IMpassion130: Atezolizumab Plus Nab-Paclitaxel in Untreated Metastatic Triple-Negative Breast Cancer

Co-primary 1 (PFS, ITT population): 7.2 vs 5.5 months — HR 0.80 (95% CI 0.69–0.92; P=0.002) Co-primary 2 (PFS, PD-L1–positive subgroup): 7.5 vs 5.0 months — HR 0.62 (95% CI 0.49–0.78; P<0.001) Co-primary 3 (OS, ITT population): 21.3 vs 17.6 months — HR 0.84 (95% CI 0.69–1.02; P=0.08 [not significant]) Co-primary 4 (OS, PD-L1–positive subgroup): 25.0 vs 15.5 months — HR 0.62 (95% CI 0.45–0.86) [not formally tested] Safety signal: Immune-related adverse events of special interest (any grade 57.3% vs 41.8%); treatment-related deaths: 3 vs 1

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Clinical Bottom Line

Adding atezolizumab to nab-paclitaxel as first-line therapy for metastatic triple-negative breast cancer (TNBC) demonstrated a statistically significant improvement in progression-free survival in the overall population, with a meaningfully larger benefit in patients whose tumors expressed PD-L1 on tumor-infiltrating immune cells. The overall survival analysis at this interim look did not reach statistical significance in the intention-to-treat population, which — due to the hierarchical testing strategy — prevented formal statistical testing of the numerically striking survival difference observed in the PD-L1–positive subgroup.

IMpassion130 was a landmark trial that introduced immune checkpoint inhibition into the treatment of metastatic TNBC and led to an accelerated FDA approval for atezolizumab in this setting. However, the subsequent final overall survival analysis (reported separately) failed to confirm a statistically significant OS benefit, and the FDA accelerated approval was voluntarily withdrawn in 2021. Concurrently, the KEYNOTE-355 trial established pembrolizumab plus chemotherapy as the preferred first-line immunotherapy approach for PD-L1–positive metastatic TNBC, using a different PD-L1 scoring system (CPS ≥10). The treatment landscape has therefore shifted substantially since this initial publication.

Clinicians should note the distinct PD-L1 assay used in IMpassion130 — the SP142 assay scoring immune cell expression — which identifies a different patient population than the 22C3 CPS scoring used with pembrolizumab. The safety profile was consistent with known toxicities of atezolizumab and nab-paclitaxel, with immune-related hypothyroidism, pneumonitis, and hepatitis warranting standard immune-mediated toxicity surveillance.

Trial Overview

Study Design

• Trial name and registration: IMpassion130; NCT02425891
• Design: Phase 3, randomized, double-blind, placebo-controlled trial; this publication reports the definitive PFS analysis and the first interim analysis of OS
• Randomization: 1:1, stratified by presence or absence of liver metastases, use or nonuse of neoadjuvant or adjuvant taxane treatment, and PD-L1 expression on tumor-infiltrating immune cells (<1% [PD-L1 negative] vs ≥1% [PD-L1 positive])
• Setting: Untreated metastatic or unresectable locally advanced triple-negative breast cancer, first-line
• Enrollment period and sites: June 2015 through May 2017; 246 sites in 41 countries

Mechanism of Action

Atezolizumab is a humanized, engineered IgG1 monoclonal antibody that selectively binds PD-L1 and blocks its interactions with both PD-1 and B7.1 (CD80) receptors. By inhibiting the PD-L1/PD-1 interaction, atezolizumab restores T-cell-mediated antitumor immunity. The engineered Fc region minimizes antibody-dependent cellular cytotoxicity toward activated T cells [2].

