Trial Outcomes & Findings for A Study of Trastuzumab Emtansine in Combination With Atezolizumab or Placebo as a Treatment for Participants With Human Epidermal Growth Factor 2 (HER2)-Positive and Programmed Death-ligand 1 (PD-L1)-Positive Locally Advanced (LABC) or Metastatic Breast Cancer (MBC) (NCT NCT04740918)

Last Updated: 2025-08-08

Results Overview

PFS was defined as the time from randomization to the first occurrence of documented disease progression (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 millimeter (mm). Median PFS was calculated using the Kaplan-Meier (KM) methodology. Data for participants without PD or death from any cause as of the data cut-off date were censored at the time of the last tumor assessment.

Recruitment status

TERMINATED

Study phase

PHASE3

Target enrollment

96 participants

Primary outcome timeframe

Up to 28 months

Results posted on

2025-08-08

Participant Flow

A total of 96 participants with human epidermal growth factor receptor 2 (HER2)-positive and programmed death-ligand 1 (PD-L1)-positive locally advanced (LABC) or metastatic breast cancer (MBC) took part in the study across 52 investigative sites in 19 countries from 07 June 2021 to 19 June 2024.

Participants were randomized in 1:1 ratio to receive trastuzumab emtansine + placebo or trastuzumab emtansine + atezolizumab.

Participant milestones

Participant milestones
Measure	Trastuzumab Emtansine 3.6 mg + Placebo Participants received trastuzumab emtansine, 3.6 milligrams (mg), every 3 weeks (Q3W) as an intravenous (IV) infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
Overall Study STARTED	50	46
Overall Study Safety Population	49	47
Overall Study ITT With Brain Metastases	5	4
Overall Study ITT With CNS Metastases	7	4
Overall Study ITT Without CNS Metastases	43	42
Overall Study ITT With Measurable Disease	49	45
Overall Study COMPLETED	0	0
Overall Study NOT COMPLETED	50	46

Reasons for withdrawal

Reasons for withdrawal
Measure	Trastuzumab Emtansine 3.6 mg + Placebo Participants received trastuzumab emtansine, 3.6 milligrams (mg), every 3 weeks (Q3W) as an intravenous (IV) infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
Overall Study Study Terminated by Sponsor	41	32
Overall Study Death	3	6
Overall Study Withdrawal by Subject	5	4
Overall Study Lost to Follow-up	1	3
Overall Study Progressive disease	0	1

Baseline Characteristics

A Study of Trastuzumab Emtansine in Combination With Atezolizumab or Placebo as a Treatment for Participants With Human Epidermal Growth Factor 2 (HER2)-Positive and Programmed Death-ligand 1 (PD-L1)-Positive Locally Advanced (LABC) or Metastatic Breast Cancer (MBC)

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Trastuzumab Emtansine 3.6 mg + Placebo n=50 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg n=46 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Total n=96 Participants Total of all reporting groups
Age, Continuous	53.2 years STANDARD_DEVIATION 11.7 • n=5 Participants	50.9 years STANDARD_DEVIATION 10.0 • n=7 Participants	52.1 years STANDARD_DEVIATION 10.9 • n=5 Participants
Sex: Female, Male Female	50 Participants n=5 Participants	46 Participants n=7 Participants	96 Participants n=5 Participants
Sex: Female, Male Male	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	7 Participants n=5 Participants	4 Participants n=7 Participants	11 Participants n=5 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	42 Participants n=5 Participants	39 Participants n=7 Participants	81 Participants n=5 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	1 Participants n=5 Participants	3 Participants n=7 Participants	4 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	1 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants
Race (NIH/OMB) Asian	17 Participants n=5 Participants	21 Participants n=7 Participants	38 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Black or African American	1 Participants n=5 Participants	1 Participants n=7 Participants	2 Participants n=5 Participants
Race (NIH/OMB) White	29 Participants n=5 Participants	23 Participants n=7 Participants	52 Participants n=5 Participants
Race (NIH/OMB) More than one race	1 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	1 Participants n=5 Participants	1 Participants n=7 Participants	2 Participants n=5 Participants

PRIMARY outcome

Timeframe: Up to 28 months

Population: ITT population included all participants who were randomized in the study, whether they received any study medication.

