Trial Outcomes & Findings for A Study of Atezolizumab Plus Carboplatin and Etoposide With or Without Tiragolumab in Patients With Untreated Extensive-Stage Small Cell Lung Cancer (NCT NCT04256421)

Last Updated: 2026-01-28

Results Overview

PFS was defined as the time from randomization to the first documented disease progression (PD) as determined by the investigator with the use of Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 or death from any cause, whichever occurred first. PD: at least a 20% increase in the sum of diameters (SOD) of target lesions, taking as reference the smallest SOD on study (including baseline). In addition to the relative increase of 20%, the SOD must also demonstrate an absolute increase of \>/= 5 millimeters (mm).

Recruitment status

COMPLETED

Study phase

PHASE3

Target enrollment

490 participants

Primary outcome timeframe

From randomization to the first occurrence of disease progression or death from any cause, whichever occurs first (up to approximately 24 months)

Results posted on

2026-01-28

Participant Flow

A total of 490 participants with extensive stage small cell lung cancer (SCLC) took part at 139 centers across 23 countries.

Participants were randomized to receive Placebo + Atezolizumab (P+A) or Tiragolumab + Atezolizumab (T+A) with carboplatin \& etoposide as induction treatment followed by either P+A or T+A as maintenance treatment. 1 participant from P+A arm and 4 from T+A arm were randomized but not treated. Results from primary analysis are reported here. Final results of the study will be made public 1 year after study completion.

Participant milestones

Participant milestones
Measure	Placebo + Atezolizumab During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Overall Study STARTED	247	243
Overall Study Safety-evaluable Set	246	239
Overall Study COMPLETED	0	0
Overall Study NOT COMPLETED	247	243

Reasons for withdrawal

Reasons for withdrawal
Measure	Placebo + Atezolizumab During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Overall Study Death	171	180
Overall Study Lost to Follow-up	1	1
Overall Study Withdrawal by Subject	9	10
Overall Study Ongoing in Study	66	52

Baseline Characteristics

A Study of Atezolizumab Plus Carboplatin and Etoposide With or Without Tiragolumab in Patients With Untreated Extensive-Stage Small Cell Lung Cancer

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Placebo + Atezolizumab n=247 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=243 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Total n=490 Participants Total of all reporting groups
Age, Continuous	65.1 years STANDARD_DEVIATION 7.9 • n=158 Participants	64.5 years STANDARD_DEVIATION 8.2 • n=157 Participants	64.8 years STANDARD_DEVIATION 8.0 • n=315 Participants
Sex: Female, Male Female	83 Participants n=158 Participants	81 Participants n=157 Participants	164 Participants n=315 Participants
Sex: Female, Male Male	164 Participants n=158 Participants	162 Participants n=157 Participants	326 Participants n=315 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	7 Participants n=158 Participants	10 Participants n=157 Participants	17 Participants n=315 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	229 Participants n=158 Participants	224 Participants n=157 Participants	453 Participants n=315 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	11 Participants n=158 Participants	9 Participants n=157 Participants	20 Participants n=315 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=158 Participants	0 Participants n=157 Participants	0 Participants n=315 Participants
Race (NIH/OMB) Asian	67 Participants n=158 Participants	63 Participants n=157 Participants	130 Participants n=315 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=158 Participants	2 Participants n=157 Participants	2 Participants n=315 Participants
Race (NIH/OMB) Black or African American	2 Participants n=158 Participants	1 Participants n=157 Participants	3 Participants n=315 Participants
Race (NIH/OMB) White	174 Participants n=158 Participants	173 Participants n=157 Participants	347 Participants n=315 Participants
Race (NIH/OMB) More than one race	0 Participants n=158 Participants	0 Participants n=157 Participants	0 Participants n=315 Participants
Race (NIH/OMB) Unknown or Not Reported	4 Participants n=158 Participants	4 Participants n=157 Participants	8 Participants n=315 Participants

PRIMARY outcome

Timeframe: From randomization to the first occurrence of disease progression or death from any cause, whichever occurs first (up to approximately 24 months)

Population: Primary analysis set (PAS): All randomized participants without presence or history of brain metastases at baseline.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=201 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=196 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Investigator-Assessed Progression Free Survival (PFS) in the Primary Analysis Set (PAS)	5.55 months Interval 5.36 to 5.85	5.36 months Interval 4.67 to 5.52

PRIMARY outcome

Timeframe: From randomization to death from any cause (up to approximately 24 months)

Population: PAS: All randomized participants without presence or history of brain metastases at baseline.

