Synthesis and evaluation of an injectable everolimus prodrug

Designing orodispersible films containing everolimus for enhanced compliance and bioavailability

INTRODUCTION

Everolimus (EVR) has been approved for the treatment of various advanced cancers and its indications are increasingly expanding. Therefore, it is crucial for patients who have difficulty in swallowing, such as pediatric and elderly patients, to obtain a convenient formulation. The oral absorption of EVR is limited due to its low solubility in water, intestinal metabolism by CYP3A4 enzyme, P-gp-mediated efflux, and metabolism in the liver. The aim of this study was to develop a novel sublingual orodispersible film loading everolimus for improving patient compliance and enhancing oral bioavailability of EVR.

RESEARCH DESIGN AND METHODS

Sublingual orodispersible films loading EVR were prepared by the solvent casting method and evaluated by in vitro and in vivo studies.

RESULTS

The properties of films were determined by scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, and Fourier-transform infrared spectrometry. The addition of acacia gum appeared to be crucial for protecting the drug from oxidation. Pharmacokinetic studies showed that loading into the sublingual orodispersible films significantly increased the oral bioavailability of EVR.

CONCLUSION

The EVR-loaded sublingual orodispersible films are a promising, economical, and convenient approach for delivering EVR efficiently in a solid dosage form.

Distal Alkenyl C-H Functionalization via the Palladium/Norbornene Cooperative Catalysis

A distal-selective alkenyl C-H arylation method is reported through a directed palladium/norbornene (Pd/NBE) cooperative catalysis. The key is to use an appropriate combination of the directing group and the NBE cocatalyst. A range of acyclic and cyclic cis-olefins are suitable substrates, and the reaction is operated under air with excellent site-selectivity. Preliminary mechanistic studies are consistent with the proposed Pd/NBE-catalyzed C-H activation instead of the Heck pathway. Initial success on distal alkylation has also been achieved using MeI and methyl bromoacetate as electrophiles.

Oligo(Lactic Acid)8-Rapamycin Prodrug-Loaded Poly(Ethylene Glycol)-block-Poly(Lactic Acid) Micelles for Injection

PURPOSE

To prepare an oligo(lactic acid)₈-rapamycin prodrug (o(LA)₈-RAP)-loaded poly(ethylene glycol)-block-poly(lactic acid) (PEG-b-PLA) micelle for injection and characterize its compatibility and performance versus a RAP-loaded PEG-b-PLA micelle for injection in vitro and in vivo.

METHODS

Monodisperse o(LA)₈ was coupled on RAP at the C-40 via DCC/DMAP chemistry, and conversion of o(LA)₈-RAP prodrug into RAP was characterized in vitro. Physicochemical properties of o(LA)₈-RAP- and RAP-loaded PEG-b-PLA micelles and their antitumor efficacies in a syngeneic 4 T1 breast tumor model were compared.

RESULTS

Synthesis of o(LA)₈-RAP prodrug was confirmed by ¹H NMR and mass spectroscopy. The o(LA)₈-RAP prodrug underwent conversion in PBS and rat plasma by backbiting and esterase-mediated cleavage, respectively. O(LA)₈-RAP-loaded PEG-b-PLA micelles increased water solubility of RAP equivalent to 3.3 mg/ml with no signs of precipitation. Further, o(LA)₈-RAP was released more slowly than RAP from PEG-b-PLA micelles. With added physical stability, o(LA)₈-RAP-loaded PEG-b-PLA micelles significantly inhibited tumor growth relative to RAP-loaded PEG-b-PLA micelles in 4 T1 breast tumor-bearing mice without signs of acute toxicity.

CONCLUSIONS

An o(LA)₈-RAP-loaded PEG-b-PLA micelle for injection is more stable than a RAP-loaded PEG-b-PLA micelle for injection, and o(LA)₈-RAP converts into RAP rapidly in rat plasma (t_1/2 = 1 h), resulting in antitumor efficacy in a syngeneic 4 T1 breast tumor model.

Codelivery of Paclitaxel and Everolimus at the Optimal Synergistic Ratio: A Promising Solution for the Treatment of Breast Cancer

Clinical studies examining the combination of paclitaxel (PTX) and everolimus (EVER), an mTOR inhibitor, have failed to result in significant improvements in efficacy and toxicity in patients with breast cancer (BC), relative to treatment with PTX alone. These disappointing clinical trial results have been attributed to poorly designed preclinical studies using the combination of PTX and EVER as well as the significantly different pharmacokinetic profiles of the two drugs. In the current work, the potential synergy between PTX and EVER was examined in a panel of six BC cell lines that differ in terms of their molecular subtype and drug sensitivity. Polymeric nanoparticles (NPs) were used to encapsulate PTX and EVER at an optimal synergistic ratio to achieve specific, colocalized delivery of the combination therapy in BC cell lines. Combinations of PTX and EVER (especially at relatively high doses of EVER) resulted in pronounced synergy in all BC cell lines evaluated. The optimal molar ratio of PTX:EVER was determined to be 1:0.5. The combination was delivered to BC cells at the synergistic ratio via encapsulation within polymeric NPs formed from the poly(ethylene glycol)- b-poly(lactide- co-glycolide) (PEG- b-PLGA) copolymer. The NPs had an average diameter of less than 100 nm and were capable of in vitro retention of the encapsulated PTX and EVER at the optimal synergistic molar ratio for over 7 days. Cytotoxicity data demonstrated that PTX+EVER-loaded NPs were significantly less cytotoxic than the free drug combination in MCF-7 and SKBR3 BC cell lines following 72 h, suggesting that PTX+EVER-loaded NPs remain stable and retain the drug combination loaded within the core after 72 h. The uptake of FITC-labeled NPs in SKBR3 cells was evaluated by flow cytometry, with approximately 41% of cells demonstrating detectable fluorescence after 24 h of exposure. The thorough and systematic approach used in this study to determine and evaluate a synergistic PTX:EVER ratio in conjunction with a potentially promising delivery vector for the drug combination could offer a future clinical benefit for patients with BC.