388434 Avidity-Driven Targeting of a Novel Biohybrid Nanoscale Carrier Engineered for High Therapeutic Payload and Extended Release of Anticancer Drugs to Treat Small Cell Lung Cancer
Avidity-Driven Targeting of a Novel Biohybrid Nanoscale Carrier Engineered for High Therapeutic Payload and Extended Release of Anticancer Drugs to Treat Small Cell Lung Cancer
Ricky J. Whitener1, 2, 3,4, Jacek Wower1, 3,4, Mark E. Byrne2, 3,4
1RNA Biochemistry Laboratories, Department of Animal and Dairy Sciences, 2 Biomimetic & Biohybrid Materials, Biomedical Devices, and Drug Delivery Laboratories, Department of Chemical Engineering, 3US Department of Education GAANN Graduate Fellowship Program in Biological & Pharmaceutical Engineering Auburn University, Auburn, AL, USA, 4Auburn University Research Initiative in Cancer
Lung cancer remains the most frequently diagnosed cancer with 1.8 million cases a year. It is also the deadliest, accounting for about a fifth of all cancer deaths worldwide. Small cell lung carcinoma (SCLC) is a subtype of lung cancer consisting of approximately 20% of all diagnoses, and is characterized by rapid growth and poor prognosis. Untreated SCLC is rapidly fatal within two to four months and with treatment only 10% of patients survive longer than 5 years. SCLC is treated today almost exactly the same way it was 30 years ago and survival rates have not significantly improved over the last 40 years. In this work, we produce the first avidity-driven high payload programmable nanocarrier that can be administered either intravenously or intratracheally.
Our nanocarrier platform for cell-specific drug delivery consists of an anchor DNA strand bound to a gold nanoparticle (AuNp), and base-paired to a DNA aptamer. Anchor DNA was bound to AuNps using a salt aging protocol. The anchor DNA chosen has been shown to have a high efficiency for binding to AuNps from previous work in our lab. Using known doxorubicin DNA binding sequences, an aptamer strand was engineered containing drug-binding sites, and a SCLC cell targeting sequence derived from Chen et al. Our therapeutic carrier was designed for binding of intercalating agents only in the drug-binding base-pair region, which is double stranded due to synthesis of a complementary strand. This complementary strand was synthesized by the Klenow DNA polymerase reaction. This reaction was stopped by two 2’O-methylated nucleotides effectively separating the double-stranded drug-binding region from the cell-specific aptamer. Addition of the complementary strand by the Klenow mechanism allows for regulation of DNA interactions resulting in reduction of undesired pairings possible, which aids in formation of the appropriate tertiary structure.
Preliminary data has shown that our nanocarrier is able to deliver more drug per particle than any other AuNp platform published for a 15-nm particle. This nanocarrier is versatile and flexible, enabling it to be reprogrammed to bind other drugs or combinations of drugs, such as doxorubicin and daunomycin as demonstrated in this study. By “Mutating” nucleic acid strands that hold the drug we were able to modulate its release. To increase the drug payload, we extended the length and changed the sequence of the double-stranded drug-binding DNA segment of the nanocarrier. Furthermore, the nanocarrier is programmable to bind either one type of target or different targets by using an array of aptamers, for instance, we tested a series of SCLC cell-specific aptamers in vitro. Many different aptamers were feasible because each nanoparticle is able to accommodate at least 100 aptamer molecules for a 15-nm AuNp using optimized techniques developed in our lab.