OS was defined as the time from randomization to death from any cause.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=201 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=196 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Overall Survival (OS) in the PAS	13.14 months Interval 12.16 to 15.11	13.11 months Interval 10.84 to 14.39

SECONDARY outcome

Timeframe: From randomization to the first occurrence of disease progression or death from any cause, whichever occurs first (up to approximately 24 months)

Population: FAS: All randomized participants, whether or not the participant received the assigned treatment.

PFS was defined as the time from randomization to the first documented PD as determined by the investigator with the use of RECIST v1.1 or death from any cause, whichever occurred first. PD: at least a 20% increase in the SOD of target lesions, taking as reference the smallest SOD on study (including baseline). In addition to the relative increase of 20%, the SOD must also demonstrate an absolute increase of \>/= 5 mm.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=247 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=243 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
PFS in the FAS	5.42 months Interval 4.47 to 5.65	5.06 months Interval 4.4 to 5.42

SECONDARY outcome

Timeframe: From randomization to death from any cause (up to approximately 24 months)

Population: FAS: All randomized participants, whether or not the participant received the assigned treatment.

OS was defined as the time from randomization to death from any cause.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=247 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=243 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
OS in the FAS	12.91 months Interval 11.99 to 14.52	12.75 months Interval 10.84 to 14.29

SECONDARY outcome

Timeframe: From randomization up to approximately 24 months

Population: PAS: All randomized participants without presence or history of brain metastases at baseline.

ORR was defined as the percentage of participants with a complete response (CR) or a partial response (PR) as determined by the investigator with the use of RECIST v1.1. CR was defined as disappearance of all target lesions or any pathological lymph nodes must have reduction in short axis to \< 10 mm. PR was defined as at least a 30% decrease in the SOD of all target lesions, taking as reference the baseline SOD, in the absence of CR.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=201 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=196 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Investigator-Assessed Confirmed Objective Response Rate (ORR) in the PAS	66.7 percentage of participants Interval 59.64 to 73.05	73.5 percentage of participants Interval 66.61 to 79.39

SECONDARY outcome

Timeframe: From randomization up to approximately 24 months

Population: FAS: All randomized participants, whether or not the participant received the assigned treatment.

ORR was defined as the percentage of participants with CR or PR as determined by the investigator with the use of RECIST v1.1. CR was defined as disappearance of all target lesions or any pathological lymph nodes must have reduction in short axis to \< 10 mm. PR was defined as at least a 30% decrease in the SOD of all target lesions, taking as reference the baseline SOD, in the absence of CR.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=247 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=243 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Investigator-Assessed Confirmed ORR in the FAS	65.6 percentage of participants Interval 59.26 to 71.42	70.8 percentage of participants Interval 64.56 to 76.33

SECONDARY outcome

Timeframe: From the first occurrence of a documented confirmed objective response to disease progression or death from any cause, whichever occurs first (up to approximately 24 months)

Population: PAS: All randomized participants without presence or history of brain metastases at baseline. DOR was analyzed in confirmed responders by investigator.

DOR was defined as the time from the first occurrence of a documented objective response (OR) to PD or death from any cause, whichever occurred first, as determined by the investigator with the use of RECIST v1.1. CR: was defined as disappearance of all target lesions or any pathological lymph nodes must have reduction in short axis to \< 10 mm PR was defined as at least a 30% decrease in the SOD of all target lesions, taking as reference the baseline SOD, in the absence of CR. PD= at least a 20% increase in the SOD of target lesions, taking as reference the smallest SOD on study (including baseline). In addition to the relative increase of 20%, the SOD must also demonstrate an absolute increase of \>/= 5 mm.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=134 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=144 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Investigator-Assessed Duration of Response (DOR) in the PAS	5.59 months Interval 4.57 to 6.93	4.19 months Interval 4.14 to 4.6

SECONDARY outcome

Timeframe: From the first occurrence of a documented confirmed objective response to disease progression or death from any cause, whichever occurs first (up to approximately 24 months)

Population: FAS: All randomized participants, whether or not the participant received the assigned treatment. DOR was analyzed in confirmed responders by investigator.

