550P - Safety and Efficacy of Panitumumab (Pmab) Monotherapy in Recurrent or Progressive Metastatic Colorectal Cancer (Mcrc): Results from a Non-Interventional Study (Vectis)

Abstract

ABSTRACT Aim: Pmab is an epidermal growth factor receptor (EGFR) inhibitor indicated for patients (pts) with wild-type RAS mCRC. EGFR inhibitors are associated with skin toxicity (ST) that is mild to moderate in severity for most pts (pts). VECTIS was designed to assess the safety and efficacy of pmab as monotherapy in daily practice with special reference to ST and its management. Methods: This was an open-label, prospective, non-interventional study of 632 pts who had EGFR-expressing wild-type KRAS mCRC and were receiving pmab monotherapy (6 mg/kg Q2W) according to the label at the time the study was initiated. The analysis includes data collected 2008-2013 from Hungary, Poland, Czech Republic, Slovakia, Slovenia, and Bulgaria. The observation period was limited to 18 cycles. The presence of non-zero correlation between best response and maximum ST was tested using chi-square test for non-zero correlation. Results: At time of reporting, 533/632 (84.3%) enrolled pts (64.6% males, median age 63.0 years) had experienced a total of 782 ST events, 43.2% Gr0-1, 56.8% Gr2-3. By the end of the study 29.2% of ST events had resolved; 2.0% had resolved with consequences; 24.2% were continued but improving; and 44.5% had not resolved. Overall, 69.8% of pts required therapeutic measures for ST. Of the 13 deaths that occurred, none was related to pmab. 5 pts have stopped pmab therapy due to adverse drug reactions including ST or other toxicity. Overall, 10.4% of pts have experienced tumor response (CR + PR), 58.9% have had disease control (CR + PR + SD), and 18.2% were reported to be free from progression (FFP) at the end of observation. A statistically significant positive correlation was observed between severity of ST and both best response (p = 0.0009) and tumor response (p = 0.0002). % (95% CI) Overall N = 632 ST Gr0-1 n = 273 ST Gr2-3 n = 359 CR + PR 10.4 (8.2, 13.1) 4.8 (2.6, 8.0) 14.8 (11.3, 18.9) CR + PR + SD 58.9 (54.9, 62.7) 53.8 (47.7, 59.9) 62.7 (57.4, 67.7) FFP 18.2 (15.3, 21.4) 13.6 (9.7, 18.2) 21.7 (17.6, 26.4) Conclusions: In clinical practice, pmab monotherapy was well tolerated and effective in pts who have recurrent or progressive mCRC with wild-type KRAS gene tumor status. Disclosure: R. Lakomy: has following interests to disclose: Advisory Board member - BMS, Research funding - BMS, GSK, Novartis, Roche, other relationship - remuneration from BMS (seminar presentation). no stock ownership; B. Piko: has following interests to disclose: Advisory board member - Roche, Bayer, Pfizer, other relationship - remunaration from Roche, Merck, Richter, Teva. No stock ownership, no research funding; Z. Mihaylova: has following interests to disclose: advisory board member - Lilly, Amgen, Merck, Sanofi. No stock ownership, no research funding, no other relationship; E. Pritzova: has following interests to disclose: research funding - Bayer, Pfizer, GSK. no stock, no advisory board member, no other relationship; L. Kvocekova: has folowing interests to disclose: stock - Amgen, other relationship - full time Amgen employee. no advisory board member, no research funding. All other authors have declared no conflicts of interest.