Outcome measures

Outcome measures
Measure	Trastuzumab Emtansine 3.6 mg + Placebo n=50 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg n=46 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
Progression-Free Survival (PFS) as Determined by Investigator Using Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST v1.1)	7.52 months Interval 6.18 to 10.94	8.61 months Interval 5.72 to 16.92

PRIMARY outcome

Timeframe: Up to 28 months

Population: ITT population included all participants who were randomized in the study, whether they received any study medication.

OS was defined as the time from the first dose of study treatment to the time of death from any cause. Participants who are alive as of the data cut-off date of the analysis were censored at the last known date they were alive. Participants with no post-baseline information were censored at the date of randomization plus 1 day. Median OS was calculated using the KM methodology.

Outcome measures

Outcome measures
Measure	Trastuzumab Emtansine 3.6 mg + Placebo n=50 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg n=46 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
Overall Survival (OS)	NA months The median and 95% confidence interval (CI) was not estimable due to insufficient number of events.	NA months Interval 21.29 to The median and upper limit of 95% CI was not estimable due to insufficient number of events.

SECONDARY outcome

Timeframe: Up to 28 months

Population: Subset ITT with measurable disease included all participants in the ITT with a measurable disease at baseline. ITT population included all participants who were randomized to the study, whether or not they received any study medication.

ORR was defined as the percentage of participants with complete response (CR) or partial response (PR) on two consecutive assessments, at least 28 days apart, as determined by the investigator using RECIST v.1.1. CR was defined as the disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) having a reduction in short axis to \<10 mm. PR was defined as at least a 30% decrease in the sum of diameters (SOD) of target lesions, taking as reference the baseline SOD. Only participants with measurable disease at baseline were analyzed for this outcome measure. Participants without a post-baseline tumor assessment were considered non-responders. An estimate of the ORR and its 95% CI (Wilson score confidence interval) were calculated for each treatment arm.

Outcome measures

Outcome measures
Measure	Trastuzumab Emtansine 3.6 mg + Placebo n=49 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg n=45 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
Objective Response Rate (ORR)	49 percentage of participants Interval 34.64 to 63.48	53.3 percentage of participants Interval 38.04 to 68.07

SECONDARY outcome

Timeframe: Up to 28 months

DOR was calculated for participants who had a best OR of CR/PR. 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. 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. Median DOR was calculated using the KM methodology.

Outcome measures

Outcome measures
Measure	Trastuzumab Emtansine 3.6 mg + Placebo n=24 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg n=24 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
Duration of Response (DOR)	8.21 months Interval 5.72 to The upper limit of 95%CI was not estimable due to insufficient number of events.	15.57 months Interval 7.06 to The upper limit of 95%CI was not estimable due to insufficient number of events.

SECONDARY outcome

Timeframe: Up to 28 months

Population: ITT with brain metastasis population included all participants in ITT with brain metastasis at randomization.

PFS was defined as the time from randomization 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. Median PFS was calculated using the KM methodology.

Outcome measures

Outcome measures
Measure	Trastuzumab Emtansine 3.6 mg + Placebo n=5 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg n=4 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
PFS in Participants With Baseline Brain Metastases as Determined by Investigator Assessment Using RECIST v1.1	7.69 months Interval 4.14 to The upper limit of 95% CI was not estimable due to insufficient number of events.	4.78 months Interval 1.31 to The upper limit of 95% CI was not estimable due to insufficient number of events.

SECONDARY outcome

Timeframe: Up to 28 months

Population: ITT with brain metastasis population included all participants in ITT with brain metastasis at randomization.

OS is defined as the time from the first dose of study treatment to the time of death from any cause. Median OS was calculated using the KM methodology.

Outcome measures

Outcome measures
Measure	Trastuzumab Emtansine 3.6 mg + Placebo n=5 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg n=4 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
OS in Participants With Baseline Brain Metastases	NA months The median and 95%CI was not estimable due to insufficient number of events.	NA months Interval 9.53 to The median and upper limit of 95%CI was not estimable due to insufficient number of events.

