Final STEPP results of prophylacatic versus reactive skin toxicity (ST) treatment (tx) for panitumumab (pmab)-related ST in patients (pts) with metastatic colorectal cancer (mCRC).

CRA4027 Background: Pmab, a fully human monoclonal antibody targeting the epidermal growth factor receptor (EGFR), is approved as monotherapy in the US for mCRC following disease progression (PD) and in the EU and Canada for tumors bearing wild-type (WT) KRAS. The most common toxicity with anti-EGFR inhibitors are ST. This study of pmab+ chemotherapy (CT) estimates the difference in the incidence of specific ≥ grade 2 ST of interest between pts receiving prophylactic (P) or reactive (R) skin tx.,Pts had unresectable mCRC after PD with 1st-line fluoropyrimidine and oxaliplatin-based CT ± bevacizumab. Pts received either pmab 6.0mg/kg/FOLFIRI Q2W or pmab 9 mg/kg/irinotecan Q3W. Within each stratum, pts were randomized 1:1 to either P ST tx 24 hrs before the 1st dose daily for 6 wks or R ST tx after ST occurred. Tx for ST included: moisturizers, sunscreen, topical steroid, and doxycycline. Efficacy and safety were evaluated by P vs R tx groups, KRAS status (mutant [MT] vs WT), and chemotherapy status. Responses were assessed using modified RECIST with confirmation. Quality of life was assessed using the Dermatology Life Quality Index at screening, wks 2-7, and follow-up.,95 pts were enrolled and randomized: 48 pts to P and 47 pts to R. During the 6 wk ST tx period, 29% of pts in the P group vs 62% of pts in the R group had protocol-specified ≥grade 2 ST. Of the 87 KRAS evaluable pts, 49 (56%) pts had WT KRAS and 38 (44%) pts had MT KRAS. Efficacy and safety are shown. Mean (SD) change in DLQI from baseline was 1.3 (2.6) for P and 4.2 (5.8) for R at wk 3 (when the median time to 1st ≥grade 2 ST was reached in the R group) and was 2.0 (2.8) for P and 2.6 (4.4) for R at wk 7.,Prophylactic use of the skin tx regimen resulted in >50% reduction in the rate of specific ≥ grade 2 STs and improved QOL during the 6-week skin tx period vs R use. Numerical differences in favor of the P group were observed for all endpoints. [Table: see text] [Table: see text].