Cohort 1: Participants will receive Atezolizumab 840 mg IV infusion on Days 1 and 15 of each 28 day cycle; Tiragolumab 420 mg IV infusion on Days 1 and 15 of each 28 day cycle; Nab-paclitaxel 125 mg/m^2 IV infusion on Days 1, 8, and 15 of each 28 day cycle; Gemcitabine 1000 mg/m^2 IV infusion on Days 1, 8, and 15 of each 28 day cycle.

Cohort 2: Participants will receive Cobimetinib 60 milligrams (mg) once daily orally on Days 1-21 of each 28-day cycle; and Atezolizumab 840 mg IV infusion on Days 1 and 15 of each 28-day cycle.

Participants who progressed on treatment may have the option of receiving Atezolizumab + RO6874281 treatment, provided they meet the eligibility criteria and the arm is open for enrollment.

Cohort 2: Participants will receive PEGPH20 3 micrograms per kilogram (mcg/kg) IV infusion on Days 1, 8 and 15 of each 21-day cycle; and Atezolizumab 1200 mg IV infusion on Day 1 of each 21-day cycle.

Participants who progressed on treatment, may have the option of receiving Atezolizumab + Cobimetinib or Atezolizumab + RO6874281 treatment, provided they meet the eligibility criteria and the arms are open for enrollment.

Cohort 2: Participants will receive BL-8040 1.25 milligrams per kilogram (mg/kg) subcutaneously (SC) on Days 1-5 of the first week, followed by combination treatment consisting of BL-8040 1.25 mg/kg SC three times a week on non-consecutive days and Atezolizumab 1200 mg IV infusion on Day 1 of each 21-day cycle.

Participants who progressed on treatment may have the option of receiving Atezolizumab + Cobimetinib or Atezolizumab + RO6874281 treatment, provided they meet the eligibility criteria and the arms are open for enrollment.

Cohort 2: Participants will receive Atezolizumab 840 mg IV infusion on days 1 and 15 of each 28 day cycle; RO6874281 will be administered 10 mg by IV infusion on day 1 and 15 mg on days 8, 15, and 22 for cycle 1 (28 day cycle). RO6874281 will be administered 15 mg by IV infusion on days 1 and 15 of each subsequent 28 day cycle.

Participants who progressed on treatment may have the option of receiving Atezolizumab + Cobimetinib, provided they meet the eligibility criteria and the arm is open for enrollment.

Cohort 2: Participants will receive Atezolizumab 1200 mg IV infusion on Day 1 of each 21 day cycle; and RO6874281 10 mg by IV infusion on day 1 of each 21 day cycle.

Participants who progressed on treatment may have the option of receiving Atezolizumab + Cobimetinib, provided they meet the eligibility criteria and the arm is open for enrollment.

Cohort 2: Participants who progressed on a prior fluoropyrimidine-based regimen will receive Nab-paclitaxel 125 mg/m^2 IV infusion on Days 1, 8, and 15 of each 28 day cycle; and Gemcitabine 1000 mg/m^2 IV infusion on Days 1, 8, and 15 of each 28 day cycle.

Participants who progressed on a prior gemcitabine-based regimen will receive 5-fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6). Participants will receive Oxaliplatin 85 mg/m^2 IV on Days 1 and 15 of each 28 day cycle; Leucovorin 400 mg/m^2 IV on Days 1 and 15 of each 28 day cycle; Fluorouracil 400 mg/m^2 IV push on Days 1 and 15 of each 28 day cycle; and Fluorouracil 2400 mg/m^2 IV continuous infusion over 46 hours on Days 1 and 2 and on Days 15 and 16 of each 28 day cycle.

Participants who progressed on treatment, may have the option of receiving Atezolizumab + Cobimetinib or Atezolizumab + RO6874281 treatment, provided they meet the eligibility criteria and the arms are open for enrollment.