SECONDARY outcome

Timeframe: Up to 28 months

Population: ITT with CNS metastasis population included all participants in ITT with CNS metastasis at randomization.

CNS PFS was defined as the time from randomization to the first occurrence of documented CNS PD, or first occurrence of symptomatic CNS disease 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. Median PFS was calculated using the KM methodology. Participants who experienced non-CNS PD at the time of analysis were censored at the date of this progression. Participants who experienced no PD and were alive at the time of analysis were censored at date of their last post-baseline tumor assessment or, if they had no post-baseline tumor assessment, on the date of randomization + 1 day.

Outcome measures

Outcome measures
Measure	Trastuzumab Emtansine 3.6 mg + Placebo n=7 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg n=4 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
Central Nervous System (CNS) PFS as Determined by Investigator Using RECIST v1.1 in Participants With Baseline CNS Metastases	10.41 months Interval 4.11 to The upper limit of 95% CI was not estimable due to insufficient number of events.	9.53 months Interval 1.31 to The upper limit of 95% CI was not estimable due to insufficient number of events.

SECONDARY outcome

Timeframe: Up to 28 months

Population: ITT without CNS metastases at baseline population included all participants in the ITT without CNS metastasis at baseline.

Outcome measures

Outcome measures
Measure	Trastuzumab Emtansine 3.6 mg + Placebo n=43 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg n=42 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
CNS PFS as Determined by Investigator Using RECIST v1.1 in Participants Without Baseline CNS Metastases	NA months The median and 95% CI were not estimable due to insufficient number of events.	NA months Interval 21.29 to The median and upper limit of 95% CI were not estimable due to insufficient number of events.

SECONDARY outcome

Timeframe: Up to 28 months

Population: Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.

An AE was any untoward medical occurrence in a participant administered a pharmaceutical product and which does not necessarily have to have a causal relationship with the treatment. An AE can therefore be any unfavorable and unintended sign (including abnormal laboratory values or abnormal clinical test results), symptom, or disease temporally associated with the use of a pharmaceutical product, whether or not considered related to the pharmaceutical product.

Outcome measures

Outcome measures
Measure	Trastuzumab Emtansine 3.6 mg + Placebo n=49 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg n=47 Participants Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
Percentage of Participants With Adverse Events (AEs)	93.9 percentage of participants	97.9 percentage of participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 28 months

Population: As prespecified in the latest protocol, following sponsor's decision to prematurely terminate the study, analysis of PFS as determined by a BICR committee was not conducted.

PFS was defined as the time from randomization to the first occurrence of documented PD, as determined by the BICR committee 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.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 28 months

Population: As prespecified in the latest protocol, following sponsor's decision to prematurely terminate the study, the analysis for EORTC QLQ-C30 was not conducted.

EORTC QLQ-C30 consists of 30 questions that assess five aspects of participant functioning (physical, emotional, role, cognitive, and social), three symptom scales (fatigue, nausea and vomiting, pain), GHS/QoL, and six single items (dyspnea, insomnia, appetite loss, constipation, diarrhea, and financial difficulties). The PF scale has 5 questions about participant's PF and daily activities (strenuous activities, long walks, short walks, bed/chair rest \& needing help with eating, dressing, washing themselves, or using the toilet). The RF scale has 2 questions about work/daily activities and hobbies/leisurely activities. The PF and RF are scored on a 4-point scale (1=Not at All to 4=Very Much). The GHS/QoL are scored on a 7-point scale (1=Very Poor to 7=Excellent). The obtained scores are linearly transformed to a score range of 0-100, where higher scores indicate a higher response level and better QoL, functioning/support.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 28 months

Population: As prespecified in the latest protocol, following sponsor's decision to prematurely terminate the study, the analysis for EORTC QLQ-C30 was not conducted.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 28 months

Population: As prespecified in the latest protocol, following sponsor's decision to prematurely terminate the study, the analysis for EORTC QLQ-C30 was not conducted.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 28 months

Population: As prespecified in the latest protocol, following sponsor's decision to prematurely terminate the study, PK objectives and outcome measures were no longer applicable. Hence sample collection was stopped, and this outcome measure was not assessed or analyzed.

