Safety Run-In (Cohort 1): Participants will receive ipatasertib orally daily on Days 1-21 of each 28 day cycle, and atezolizumab will be administered by IV infusion on Days 1 and 15 of each 28 day cycle. Nab-paclitaxel will be administered by IV infusion on Days 1, 8, and 15 of each 28 day cycle. All participants in this cohort will continue to be treated until loss of clinical benefit, unacceptable toxicity, or withdrawal of consent.

Expansion (Cohort 1): Participants will receive ipatasertib orally daily on Days 1-21 of each 28 day cycle, and atezolizumab will be administered by IV infusion on Days 1 and 15 of each 28 day cycle. Nab-paclitaxel will be administered by IV infusion on Days 1, 8, and 15 of each 28 day cycle. All participants in this cohort will continue to be treated until loss of clinical benefit, unacceptable toxicity, or withdrawal of consent.

Safety Run-In (Cohort 1): Participants will receive a 2-week lead in of ipatasertib in combination with paclitaxel, followed by atezolizumab in an initial 28-day (1 cycle) period. Ipatasertib will be administered orally daily on Days 1-21, with paclitaxel administered by IV infusion on Days 1, 8 and 15. Atezolizumab will be administered by IV infusion on Day 15. In all subsequent treatment cycles, ipatasertib will be administered orally daily on Days 1-21, paclitaxel will be administered by IV infusion on Days 1, 8, and 15 and atezolizumab will be administered by IV infusion on Days 1 and 15. All participants in this cohort will continue to be treated until loss of clinical benefit, unacceptable toxicity, or withdrawal of consent.

Expansion (Cohort 1): Participants will receive a 2-week lead in of ipatasertib in combination with paclitaxel, followed by atezolizumab in an initial 28-day (1 cycle) period. Ipatasertib will be administered orally daily on Days 1-21, with paclitaxel administered by IV infusion on Days 1, 8 and 15. Atezolizumab will be administered by IV infusion on Day 15. In all subsequent treatment cycles, ipatasertib will be administered orally daily on Days 1-21, paclitaxel will be administered by IV infusion on Days 1, 8, and 15 and atezolizumab will be administered by IV infusion on Days 1 and 15. All participants in this cohort will continue to be treated until loss of clinical benefit, unacceptable toxicity, or withdrawal of consent.

Safety Run-In (Cohort 1): Participants will receive a 2-week lead in of atezolizumab in combination with paclitaxel, followed by ipatasertib in an initial 28-day (1 cycle) period. Atezolizumab will be administered via IV infusion on Days 1 and 15, with paclitaxel administered by IV infusion on Days 1, 8 and 15. Ipatasertib will be administered orally daily on Days 15-21. In all subsequent treatment cycles, ipatasertib will be administered orally daily on Days 1-21, paclitaxel will be administered by IV infusion on Days 1, 8, and 15 and atezolizumab will be administered by IV infusion on Days 1 and 15. All participants in this cohort will continue to be treated until loss of clinical benefit, unacceptable toxicity, or withdrawal of consent.

Expansion (Cohort 1): Participants will receive a 2-week lead in of atezolizumab in combination with paclitaxel, followed by ipatasertib in an initial 28-day (1 cycle) period. Atezolizumab will be administered via IV infusion on Days 1 and 15, with paclitaxel administered by IV infusion on Days 1, 8 and 15. Ipatasertib will be administered orally daily on Days 15-21. In all subsequent treatment cycles, ipatasertib will be administered orally daily on Days 1-21, paclitaxel will be administered by IV infusion on Days 1, 8, and 15 and atezolizumab will be administered by IV infusion on Days 1 and 15. All participants in this cohort will continue to be treated until loss of clinical benefit, unacceptable toxicity, or withdrawal of consent.

Participants (Cohort 2) will receive Ipatasertib orally daily on Days 1-28 of Cycle 1 (35-day cycle) and on Days 1-21 of subsequent cycles (28-day cycles). Atezolizumab will be administered by IV infusion on Days 8 and 22 of Cycle 1 and on Days 1 and 15 of subsequent cycles. All participants in this cohort will continue to be treated until loss of clinical benefit, unacceptable toxicity, or withdrawal of consent.