DOR was defined as the time from the first occurrence of a documented OR to PD or death from any cause, whichever occurred first, as determined by the investigator with the use of RECIST v1.1. CR: was defined as disappearance of all target lesions or any pathological lymph nodes must have reduction in short axis to \< 10 mm PR was defined as at least a 30% decrease in the SOD of all target lesions, taking as reference the baseline SOD, in the absence of CR. PD= at least a 20% increase in the SOD of target lesions, taking as reference the smallest SOD on study (including baseline). In addition to the relative increase of 20%, the SOD must also demonstrate an absolute increase of \>/= 5 mm.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=162 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=172 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Investigator-Assessed DOR in the FAS	5.11 months Interval 4.37 to 5.75	4.17 months Interval 4.07 to 4.37

SECONDARY outcome

Timeframe: Month 6, Month 12

Population: PAS: All randomized participants without presence or history of brain metastases at baseline. Overall number of participants analyzed is the number of participants with data available for analyses. Number analyzed is the number of participants with data available for analyses at the specified timepoints.

PFS rate at 6 months and 12 months was defined as the percentage of participants who were event free at these specific time points. Percentages have been rounded off to the nearest decimal point. A point estimate of the event-free rate is a single, numerical value used to approximate the true event-free rate of the entire population at a specific point in time. This value is calculated from ordered data (Event, Censoring) of each patient, using the Kaplan-Meier method, and accounts for censored observations( so Event free rates may not directly be calculated based only on patients remaining at risk).

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=84 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=67 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Investigator-Assessed PFS Rates at 6 Months and 12 Months in the PAS Month 6	42.42 percentage of participants Interval 35.54 to 49.31	35.15 percentage of participants Interval 28.41 to 41.9
Investigator-Assessed PFS Rates at 6 Months and 12 Months in the PAS Month 12	17.29 percentage of participants Interval 11.9 to 22.69	14.21 percentage of participants Interval 9.06 to 19.35

SECONDARY outcome

Timeframe: Month 6, Month 12

Population: FAS: All randomized participants, whether or not the participant received the assigned treatment. Overall number of participants analyzed is the number of participants with data available for analyses. Number analyzed is the number of participants with data available for analyses at the specified timepoints.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=92 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=74 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Investigator-Assessed PFS Rates at 6 Months and 12 Months in the FAS Month 6	37.95 percentage of participants Interval 31.85 to 44.05	31.30 percentage of participants Interval 25.41 to 37.19
Investigator-Assessed PFS Rates at 6 Months and 12 Months in the FAS Month 12	14.07 percentage of participants Interval 9.59 to 18.55	12.33 percentage of participants Interval 7.9 to 16.75

SECONDARY outcome

Timeframe: Month 12, Month 24

Overall survival rate at 12 months and 24 months was defined as the percentage of participants who were alive at these specific time points. Percentages have been rounded off to the nearest decimal point. A point estimate of the event-free rate is a single, numerical value used to approximate the true event-free rate of the entire population at a specific point in time. This value is calculated from ordered data (Event, Censoring) of each patient, using the Kaplan-Meier method, and accounts for censored observations( so Event free rates may not directly be calculated based only on patients remaining at risk).

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=112 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=103 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Overall Survival Rates at 12 Months and 24 Months in the PAS Month 12	57.74 percentage of participants Interval 50.82 to 64.66	54.00 percentage of participants Interval 46.97 to 61.03
Overall Survival Rates at 12 Months and 24 Months in the PAS Month 24	27.68 percentage of participants Interval 20.43 to 34.94	19.56 percentage of participants Interval 13.16 to 25.96

SECONDARY outcome

Timeframe: Month 12, Month 24

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=133 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=125 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Overall Survival Rates at 12 Months and 24 Months in the FAS Month 12	55.84 percentage of participants Interval 49.58 to 62.1	52.82 percentage of participants Interval 46.49 to 59.15
Overall Survival Rates at 12 Months and 24 Months in the FAS Month 24	25.82 percentage of participants Interval 19.19 to 32.46	20.53 percentage of participants Interval 14.54 to 26.52

SECONDARY outcome

Timeframe: From randomization until the first confirmed clinically meaningful deterioration up to approximately 24 months

Population: PAS: All randomized participants without presence or history of brain metastases at baseline.

