Survivors of pediatric cancers disproportionately experience subsequent cardiovascular disease. Pediatric cancer survivors are seven times more likely to die of cardiovascular disease compared to the general population. Commonly used anthracycline chemotherapeutic agents, particularly doxorubicin, have been implicated in late cardiovascular disease in cancer survivors, with cumulative dose being the most important risk factor. Studies have shown that even at lower doses of anthracycline exposure (under 100mg/m2), 30% of patients’ hearts show signs of structural abnormalities 6 to 20 years after diagnosis. Strategies to reduce anthracycline-induced cardiotoxicity, including continuous infusion of liposomal doxorubicin or administration of dexrazoxane have not been approved for pediatric use and are not widely adopted in this patient population. This project seeks to advance the development of a patented Apo-A1 mimetic peptide / fatty acid conjugate that self-assembles into micellar structures termed Myr5A-nanoparticles (Myr5A NPs). Myr5A NPs can encapsulate and deliver therapeutic payloads to cancer cells. The synthetic Apo-A1 mimetic peptide component, like Apo-A1 found in physiologic HDL, functionally engages the scavenger receptor class B type 1 (SR-B1) cell surface receptor, resulting in the transfer Myr5A NP drug payloads into the target cell through selective uptake. The selective uptake process is not endosomally-mediated, resulting in delivery of Myr5A NP payloads directly to the cytoplasm. In addition, highly hydrophobic payloads may be efficiently delivered. Myr5A NPs have exhibited long circulating half-lives in animal studies and would be inexpensive to produce at commercial scale. Previous studies have demonstrated SR-B1 expression in a range of tumor cells, in addition to hepatocytes, steroidogenic tissues, and macrophages. The Yustein Lab at Texas Children’s Hospital has confirmed expression of SR-B1 in Ewing sarcoma and other pediatric sarcomas. Based on these observations, we hypothesize that agents encapsulated in Myr5A NPs will selectively target Ewing sarcoma cells with high expression of SR-B1 and spare normal tissues with low SR-B1 expression, such as the heart and kidneys. To test this hypothesis, the Aune Lab will work collaboratively with the Yustein Lab at Texas Children’s Hospital and Qana Therapeutics to evaluate the expression of key DNA damage markers induced by Myr5A NPs loaded with novel anthracyclines (AD198 and valrubicin) in EWS cell lines and cardiac cells in vitro. In addition, we will simultaneously evaluate the antitumor efficacy and cardiac toxicity profile of these agents in vivo, using a unique model developed by the Aune lab to study anthracycline-induced cardiotoxicity. This project will facilitate collection of critical preclinical data by this collaborative group that will lay the foundation for a collaborative clinical trial supported by academia, industry and advocacy groups. Further clinical development could yield a new therapeutic entity that improves outcomes and long-term quality of life for Ewing’s sarcoma patients and other pediatric cancer patients.

Treatment-related toxicity, particularly cardiotoxicity, remains a serious health risk for patients with pediatric cancers, including Ewing sarcoma. This project seeks to advance a targeted vehicle to deliver novel anti- cancer compounds to tumor cells. These encapsulated agents are related to the commonly used chemotherapeutic agent, doxorubicin, and may provide effective therapy with fewer side effects, improving long-term outcomes for pediatric cancer patients.