The gene encoding for the catalytic subunit of the phosphatidylinositol-3-kinase (PI3K), p110a (PIK3CA) is the most frequently mutated kinase in cancer. This discovery triggered the development of small molecule anti-PI3K inhibitors, such as NVP-BYL719. However, the PI3K / Akt signaling pathway plays not only an important role in promoting cell growth, proliferation and survival but also in regulating glucose homeostasis by directly mediating insulin-stimulated glucose uptake into insulin sensitive tissues (adipocytes and muscles). NVP-BYL719 (a selective inhibitor of the class Ia PI3K isoform alpha) given in the morning is facing on-target tolerability challenge (hyperglycemia) in clinical trials limiting the dose being administered to patient (1). As glucose metabolism is highly impacted by circadian rhythms in patients and rodents, we have decided to adopt an integrative circadian-timing approach in our pre-clinical models to interrogate the benefit of morning vs evening dosing for BYL719. By using a newly developed radio-telemetry technology (2), we were able to record in real time and 'around-the-clock' blood glucose levels in stress-free, freely moving rats dosed with NVP-BYL719 at different regimens. The dynamic profile of hyperglycemia observed after active or inactive period dosing of NVP-BYL719 (50 mg/kg qd p.o.) were similar. Dosing before the inactive phase (10 a.m.) allowed blood glucose to normalize in between 2 doses, which could not be achieved when dosing before the active phase (5 p.m.). After treatment discontinuation a significant hyperglycemia remained for a period up to 12h in the group dosed before the active phase (5 p.m.). Circadian “evening” NVP-BYL719 dosing is associated with a better control of glycaemia. Clinically this could potentially translate to better compliance and longer time on treatment hence better efficacy for patient. Based on these findings we could recommend optimized treatment schedules for future combination experiments in the clinic with NVP-BYL719. 1) Juric et al, “Phase I study of the PI3Kα Inhibitor BYL719, as a Single Agent in Patients with Advanced Solid Tumors (AST)”, Annals of Oncology (2014), 25 (Supp. 4) 2) Brockway et al, “Fully Implantable Arterial Blood Glucose Device for Metabolic Research Applications in Rats for Two Months”, J Diabetes Sci Technol (2015), 9(4):771-81

Citation Format: Christian R. Schnell, Thomas Ferrat, Daniel Wyss, Walter Tinetto, Sonja Tobler, Christine Fritsch, Michael Jensen. Circadian timing regimen for alpelisib (NVP-BYL719), a selective inhibitor of the class Ia PI3K isoform alpha to maximize therapeutic index [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3933.