The overall goal of this research is to demonstrate that our newly developed high-affinity and high-specificity targeting ligand (LLP2A) for lymphoid cancers, when incorporated onto the surface of nanoparticle drugs, such as Abraxane(r) (Human serum albumin-bound paclitaxel nanoparticle), will greatly enhance the modified drug's therapeutic efficacy. Nanotechnology is an emerging field that has shown promise for the development of novel diagnostic, imaging and therapeutic agents for a variety of diseases, including cancer. Abraxane(r) is among the first nanotherapeutics approved by the FDA. It is a nanoparticle (~130nm diameter) that consists of human serum albumin shell around a core of paclitaxel. Abraxane(r) has been demonstrated to be more effective and less toxic than the standard paclitaxel formulation (Taxol) currently used in the clinic. One major obstacle of effective clinical application of nano-therapeutic or nano-imaging agents is the lack of high affinity and high specificity targeting ligands that can deliver these nanomedicines to the tumor or organ target site in with high efficiency in vivo. We have recently reported 1 the identification of a high-affinity (IC50=2 pM) peptidomimetic ligand (LLP2A) against activated a4?1 integrin using both diverse and highly focused one-bead one-compound (OBOC) combinatorial peptidomimetic libraries in conjunction with a high stringency screening method. We further demonstrated that LLP2A is able to image a4?1-expressing lymphomas with high sensitivity and specificity when conjugated to a near infrared fluorescent dye in a murine xenograft model. In this application, we hypothesize that LLP2A or its analogues, when conjugated onto the surface of Abraxane(r), can facilitate the binding of the nanoparticle drug to the cell surface of lymphoid malignancies and, as a result, improve in vitro cytotoxicity as well as in vivo pharmacokinetic parameters, tissue distribution, and anti-tumor performance when compared to Abraxane with no surface modification.
The specific aims of this application are as follows:
Aim 1 : To develop and optimize methods to prepare Abraxane-LLP2A conjugate, and to characterize the conjugates physically, chemically, and biologically: (a) To develop methods to introduce LLP2A to Abraxane nanoparticle;(b) To determine the number of introduced LLP2A per Abraxane nanoparticle, and the physical characteristics Abraxane-LLP2A;and (c) To determine the cell binding specificity and cytotoxicity of the Abraxane-LLP2A conjugate.
Aim 2 : To evaluate the biodistribution and anti-tumor efficacy of Abraxane-LLP2A in vivo: (a) To characterize the uptake-kinetics and organ distribution of Abraxane-LLP2A in the murine xenograft model for lymphoid malignancies;and (b) To characterize the anti-tumor activity of Abraxane-LLP2A in the murine xenograft model for lymphoid malignancies.
Aim 3 : To evaluate the biodistribution of 99TmTc-labeled Abraxane-LLP2A in companion dogs with lymphoma.
