This is a multinational, multicenter, randomized controlled, open-label, adaptive study to evaluate the efficacy of PaCE chemotherapy in chemotherapy naive subjects with extensive-stage SCLC. Eligible subjects will be stratified according to age, gender, and Eastern Cooperative Oncology Group (ECOG) performance status, and randomized in a 1:1 ratio to receive either PaCE or CE chemotherapy.

The study design uses an adaptive group sequential approach with sample size re-estimation at the interim analysis.

Secondary efficacy endpoints include ORR, PFS, duration of response and changes in QOL and disease-related symptoms. Tumor-related endpoints will be assessed according to the Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 guidelines.

The safety of study treatments will be assessed by the frequency and severity of adverse events as determined by National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) v4.03. To provide an initial confirmation of safety, an early interim analysis of safety data only will be performed.

An independent Data Monitoring Committee (DMC) will be convened to assess the safety and efficacy of the study interventions and to monitor the overall conduct of the clinical trial.

Inclusion Criteria:

• Documented extensive-stage small cell lung cancer.
• Patient has received no prior chemotherapy, adjuvant therapy, or radiotherapy for lung cancer.
• ECOG Performance Status of 0, 1 or 2.
• Adequate bone marrow and organ function based on the results of protocol- specified laboratory tests.
• Male and female patients must agree to use a highly reliable method of birth control during study participation.
• Able to provide informed consent

Exclusion Criteria:

• Previously untreated (non-irradiated), symptomatic brain metastases.
• Known allergy to any of the study drugs or their excipients.
• Any unstable or clinically significant concurrent medical condition that would, in the opinion of the investigator, jeopardize the safety of a patient and/or their compliance with the protocol, based on screening tests, physical examination and medical history (as specifically defined in the clinical protocol).
• Any malignancy other than small cell lung cancer within the last 5 years prior to randomization, with the exception of cervical carcinoma in situ, nonmelanoma skin cancer, or superficial bladder tumors (Ta, Tis, or T1) that have been successfully and curatively treated with no evidence of recurrent or residual disease. (Exception: Subjects with a history of malignancy other than small cell lung cancer may be enrolled after consultation with the medical monitor provided the patient's prognosis is best defined by the extensive-stage small cell lung cancer).
• Currently pregnant or nursing.