Safety Run-In (Cohort 3): Participants will receive in Cycles 1 and 2 (28 day cycles), Ipatasertib orally daily on Days 1-21, Atezolizumab via IV infusion on Days 1 and 15 and AC (Doxorubicin and Cyclophosphamide) via IV infusion on Days 1 and 15. In Cycles 3-5, participants will receive Ipatasertib orally daily on Days 1-21, Atezolizumab via IV infusion on Days 1 and 15, with Paclitaxel administered by IV infusion on Days 1, 8, 15 and 22. All participants in this cohort will continue to be treated for five cycles (28-day cycles; 20 weeks) or until disease progression or unacceptable toxicity, whichever occurs first.

Expansion (Cohort 3): Participants will receive in Cycles 1 and 2 (28 day cycles), Ipatasertib orally daily on Days 1-21, Atezolizumab via IV infusion on Days 1 and 15 and AC (Doxorubicin and Cyclophosphamide) via IV infusion on Days 1 and 15. In Cycles 3-5, participants will receive Ipatasertib orally daily on Days 1-21, Atezolizumab via IV infusion on Days 1 and 15, with Paclitaxel administered by IV infusion on Days 1, 8, 15 and 22. All participants in this cohort will continue to be treated for five cycles (28-day cycles; 20 weeks) or until disease progression or unacceptable toxicity, whichever occurs first.

Safety Run-In (Cohort 3): Participants will receive in Cycles 1 and 2 (28 day cycles), Ipatasertib orally daily on Days 1-21, Atezolizumab via IV infusion on Days 1 and 15 and AC (Doxorubicin and Cyclophosphamide) via IV infusion on Days 1 and 15. In Cycles 3-5, participants will receive Ipatasertib orally daily on Days 1-21, Atezolizumab via IV infusion on Days 1 and 15, with Paclitaxel administered by IV infusion on Days 1, 8, 15 and 22. All participants in this cohort will continue to be treated for five cycles (28-day cycles; 20 weeks) or until disease progression or unacceptable toxicity, whichever occurs first.

Expansion (Cohort 3): Participants will receive in Cycles 1 and 2 (28 day cycles), Ipatasertib orally daily on Days 1-21, Atezolizumab via IV infusion on Days 1 and 15 and AC (Doxorubicin and Cyclophosphamide) via IV infusion on Days 1 and 15. In Cycles 3-5, participants will receive Ipatasertib orally daily on Days 1-21, Atezolizumab via IV infusion on Days 1 and 15, with Paclitaxel administered by IV infusion on Days 1, 8, 15 and 22. All participants in this cohort will continue to be treated for five cycles (28-day cycles; 20 weeks) or until disease progression or unacceptable toxicity, whichever occurs first.

Participants (Cohort 4) will receive ipatasertib orally daily on Days 1-21 of each 28 day cycle, and atezolizumab will be administered by intravenous (IV) infusion on Days 1 and 15 of each 28 day cycle. Paclitaxel will be administered by IV infusion on Days 1, 8, and 15 of each 28 day cycle. All participants in this cohort will continue to be treated until loss of clinical benefit, unacceptable toxicity, or withdrawal of consent.

Paclitaxel will be administered at a dose of 80 milligrams per square meter (mg/m^2) as IV infusion on Days 1, 8, and 15 of each 28 day cycle for all arms, with the exceptions of Arms F1, F2, G1 and G2, where it will be also administered on Day 22 as well, of each 28 day cycle.

Atezolizumab will be administered by IV infusion at a fixed dose of 840 mg on Days 1 and 15 of each 28 day cycle for all arms, although in Arms C1/C2, it will be administered on Day 15 of Cycle 1 followed by Days 1 and 15 in subsequent cycles.

Nab-paclitaxel will be administered by IV infusion at a dose of 100 mg/m^2 on Days 1, 8, and 15 of each 28 day cycle.

AC (Doxorubicin and Cyclophosphamide) will be administered by IV infusion at 60 mg/m^2 and 600 mg/m^2 respectively on Days 1 and 15 of Cycles 1 and 2 for Arms F1, F2, G1 and G2.

PFS: time from enrollment to date of 1st recorded occurrence of PD, as determined by investigator according to RECIST v1.1 or death from any cause, whichever occurs first. PD: at least a 20% increase in sum of diameters of target lesions, taking as reference smallest sum on study (nadir) including baseline; appearance of one or more new lesions. Data for participants who did not experience PD or death was censored at last date of evaluable tumor assessment. No participants were enrolled in cohort 4, and hence no data was reported.

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

Since, Cohort 4 did not enroll any participants, data is only reported for Cohort 1.

Since, Cohort 4 did not enroll any participants, data is only reported for Cohort 1.

