Gelmon K, Walshe JM, Mahtani R, et al. - Given a prolonged progression-free survival (PFS) and an acceptable safety profile were provided by palbociclib in combination with letrozole in patients with estrogen receptor–positive/human epidermal growth factor receptor–negative advanced breast cancer in the PALOMA-2 trial, researchers undertook this post hoc analysis of PALOMA-2 to assess the efficacy as well as safety of palbociclib plus letrozole in patients with preexisting conditions grouped by Medical Dictionary for Regulatory Activities (MedDRA) System Organ Class (SOC). It was found that a prolonged PFS was conferred by palbociclib plus letrozole, vs placebo plus letrozole, irrespective of baseline preexisting condition. Findings of this post hoc analysis of PALOMA-2 revealed that palbociclib not only exerted a favorable impact on PFS but also displayed a safety profile consistent with previous observations, irrespective of underlying preexisting condition.