TTCD was the time from randomization until the first confirmed clinically meaningful deterioration in physical functioning. TTCD was determined based on patient-reported physical functioning (items 1-5) as collected and measured by the EORTC QLQ-C30. The PF is measured on 4-point scale (1='Not at all' to 4='Very much'). A high score for the physical function subscale represented a high/healthy level of functioning. The scale was linearly transformed so that each score ranged from 0 to 100. A score change of at least 10-point in physical functioning subscale score was perceived by participants as clinically meaningful. Confirmed clinically meaningful deterioration was defined as a clinically meaningful decrease from baseline that was held for at least two consecutive assessments or an initial clinically meaningful decrease from baseline followed by death from any cause within 3 weeks.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=201 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=196 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Time to Confirmed Deterioration (TTCD) of European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire-Core (QLQ-C30) Physical Functioning in the PAS	19.35 months Interval 19.35 to NA = not estimable due to an insufficient number of events	15.67 months Interval 12.81 to NA = not estimable due to an insufficient number of events

SECONDARY outcome

Timeframe: From randomization until the first confirmed clinically meaningful deterioration up to approximately 24 months

Population: FAS: All randomized participants, whether or not the participant received the assigned treatment.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=247 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=243 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
TTCD of EORTC QLQ-C30 Physical Functioning in the FAS	19.35 months Interval 12.42 to NA = not estimable due to an insufficient number of events	15.67 months Interval 11.83 to NA = not estimable due to an insufficient number of events

SECONDARY outcome

Timeframe: From randomization until the first confirmed clinically meaningful deterioration up to approximately 24 months

Population: PAS: All randomized participants without presence or history of brain metastases at baseline.

TTCD was the time from randomization until the first confirmed clinically meaningful deterioration in patient-reported global health status (GHS)/ quality of life (QoL). TTCD was determined based on patient-reported GHS/QoL (items 29-30) as collected and measured by the EORTC QLQ-C30. HS/QoL items are scored on a 7-point scale that ranges from "very poor" to "excellent". A high score for the GHS/QoL subscale represented a high health related quality of life. The scale was linearly transformed so that each score ranged from 0 to 100. A score change of at least 10-point in GHS/QoL subscale score was perceived by participants as clinically meaningful. Confirmed clinically meaningful deterioration was defined as a clinically meaningful decrease from baseline that was held for at least two consecutive assessments or an initial clinically meaningful decrease from baseline followed by death from any cause within 3 weeks.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=201 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=196 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
TTCD of EORTC QLQ-C30 Global Health Status (GHS)/Quality of Life (QoL) in the PAS	NA months NA = not estimable due to an insufficient number of events	NA months Interval 14.55 to NA = not estimable due to an insufficient number of events

SECONDARY outcome

Timeframe: From randomization until the first confirmed clinically meaningful deterioration up to 24 months

Population: FAS: All randomized participants, whether or not the participant received the assigned treatment.

TTCD was the time from randomization until the first confirmed clinically meaningful deterioration in patient-reported global health status (GHS)/ quality of life (QoL). TTCD was determined based on patient-reported GHS/QoL (items 29-30) as collected and measured by the EORTC QLQ-C30. HS/ QoL items are scored on a 7-point scale that ranges from "very poor" to "excellent". A high score for the GHS/QoL subscale represented a high health related quality of life. The scale was linearly transformed so that each score ranged from 0 to 100. A score change of at least 10-point in GHS/QoL subscale score was perceived by participants as clinically meaningful. Confirmed clinically meaningful deterioration was defined as a clinically meaningful decrease from baseline that was held for at least two consecutive assessments or an initial clinically meaningful decrease from baseline followed by death from any cause within 3 weeks.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=247 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=243 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
TTCD of EORTC QLQ-C30 GHS/QoL in the FAS	NA months NA = not estimable due to an insufficient number of participants with events	NA months Interval 14.55 to NA = not estimable due to an insufficient number of participants with events

SECONDARY outcome

Timeframe: Up to 65 months

An adverse event is any untoward medical occurrence in a subject administered a pharmaceutical product and which does not necessarily have to have a causal relationship with the treatment. An adverse event can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding, for example), symptom, or disease temporally associated with the use of a pharmaceutical product, whether or not considered related to the pharmaceutical product. Preexisting conditions which worsen during a study are also considered as adverse events.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: At the end of each cycle (each cycle is 21 days) of Cycles 1, 2, 3, 7, 11 and 15 (approximately 11 months)

