLCs) were developed and investigated to prolong the plasma circulation time of TMZ. Industrially feasible membrane extrusion and modified hot melt emulsification techniques were utilized during the formulation. Liposomes and LLCs in the particle size range of 80-120 nm were obtained with up to 50 % entrapment efficiency. The nanocarriers were found to show a prolonged release of up to 72 h. The cytotoxicity studies in glioblastoma cell lines revealed a ∼1.6-fold increased cytotoxicity compared to free TMZ. PEGylated liposomes and PEGylated LLCs were found to show a 3.47 and 3.18-fold less cell uptake in macrophage cell lines than uncoated liposomes and LLCs, respectively. A 1.25 and 2-fold increase in the plasma t1/2 was observed with PEGylated liposomes and PEGylated LLCs, respectively, compared to the TMZ when administered intravenously. Extending plasma circulation time of TMZ led to significant increase in brain bioavailability. Overall, the observed improved pharmacokinetics and biodistribution of TMZ revealed the potential of these PEGylated nanocarriers in the efficient treatment of glioblastoma.

Development of nanocubosomes co-loaded with dual anticancer agents curcumin and temozolomide for effective Colon cancer therapy

Current research aimed to develop nanocubosomes co-loaded with dual anticancer drugs curcumin and temozolomide for effective colon cancer therapy. Drugs co-loaded nanocubosomal dispersion was prepared by modified emulsification method using glyceryl monooleate (GMO), pluronic F127 and bovine serum albumin (BSA) as a lipid phase, surfactant, and stabilizer, respectively. The resulting nanocubosomes were characterized by measuring hydrodynamic particle size, particle size distribution (PSD), drug loading capacity (DL), encapsulation efficiency (EE), colloidal stability and drug release profile. We also physiochemically characterized the nanocubosomes by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and x-rays diffraction (XRD) for their morphology, polymer drug interaction and its nature, respectively. Further, the in-vitro cell-uptake, mechanism of cell-uptake, in-vitro anti-tumor efficacy and apoptosis level were evaluated using HCT-116 colon cancer cells. The prepared nanocubosomes exhibited a small hydrodynamic particle size (PS of 150 ± 10 nm in diameter) with nearly cubic shape and appropriate polydispersity index (PDI), enhanced drug loading capacity (LC of 6.82 ± 2.03% (Cur) and 9.65 ± 1.53% (TMZ), high entrapment efficiency (EE of 67.43 ± 2.16% (Cur) and 75.55 ± 3.25% (TMZ), pH-triggered drug release profile and higher colloidal stability in various physiological medium. Moreover, the nanocubosomes showed higher cellular uptake, in-vitro cytotoxicity and apoptosis compared to free drugs, curcumin and temozolomide, most likely because its small particle size. In addition, BSA-stabilized nanocubosomes were actively taken by aggressive colon cancer cells that over-expressed the albumin receptors and utilized BSA as nutrient source for their growth. In short, this study provides a new and simple strategy to improve the efficacy and simultaneously overawed the adaptive treatment tolerance in colon cancer.

Temozolomide: an Overview of Biological Properties, Drug Delivery Nanosystems, and Analytical Methods

Temozolomide (TMZ) is an imidazotetrazine prodrug used to treat glioblastoma multiforme. Its physicochemical prop-erties and small size confer the ability to cross the blood-brain barrier. The antitumor activity depends on pH-dependent hydrolysis of the methyldiazonium cation, which is capable of methylating purine bases (O6-guanine; N7-guanine, and N3-adenine) and causing DNA damage and cell death. TMZ is more stable in acidic media (pH ≤ 5.0) than in basic media (pH ≥ 7.0) due to the protonated form that minimizes the catalytic process. Because of this, TMZ has high oral bioavailability, but it has a half-life of 1.8 h and low brain distribution (17.8%), requiring a repeated dos-ing regimen that limits its efficacy and increases adverse events. Drug delivery Nanosystems (DDNs) improve the phys-icochemical properties of TMZ and may provide controlled and targeted delivery. Therefore, DDNs can increase the efficacy and safety of TMZ. In this context, to ensure the efficiency of DDNs, analytical methods are used to evaluate TMZ pharmacokinetic parameters, encapsulation efficiency, and the release profile of DDNs. Among the methods, high-performance liquid chromatography is the most used due to its detection sensitivity in complex matrices such as tissues and plasma. Micellar electrokinetic chromatography features fast analysis and no sample pretreatment. Spec-trophotometric methods are still used to determine encapsulation efficiency due to their low cost, despite their low sen-sitivity. This review summarizes the physicochemical and pharmacological properties of free TMZ and TMZ-loaded DDNs. In addition, this review addresses the main analytical methods employed to characterize TMZ in different ma-trices.

Approaching Sites of Action of Temozolomide for Pharmacological and Clinical Studies in Glioblastoma

Temozolomide (TMZ), together with bulk resection and focal radiotherapy, is currently a standard of care for glioblastoma. Absorption, distribution, metabolism, and excretion (ADME) parameters, together with the mode of action of TMZ, make its biochemical and biological action difficult to understand. Accurate understanding of the mode of action of TMZ and the monitoring of TMZ at its anatomical, cellular, and molecular sites of action (SOAs) would greatly benefit precision medicine and the development of novel therapeutic approaches in combination with TMZ. In the present perspective article, we summarize the known ADME parameters and modes of action of TMZ, and we review the possible methodological options to monitor TMZ at its SOAs. We focus our descriptions of methodologies on mass spectrometry-based approaches, and all related considerations are taken into account regarding the avoidance of artifacts in mass spectrometric analysis during sampling, sample preparation, and the evaluation of results. Finally, we provide an overview of potential applications for precision medicine and drug development.