(504e) Paclitaxel-Conjugated Virus Nanoparticles for Targeted Breast Cancer Treatment

A
critical difficulty in designing nanotherapeutics is in developing highly
targeted platforms that can reach target sites with high efficiency. Purely
rational improvements to nanoparticle design can be extremely difficult.
Additionally, due to the high degree of heterogeneity in breast tumors within a
patient as well as between patients, there is currently no one biomarker
available that specifically identifies all breast cancer cells.  To overcome
these obstacles, we are developing a novel drug delivery system based on
adeno-associated virus (AAV) nanoparticles to deliver chemotherapeutic agents
specifically to breast cells and limit the exposure of drugs to normal
non-breast tissues. AAV is a 25 nm virus nanoparticle that is currently in
clinical trials for a variety of gene therapy applications. The AAV capsid is a
supramolecular assembly of 60 protein subunits, lending itself well to
multivalent conjugation of drug molecules. We have used directed evolution to
create virus nanoparticles that can specifically bind breast tissue. 
Paclitaxel (taxol), chemically modified with N-hydroxysuccinimide, was
covalently attached to the virus capsid surface. Free taxol was successfully
removed from the AAV-taxol conjugation.  AAV-taxol was assayed for degree of
conjugation with UV-vis, Electrospray Ionization Mass Spectrometry (ESI-MS) and
immunoblotting; proper capsid assembly with Enzyme-Linked Immunosorbent Assay (ELISA)
and Transmission Electron Microscopy (TEM);
genomic packaging with Quantitative Polymerase Chain Reaction (Q-PCR); and
cytotoxicity with cell viability assays. This work will offer superior
targeting of breast tissues and provide greater drug payload. It has the
potential of significantly decreasing the morbidity associated with systemic
chemotherapy.