Population: PK-evaluable set: All participants who received at least one dose of study treatment and who had at least one post-baseline PK sample available. Number analyzed is the number of participants with data available for analyses at the specified timepoints.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=218 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Minimum Serum Concentration (Cmin) of Tiragolumab Cycle 1	29.5 microgram/milliliter (mcg/mL) Geometric Coefficient of Variation 49.2	—
Minimum Serum Concentration (Cmin) of Tiragolumab Cycle 2	46.5 microgram/milliliter (mcg/mL) Geometric Coefficient of Variation 47.5	—
Minimum Serum Concentration (Cmin) of Tiragolumab Cycle 3	56.3 microgram/milliliter (mcg/mL) Geometric Coefficient of Variation 83.5	—
Minimum Serum Concentration (Cmin) of Tiragolumab Cycle 7	76.3 microgram/milliliter (mcg/mL) Geometric Coefficient of Variation 48.2	—
Minimum Serum Concentration (Cmin) of Tiragolumab Cycle 11	78.8 microgram/milliliter (mcg/mL) Geometric Coefficient of Variation 246	—
Minimum Serum Concentration (Cmin) of Tiragolumab Cycle 15	96.4 microgram/milliliter (mcg/mL) Geometric Coefficient of Variation 43.8	—

SECONDARY outcome

Timeframe: At the end of each cycle (each cycle is 21 days) of Cycles 1, 2, 3, 7, 11 and 15 (approximately 11 months)

Population: PK-evaluable set: All participants who received at least one dose of study treatment and who had at least one post-baseline PK sample available. Overall number of participants analyzed is the number of participants with data available for analyses. Number analyzed is the number of participants with data available for analyses at the specified timepoints.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=226 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=217 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Cmin of Atezolizumab Cycle 1	75.0 mcg/mL Geometric Coefficient of Variation 63.2	75.4 mcg/mL Geometric Coefficient of Variation 70.8
Cmin of Atezolizumab Cycle 2	121 mcg/mL Geometric Coefficient of Variation 55.8	125 mcg/mL Geometric Coefficient of Variation 38.4
Cmin of Atezolizumab Cycle 3	144 mcg/mL Geometric Coefficient of Variation 49.8	155 mcg/mL Geometric Coefficient of Variation 81.5
Cmin of Atezolizumab Cycle 7	205 mcg/mL Geometric Coefficient of Variation 45.3	198 mcg/mL Geometric Coefficient of Variation 46.4
Cmin of Atezolizumab Cycle 11	226 mcg/mL Geometric Coefficient of Variation 37.3	244 mcg/mL Geometric Coefficient of Variation 37
Cmin of Atezolizumab Cycle 15	198 mcg/mL Geometric Coefficient of Variation 75.5	253 mcg/mL Geometric Coefficient of Variation 36.6

SECONDARY outcome

Timeframe: Predose and 30 minutes post end of infusion (EOI) on Day 1 of Cycle 1 (each cycle is 21 days)

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=213 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Maximum Serum Concentration (Cmax) of Tiragolumab	188 mcg/mL Geometric Coefficient of Variation 24.2	—

SECONDARY outcome

Timeframe: Predose and 30 minutes post EOI on Day 1 of Cycle 1 (each cycle is 21 days)

Population: PK-evaluable set: All participants who received at least one dose of study treatment and who had at least one post-baseline PK sample available.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=233 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=224 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Cmax of Atezolizumab	398 mcg/mL Geometric Coefficient of Variation 28.2	405 mcg/mL Geometric Coefficient of Variation 23.0

SECONDARY outcome

Timeframe: Predose on Day 1 of Cycles 1 (each cycle is 21 days), 2, 3, 4, 8,12 and 16 and at treatment discontinuation (TD) visit (up to 24 months)

Population: Tiragolumab ADA-evaluable set: All participants who received at least one dose of tiragolumab treatment and with an ADA assay result from at least one sample result. Number analyzed is the number of participants with data available for analyses at the specified timepoints.

