Amrubicin monotherapy for refractory, relapsed, small cell lung cancer in elderly patients

Background Amrubicin monotherapy has been used in Japan for patients with refractory, relapsed, small cell lung cancer (SCLC). However, the clinical guidelines do not specify a recommended initial dose for elderly patients. This retrospective study aimed to explore the appropriate initial dose of amrubicin for elderly patients with refractory, relapsed SCLC. Methods This study included elderly patients (aged ≥70 years) with refractory, relapsed SCLC who received amrubicin monotherapy at Nagoya City University Hospital between April 2009 and March 2023. Patients were divided into two groups based on the initial dose: the low-dose group (<40 mg/m2) and the high-dose group (≥40 mg/m2). Results Forty-seven patients were included, thirty-eight in the low-dose group and nine in the high-dose group. Median progression-free survival was significantly longer in the low-dose group than in the high-dose group (3.64 vs. 1.5 months, P = 0.04), whereas overall survival was not significantly different (10.18 vs. 8.18 months, P = 0.58). Febrile neutropenia occurred in seven patients. Treatment discontinuation due to adverse events was more frequent in the high-dose group (44.4%) than in the low-dose group (13.5%). Non-infectious adverse events such as interstitial pneumonia, arrhythmia, and myocardial infarction were observed in five patients who discontinued treatment. Conclusions Both hematological and non-infectious adverse events may have contributed to shorter progression-free survival in the high-dose group. Low-dose administration, granulocyte colony-stimulating factor support, and close monitoring for non-infectious toxicities may be important in elderly patients.