Lower optimal dose of amrubicin for relapsed small-cell lung cancer: a retrospective study

Background Amrubicin (AMR) is one of the most active agents for small-cell lung cancer (SCLC). However, hematologic toxicity and infection at a commonly used dose (40 mg/m 2 ) is problematic; the optimal dose remains undetermined. Patients and methods To evaluate the optimal dose of AMR in terms of efficacy and safety, we reviewed consecutive data on patients with relapsed SCLC who received AMR at doses of 40, 35, and 30 mg/m 2 (on days 1–3) at Nippon Medical School Hospital between October 2010 and November 2021. Results We reviewed the data of 86 patients (20, 45, 27 who received AMR doses of 40, 35, 30 mg/m 2 , respectively) according to our study criteria. For patients ≥ 75 years, the proportion who received second-line treatment tended to be higher in the 30–35 mg/m 2 group. Objective response rates were 37/46/35%, median progression-free survival (PFS) were 3.0/4.7/3.2 months, and median overall survival (OS) were 7.8/16.3/8.0 months, respectively. Grade 4 neutropenia occurred in 58/39/31% of patients, which was higher for the 40 mg/m 2 group. The incidence of febrile neutropenia did not differ between groups. Multivariate analysis identified the AMR dose was not associated with longer PFS and OS. Conclusion Treatment with AMR between 30 and 35 mg/m 2 showed relatively mild hematologic toxicity compared with AMR at 40 mg/m 2 , without any significant difference in efficacy. Lower dose of AMR for relapsed SCLC could be a promising treatment option.