Sistemas biorresponsivos para liberação sustentada de fármacos visando a quimioprevenção do câncer de mama.

Abstract

Despite the high incidence of breast cancer, there are few pharmacological strategies for chemoprevention, and their serious adverse effects, result in low adherence. Retinoids are capable of inhibiting mammary tumors development due to regulation of cell growth and differentiation, and, among them, fenretinide is considered promising for breast cancer chemoprevention for its ability to accumulate in breast tissue. However, the drug presents serious adverse effects, and its high lipophilicity results in low oral bioavailability. To overcome these limitations and enable its use in chemoprevention, the present study aimed at developing bioresponsive microemulsions capable of uptaking in situ fluids after subcutaneous administration and transforming into a liquid crystalline phase that provides prolonged and local fenretinide release. Several microemulsions were prepared, and those composed of [phosphatidylcholine]:[monoolein:tricaprylin]-propylene glycol in the proportions 1:1-30% and 9:1-50% were selected. They presented diameters below 230 nm, originated liquid-crystalline phase when added 1% or more of water, and prolonged Alexa Fluor 647 release in vivo for more than 30 days; however, the microemulsion 1:1-30% caused local irritation and the formation of a fibrous capsule. Fenretinide was incorporated at a concentration of 1% (m/m), and its release followed pseudo-first order kinetics, Treatment of MCF-7 and T47D cells with the formulation 9:1-50% loaded with fenretinide was more cytotoxic compared to 1:1-30%, leading to its the selection for subsequent studies. Treatment with the fenretinide-loaded 9:1-50% formulation reduced cell migration by 65.2 and 75.9% when used in concentrations equivalent to IC5 and IC15 (concentrations required to reduce viability by 5 or 15%) compared to untreated cells, respectively. In 3D models, treatment with 9:1-50% at a concentration equivalent to IC30 reduced the viability of spheroids by 28.8% compared to the untreated control. In the animal model of chemically induced carcinogenesis, the 9:1-50% formulation was safe and effective, inhibiting the development of breast tumors.The promising results point to the potential of this formulation as new platform for chemoprevention of breast cancer.