Abstract 1683: Combining annamycin, a non-cardiotoxic potent topo II poison, with azacitidine, cytarabine, gemcitabine, ifosfamide, trabectedin, or vincristine to synergize anticancer effects and identify potential clinical applications

Abstract Background: Annamycin (ANN) is a potent topoisomerase II poison structurally related to doxorubicin (DOX) but displaying superior biological properties, such as high in vivo efficacy, reduced toxic side effects, and activity against cancers resistant to common therapeutic agents. ANN is currently clinically evaluated as a liposome formulated drug product, L-ANN. Importantly, L-ANN preclinical and clinical data clearly indicate a lack of cardiotoxic activity, which is a common dose-limiting factor in this class of therapeutics. In addition, ANN and L-ANN display unique organotropism that significantly differs from that of DOX. This finding further increased our interest to study the potential synergistic or additive effects of combining ANN with different anticancer agents. The efficacy of L-ANN has been established in multiple tumor models covering both liquid cancers and solid tumors, further strengthening the rationale of this study. Objective The objective of the study was to assess the efficacy of ANN in combination with different anticancer agents in order to identify the potential clinical application of ANN alone and with a therapeutic partner. Methods: The activity of ANN in combination with selected FDA approved drugs was assessed in vitro after 72 hours of treatment using a cytotoxicity assay followed by determination of the combination indexes. In separate in vitro experiments, ANN activity was tested against drug resistant cell lines, including cells resistant to cytarabine and venetoclax. The most efficacious drug combinations from the in vitro studies were then tested using in vivo models of leukemia and solid tumors, including sarcoma and pancreatic cancer. Results: The in vitro screening performed in set of cancer cell lines led to selection of the following agents combined with ANN for testing efficacy in clinically relevant animal models: 1) Cytarabine, 2) Azacitidine, 3) Venetoclax, 4) Vincristine in AML model; 5) Ifosfamide in fibrosarcoma; 6) Irinotecan and 7) Gemcitabine in PATC53 pancreatic cancer model. All combinations listed above showed improved survival when compared to single agent control groups. Importantly, our preclinical studies led to the clinical development of L-ANN plus cytarabine regimen, a combination that demonstrated clinical anticancer activity in Phase I/II studies in AML patients. Phase III clinical studies of L-ANN in a combination with cytarabine is expected to be initiated in early 2025. Conclusion: ANN appears to be a versatile drug forming efficacious combinations with numerous mechanistically different anticancer agents. Our studies are working toward identifying new clinical applications for ANN with a long-term goal of developing novel therapeutic strategies for drug-resistant cancers. Citation Format: Rafal J. Zielinski, Krzysztof Grela, Stanislaw Skora, Izabela Fokt, Roberto Cardenaz-Zuniga, Natalia Baran, Waldemar Priebe. Combining annamycin, a non-cardiotoxic potent topo II poison, with azacitidine, cytarabine, gemcitabine, ifosfamide, trabectedin, or vincristine to synergize anticancer effects and identify potential clinical applications [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1683.