Strategies to stimulate dendritic cell (DC) activity, such as ex vivo generation and priming of DC vaccines, have been explored as cancer immunotherapies owing to their potential to elicit antitumor T cell responses. Despite decades of research, the success of DC vaccines has been limited, potentially because of unidentified tolerance-enforcing mechanisms. Here we show that GM-CSF–IL-4-induced differentiating DCs express ALDH1A2 and produce retinoic acid, inhibiting DC maturation. Genetic knockout of Aldh1a2 releases this natural brake and enhances DC function. We further develop an ALDH1A2 inhibitor with high potency, favorable drug-like properties and no evidence of off-target effects. Treatment with this inhibitor promotes DC activity, which in turn enhances antigen-specific T cell responses, improving the efficacy of DC vaccines. Our study demonstrates the unique role of the ALDH1A2–retinoic acid axis in regulating DC functions and further presents a new small-molecule inhibitor of ALDH1A2 as a potential immunotherapeutic agent for cancer. Differentiating DCs express ALDH1A2, which produces retinoic acid and suppresses DC activity. Blocking this pathway with a new inhibitor, KyA33, enhances immune responses and boosts the effectiveness of DC cancer vaccines in mouse models.
KRAS G12C is one of the most prevalent oncogenic mutations in nonsmall cell lung cancer. Herein we describe the discovery and optimization of divarasib (GDC-6036), an orally available, highly potent, and selective covalent KRAS G12C inhibitor. We demonstrate a significant noncovalent binding component of divarasib that contributes to its potency and rapid kinetics. Divarasib has greater potency and kinetics of alkylation compared with other KRAS G12C inhibitors in vitro and shows robust tumor growth inhibition in multiple KRAS G12C-positive cell lines.
Mutant KRAS is highly prevalent in human cancer and has been actively pursued as a target for drug discovery. Much progress has been made in drugging KRAS G12C, owing to the ability of inhibitors to covalently target its oncogenic cysteine mutation at codon 12. A number of KRAS G12C inhibitors have advanced to clinical development and are being investigated for the treatment of a variety of solid tumors. Notably, many patients with KRAS G12C-positive non-small cell lung cancer develop brain metastases. Herein, we report the discovery and development of a brain-penetrant inhibitor of KRAS G12C using divarasib as a starting point. Optimization efforts focused on reducing molecular weight and topological polar surface area as well as shielding of hydrogen bond donors. In this manner, active transport by both P-gp and breast cancer resistance protein (BCRP) was attenuated, and high exposure in rodent brain tissue was achieved.
This study presents a DNA-compatible synthesis of diverse N-fused imidazopyridines via a catalyst-free Ugi-type multicomponent reaction using TMSCN as a functional isonitrile equivalent. The desilylation activation occurs efficiently in water without additional catalysts. The method exhibits a broad substrate scope for aldehydes and heterocyclic amidines and excellent chemoselectivity, underscoring its utility for constructing privileged heteroaromatic scaffolds in DNA-encoded library technology.
Targeted covalent inhibitors, such as acrylamide covalent drugs (ACDs), offer advantages in potency, selectivity, and duration of effect compared with traditional small-molecule inhibitors. However, ACDs undergo unique biotransformation pathways in humans, including CYP-mediated metabolism, protein covalent binding, and nonenzymatic glutathione (GSH) adduction, which make standard in vitro metabolism assays for small molecules unsuitable for characterizing ACDs. This study aimed to develop a specialized panel of in vitro metabolism experiments for characterizing ACDs. The approach included metabolism stability assays in human liver microsomes with or without NADPH, covalent binding to human serum albumin with or without GSH, and metabolite profiling in human liver microsomes with or without GSH. In vitro metabolic data were generated for 5 ACDs, abivertinib, afatinib, osimertinib, ibrutinib, and pyrotinib, and compared with reported human metabolism and disposition data. In general, in vitro biotransformation pathways determined in this study are consistent with major metabolic clearance pathways observed in humans. For example, osimertinib showed the highest nonspecific protein covalent binding, a high oxidation-to-GSH adduct ratio, and moderate NADPH-dependent metabolic rates, supporting protein covalent binding as the major metabolic pathway in humans. In contrast, afatinib exhibited minimal CYP-mediated metabolism after accounting for covalent binding to microsomal proteins, low serum protein binding, and a very low oxidation-to-GSH adduct ratio, consistent with GSH adduction being the predominant biotransformation pathway in humans. The results demonstrate that the newly developed in vitro metabolism workflow enables more accurate predictions of CYP-mediated clearance rates and clarifies the relative contributions of CYP metabolism, nonspecific protein covalent binding, and GSH adduction to overall metabolic clearance in humans. SIGNIFICANT STATEMENT: This study established a novel in vitro metabolism approach for characterizing acrylamide covalent drugs. By comparing in vitro metabolic data for abivertinib, afatinib, osimertinib, ibrutinib, and pyrotinib with reported human metabolism and disposition data, we demonstrated that this method improves the accuracy of predicting CYP-mediated metabolic rates. Furthermore, it provides clearer insights into the relative contributions of CYP metabolism, nonspecific protein covalent binding, and glutathione adduction to the overall metabolic clearance of acrylamide covalent drugs in humans.
