Abstract PO5-27-06: Development of TTX-MC138, a First-In-Class miRNA-10b-Targeted Therapeutic Against Metastatic Cancers of Diverse Primary Disease Origins

Abstract Conventional therapies targeted towards the primary tumor cell oftentimes do not affect the metastatic cell and, in fact, may promote metastasis. For these reasons, our research has focused on developing therapies specific to unique properties of metastatic tumor cells. In our earlier work, we identified miRNA-10b as a master regulator of the viability of metastatic tumor cells. We determined that miRNA-10b not only promotes the capacity of tumor cells to migrate and invade surrounding tissue, but, importantly, serves as a powerful master regulator of the viability of cancer cells. This knowledge allowed us to develop a therapeutic miR-10b inhibitor, named TTX-MC138, which is effectively delivered to metastatic tumor cells and can elicit complete responses and life-long disease remissions in preclinical models of breast and pancreatic adenocarcinoma. As a critical step towards de-risking further clinical development of TTX-MC138, we have embarked on a Phase 0 clinical trial with Cu64-labeled TTX-MC138. The trial involves microdose injection of Cu64-labeled TTX-MC138 into stage IV breast cancer patients, followed by positron emission tomography-magnetic resonance imaging (PET-MRI). The study seeks to determine the pharmacokinetics of TTX-MC138 and its uptake in metastatic lesions. The impact of this work is three-fold. First it can establish that TTX-MC138, which is so effective in mice, will also accumulate in human metastases. This greatly de-risks the clinical development of the therapeutic because it shows drug delivery is indeed feasible. Second, the Phase 0 studies will reveal the pharmacokinetic behavior of TTX-MC138 which will allow one to establish dosing during therapy. Third, once TTX-MC138 reaches late-stage clinical trials, one can use the radiolabeled therapeutic to select patients for treatment, based on which patients’ metastases accumulate the drug. Studies that we present in support of the Phase 0 trial include dosimetry/PK and tissue distribution studies, as well as metabolite analysis in non-human primates. In non-human primates injected with Cu64-labeled TTX-MC138 at a dose of 100 microg, the organs with the highest uptake were the liver, heart, lung and spleen. The mean whole blood half-life was 12.2 ± 2.3 h (mean ± standard deviation) and the mean plasma blood half-life was 11.5 ± 1.8 h. RadioHPLC analysis of plasma samples showed that the drug is very stable with respect to metabolism. Combined, these studies support first-in-human testing of TTX-MC138 for the treatment of metastatic cancer and, by addressing the issue of drug delivery, enable the clinical development of a wide array of TTX-based therapeutics. Citation Format: Zdravka Medarova, Neil Robertson, Subrata Ghosh, Andreas Varkaris, Peter Caravan, Susan Duggan. Development of TTX-MC138, a First-In-Class miRNA-10b-Targeted Therapeutic Against Metastatic Cancers of Diverse Primary Disease Origins abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-27-06.