Cohort 1: Participants will receive Tocilizumab 8 mg/kg IV infusion on Day 1 of each 28 day cycle; Atezolizumab 1680 mg IV infusion on Day 1 of each 28 day cycle; Nab-paclitaxel 125 mg/m^2 IV infusion on Days 1, 8, and 15 of each 28 day cycle; and Gemcitabine 1000 mg/m^2 IV infusion on Days 1, 8, and 15 of each 28 day cycle.

Gemcitabine will be administered as per the schedule specified in the respective arm.

Oxaliplatin will be administered as per the schedule specified in the respective arm.

Leucovorin will be administered as per the schedule specified in the respective arm.

Fluorouracil will be administered as per the schedule specified in the respective arm.

Atezolizumab will be administered as per the schedule specified in the respective arm.

Cobimetinib will be administered as per the schedule specified in the respective arm.

PEGPH20 will be administered as per the schedule specified in the respective arm.

BL-8040 will be administered as per the schedule specified in the respective arm.

Selicrelumab will be administered as per the schedule specified in the respective arm.

Bevacizumab will be administered as per the schedule specified in the respective arm.

RO6874281 will be administered as per the schedule specified in the respective arm

AB928 will be administered as per the schedule specified in the respective arm.

Tiragolumab will be administered as per the schedule specified in the respective arm.

Tocilizumab will be administered as per the schedule specified in the respective arm.

PFS was defined as the time from study treatment initiation to the first occurrence of documented PD, as determined by the investigator according to RECIST v1.1 or death from any cause, whichever occurs first. PD was defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum in the study, including baseline, in addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. Kaplan-Meier (K-M) method was used to estimate PFS.

OS was defined as the time from randomization to death from any cause. K-M method was used to estimate OS.

OS was defined as the time from randomization to death from any cause. OS rate at 6 months was defined as the percentage of participants who did not experience death from any cause at 6 months from randomization. K-M method was used to estimate OS. Percentages have been rounded off.

DOR was defined as time from first occurrence of a documented OR until the time of documented PD or death from any cause, whichever occurs first as determined by investigator assessment using RECIST v1.1. DOR was calculated for participants who had a best confirmed OR of CR/PR. CR=the disappearance of all target lesions or any pathological lymph nodes (whether target or non-target) having a reduction in short axis to <10 mm. PR=at least a 30% decrease in the SOD of target lesions, taking as reference the baseline SOD. PD=at least a 20% increase in the SOD of target lesions, taking as reference the smallest sum on the study including baseline (nadir). In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. K-M method was used to estimate DOR.

DC was defined as stable disease (SD) for ≥ 12 weeks or a CR or PR, as determined by the investigator according to RECIST v1.1 Disease control rate (DCR) was defined as the percentage of participants with DC. CR was defined as the disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) have a reduction in short axis to <10 mm. PR was defined as at least a 30% decrease in the SOD of target lesions, taking as reference the baseline SOD. SD was defined as neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD. Percentages have been rounded off.

Participants received atezolizumab, 840 mg, and bevacizumab, 10 milligrams/kilograms (mg/kg), IV infusion on Days 1 and 15 of each cycle along with nab-paclitaxel 125 mg/m^2, and gemcitabine, 1000 mg/m^2 also administered as IV infusion on Days 1, 8, and 15 of each cycle until unacceptable toxicity or loss of clinical benefit (1 cycle = 28 days).

Participants received AB928, 150 mg, orally, once daily (QD) on Days 1 to 28 of each cycle; atezolizumab 840 mg, IV infusion on Days 1 and 15 of each cycle and nab-paclitaxel, 125 mg/m^2, and gemcitabine, 1000 mg/m^2, also administered as IV infusion, on Days 1, 8, and 15 of each cycle until unacceptable toxicity or loss of clinical benefit (1 cycle = 28 days).

Participants received atezolizumab, 840 mg and tiragolumab, 420 mg, IV infusion on Days 1 and 15 of each cycle along with nab-paclitaxel, 125 mg/m^2 and gemcitabine, 1000 mg/m^2, also administered as IV infusion on Days 1, 8, and 15 of each cycle until unacceptable toxicity or loss of clinical benefit (1 cycle = 28 days).

