Abstract P4-06-13: Discovering serum biomarkers for predicting accumulation of nanotherapeutics to different tumor and organ microenvironments

Surrogate biomarkers in the circulation for the enhanced permeation and retention (EPR) effect in different tumor and organ microenvironment shall aid in selecting patients who are likely to accumulate higher amount of nanotherapeutics to tumors and thus show better response to the therapeutics. In this study, 4T1 and 3LL murine cancer cell lines, known to have similar sensitivity to pegylated liposomal doxorubicin (PLD) in vitro, were shown to accumulate significantly different quantities of PLD in vivo. PLD accumulation correlated with tumor-specific differences in therapeutic efficacy and vascular permeability, which was modulated by the extent of coverage of tumor-associated endothelial cells by basement membrane. Matrix metalloproteinase (MMP)-9 and its endogenous inhibitor, tissue inhibitor of metalloproteinase (TIMP)-1, played a pivotal role in these phenomena. Differences in vascular permeability and PLD accumulation were also organ-specific and significantly correlated with the relative ratio of MMP-9 and TIMP-1 in the systemic circulation of the tumor-bearing mice. Our findings support the further development of MMP-9 and TIMP-1 as paired serum biomarkers for predicting accumulation of PLD to tumor and the application of these biomarkers could be expanded to other types of nanotherapeutics utilizing the EPR effect for the personalization of cancer therapy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-06-13.

Abstract P6-11-12: Nanoparticle-enhanced chemotherapeutics delivery in drug-resistant triple-negative breast cancer

Chemotherapeutics delivery is generally poor in tumors characterized by rapid perfusion and low blood volume fraction. Systemically administered nanoparticles can be engineered to overcome abnormal flow conditions to act as intravascular drug depots for the localized delivery of high concentrations of chemotherapeutics. The feasibility of this approach was first demonstrated using melanoma, and is now being further investigated using well-characterized human triple-negative breast cancer biopsies implanted into mice. Intravital microscopy studies of human cancer-in-mice selected for differing vascular morphologies have yielded intriguing preliminary data regarding the role of tumor vascularity in drug and particle delivery. The first-pass perfusion of a 40kDa dextran tracer revealed that BCM-2665 tumors are perfused ∼6x more rapidly than BCM-4195 tumors (11.3 ± 2.3s vs. 67.6 ± 11.0) and contain ∼30% lower volume fraction of blood (0.046 ± 0.011 vs. 0.062 ± 0.015). Interestingly, flow parameters that adversely impact drug accumulation appear to favor plateloid particle accumulation. BCM-2665 xenografts receiving an i.v. injection of 1000×400 nm particles show ∼10x more particle accumulation than BCM-4195 tumors (24.8 ± 3.2 × 103/mm3 vs. 3.5 ± 0.4 × 103/mm3). The ability of these therapeutic particles to reach tumors appears to be primarily driven by flow-related parameters, which we characterize using a combination of intravital microscopy, computed tomography, and mathematical modeling. The total number of particles accumulated within a given tumor appears to be largely driven by the number of particles entering the tumor, since ∼65–70% of entering plateloid particles are retained by the tumor vasculature. This suggests that cytotoxic intravascular drug depots may be a promising strategy for increasing the efficiency of chemotherapeutics delivery to drug-resistant tumors and is the premise of ongoing therapeutic response studies. Clearly if more drugs can be delivered to the tumors, better outcomes can be expected for the patients.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-11-12.