Konstantinopoulos PA, et al. - Researchers performed this multicentre, open-label, phase 1b trial following a 3 + 3 dose-escalation design to examine the safety and seek the recommended phase 2 dose of the poly (ADP-ribose) polymerase (PARP) inhibitor olaparib in combination with the PI3K inhibitor alpelisib in patients with epithelial ovarian cancer and in patients with breast cancer. Thirty-four patients (28 in the dose-escalation cohort and six in the dose-expansion cohort) were recruited; two in the dose-escalation cohort were ineligible at the day of scheduled study initiation. They identified alpelisib 200 mg once a day plus olaparib 200 mg twice a day (dose level 3) as the maximum tolerated dose and recommended phase 2 dose. Outcomes support the feasibility of combining alpelisib and olaparib with no unexpected toxic effects. This work provides preliminary clinical evidence of synergism between olaparib and alpelisib, especially in epithelial ovarian cancer, and justifies further investigation.