Monday, May 6, 2024
5/6/2024
PROJECT SUMMARY Targeting a single oncogenic pathway for cancer therapy is feasible but generally not very effective, as patient responses are short-lived, hampered by toxicity and invariably supplanted by progressive disease. An alternative strategy is to target global cancer networks. This is expected to disable multiple mechanisms of tumor growth at once, circumvent the emergence of drug resistance and be effective in disparate malignancies, regardless of genetic or molecular heterogeneity. A pool of Heat Shock Protein-90 (Hsp90) chaperones localized in mitochondria orchestrates one such cancer network. Mitochondrial Hsp90s are overexpressed in cancer, compared to normal tissues, support multiple mechanisms of tumor growth through heightened protein folding, and confer worse disease outcome in the clinic. Unexpectedly, this pathway could not be targeted pharmacologically, as none of the Hsp90 antagonists developed so far has the ability to accumulate in mitochondria. For this reason, we developed Gamitrinib (GA mitochondrial matrix inhibitor), the first-in-class, mitochondrial-targeted, small molecule Hsp90 inhibitor. With a unique combinatorial structure, Gamitrinib selectively accumulates in mitochondria, disrupts the organelle protein folding environment, and shuts down multiple pathways of bioenergetics, metabolism, and cell survival required for tumor growth. In turn, this translates in potent cytotoxic activity against heterogeneous tumors as monotherapy or in combination, and inhibition of primary and metastatic tumor growth in xenograft and transgenic disease models. Advanced solely through public funding, the preclinical development of Gamitrinib is now complete (PIND #132453), showing favorable drug-like properties, encouraging safety in two animal species, and a unique signature of “cellular starvation” as biomarker of target inhibition, in vivo. Therefore, the hypothesis that Gamitrinib provides the first subcellularly-directed cancer therapy targeting a mitochondrial network of tumor maintenance can be formulated, and will constitute the focus of the present application. The first specific aim will support a first-in-human, phase I clinical trial of weekly intravenous infusion of Gamitrinib in patients with advanced cancer. These studies will determine the maximum tolerated dose (MTD), dose-limiting toxicities (DLT) and pharmacokinetics of Gamitrinib using an accelerated dose-escalation protocol with expansion cohort at MTD. The second specific aim will characterize the pharmacodynamics of Gamitrinib in pre- and post-treatment tumor biopsies and peripheral blood mononuclear cells harvested from the patient expansion cohort. These studies will profile the metabolic defects of Gamitrinib therapy and evaluate a “cellular starvation” signature comprising inhibition of AMPK signaling, induction of autophagy, modulation of proteotoxic stress and suppression of mTOR signaling. Overall, the proposal is designed to bring to the clinic a novel anticancer agent with a unique mechanism of action and broad, “tumor-agnostic” efficacy.
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