Vanderbilt Summer Science Academy

Exploring the Effect of Loading on Immunostimulatory Potency in 2'3'-cGAMP Nanoparticulate Formulations

Immunostimulatory drugs have shown potential in antitumor therapy through their ability to stimulate the immune system to target cancerous cells.  However, their use in the clinic has often resulted in poor drug potency arising from inefficient delivery to cellular receptors.  In response, many investigators formulate drugs with stimuli responsive nanoparticulate carriers to increase intracellular drug localization by maximizing loading to minimize toxicity and off-target immunogenicity caused by the drug carrier.  However, this approach neglects the possibility for differential drug potency or toxicity that can arise from packing relatively large quantities of immunostimulatory drugs into discretized particulates for cellular uptake.

This report will focus on exploring if drug loading is an important parameter in optimizing drug formulation, and the effect of cGAMP loading on drug potency and toxicity.  We will synthesize a poly[(ethylene glycol)-b-[(2-(diethylamino)ethyl methacrylate)-co-(butyl methacrylate)-co-(2-(pyridyl disulfide)ethyl methacrylate)]] (PEG-EBP) pH responsive diblock polymer, and confirm  it via gel permeation chromatography and nuclear magnetic resonance spectroscopy, with its self-assembly properties and ability to encapsulate 2’3’-cGAMP confirmed via transmission electron microscopy and high performance liquid chromatography, respectively.

PEG-EBP will be loaded with 2’3’-cGAMP to varying w/w% of polymer to encapsulated drug, and THP-1 monocytes, DC2.4 dendritic cells, and RAW 264.7 macrophages will be treated. Unloaded PEG-EBP particles will be added to equalize the concentration of polymer at each point in the cell viability curve to determine the effect that cGAMP loading has on cell viability. A similar study will be performed to determine the effect of loading on formulation potency using IFN-I output.