Physiologically Based Pharmacokinetic Modelling of Cytochrome P450 2C9-Related Tolbutamide Drug Interactions with Sulfaphenazole and Tasisulam

Background and Objectives: Cytochrome P450 2C9 (CYP2C9) is involved in the biotransformation of many commonly used drugs, and significant drug interactions have been reported for CYP2C9 substrates. Previously published physiologically based pharmacokinetic (PBPK) models of tolbutamide are based on an assumption that its metabolic clearance is exclusively through CYP2C9; however, many studies indicate that CYP2C9 metabolism is only responsible for 80–90% of the total clearance. Therefore, these models are not useful for predicting the magnitude of CYP2C9 drug–drug interactions (DDIs). This paper describes the development and verification of SimCYP-based PBPK models that accurately describe the human pharmacokinetics of tolbutamide when dosed alone or in combination with the CYP2C9 inhibitors sulfaphenazole and tasisulam. Methods: A PBPK model was optimized in SimCYP for tolbutamide as a CYP2C9 substrate, based on published in vitro and clinical data. This model was verified to replicate the magnitude of DDI reported with sulfaphenazole and was further applied to simulate the DDI with tasisulam, a small molecule investigated for the treatment of cancer. A clinical study (CT registration # NCT01185548) was conducted in patients with cancer to assess the pharmacokinetic interaction of tasisulum with tolbutamide. A PBPK model was built for tasisulam, and the clinical study design was replicated using the optimized tolbutamide model. Results: The optimized tolbutamide model accurately predicted the magnitude of tolbutamide AUC increase (5.3–6.2-fold) reported for sulfaphenazole. Furthermore, the PBPK simulations in a healthy volunteer population adequately predicted the increase in plasma exposure of tolbutamide in patients with cancer (predicted AUC ratio = 4.7–5.4; measured mean AUC ratio = 5.7). Conclusions: This optimized tolbutamide PBPK model was verified with two strong CYP2C9 inhibitors and can be applied to the prediction of CYP2C9 interactions for novel inhibitors. Furthermore, this work highlights the utility of mechanistic models in navigating the challenges in conducting clinical pharmacology studies in cancer patients

nab-paclitaxel/carboplatin induction in squamous NSCLC: longitudinal quality of life while on chemotherapy

Michael Thomas,1,2 David R Spigel,3 Robert M Jotte,4 Michael McCleod,5 Mark A Socinski,6 Ray D Page,7 Laurent Gressot,8 Jeanna Knoble,9 Oscar Juan,10 Daniel Morgensztern,11 Dolores Isla,12 Edward S Kim,13 Howard West,14 Amy Ko,15 Teng Jin Ong,15 Nataliya Trunova,15 Cesare Gridelli16 On behalf of ABOUND.sqm investigators 1Department of Thoracic Oncology/Internal Medicine, Thoraxklinik im Universitätsklinikum Heidelberg, 2Translational Lung Research Center Heidelberg, Heidelberg, Germany; 3Sarah Cannon Research Institute, Nashville, TN, 4Department of Medical Oncology/Hematology, Rocky Mountain Cancer Centers, Denver, CO, 5Florida Cancer Specialists, Fort Myers, 6Florida Hospital Cancer Institute, Orlando, FL, 7The Center for Cancer and Blood Disorders, Fort Worth, 8North Cypress Cancer Center, Cypress, TX, 9The Mark H. Zangmeister Center, Columbus, OH, USA; 10Department of Medical Oncology, Hospital Universitari i Politécnic La Fe, Valencia, Spain; 11Department of Medical Oncology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; 12Department of Medical Oncology, University Hospital Lozano Blesa, Zaragoza, Spain; 13Levine Cancer Institute, Carolinas HealthCare System, Charlotte, NC, 14Thoracic Oncology Program, Swedish Cancer Institute, Seattle, WA, 15Celgene Corporation, Summit, NJ, USA; 16Department of Oncology/Hematology, S.G. Moscati Hospital, Avellino, Italy Background: Longitudinal data on the impact of treatment on quality of life (QoL) in advanced non-small cell lung cancer (NSCLC) are limited. In this palliative setting, treatment that does not deteriorate QoL is key. Here we report longitudinal QoL in patients with squamous NSCLC, receiving ≤4 cycles of nab-paclitaxel/carboplatin combination chemotherapy. Methods: Patients received nab-paclitaxel 100 mg/m2 days 1, 8, 15 + carboplatin area under the curve 6 mg•min/mL day 1 (q3w) for four cycles. QoL was assessed by the Lung Cancer Symptom Scale (LCSS) and Euro-QoL-5 Dimensions-5 Levels (EQ-5D-5L) at baseline and each cycle (day 1). Results: Two-hundred and six lesion-response-evaluable patients completed baseline + ≥1 postbaseline QoL assessment and were QoL evaluable. LCSS average total score and symptom burden index improved from baseline throughout four cycles. In the LCSS pulmonary symptoms score, 46% of patients reported clinically meaningful improvement (≥10 mm visual analog scale) from baseline. Individual EQ-5D-5L dimensions remained stable/improved in ≥83% of patients; ≈33% reported complete resolution of baseline problems at least once during four cycles. Generally, responders (unconfirmed complete/partial response) had higher scores vs nonresponders. Conclusion: In patients with squamous NSCLC, four cycles of nab-paclitaxel/carboplatin demonstrated clinically meaningful QoL improvements, with greater benefits in responders vs nonresponders. Keywords: nab-paclitaxel, non-small cell lung cancer, quality of life, response, squamou