The findings proposed that the <i>PIK3CA</i> rs6443624 SNP significantly decreased the risk of BC (OR=0.44, 95 % CI=0.30-0.65, p<0.0001 CA vs CC; OR=0.35, 95 % CI=0.16-0.78, p=0.0107, AA vs CC; OR=0.60, 95 % CI=0.46-0.79, p=0.0002, A vs T).
Potential predictive biomarkers for pictilisib were evaluated, and RNA sequencing was performed to explore drug resistance mechanisms.<b>Results:</b> The bladder cancer cell line TCCSUP, which harbors a <i>PIK3CA</i> E545K mutation, was sensitive to pictilisib compared to cell lines with wild-type <i>PIK3CA</i> Pictilisib exhibited stronger antitumor activity in bladder cancer PDX models with <i>PI3KCA</i> H1047R mutation or amplification than the control PDX model.