Participants were considered to be ADA positive if they were ADA negative or were missing data at Baseline but developed an ADA response following study drug exposure (treatment-induced ADA response), or if they were ADA positive at Baseline and the titer of one or more postbaseline samples was at least 0.60 titer unit greater than the titer of the Baseline sample (treatment-enhanced ADA response). Participants were considered to be ADA negative if they were ADA negative or had missing data at Baseline and all postbaseline samples were negative, or if they were ADA positive at Baseline but did not have any postbaseline samples with a titer that was at least 0.60 titer unit greater than the titer of the baseline sample (treatment unaffected). Since, Cohort 4 did not enroll any participants, data is only reported for Cohort 1.

Since, Cohort 4 did not enroll any participants, data is only reported for Cohort 1.

CBR was defined as percentage of participants with stable disease (SD) for at least 24 weeks or with confirmed CR or PR as determined by the investigator according to RECIST v1.1. SD was defined as neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD, taking as reference the smallest sum on study. CR was defined as the disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) must have reduction in short axis to < 10 mm. PR was defined as at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of diameters. Since, Cohort 4 did not enroll any participants, data is only reported for Cohort 1.

Participants with locally advanced or metastatic TNBC who had not previously received chemotherapy in the advanced setting received 400 mg of Ipat orally, QD on Days 1-21, 840 mg IV of Atezo on Days 1 and 15, and 100 mg/m^2 IV nab-paclitaxel (Nab-Pac) on Days 1, 8, and 15 of each 28-day cycle. Following completion of a safety run-in cohort (B1), a subsequent expansion arm enrolled (B2). All participants in Arm B continued to receive treatment until loss of clinical benefit, unacceptable toxicity, withdrawal of consent, or end of the study.

Participants with locally advanced or metastatic TNBC who had not previously received chemotherapy in the advanced setting received 400 mg of Ipat orally, QD on Days 1-21, 80 mg/m2 IV Pac on Days 1, 8, and 15 and 840 mg IV Atezo on Day 15 of Cycle 1 (28 day cycle). In Cycles ≥ 2, participants received 400 mg Ipat orally on Days 1-21, 840 mg IV Atezo on Days 1 and 15 and 80 mg/m2 IV Pac on Days 1, 8, and 15 of each 28-day Cycle. Following completion of the safety run-in cohort (C1), a subsequent expansion cohort (C2) enrolled. All participants in Arm C continued to receive treatment until loss of clinical benefit, unacceptable toxicity, withdrawal of consent, or end of the study.

Participants with locally advanced or metastatic TNBC who had not previously received chemotherapy in the advanced setting received 840 mg IV Atezo on Days 1 and 15, 80 mg/m2 IV Pac on Days 1, 8, and 15 and 400 mg Ipat orally on days 15-21 of Cycle 1 (28 day cycle). In Cycles ≥ 2, participants received 400 mg Ipat orally on Days 1-21, 80 mg/m2 IV Pac on Days 1, 8, and 15 and 840 mg IV Atezo on Days 1 and 15 of each 28 day Cycle. Following completion of the safety run-in cohort (D1), a subsequent expansion cohort (D2) enrolled. All participants in Arm D continued to receive treatment until loss of clinical benefit, unacceptable toxicity, withdrawal of consent, or end of the study.

Participants in the second-line and third-line setting with locally advanced or metastatic TNBC received 400 mg Ipat orally QD on Days 1-28 and 840 mg IV Atezo on Days 8 and 22 of Cycle 1 (Cycle 1 = 35 days). In Cycles ≥ 2, participants received 400 mg Ipat orally on Days 1-21 and 840 mg IV Atezo on Days 1 and 15 of each cycle (Cycles ≥ 2 = 28-days) until loss of clinical benefit, unacceptable toxicity, withdrawal of consent, or end of the study.

Participants in the safety run-in stage (arm F1) with locally advanced T2-4 TNBC received 300 mg Ipat orally QD on Days 1-21, 840mg IV Atezo on Days 1 and 15, 60 mg/m2 IV doxorubicin and 600 mg/m2 IV cyclophosphamide on Days 1 and 15 of Cycles 1 and 2 (1 Cycle=28-days). Participants then received 400 mg Ipat orally QD on Days 1-21, 840mg IV Atezo on Days 1 and 15 and 80 mg/m2 IV Pac on Days 1, 8, 15, and 22 of Cycles 3-5, until completion of 5 cycles or disease progression or unacceptable toxicity, whichever occurred first.

Safety population included all participants who received any study treatment.