We found that PDOs obtained from patients with a left-sided RAS/BRAF-wildtype tumour (n = 4) were more sensitive to EGFR-inhibitor panitumumab, compared to PDOs obtained from patients with right-sided or rectal RAS/BRAF-wildtype tumours, RAS-mutant tumours and BRAF-mutant tumours (n = 19, median normalized GRAUC 0.17 vs 0.74, p = 0.138). Here, BRAF is linked to neoplasm.