As prespecified in the latest protocol, following sponsor's decision to prematurely terminate the study, PK objectives and outcome measures were no longer applicable. Hence sample collection was stopped, and this outcome measure was not assessed or analyzed.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 28 months

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 28 months

Population: As prespecified in the latest protocol, following sponsor's decision to prematurely terminate the study, immunogenicity objectives and outcome measures were no longer applicable.

As prespecified in the latest protocol, following sponsor's decision to prematurely terminate the study, immunogenicity objectives and outcome measures were no longer applicable.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 28 months

Population: As prespecified in the latest protocol, following sponsor's decision to prematurely terminate the study, immunogenicity objectives and outcome measures were no longer applicable.

As prespecified in the latest protocol, following sponsor's decision to prematurely terminate the study, immunogenicity objectives and outcome measures were no longer applicable.

Outcome measures

Outcome data not reported

Adverse Events

Trastuzumab Emtansine 3.6 mg + Placebo

Serious events: 9 serious events

Other events: 46 other events

Deaths: 3 deaths

Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg

Serious events: 14 serious events

Other events: 46 other events

Deaths: 6 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

Measure	Trastuzumab Emtansine 3.6 mg + Placebo n=49 participants at risk Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab matching placebo, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.	Trastuzumab Emtansine 3.6 mg + Atezolizumab 1200 mg n=47 participants at risk Participants received trastuzumab emtansine, 3.6 mg, Q3W as an IV infusion in combination with atezolizumab, 1200 mg, Q3W as an IV infusion on Day 1 of each 21-day cycle until radiographic disease progression, intolerable toxicity, withdrawal of consent, death or study termination by the sponsor.
Cardiac disorders Cardiac failure acute	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Gastrointestinal disorders Abdominal pain	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Gastrointestinal disorders Colitis	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Gastrointestinal disorders Gastrointestinal haemorrhage	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Gastrointestinal disorders Gastrointestinal inflammation	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Gastrointestinal disorders Vomiting	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
General disorders Pyrexia	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Hepatobiliary disorders Biliary obstruction	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Hepatobiliary disorders Cholecystitis	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Hepatobiliary disorders Hepatic function abnormal	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Infections and infestations COVID-19	2.0% 1/49 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Infections and infestations Peritonitis	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 2 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Infections and infestations Pneumonia viral	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Infections and infestations Sepsis	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Infections and infestations Urinary tract infection	2.0% 1/49 • Number of events 2 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	0.00% 0/47 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Infections and infestations Vascular device infection	2.0% 1/49 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	0.00% 0/47 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Injury, poisoning and procedural complications Humerus fracture	2.0% 1/49 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	0.00% 0/47 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Injury, poisoning and procedural complications Infusion related reaction	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Investigations Aspartate aminotransferase increased	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 2 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Investigations Platelet count decreased	2.0% 1/49 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	4.3% 2/47 • Number of events 4 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Nervous system disorders Neuropathy peripheral	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Nervous system disorders Seizure	4.1% 2/49 • Number of events 2 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	0.00% 0/47 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Respiratory, thoracic and mediastinal disorders Dyspnoea	2.0% 1/49 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	0.00% 0/47 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Respiratory, thoracic and mediastinal disorders Pleural effusion	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Respiratory, thoracic and mediastinal disorders Pulmonary embolism	0.00% 0/49 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	2.1% 1/47 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.
Respiratory, thoracic and mediastinal disorders Respiratory failure	2.0% 1/49 • Number of events 1 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.	0.00% 0/47 • Up to 28 months Safety evaluable population included all participants who received at least one full or partial dose of study drug. One participant randomized to Trastuzumab Emtansine + Placebo moved to Trastuzumab Emtansine + Atezolizumab 1200 mg. Hence, has been represented in the later arm for safety analysis.