Participants received atezolizumab, 1680 mg and tocilizumab, 8 mg/kg, IV infusion on Days 1 of each cycle along with nab-paclitaxel, 125 mg/m^2 and gemcitabine, 1000 mg/m^2, also administered as IV infusion on Days 1, 8, and 15 of each cycle until unacceptable toxicity or loss of clinical benefit (1 cycle = 28 days).

Participants who progressed on a prior gemcitabine-based regimen received mFOLFOX6 which is oxaliplatin, 85 mg/m^2 and leucovorin, 400 mg/m^2 as IV infusion, and 5-fluorouracil, 400 mg/m^2, IV push on Days 1 and 15 of each cycle along with 5-fluorouracil, 2400 mg/m^2, IV continuous infusion on Days 1, 2, 15 and 16 of each cycle until unacceptable toxicity or PD (1 cycle=28 days).

Participants who progressed on a prior fluoropyrimidine-based regimen received nab-paclitaxel, 125 mg/m^2 and gemcitabine, 1000 mg/m^2, also administered as IV infusion on Days 1, 8, and 15 of each cycle until unacceptable toxicity or PD (1 cycle=28 days).

Participants received BL-8040, 1.25 mg/kg, SC injection on Days 1-5 of the first week, as priming treatment, and thereafter three times a week (Days 1, 3, 5, 8, 10, 12, 15, 17, and 19) along with atezolizumab, 1200 mg, IV infusion on Day 1 of each cycle until unacceptable toxicity or loss of clinical benefit (1 cycle = 21 days).

Participants received atezolizumab, 840 mg, IV infusion on Days 1 and 15 of each cycle and cobimetinib 60 mg, orally, QD on Days 1-21 of each cycle until unacceptable toxicity or loss of clinical benefit (1 cycle = 28 days).

Participants received atezolizumab, 1200 mg, IV infusion on Day 1 of each cycle and PEGPH20, 3 micrograms per kilogram (µg/kg), IV infusion on Days 1, 8 and 15 of each cycle until unacceptable toxicity or loss of clinical benefit (1 cycle = 21 days).

Participants received atezolizumab, 1200 mg, IV infusion and RO6874281, 10 mg, IV infusion on Day 1 of each cycle until unacceptable toxicity or loss of clinical benefit (1 cycle = 21 days).

Participants received atezolizumab, 840 mg, IV infusion on Days 1 and 15 of each cycle and RO6874281, 10 mg, IV infusion on Day 1 and 15 mg on Days 8, 15, and 22 of Cycle 1 and thereafter 15 mg on Days 1 and 15 of subsequent cycles until unacceptable toxicity or loss of clinical benefit (1 cycle = 28 days).

Participants in Cohort 2 control and experimental arms (other than atezolizumab + cobimetinib) who experienced PD, loss of clinical benefit, or unacceptable toxicity during Stage 1 and met the eligibility criteria to enroll in Stage 2 received atezolizumab, 840 mg, IV infusion on Days 1 and 15 of each cycle and cobimetinib, 60 mg, orally, QD on Days 1-21 of each cycle until unacceptable toxicity or loss of clinical benefit (1 cycle = 28 days).

Participants in cohort 2 control and experimental arms (other than atezolizumab + RO6874281 Q3W) who experienced PD, loss of clinical benefit, or unacceptable toxicity during Stage 1 received atezolizumab, 1200 mg, IV infusion and RO6874281, 10 mg, as IV infusion on Day 1 of each cycle until unacceptable toxicity or loss of clinical benefit (1 cycle = 21 days).

Participants in cohort 2 control and experimental arms (other than atezolizumab + RO6874281 Q2W) who experienced PD, loss of clinical benefit, or unacceptable toxicity during Stage 1 received atezolizumab, 840 mg, IV infusion on Days 1 and 15 of each cycle and RO6874281, 10 mg, IV infusion on Day 1 and 15 mg on Days 8, 15, and 22 of Cycle 1 and thereafter 15 mg on Days 1 and 15 of subsequent cycles until unacceptable toxicity or loss of clinical benefit (1 cycle = 28 days).

Safety population included all participants who received any amount of study treatment.