A UHPLC-UV-QTOF study on the stability of carfilzomib, a novel proteasome inhibitor

Polymeric micelles loaded with carfilzomib increase tolerability in a humanized bone marrow-like scaffold mouse model

Carfilzomib-loaded polymeric micelles (CFZ-PM) based on poly(ethylene glycol)-b-poly(N-2-benzoyloxypropyl methacrylamide) (mPEG-b-p(HPMA-Bz)) were prepared with the aim to improve the maximum tolerated dose of carfilzomib in a “humanized” bone marrow-like scaffold model. For this, CFZ-PM were prepared and characterized for their size, carfilzomib loading and cytotoxicity towards multiple myeloma cells. Further, circulation and tumor & tissue distribution of fluorescently labeled micelles were determined. Tolerability of CFZ-PM versus the clinical approved formulation – Kyprolis® – was assessed. CFZ-PM presented small diameter below 55 nm and low PDI < 0.1. Cy7-labeled micelles circulated for extended periods of time with over 80% of injected dose in circulation at 24 h after intravenous injection and 1.3% of the injected dose of Cy7-labeled micelles accumulated in myeloma tumor-bearing scaffolds. Importantly, CFZ-PM were well tolerated whereas Kyprolis® showed adverse effects. Kyprolis® dosed at the maximum tolerated dose, as well as CFZ-PM, did not show therapeutic benefit, while multiple myeloma cells showed sensitivity in vitro, underlining the importance of the bone marrow crosstalk in testing novel formulations. Overall, this work indicates that PM are potential drug carriers of carfilzomib.

Second-generation proteasome inhibitor carfilzomib sensitizes neuroblastoma cells to doxorubicin-induced apoptosis

Neuroblastoma (NB), which accounts for about 15% of cancer-related mortality in children, is the most common extracranial malignant neoplasm in children. Elevated level of proteasome activity promotes cancer development and the inhibition of proteasome activity is a promising strategy for cancer treatment. Therefore, targeting proteasome by small molecule inhibitors may be a viable option for NB therapy. Here in this study, we show that a novel proteasome inhibitor Carfilzomib (CFZ) exerts anti-tumor effect on NB. CFZ caused decreased cell viability and attenuated colony formation ability of a subset of NB cell lines. CFZ induced cell apoptosis in NB cells. Moreover, CFZ enhanced the cytotoxic effect of doxorubicin (Dox) on NB cells and Dox-induced p38 and JNK phosphorylation. In addition, CFZ inhibited Dox-induced NF-κB activation by stabilizing the protein level of IκBα. Furthermore, CFZ induced apoptosis and augmented Dox-induced apoptosis in NB tumor cells in orthotopic xenograft mouse models. In summary, our study suggests that proteasome is a therapeutic target in NB and proteasome inhibition by CFZ is a potential therapeutic strategy for treating NB patients.

Tethered polymer nanoassemblies for sustained carfilzomib release and prolonged suppression of proteasome activity

AIM

Proteasome inhibitors, such as carfilzomib (CFZ), have shown potential to treat various types of cancers in preclinical models, but clinical applications are limited likely due to formulation and delivery issues. Results & methodology: Tethered polymer nanoassemblies (TNAs) were synthesized by tethering hydrophilic polymers and hydrophobic groups to charged polymer scaffolds, and then end-capping remaining amines on scaffold. Drug entrapment and drug release half-lives increased as charge was removed from scaffold. TNAs with sustained CFZ release maintained drug efficacy after preincubation and increased duration of proteasome inhibition in cancer cells compared with free CFZ.

CONCLUSION

TNAs fine-tuned CFZ release as charge was removed from polymer scaffold, which allowed for sustained proteasome inhibition in cancer cells and potentially enhanced anticancer efficacy.

Quantitative determination of carfilzomib in mouse plasma by liquid chromatography-tandem mass spectrometry and its application to a pharmacokinetic study

A highly sensitive and rapid LC-MS/MS method was developed and validated to determine the levels of carfilzomib in mice plasma by using chlorpropamide as an internal standard. Carfilzomib and chlorpropamide were extracted from 5 μL of plasma after protein precipitation with acetonitrile. Chromatographic separation was performed on Phenomenex Luna C₁₈ column (50×2.0mm id, 3μm). The mobile phase consisted of 0.1% formic acid in acetonitrile -0.1% formic acid in water (1:1v/v) and the flow rate was 0.3mL/min. The total chromatographic run time was 2.5min. Detection was performed on a triple quadrupole mass spectrometer equipped with positive-ion electrospray ionization by selected reaction monitoring of the transitions at m/z 720.20>100.15 (for carfilzomib) and m/z 277.05>111.05 (for the internal standard). The lower limit of quantification was 0.075ng/mL and the linear range was 0.075-1250ng/mL (r≥0.9974). All validation data, including selectivity, precision, accuracy, matrix effect, recovery, dilution integrity, stability, and incurred sample reanalysis, were well within acceptance limits. This newly developed bioanalytical method was simple, highly sensitive, required only a small volume of plasma, and was suitable for application in pharmacokinetic studies in mice that used serial blood sampling.

Physicochemical stability of carfilzomib (Kyprolis®) containing solutions in glass vials, ready-to-administer plastic syringes and infusion bags over a 28-day storage period

Centralized aseptic preparation of ready-to-administer carfilzomib containing parenteral solutions in plastic syringes and polyolefine (PO) infusion bags needs profound knowledge about the physicochemical stability in order to determine the beyond-use-date of the preparations. Therefore, the purpose of this study was to determine the physicochemical stability of carfilzomib solution marketed as Kyprolis® powder for solution for infusion. Reconstituted solutions and ready-to-administer preparations of Kyprolis® stored under refrigeration (2-8℃) or at room temperature (25℃) were analyzed at predetermined intervals over a maximum storage period of 28 days. Chemical stability of carfilzomib was planned to be determined with a stability-indicating reversed-phase high-performance liquid chromatography assay. Physicochemical stability was planned to be determined by visual inspection of clarity and color as well as pH measurement. The study results show that reconstituted carfilzomib containing parenteral solutions are stable in glass vials as well as diluted solutions in plastic syringes and PO infusion bags over a period of at least 28 days when stored light protected under refrigeration. When stored at room temperature, reconstituted and diluted carfilzomib solutions are physicochemically stable over 14 days and 10 days, respectively. The physicochemical stability of carfilzomib infusion solutions allows cost-saving pharmacy-based centralized preparation of ready-to-administer preparations.