Patient Population

• Key eligibility: Patients aged ≥18 years with metastatic or unresectable locally advanced, histologically documented TNBC; no prior chemotherapy or targeted therapy for metastatic TNBC; measurable disease per RECIST v1.1; ECOG performance-status score 0 or 1; representative tumor specimen available for PD-L1 testing. Key exclusions included untreated CNS disease, history of autoimmune disease, and previous immune checkpoint–targeting therapies.
• Biomarker selection: PD-L1 expression on tumor-infiltrating immune cells assessed by SP142 PD-L1 immunohistochemical assay (Ventana Medical Systems); ≥1% defined as PD-L1 positive. All patients enrolled regardless of PD-L1 status; PD-L1 was a stratification factor and defined a co-primary analysis subgroup.
• Sample size flow: 1,235 screened → 902 randomized (451 per arm) → 890 treated (445 per arm) → 902 analyzed (ITT); safety population: 890 (452 atezolizumab + nab-paclitaxel, 438 placebo + nab-paclitaxel). The PD-L1–positive subgroup included 369 patients (185 atezolizumab, 184 placebo).

Note: Seven patients from the placebo + nab-paclitaxel group received one dose of atezolizumab and were included in the atezolizumab safety population (hence 452 rather than 445).

Baseline Characteristics

Baseline characteristics were well balanced between arms. Approximately 90% of patients had metastatic disease, and roughly half had received prior taxane therapy in the neoadjuvant or adjuvant setting. The PD-L1–positive subgroup comprised 40.9% of the total population.

Treatment Protocol

Experimental Arm: Atezolizumab + Nab-Paclitaxel (n=451 randomized; safety population n=452)

Atezolizumab 840 mg IV on days 1 and 15, plus nab-paclitaxel 100 mg/m² IV on days 1, 8, and 15 of every 28-day cycle - Dose and schedule: Atezolizumab 840 mg IV days 1 and 15; nab-paclitaxel 100 mg/m² IV days 1, 8, and 15 every 28 days - Treatment duration: Until progression per RECIST v1.1 or unacceptable toxicity - Median treatment duration: Atezolizumab: 24.1 weeks; nab-paclitaxel: 22.1 weeks - Mean cumulative dose of nab-paclitaxel: 1980.0±1303.1 mg/m² - Median relative dose intensity: Not reported in this publication

Control Arm: Placebo + Nab-Paclitaxel (n=451 randomized; safety population n=438)

Placebo IV on days 1 and 15, plus nab-paclitaxel 100 mg/m² IV on days 1, 8, and 15 of every 28-day cycle - Dose and schedule: Placebo IV days 1 and 15; nab-paclitaxel 100 mg/m² IV days 1, 8, and 15 every 28 days - Treatment duration: Until progression per RECIST v1.1 or unacceptable toxicity - Median treatment duration: Placebo: 22.1 weeks; nab-paclitaxel: 21.8 weeks - Mean cumulative dose of nab-paclitaxel: 1764.4±1238.3 mg/m²

Efficacy Outcomes

Co-Primary Endpoint 1: Progression-Free Survival — Intention-to-Treat Population

Definition: Investigator-assessed progression-free survival per RECIST version 1.1 Analysis population: Intention-to-treat (N=902) Alpha allocation: 0.01 Median follow-up: 12.9 months (13.0 months atezolizumab arm, 12.5 months placebo arm)

Atezolizumab + Nab-Paclitaxel: Median PFS 7.2 months (95% CI, 5.6–7.5); 358 events in 451 patients (79.4%) Placebo + Nab-Paclitaxel: Median PFS 5.5 months (95% CI, 5.3–5.6); 378 events in 451 patients (83.8%) Comparison: HR 0.80 (95% CI, 0.69 to 0.92; P=0.002)

Sensitivity analysis by blinded independent central review confirmed the result: stratified HR 0.78 (95% CI, 0.67 to 0.91).

Co-Primary Endpoint 2: Progression-Free Survival — PD-L1–Positive Subgroup

Definition: Investigator-assessed progression-free survival per RECIST version 1.1 in the PD-L1–positive subgroup (≥1% PD-L1 expression on tumor-infiltrating immune cells) Analysis population: PD-L1–positive subgroup (N=369; 185 atezolizumab, 184 placebo) Alpha allocation: 0.01

Atezolizumab + Nab-Paclitaxel: Median PFS 7.5 months (95% CI, 6.7–9.2); 138 of 185 patients (74.6%) had progression or died Placebo + Nab-Paclitaxel: Median PFS 5.0 months (95% CI, 3.8–5.6); 157 of 184 patients (85.3%) had progression or died Comparison: HR 0.62 (95% CI, 0.49 to 0.78; P<0.001)

At 1 year, the PFS rate was 29.1% in the atezolizumab arm versus 16.4% in the placebo arm within the PD-L1–positive subgroup.

