Abstract LB435: Novel MDK targeted therapy for treating triple negative breast cancer

Abstract Background: Triple-negative breast cancer (TNBC) is an aggressive and heterogeneous subtype of breast cancer with poor clinical outcome. Current therapies are not effective as TNBC tend to develop resistant to treatment. There is a dire need for the development of new therapies that impede the progression of TNBC. Midkine (MDK), a multifunctional cytokine/growth factor, was identified as an oncoprotein and its expression is elevated in various human cancers, including TNBC. Moreover, MDK is implicated in the emergence of chemotherapeutic resistance. The absence of direct inhibitors of MDK constitutes a knowledge gap for its therapeutic application. In this study, we identified HBS-101 as a potent MDK inhibitor, and its efficacy in the treatment of TNBC was evaluated. Methods: In silico docking studies were used to identify the putative interaction between HBS-101 and MDK. The status of MDK in TNBC was determined using the TNM plot database. The effect of MDK inhibitor, HBS-101, on cell survival, colony formation, invasion, and apoptosis were evaluated using multiple TNBC cells. Mechanistic studies were conducted using Western blotting, siRNA or CRISPR/Cas9 KOs, reporter assays, RNA-seq, and RT-qPCR. Pharmacokinetics and Maximum Tolerable Dose studies were conducted using in vivo mice models. Preclinical assessments were carried out through cell line-derived xenografts and patient-derived xenografts. Results: Gene expression data from the TNM plot showed that MDK is highly expressed in primary and metastatic breast tumors compared to normal tissues. Molecular docking studies showed that HBS-101 interacts at the MDK-Receptor binding interface. MST studies confirmed the direct interaction of HBS-101 with MDK. MTT assay results showed that HBS-101 significantly reduced the cell viability of primary and metastatic TNBC cells with an IC50 of 1-5 µM. HBS-101 treatment reduced cell survival and invasiveness and promoted apoptosis of TNBC cells. The underlying mechanism of HBS-101 mediated cytotoxicity appeared to imply suppression of NF-kB/mTOR/STAT3 pathways and activation of apoptotic cell death. Further, STAT3 and NF-kB reporter gene activities were reduced with the treatment of HBS-101. Importantly, HBS-101 exhibits distinct pharmacologic advantages, including oral bioavailability, blood-brain barrier penetration, and in vivo stability. HBS-101 up to a dose of 10 mg/kg showed no observable organ toxicity and had no effect on the mice's body weight. Dose range studies identified 5 mg/kg oral as the minimal effective dose, achieving more than 50% tumor reduction. Using the TNBC-brain metastatic model cells (MDA-MB-231-BrM), we showed that HBS-101 treatment markedly reduced metastatic tumor growth and prolonged mice survival in orthotopic mice models. Conclusion: Collectively, these studies discovered a First-in-class MDK inhibitor, HBS-101, and identified a prospective therapeutic opportunity in the targeting of MDK for the treatment of TNBC. COI: HiBis Associates LLC company has patents on HBS-101 Citation Format: Megharani Mahajan, Alondra L. Rodriguez Sanchez, Sridharan Jayamohan, Jessica D. Johnson, John R. Sanchez II, Panneerdoss Subbarayalu, Manjeet K. Rao, Ratna K. Vadlamudi, Gangadhara R. Sareddy, Hareesh B. Nair, Suryavathi Viswanadhapalli. Novel MDK targeted therapy for treating triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB435.