PROPSEA, safety evaluation of palbociclib and ribociclib in older patients with breast cancer: A prospective real-world TOG study.

INTRODUCTION

In this study, the toxicities and management of palbociclib and ribociclib in older patients (≥65 years) with metastatic breast cancer patients were investigated.

MATERIALS AND METHODS

Among older patients receiving palbociclib and ribociclib, Geriatric 8 (G8) and Groningen Frailty Index were used to evaluate frailty status. Dose modifications, drug withdrawal and other serious adverse events (SAEs) were recorded and analyzed according to baseline patient characteristics.

RESULTS

A total of 160 patients from 28 centers in Turkey were included (palbociclib = 76, ribociclib = 84). Forty-three patients were ≥ 75 years of age. The most common cause of first dose modification was neutropenia for both drugs (97% palbociclib, 69% ribociclib). Liver function tests elevation (10%) and renal function impairment (6%) were also causes for ribociclib dose modification. Drug withdrawal rate was 3.9% for palbociclib and 6% for ribociclib. SAEs were seen in 11.8% of those taking palbociclib and 15.5% of those on riboclib. An ECOG performance status of ≥2 and being older than 75 years were associated with dose reductions. Severe neutropenia was more common in patients with non-bone-only metastatic disease, those receiving treatment third-line therapy or higher, coexistance of non-neutropenic hematological side effects (for ribociclib). Neutropenia was less common among patients with obesity.

DISCUSSION

Our results show that it can be reasonable to start palbociclib and ribociclib at reduced dose in patients aged ≥75 years and/or with an ECOG performance status ≥2.