Investigational cyclin-dependent kinase 4/6 inhibitor GLR2007 demonstrates activity against isocitrate dehydrogenase wild-type glioblastoma and other solid tumors in mice xenograft models.

Cyclin-dependent kinases, CDK4 and CDK6, are essential in regulating the cell cycle, which is disrupted in cancers like isocitrate dehydrogenase wild-type glioblastoma (GBM). Currently marketed CDK4/6 inhibitors, including abemaciclib, have shown preclinical efficacy in solid tumors, but factors such as poor blood-brain barrier (BBB) penetration limit their efficacy in GBM. GLR2007 is an investigational CDK4/6 inhibitor with the potential for improved BBB penetration. In vitro assays were used to assess the potency and inhibition of CDK4/6 enzymatic activity of GLR2007. Using in vivo assays, the distribution of radiolabeled GLR2007 in rats was determined through quantitative whole-body autoradiography. The antitumor efficacy of GLR2007 was evaluated in human GBM and breast cancer orthotopic mice xenograft models, and human lung, colorectal, and liver cancer in a subcutaneous xenograft model. In tumor cell line proliferation assays, GLR2007 inhibited proliferation at lower concentration values than abemaciclib in 19 of 20 GBM, five of seven breast, 20 of 21 lung, and 24 of 24 liver cancer cell lines. Total levels of radiolabeled GLR2007 in the brains of rats exceeded those in plasma by 2.3-4.5-fold from 2-6 hours after dosing. A xenograft model showed that, compared with vehicle control, 50 mg/kg GLR2007 induced 95.9% tumor growth inhibition (TGI) (P<0.001) in GBM orthotopic xenografts, 81.4% TGI (P=0.037) in breast cancer orthotopic xenografts, and 91.5% TGI (P<0.001) in colorectal cancer subcutaneous xenografts. These studies show possible BBB penetration of GLR2007 and demonstrate its potential as a CDK4/6 inhibitor for the treatment of solid tumors, including GBM.

GZR18, a novel long-acting GLP-1 analog, demonstrated positive in vitro and in vivo pharmacokinetic and pharmacodynamic characteristics in animal models.

GZR18 is a novel analog of glucagon-like peptide-1 (GLP-1). This study evaluates the pharmacology, pharmacokinetics, and efficacy of GZR18, and its potential for the treatment of Type 2 diabetes mellitus (T2DM). In vitro pharmacology and activity of GZR18 were characterized by a binding assay of GZR18 using human serum albumin (HSA), an activation assay in human GLP-1 receptor-expressing cell lines, and its effect on glucose-stimulated insulin secretion (GSIS) in primary mice islets. Pharmacokinetic profiling was performed in Sprague Dawley rats and cynomolgus monkeys, and efficacy evaluated using GZR18 single or repeated doses in db/db mice. GZR18 showed similar binding affinity for HSA and GLP-1 receptor compared with semaglutide and liraglutide. GZR18 increased GSIS, which was confirmed by dynamic islet perifusion and fluorescence imaging using PKZnR-5 for real-time detection. In cynomolgus monkeys, the average GZR18 maximal concentration was 527 nmol L-1, the terminal half-life (T1/2) was 61.3 h, and the time to maximum concentration was 14 h. Single-dose GZR18 lowered blood glucose levels and reduced body weight over 72 h in db/db mice. GZR18 successive administration (every three days for 33 days, i.e. 11 doses) lowered nonfasting and fasting blood glucose levels (p < 0.05 versus control) and glycated hemoglobin, following the 11th dose. Food and water consumption in db/db mice was lowered following repeated doses of GZR18 (p < 0.05 versus control), without a reduction in body weight. These results demonstrate the potential of GZR18 as a long-acting GLP-1 analog for the treatment of T2DM.