Abstract P4-06-06: Consistent dosing-time dependent tolerability of everolimus (EV) in a pilot study in women with metastatic breast cancers (MBC) and in a mouse chronopharmacology investigation

Abstract

Abstract Background The molecular circadian clock regulates mTOR activity, the main target of EV. EV use is hampered by adverse events in MBC patients (pts). Knowing the optimal timing of EV oral intake could improve tolerability, thus compliance and treatment efficacy. Objective: To assess the relevance of EV timing for side effects in MBC pts, and to determine the impact of EV timing for body weight, circadian rest-activity pattern, and liver circadian clock in mice. Materials and methods: From 2013 to 2014, 19 MBC pts were treated with EV 10mg plus hormonotherapy at St Louis hospital Breast Cancer unit. Morning or Evening oral intake was prescribed by the medical oncologist in charge of each patient for both EV and hormonotherapy. Side effects were compared according to EV timing. We further investigated whether oral (po) EV timing mattered mice regarding tolerability. EV (5-20 mg/kg/day x 14 days) was administered through oral gavage at 4 circadian times, 6 hours apart to different groups of synchronized male or female B6D2F1 mice (n=32/sex). Body weight change and lethal toxicity were the endpoints. EV effects were further determined on clock gene Per2 expression in the liver of Per2::luciferase (Per2::luc) mice. Per2::luc expression was monitored in freely-moving mice every minute for 3 days before, 5 days during and 3 days after daily EV at one of two timepoints using Real Time-Biolumicorder (RT-BIO, Geneva, Sw). Periods and amplitudes of Per2::luc rhythms were determined with spectral analysis. Results: Nine pts took EV in the morning and 10 in the evening for a median duration of 7.5 months (1.3-19.2 m). Median age was 59 (39-85), median delay between metastatic disease and EV treatment was 52.5 months. Pts had a median of 3 prior lines of treatment for MBC. EV was associated with exemestane (13 pts), or tamoxifen (6 pts). Evening EV was associated with higher occurrence of edema (6 vs 2 pts), fatigue (9 vs 2 pts), and pneumonia (3 vs 0 pts). Equitoxic doses of EV were twice as high in female as compared to male mice. EV timing at the beginning of the light (rest) span resulted in a lethal toxicity rate of 25% in female mice receiving 20 mg/kg/d and 50% in male mice dosed with 10 mg/kg/d). In contrast all the mice treated with EV at the beginning of the dark (activity) span survived, irrespective of dose level. Maximum body weight loss ranged from 5% following EV timing near activity onset to 12% after EV delivery near rest onset, both in males (5 mg/kg/d) and females (10 mg/kg/d) (ANOVA p<0.001). The circadian expression of liver Per2::luc was abolished following EV dosing near rest onset. Per2::luc remained rhythmic in mice receiving EV at the beginning of the activity span. Conclusion: Tolerability was largely improved by the delivery of EV near the onset of the activity span both in women with MBC and in male or female mice. Morning administration of EV could minimize metabolic alterations and fatigue in humans. This timing should further avoid circadian disruption in the liver molecular clocks thus ensure better treatments tolerability. Citation Format: Giacchetti S, Li XM, Ozturk N, Cuvier C, Machowiak J, Arrondeau J, Chang-Marchand Y, Espié M, Okyar A, Lévi F. Consistent dosing-time dependent tolerability of everolimus (EV) in a pilot study in women with metastatic breast cancers (MBC) and in a mouse chronopharmacology investigation [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-06-06.