• Histologically or cytologically confirmed ES-SCLC

• No prior treatment for ES-SCLC

• Measurable disease, as defined by RECIST v1.1. Previously irradiated lesions can be considered as measurable disease only if progressive disease has been unequivocally documented at that site since radiation.

• ECOG performance status of 0 or 1

• Life expectancy \>= 3 months

• Adequate hematologic and end-organ function

• For participants receiving therapeutic anticoagulation: stable anticoagulant regimen

• Negative human immunodeficiency virus (HIV) test at screening

• Negative hepatitis B surface antigen (HBsAg) test at screening

⁃ Positive hepatitis B surface antibody (HBsAb) test at screening, or negative HBsAb at screening accompanied by either of the following: Negative total hepatitis B core antibody (HBcAb), or positive total HBcAb test followed by a negative hepatitis B virus (HBV) DNA test. The HBV DNA test will be performed only for participants who have a negative HBsAg test, a negative HBsAb test, and a positive total HBcAb test.

⁃ Negative hepatitis C virus (HCV) antibody test at screening, or positive HCV antibody test followed by a negative HCV RNA test at screening. The HCV RNA test will be performed only for participants who have a positive HCV antibody test.

⁃ For women of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraception

⁃ For men: agreement to remain abstinent (refrain from heterosexual intercourse) or use a condom, and agreement to refrain from donating sperm