Reported here is the number of participants who had a positive ADA assay result at baseline and the number of participants positive for treatment emergent ADAs. The participants positive for treatment emergent ADAs include treatment-induced and treatment-enhanced ADA positive participants. Treatment-induced ADAs are participants with negative or missing baseline ADA result(s) and at least one positive post-baseline ADA result. Treatment-enhanced ADAs are participants with a positive ADA result at baseline who had one or more post-baseline titer results that were at least 0.60 t.u. greater than the baseline titer result. The total number of participants who developed ADAs to tiragolumab was determined by summing the ADA-positive participants across all timepoints.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=235 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Number of Participants With Anti-Drug Antibodies (ADAs) to Tiragolumab Participants with Positive Sample at Baseline	2 Participants	—
Number of Participants With Anti-Drug Antibodies (ADAs) to Tiragolumab Participants positive for Treatment Emergent ADAs	3 Participants	—
Number of Participants With Anti-Drug Antibodies (ADAs) to Tiragolumab Treatment-induced ADAs	3 Participants	—
Number of Participants With Anti-Drug Antibodies (ADAs) to Tiragolumab Treatment-enhanced ADAs	0 Participants	—

SECONDARY outcome

Timeframe: Predose on Day 1 of Cycles 1 (each cycle is 21 days), 2, 3, 4, 8,12 and 16 and at TD visit (up to 24 months)

Population: Atezolizumab ADA-evaluable set: All participants who received at least one dose of atezolizumab treatment and with an ADA assay result from at least one sample result. Number analyzed is the number of participants with data available for analyses at the specified timepoints.

Reported here is the number of participants who had a positive ADA assay result at baseline and the number of participants positive for treatment emergent ADAs. The number of participants positive for treatment emergent ADAs includes treatment-induced and treatment-enhanced ADA positive participants. Treatment-induced ADAs are participants with negative or missing baseline ADA result(s) and at least one positive post-baseline ADA result. Treatment-enhanced ADAs are participants with a positive ADA result at baseline who had one or more post-baseline titer results that were at least 0.60 t.u. greater than the baseline titer result. The total number of participants who developed ADAs to atezolizumab was determined by summing the ADA-positive participants across all timepoints.

Outcome measures

Outcome measures
Measure	Placebo + Atezolizumab n=244 Participants During induction treatment participants received atezolizumab, 1200 milligram (mg) followed by placebo and carboplatin, as intravenous (IV) infusion, to achieve an initial target area under the concentration-time curve (AUC) of 5 milligram/milliliter/minute (mg/mL/min) on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 milligram per square meter (mg/m\^2) was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ placebo on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.	Tiragolumab + Atezolizumab n=236 Participants During induction treatment participants received atezolizumab, 1200 mg followed by tiragolumab, 600mg and carboplatin, as IV infusion, to achieve an initial target AUC of 5 mg/mL/min on Day 1 of each 21-day cycle for 4 cycles. Etoposide 100 mg/m\^2 was also administered as IV infusion on Days 1, 2 and 3 of each 21-day cycle for 4 cycles. Participants then received maintenance treatment with atezolizumab+ tiragolumab on Day 1 of each 21-day cycle at the same dose as during induction treatment until disease progression or loss of clinical benefit.
Number of Participants With ADAs to Atezolizumab Participants with Positive Sample at Baseline	2 Participants	1 Participants
Number of Participants With ADAs to Atezolizumab Participants positive for Treatment Emergent ADAs	48 Participants	22 Participants
Number of Participants With ADAs to Atezolizumab Treatment-induced ADAs	48 Participants	22 Participants
Number of Participants With ADAs to Atezolizumab Treatment-enhanced ADAs	0 Participants	0 Participants

SECONDARY outcome

Timeframe: From baseline up to 65 months

The EQ-5D-5L is a validated self-report health status questionnaire that was used to calculate a health status utility score for use in health economic analyses. There were two components to the EQ-5D-5L: a five-item health state profile that assessed mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, as well as a visual analog scale (VAS) that measured health state. The EQ VAS records the participant's self-rated health on a vertical visual analogue scale ranging from 0 to 100 A single composite score was calculated based on the responses as an indicator of the participant's health status. The scale ranges 0-100, 0=worst health and 100=best health.

Outcome measures

Outcome data not reported

Adverse Events

Placebo + Atezolizumab

Serious events: 104 serious events

Other events: 233 other events

Deaths: 171 deaths

Tiragolumab + Atezolizumab

Serious events: 108 serious events

Other events: 228 other events

Deaths: 180 deaths

Serious adverse events

Other adverse events

Additional Information

Medical Communications

Hoffmann-La Roche

Phone: 800 821-8590

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee The Study being conducted under this Agreement is part of the Overall Study. Investigator is free to publish in reputable journals or to present at professional conferences the results of the Study, but only after the first publication or presentation that involves the Overall Study. The Sponsor may request that Confidential Information be deleted and/or the publication be postponed in order to protect the Sponsor's intellectual property rights.
Publication restrictions are in place

Restriction type: OTHER