Participants received intravenous infusions of QL1706 5mg/kg in combination with carboplatin to achieve an initial target area under the concentration-time curve (AUC) of 5 mg/mL/min followed by etoposide 100 mg/m^2 on Day 1 of every 21-day cycle for 4-6 cycles. On Days 2 and 3 of every 21-day cycle, etoposide 100 mg/m^2 was administered alone for 4-6 cycles. Thereafter, participants received maintenance QL1706 5mg/kg on Day 1 of every 21-day cycle until progressive disease, intolerable toxicity, withdrawal of consent, death, or study termination by the Sponsor.

Intravenous infusions of QL1706 5mg/kg on Day 1 of every 21-day cycle.

An AE was defined as any untoward medical occurrence in a participant administered a study treatment and which does not necessarily have to have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product or protocol-specified procedure, whether or not considered related to the study treatment or protocol-specified procedure. Any worsening (i.e., any clinically significant adverse change in frequency and/or intensity) of a pre-existing condition that is temporally associated with the use of study treatment, is also an AE. The number of all participants who experienced at least one AE is presented.

The efficacy outcome of objective response rate (ORR) as assessed by the investigator using RECIST v1.1