In vitro determination of the preclinical safety of Pheroid® doxorubicin formulations using patch clamp assays

Abstract

One of the most active, widely used and well-known drugs in breast cancer chemotherapy, doxorubicin (DOX), is an anthracycline ring antibiotic derived from the bacteria Streptomyces peucetius. Its clinical use is however, hampered by dangerous side effects like cumulative dose-dependent cardiotoxicity (leading to myocardiopathy). Consequently, DOX often has a narrow therapeutic index and compromised therapeutic potential. DOX-induced myocardiopathy is a fatal ailment and with the development of heart failure the mortality rate is approximately 50%. Acute DOX cardiotoxicity is characterized by electrocardiogram irregularities like prolongation of the interval between the Q and T waves. With the absence of effective treatment for DOX-induced myocardiopathy, preventive measures include limiting the lifetime cumulative dose of Basic Live/dead differentiation Sensitivity Sensitivity 80% Cohort n = 20 60% Cohort n = 20 100% (S + C+) n = 11 82% (S + C+) n = 11 56% (S-C+) n = 9 33% (S-C+) n = 9 Specificity Specificity 84% Cohort n = 68 88% Cohort n = 68 87% (S–C–) n = 60 90% (S–C–) n = 63% (S + C-) n = 8 75% (S + C–) n = 8 Abstracts 3 DOX to b450 mg/m2 , use of continuous slow infusion in place of normal infusion protocols, replacement of DOX with anthracycline analogues, and use of different drug delivery carriers. The aim of this project is to develop a functionalized Pheroid® drug delivery carrier, with extravesicular targeting ligands specifically directing delivery of DOX to breast cancer cells which will increase therapeutic efficacy and reduce toxicity to healthy cells. In vitro patch clamp assays will be conducted to evaluate the effect of entrapping DOX in Pheroid® formulations on acute QT prolongation. We would analyze the IKr (rapid component of the delayed rectifier current) and IKs (second component of the delayed rectifier current) of cultured HEK (human embryonic kidney)-293 cells permanently transfected with the human ether-a-go-go related gene (hERG) and KCNQ1/KCNE1 genes, respectively, using the whole-cell configuration of the patch clamp technique. Functionalized Pheroids, with ligands specific to receptors overexpressed on breast cancer cells, as drug delivery vehicles for DOX could improve drug accumulation at the cancerous tissue through passive and active targeting and minimize acute cardiotoxicity of DOX. From this study we would be able to determine in vitro the preclinical safety with respect to the torsadogenic potential of formulations of DOX in Pheroids