Targeting a lineage-specific PI3KÉ£-Akt signaling module in acute myeloid leukemia using a heterobifunctional degrader molecule.

Dose-limiting toxicity poses a major limitation to the clinical utility of targeted cancer therapies, often arising from target engagement in nonmalignant tissues. This obstacle can be minimized by targeting cancer dependencies driven by proteins with tissue-restricted and/or tumor-restricted expression. In line with another recent report, we show here that, in acute myeloid leukemia (AML), suppression of the myeloid-restricted PIK3CG/p110γ-PIK3R5/p101 axis inhibits protein kinase B/Akt signaling and compromises AML cell fitness. Furthermore, silencing the genes encoding PIK3CG/p110γ or PIK3R5/p101 sensitizes AML cells to established AML therapies. Importantly, we find that existing small-molecule inhibitors against PIK3CG are insufficient to achieve a sustained long-term antileukemic effect. To address this concern, we developed a proteolysis-targeting chimera (PROTAC) heterobifunctional molecule that specifically degrades PIK3CG and potently suppresses AML progression alone and in combination with venetoclax in human AML cell lines, primary samples from patients with AML and syngeneic mouse models.

Zidovudine-ß-Lactam Pronucleoside Strategy for Selective Delivery into Gram-Negative Bacteria Triggered by ß-Lactamases.

Addressing antibacterial resistance is a major concern of the modern world. The development of new approaches to meet this deadly threat is a critical priority. In this article, we investigate a new approach to negate bacterial resistance: exploit the ß-lactam bond cleavage by ß-lactamases to selectively trigger antibacterial prodrugs into the bacterial periplasm. Indeed, multidrug-resistant Gram-negative pathogens commonly produce several ß-lactamases that are able to inactivate ß-lactam antibiotics, our most reliable and widely used therapeutic option. The chemical structure of these prodrugs is based on a monobactam promoiety, covalently attached to the active antibacterial substance, zidovudine (AZT). We describe the synthesis of 10 prodrug analogues (5a-h) in four to nine steps and their biological activity. Selective enzymatic activation by a panel of ß-lactamases is demonstrated, and subsequent structure-activity relationships are discussed. The best compounds are further evaluated for their activity on both laboratory strains and clinical isolates, preliminary stability, and toxicity.