Sensitivity analysis by central review confirmed the result: stratified HR 0.63 (95% CI, 0.49 to 0.81).

Co-Primary Endpoint 3: Overall Survival — Intention-to-Treat Population (First Interim Analysis)

Definition: Overall survival in the intention-to-treat population Analysis population: Intention-to-treat (N=902) Alpha allocation: 0.04

Atezolizumab + Nab-Paclitaxel: Median OS 21.3 months (95% CI, 17.3–23.4); 181 of 451 patients (40.1%) had died Placebo + Nab-Paclitaxel: Median OS 17.6 months (95% CI, 15.9–20.0); 208 of 451 patients (46.1%) had died Comparison: HR 0.84 (95% CI, 0.69 to 1.02; P=0.08 [not significant])

The OS boundary for statistical significance was not crossed at this first interim analysis.

Co-Primary Endpoint 4: Overall Survival — PD-L1–Positive Subgroup (First Interim Analysis)

Definition: Overall survival in the PD-L1–positive subgroup Analysis population: PD-L1–positive subgroup (N=369) Alpha allocation: 0.04

Because of the hierarchical statistical analysis procedure, formal testing of overall survival in the PD-L1–positive subgroup was not conducted at this interim analysis, as OS in the ITT population did not reach significance.

Atezolizumab + Nab-Paclitaxel: Median OS 25.0 months (95% CI, 22.6–NE); 64 of 185 patients (34.6%) had died Placebo + Nab-Paclitaxel: Median OS 15.5 months (95% CI, 13.1–19.4); 88 of 184 patients (47.8%) had died Comparison (descriptive): HR 0.62 (95% CI, 0.45 to 0.86) — not formally tested

Multiplicity Control

The type I error (0.05) was split: alpha=0.01 for PFS and alpha=0.04 for OS. PFS was tested in both the ITT population and the PD-L1–positive subgroup and was significant in both. OS was tested hierarchically: first in the ITT population, then (if significant) in the PD-L1–positive subgroup. Because OS in the ITT population did not reach significance (P=0.08), formal statistical testing of OS in the PD-L1–positive subgroup could not proceed despite the numerically large difference observed (HR 0.62). This is a critical statistical nuance — the 9.5-month difference in median OS in the PD-L1–positive subgroup cannot be claimed as statistically significant under the prespecified testing framework.

Key Secondary Endpoints

Objective Response Rate — ITT Population

Definition: Rate of objective response assessed by investigators per RECIST v1.1 Analysis population: Intention-to-treat (patients with measurable disease at baseline) Formally tested: Yes

Atezolizumab + Nab-Paclitaxel: ORR 56.0% (95% CI, 51.3–60.6); 252 responders. Complete response rate: 7.1% (32 patients) Placebo + Nab-Paclitaxel: ORR 45.9% (95% CI, 41.2–50.6); 206 responders. Complete response rate: 1.6% (7 patients) Comparison: OR 1.52 (95% CI, 1.16–1.97; P=0.002)

Objective Response Rate — PD-L1–Positive Subgroup

Analysis population: PD-L1–positive subgroup (patients with measurable disease at baseline) Formally tested: Yes

Atezolizumab + Nab-Paclitaxel: ORR 58.9% (95% CI, 51.5–66.1); 109 responders. Complete response rate: 10.3% (19 patients) Placebo + Nab-Paclitaxel: ORR 42.6% (95% CI, 35.4–50.1); 78 responders. Complete response rate: 1.1% (2 patients) Comparison: OR 1.96 (95% CI, 1.29–2.98; P=0.002)

Duration of Response — ITT Population

Analysis population: Intention-to-treat (responders) Formally tested: This endpoint was not formally tested in the statistical hierarchy.

