👤 Aimee M Crago

We conducted research on CDK4/6 inhibitors (CDK4/6i) simultaneously in the preclinical and clinical spaces to gain a deeper understanding of how senescence influences tumor growth in humans. We coordinated a first-in-kind phase II clinical trial of the CDK4/6i abemaciclib for patients with progressive dedifferentiated liposarcoma (DDLS) with cellular studies interrogating the molecular basis of geroconversion. Thirty patients with progressing DDLS enrolled and were treated with 200 mg of abemaciclib twice daily. The median progression-free survival was 33 weeks at the time of the data lock, with 23 of 30 progression-free at 12 weeks (76.7%, two-sided 95% CI, 57.7%-90.1%). No new safety signals were identified. Concurrent preclinical work in liposarcoma cell lines identified ANGPTL4 as a necessary late regulator of geroconversion, the pathway from reversible cell-cycle exit to a stably arrested inflammation-provoking senescent cell. Using this insight, we were able to identify patients in which abemaciclib induced tumor cell senescence. Senescence correlated with increased leukocyte infiltration, primarily CD4-positive cells, within a month of therapy. However, those individuals with both senescence and increased TILs were also more likely to acquire resistance later in therapy. These suggest that combining senolytics with abemaciclib in a subset of patients may improve the duration of response. Abemaciclib was well tolerated and showed promising activity in DDLS. The discovery of ANGPTL4 as a late regulator of geroconversion helped to define how CDK4/6i-induced cellular senescence modulates the immune tumor microenvironment and contributes to both positive and negative clinical outcomes. See related commentary by Weiss et al., p. 649. Show less

Organophosphates insecticides (OPs) are common surface water contaminants in both urban and agricultural landscapes. Neurobehavioral effects on larval fish are known to occur at concentrations higher than those reported in the environment. The aim of this study was to perform a comparative analysis of neurobehavioral, molecular, and biochemical responses of four OPs (diazinon, dichlorvos, malathion, methyl-parathion) via the following endpoint measurements: distance traveled, velocity, gene expression (AChE, c-Fos, LINGO-1B, GRIN-1B), enzymatic acetylcholinesterase (AChE) activity, and carboxylesterase (CES) activity. OP exposures (5 hpf - 120 dpf) on embryo-larval zebrafish (Danio rerio) were assessed using a larval zebrafish behavior assay at concentrations: 0.01, 0.1, 10, and 100 μg/L. Individual OPs had varying degrees of neurotoxicity. Significant hypoactivity was observed in the 100 μg/L treatments for diazinon and malathion (p < 0.05) as compared to the controls. Diazinon-exposed larvae exhibited a 26% locomotor decrease, and hypoactivity was observed in malathion-exposed larvae at a reduction of 22% and 29% for distance traveled and velocity, respectively. Gene regulation and enzymatic activity changes were measured for both 0.1 and 100 μg/L exposures across OP treatments. Increased CES activity was observed for the 0.1 μg/L treatments of diazinon and methyl-parathion as well as the 100 μg/L treatment of dichlorvos; meanwhile, decreased CES activity was observed for 100 μg/L treatments of diazinon and malathion. Relative enzymatic activity of AChE was inhibited as compared to the control for the 0.1 μg/L diazinon. No other treatment group exhibited a significant effect on biochemical AChE activity; however, AChE upregulation was observed in the 0.1 μg/L exposure for diazinon, dichlorvos, and malathion. Methyl-parathion was observed to downregulate c-Fos at 0.1 μg/L exposure. Malathion upregulated LINGO-1B at 100 μg/L, a gene associated with neuronal regeneration; meanwhile, downregulation of LINGO-1B was observed for 0.1 μg/L exposure of methyl-parathion. Additional downregulation was observed for GRIN-1B in the 100 μg/L diazinon, 100 μg/L dichlorvos, and 0.1 μg/L methyl-parathion treatments. Exposure of ZF embryos to independent concentrations of 100 μg/L concentrations of diazinon and malathion resulted in hypoactivity and decreased CES activity at 5 dfp. No changes in swimming behavior were observed for either the 0.1 μg/L or 100 μg/L dichlorvos or methyl-parathion treatments. Observations from this study indicate that AChE inhibition may not be the most sensitive biomarker of OP pesticide exposure in zebrafish. Rather, the enzyme CES demonstrated higher sensitivity as a biomarker of OP toxicity. Show less