Abstract 1026: PEG-LPrA2 is a non-toxic adjuvant for triple negative breast cancer

Abstract

Abstract Background: Triple Negative Breast Cancer (TNBC) is an aggressive cancer with poor prognosis and is difficult to treat. Current standard therapy for the disease includes a combination of chemotherapeutic drugs: doxorubicin (DOX), paclitaxel (TAX), and cyclophosphamide (CTX). These drugs are ineffective as they exhibit shortcomings and several side effects. TNBC patients develop chemoresistance that may be enhanced by leptin, which affects survival, proliferation, and angiogenesis. Our lab developed and tested a novel and specific inhibitor of leptin signaling, LPrA2. A pegylated derivative of LPrA2 (PEG-LPrA2), with enhanced bioavailability, was successfully used in mouse breast cancer models. Preliminary data showed that PEG-LPrA2 was non-toxic in vitro. Therefore, it is hypothesized that PEG-LPrA2 is not toxic in vivo. Methods: To determine potential toxicity of PEG-LPrA2, in vitro and in vivo assays were performed. In vitro toxicity of PEG-LPrA2 was tested in a human non-malignant mammary epithelial cell line (MCF-10A). MCF-10A cells were cultured in 96 well plates (5,000 cells/ well) and grown to 70-80% confluence. Cells were treated with PEG-LPrA2 for 24 hrs and viability was determined via MTT assay. In vivo toxicity studies were performed in obese mice. Fifty-seven, eight week old C57BL/6J mice (Charles River Laboratories) were divided into 6 groups. Control mice were fed a low fat diet (10% Kcal from fat) and the rest of the mice were fed a high fat diet (60% Kcal from fat) for 11 weeks. Obesity was characterized as body weight (BW) ≥ 25% BW of control mice. Obese mice were divided into six groups (n = 7/each). Mice were injected with 50 μL of either Sc-PEG-LPrA2 (scramble control) or active inhibitor, PEG-LPrA2, (0.1 mM, 1 mM, or 5 mM) two times a week, for eight weeks. Blood chemistries were analyzed. Additionally, heart, liver, and kidney tissue were harvested and examined to determine toxicity. The tissues were probed for OB-R via immuno histochemistry. Results: The results showed no changes in BW or food intake. Additionally, no evident changes in blood parameters and organ histology were found. Conclusions: PEG-LPrA2 is non-toxic and could serve as an adjuvant therapy for standard TNBC chemotherapeutics. Citation Format: Courtney D. Dill, Adriana Harbuzariu, Antonio Rampoldi, Crystal C. Lipsey, Viola Lanier, Tia Harmon, Danielle Daley-Brown, Cynthia Tchio, Pierre Candelaria, Ruben Rene Gonzalez-Perez. PEG-LPrA2 is a non-toxic adjuvant for triple negative breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1026.