3637 Background: At ESMO2019, we reported the primary results of a randomized controlled trial (FAEISS study) investigating the efficacy of topical corticosteroid treatment to facial acneiform rash (AR) by EGFR inhibitors comparing groups starting with a very strong topical corticosteroid and the standard weak topical corticosteroid. As an ancillary analysis, we investigated the association between AR and the pre-treatment skin types, as well as between the skin types and therapeutic effects of EGFR inhibitors on the primary disease. Methods: Utilizing pre-treatment clinical photos of the face taken according to the method determined by FAEISS study protocol, we divided the skin types into categories including enlarged pore, oiliness, xerosis, wrinkles, skin color/redness, and allocated the score (1-3) by central review. The severity of AR occurred during the study was graded and was evaluated the association with the specific skin type by Fisher’s exact test. We also investigated the association between the skin types and the best overall response (RECISTv1.1) to EGFR inhibitor therapy on the primary disease using the Cochran-Armitage trend test. Results: Of the registered 172 cases of RAS wild-type metastatic colorectal cancer [104 men and 68 women, median age = 68 (26-79)], omitting the cases with unevaluable data, finally we analyzed 146 cases for associations between the skin types and AR and 147 cases for best overall response. Interestingly, AR developed 13.6% of enlarged pore score 1, 29% of score 2 and 45.8% of score 3, and patients with enlarged pore tended to have more AR (p = 0.058). Surprisingly, the response(CR/PR/SD) of the primary disease were 59.1% of the enlarged pore score 1, 70.6% of score 2 and 87.0% of score 3, and showed statistically significant trend(p < 0.038). Conclusions: This study suggested that a skin type (enlarged pore) is a possible marker predicting AR risk in EGFR inhibitor therapy for RAS wild-type metastatic colorectal cancer, and better therapeutic effects of EGFR inhibitors.
Biomarker testing and mutation prevalence in metastatic colorectal cancer patients in five European countries using a large oncology database
