656PMiddle East & North Africa registry to characterize RAS mutation status and tumour specifications in recently diagnosed patients with metastatic colorectal cancer (MORE-RAS Study)

Abstract Background RAS mutational status is an essential criterion to guide first-line treatment in metastatic colorectal cancer (mCRC). MORE-RAS was a multicenter, multicountry, observational, ambispective (retrospective + prospective) study conducted in the Middle East and North Africa (MENA) region to assess RAS testing practices and tumor characteristics in newly diagnosed patients (pts) with mCRC. Results of the retrospective analysis are presented here. Methods Eligible pts included adults aged ≥18 with mCRC who had already initiated first-line therapy, had at least 1 post-baseline visit for disease evaluation, and had available survival data. Pts with incomplete and unavailable data or presence of other coexisting malignancies were excluded. Data from eligible pts were retrospectively analysed 2 years back from the day of patient consent. Results A total of 495 pts (median age: 57 y) were enrolled; majority were male (55.6%), with adenocarcinoma histology, stage IV disease (86.8%) and left-sided tumors (79%). Primary tumor site was sigmoid (40.9%), followed by rectal (26.1%), ascending (17.2%), descending (12.1%), and transverse (3.8%) colon. RAS testing was requested in 417 (78%) pts; reasons for not prescribing included test unavailability, financial/medical decision, or other. Testing samples were mostly paraffin-embedded (91.7%) primary tumors (92.5%); sequencing was the most common test method used. RAS testing found that 33.9% of tumors harbored mutations and 66.1% carried wild-type (WT) sequences. The most common mutation was KRAS (94.1%), occurring largely in Exon2-Codon12 (70.5%). RAS testing was typically prescribed after initiation of first-line treatment, significantly more in pts with stage IV disease (p