14609 Background: Angiogenesis inhibitor therapies represent an advance in the treatment (tx) of RCC. Little is known about side effects of these agents and associated costs in a real-world setting. The frequency and cost of key adverse events (AEs) associated with the use of oral sunitinib, oral sorafenib and IV bevacizumab (off-label) in patients (pts) with RCC are quantified. Methods: Pts with ≥ 2 RCC claims (ICD-9 189.0, 198.0) receiving sunitinib (n=244), sorafenib (n=234) or bevacizumab (n=106) were identified from a large US health insurance claims database covering over 39 million people between Jan 02 - Dec 06. Pts were observed from their first angiogenesis inhibitor claim until the end of tx. Per pt per year incidence rates were calculated by agent for pts without prior AE at baseline for 7 key AEs identified during clinical trials: fatigue, diarrhea, hypertension, hand-foot syndrome (HFS), stomatitis, hemorrhage, and GI perforation. In the data, these AEs were severe enough to incur medical costs which were calculated for outpatient visits and hospitalizations associated with these AEs. Cost data represented payments made by insurers, not charges in submitted claims. Results: These AEs were frequent and associated with significant medical costs. 46% sunitinib, 51% sorafenib, and 29% bevacizumab pts developed hypertension each year, suggesting the need to monitor these pts for cardiac events. 21% sunitinib, 13% sorafenib, and 12% bevacizumab pts had fatigue. The outpt costs of managing AEs vary across tx, with hemorrhage and diarrhea for sunitinib, hemorrhage and HFS for sorafenib, and fatigue and hypertension for bevacizumab being the most costly AEs. When hospitalizations occurred, inpt costs were substantial for some of these AEs. Conclusions: Certain AEs occurring with available angiogenesis inhibitors incur significant medical costs. New tx strategies for RCC should consider the balance between efficacy and toxicity to optimize clinical and economic outcomes. Incidence Rate (per Pt-Year) Outpatient Inpatient No. of Visits Cost per Visit ($) Mean ± SD No. of Visits Cost per Visit ($) Mean ± SD Hospital Length of Stay (Days) Sunitinib Diarrhea 0.11 26 325±942 1 12,749±0 6.0±0 Fatigue 0.21 16 136±167 4 8,506±7,928 7.3±4.3 HFS 0.02 2 73±28 - - - Hypertension 0.46 41 179±299 6 13,017±9,599 7.2±4.5 Stomatitis 0.01 1 69±0 - - - Hemorrhage 0.07 5 306±347 2 4,130±4,695 6.0±1.4 GI perforation 0.05 4 51±12 2 11,776±4,540 18.0±21.2 Sorefanib Diarrhea 0.13 16 223±267 3 22,678±27,731 8.3±4.6 Fatigue 0.13 12 297±447 3 2,667±3,018 5.7±3.2 HFS 0.04 4 1,329±2,544 - - - Hypertension 0.51 48 157±307 3 5,462±5,577 6.0±1.0 Stomatitis 0.01 1 40±0 - - - Hemorrhage 0.15 13 1,040±2,761 8 17,607±27,966 6.4±4.9 GI perforation 0.04 5 129±89 - - - Bevacizumab Diarrhea 0.07 5 116±74 1 10,606±0 5.0±0 Fatigue 0.12 10 295±524 2 63,260±77,948 13.5±16.3 HFS 0.02 1 62±0 - - - Hypertension 0.29 16 346±841 3 17,357±10,385 4.0±1.7 Stomatitis 0.00 - - - - - Hemorrhage 0.07 8 185±182 4 5,768±2,292 10.0±15.3 GI perforation 0.05 2 93±52 2 142,303±142,315 12.0±4.2 Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration GlaxoSmithKline GlaxoSmithKline Bayer-Onyx, Genentech, GlaxoSmithKline, Pfizer