Inclusion Criteria:

- Male or female subjects aged >/=18 years

- Histologically or cytologically confirmed, extensive disease SCLC

- At least 1 solid tumor lesion measurable by computer tomography (CT) scan or magnetic
resonance imaging (MRI) according to RECIST 1.1. Subjects with non-measurable disease
according to RECIST 1.1 can be included in the Phase Ib part of the study

- Eastern Cooperative Oncology Group (ECOG) performance status of 0 - 1

- Life expectancy of at least 12 weeks

- Serum sodium >/=130 mmol/L

Exclusion Criteria:

- Prior systemic anticancer therapy

- Prior radiotherapy (local palliative radiotherapy is permitted)

- History of cardiac disease: congestive heart failure > NYHA Class II, unstable angina
(anginal symptoms at rest), any episodes of angina or history of myocardial
infarction, cardiac arrhythmias requiring anti-arrhythmic therapy (beta blockers or
digoxin are permitted), previous venous or arterial thrombotic events, pulmonary
embolism

- Moderate or severe hepatic impairment, ie Child-Pugh class B or C

- Known human immunodeficiency virus (HIV) infection or chronic hepatitis B or C