[Phase I Study of Etoposide and Cisplatin Chemotherapy Dose Escalation 
with Concurrent Twice-daily Radiotherapy for Patients 
with Limited-stage Small Cell Lung Cancer].

Background: Concurrent twice-daily radiotherapy with chemotherapy of EP regimen is one of the current standard treatments for limited-stage small cell lung cancer. However, the safely tolerated dose of standard chemotherapy for Chinese patients is not decided. This study was to evaluate the toxicity and the maximum tolerated dose (MTD) of etoposide and cisplatin concurrent with thoracic radiation therapy for patients with limited-stage small cell lung cancer.
Methods: Patients with histologically proven limited-stage small cell lung cancer (LS-SCLC) were eligible. The patients underwent thoracic radiotherapy (45 Gy, 1.5 Gy bid, 30 fractions for 3 weeks) delivered concurrently with etoposide (100 mg/m2 iv, days 1-3) and cisplatin dose escalating from the two levels ( 70 mg/m2 and 75 mg/m2 on d1). The primary endpoints were hematologic toxicities during treatment. The secondary endpoints were non-hematologic toxicities, overall survival (OS) and progression-free survival (PFS). According to Common Terminology Criteria for Adverse Events 4.0 (CTC-AE 4.0), maximum tolerant dosage (MTD) was defined as the highest safely tolerated dose at which no more than one patient out of six experiences dose-limiting toxicity (Grades 4 hematologic), with the next higher dose having at least two out of six patients experience dose-limiting toxicity.
Results: From January 2013 to August 2016, 20 patients were enrolled in this study. The median age was 49.5 (30-68). After the first 6 patients were enrolled in Arm 1 (70 mg/m2 on d1), one patient had Grade 4 neutropenia. Another 14 patients were enrolled in Arm 2 (75 mg/m2 on d1), one patient had Grade 4 neutropenia. The MTD was determined to be etoposide (100 mg/m2 iv, d1-d3) and cisplatin dose (75 mg/m2 on d1). 4 patients had ≥Grade 3 neutropenia and 1 patients had ≥Grade 3 acute esophagitis in Arm 1. 10 patients had ≥Grade 3 neutropenia and no patient had ≥Grade 3 acute esophagitis in Arm 2. All patients with a median follow-up time was 9.0 months, median OS and PFS were not achieved, 1-year OS and PFS were 91% and 61%, respectively.
Conclusions: The MTD of RT with concurrent chemotherapy of EP regimen for patients with LS-SCLC was etoposide (100 mg/m2 iv, d1-d3) and cisplatin dose (75 mg/m2 on d1).
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