Phase I study of amrubicin plus cisplatin and concurrent accelerated hyperfractionated thoracic radiotherapy for limited-disease small cell lung cancer: protocol of ACIST study

Background: Etoposide plus cisplatin (EP) combined with concurrent accelerated hyperfractionated thoracic radiotherapy (AHTRT) is the standard treatment strategy for unresectable limited-disease (LD) small cell lung cancer (SCLC), which has remained unchanged for over two decades. Based on a previous study that confirmed the non-inferiority of amrubicin (AMR) plus cisplatin (AP) when compared with EP for extensive-disease (ED) SCLC, we have previously conducted a phase I study assessing AP with concurrent TRT (2 Gy/time, once daily, 50 Gy in total) for LD-SCLC therapy. Our findings revealed that AP with concurrent TRT could prolong overall survival to 39.5 months with manageable toxicities. Therefore, we plan to conduct a phase I study to investigate and determine the effect of AP combined with AHTRT, recommended dose (RD), maximum tolerated dose (MTD), and dose-limiting toxicity (DLT) of AP in patients with LD-SCLC. Methods: Treatment-naive patients with LD-SCLC, age between 20 and 75 years, who had a performance status of 0 or 1 and adequate organ functions will be enrolled. For chemotherapy, cisplatin 60 mg/m²/day (day 1) and AMR (day 1 to 3) will be administered with AHTRT (1.5 Gy/time, twice daily, 45 Gy in total). The initial AMR dose is set to 25 mg/m²/day. RD and MTD will be determined by evaluating toxicities. Discussion: Based on our previous study, the initial dose of AMR 25 mg/m² is expected to be tolerated and acceptable. Here, we aim to determine whether treatment with AP and concurrent AHTRT would be an optimal choice with manageable toxicities for LD-SCLC.