Atezolizumab + Nab-Paclitaxel: Median DOR 7.4 months (95% CI, 6.9–9.0); 78 patients (31.0%) had ongoing response at data cutoff Placebo + Nab-Paclitaxel: Median DOR 5.6 months (95% CI, 5.5–6.9); 52 patients (25.2%) had ongoing response at data cutoff Comparison: HR 0.78 (95% CI, 0.63–0.98)

Duration of Response — PD-L1–Positive Subgroup

Analysis population: PD-L1–positive subgroup (responders) Formally tested: This endpoint was not formally tested in the statistical hierarchy.

Atezolizumab + Nab-Paclitaxel: Median DOR 8.5 months (95% CI, 7.3–9.7); 39 patients (35.8%) had ongoing response at data cutoff Placebo + Nab-Paclitaxel: Median DOR 5.5 months (95% CI, 3.7–7.1); 19 patients (24.4%) had ongoing response at data cutoff Comparison: HR 0.60 (95% CI, 0.43–0.86)

Exploratory Endpoints

At 1 year, the PFS rate in the ITT population was 23.7% in the atezolizumab arm versus 17.7% in the placebo arm. At 2 years, the OS rate in the ITT population was 42.1% versus 39.7%; in the PD-L1–positive subgroup, the 2-year OS rate was 53.5% versus 36.6%.

Safety

Safety Population

Atezolizumab + Nab-Paclitaxel: n=452; Placebo + Nab-Paclitaxel: n=438

Safety Summary

The rate of adverse events of grade 3 or 4 was 48.7% in the atezolizumab + nab-paclitaxel group and 42.2% in the placebo + nab-paclitaxel group (note: these are reported as a combined grade 3/4 rate; individual grade 3 and grade 4 rates were not reported separately for the overall summary in this publication). Grade ≥3 TEAEs by individual category, treatment-related AE rates overall, dose reduction rates, and dose interruption rates were not reported in this publication.

Discontinuation of atezolizumab specifically due to adverse events occurred in 29 patients (6.4%); discontinuation of placebo due to adverse events occurred in 6 patients (1.4%).

Grade 3 or 4 Adverse Events of Clinical Significance

Note: Grade 3 and grade 4 rates are reported combined as "grade 3 or 4" in the source; they are not separated individually.

Adverse Events of Special Interest

⚠️ Immune-Related Adverse Events: Critical Safety Signal

Adverse events of special interest — suggestive of a potential immune-related cause — were more frequent in the atezolizumab arm: - Any grade: 259 (57.3%) vs 183 (41.8%) - Grade 3 or 4: 34 (7.5%) vs 19 (4.3%) - Grade 5 (immune-related): 2 events total — autoimmune hepatitis (1 patient, atezolizumab arm) and hepatic failure (1 patient, placebo arm)

Immune-related hypothyroidism occurred in 17.3% of patients in the atezolizumab arm versus 4.3% in the placebo arm. All events were grade 1 or 2, and none led to discontinuation of the trial regimen.

Pneumonitis occurred in 3.1% of patients in the atezolizumab arm versus 0.2% in the placebo arm. Only 1 patient (in the atezolizumab arm) had a grade 3 or 4 event.

Clinical implication: Standard immune checkpoint inhibitor monitoring protocols apply — thyroid function testing at baseline and periodically during treatment, vigilance for pneumonitis symptoms, and hepatic function surveillance. Management guidelines per the atezolizumab prescribing information should be followed [2].

⚠️ Peripheral Neuropathy

Grade 3 or 4 peripheral neuropathy was numerically higher with atezolizumab + nab-paclitaxel (5.5%, 25 patients) than with placebo + nab-paclitaxel (2.7%, 12 patients), despite similar any-grade rates (21.7% vs 22.1%). This difference may reflect the longer median nab-paclitaxel exposure in the atezolizumab arm (22.1 weeks vs 21.8 weeks) and/or immune-mediated potentiation of chemotherapy-induced neuropathy. Monitoring for neuropathy and timely dose modification of nab-paclitaxel remain important.

