Axitinib: Common Questions Related To Real-World Use Of A New Treatment Option In Advanced Renal Cell Carcinoma.

538 Background: Axitinib is a next generation VEGFR inhibitor approved in the US in Jan 2012 for advanced RCC after failure of one prior systemic therapy. Post approval questions may arise in the medical community regarding clinical scenarios which may not have been addressed in the clinical trials. We present the most common inquiries for axitinib submitted to Pfizer US Medical Information (MI) during the first 18 months post FDA approval and review available information that addresses these questions. Methods: MI inquiries were analyzed during the 6-mo period immediately post FDA approval and a second 6-mo period approximately 1 yr later. To gain insight into real-world dosing patterns, de-identified prescription data from Feb 2012-July 2013 obtained from the 21 specialty pharmacies (SP) in the US that distribute axitinib (Inlyta) were analyzed. Algorithms were developed to define dose modifications using dosage strengths dispensed and time between prescription fills over 2 day and 14 day windows. Results: The most frequent inquiries (>5%) common to both time periods included use in patients (pts) who were unable to swallow medication, use in patients with renal impairment (RI), and general dosage and administration questions. A method for preparation of an axitinib oral suspension for NG tube administration was developed for use in pts unable to swallow axitinib tablets. No dose adjustments are recommended for pts with RI; however axitinib should be used with caution in pts with end stage renal disease. The most common dose dispensed, using a 2 day window, was 5 mg bid, comprising 9659 (70%) of all dispensed prescriptions, with 789 (6%) at the 10 mg bid dose. An assessment of the most recent 7 months in the evaluation period shows that 16% and 19% of prescriptions were for doses >5 mg bid or <5 mg bid, respectively. Similar findings were observed using a 14 day window. Conclusions: Axitinib questions in the medical community revolve primarily around use in specific populations and dosing. Analysis of SP data revealed that dose modifications occurred at a lower frequency than observed in clinical trials. Further analysis is needed to understand outcomes associated with the dose modifications made in these patients.