Deaths

• Total deaths (ITT): 181 of 451 (40.1%) in the atezolizumab arm and 208 of 451 (46.1%) in the placebo arm
• Fatal adverse events: 6 (1.3%) in the atezolizumab arm and 3 (0.7%) in the placebo arm
• Treatment-related deaths: 3 in the atezolizumab arm (autoimmune hepatitis, mucosal inflammation, and septic shock, 1 patient each) and 1 in the placebo arm (hepatic failure)

Subgroup Analyses

Note: The subgroup forest plot (Figure 3) reports unstratified hazard ratios, which differ slightly from the stratified HR of 0.80 reported for the ITT population overall.

The most striking subgroup finding is the differential benefit by PD-L1 status: the PFS benefit was driven largely by PD-L1–positive patients (HR 0.64), with minimal benefit in PD-L1–negative patients (HR 0.95). Patients with lymph node–only disease showed a notably favorable HR (0.44), though this subgroup was small. Patients with bone metastases showed no apparent PFS benefit (HR 1.02).

These subgroup analyses were not powered for formal statistical comparisons. Results should be interpreted as hypothesis-generating.

Key Comparator Trials

Cross-trial comparisons are limited by differences in patient populations, trial designs, and endpoints. These data are presented for context, not for direct statistical comparison.

Contextual Notes

IMpassion130 established proof of concept for checkpoint inhibitor plus chemotherapy in first-line metastatic TNBC. However, several subsequent developments reshaped the treatment landscape:

First, the final OS analysis of IMpassion130 did not confirm a statistically significant overall survival benefit in either the ITT or PD-L1–positive populations, leading to the voluntary withdrawal of the FDA accelerated approval for atezolizumab in TNBC in August 2021. Second, IMpassion131 demonstrated that atezolizumab combined with solvent-based paclitaxel (rather than nab-paclitaxel) did not improve PFS, raising important questions about the chemotherapy backbone and suggesting the benefit may be specific to nab-paclitaxel [5]. Third, KEYNOTE-355 demonstrated both PFS and OS benefits for pembrolizumab plus chemotherapy in patients with CPS ≥10 metastatic TNBC, establishing pembrolizumab as the preferred first-line immunotherapy in this setting [4].

The differing PD-L1 assays — SP142 (immune cell scoring) for atezolizumab versus 22C3 (CPS, which scores both tumor and immune cells) for pembrolizumab — identify partially overlapping but distinct patient populations. Clinicians must ensure the appropriate companion diagnostic is used when selecting immunotherapy.

Grey Zones and Unanswered Questions

• OS hierarchy failure limits interpretation of the PD-L1–positive subgroup survival data. The 9.5-month difference in median OS in PD-L1–positive patients (25.0 vs 15.5 months; HR 0.62) could not be formally tested due to the hierarchical design. The subsequent final OS analysis did not confirm significance, leaving the true survival impact in this subgroup uncertain.

• Nab-paclitaxel specificity is unexplained. IMpassion131 showed that atezolizumab combined with solvent-based paclitaxel did not improve outcomes, suggesting the chemotherapy backbone matters. Whether this reflects immunomodulatory differences between nab-paclitaxel and paclitaxel formulations, steroid premedication requirements for paclitaxel blunting immune responses, or chance finding remains unresolved.

• PD-L1–negative patients derive minimal PFS benefit. The subgroup HR of 0.95 (95% CI, 0.79–1.15) in PD-L1–negative patients indicates no meaningful benefit from adding atezolizumab. This reinforces the importance of PD-L1 testing but does not clarify whether alternative biomarkers (tumor mutational burden, TIL density) might identify PD-L1–negative patients who could benefit.

• Patients with bone metastases showed no benefit. The subgroup HR of 1.02 (95% CI, 0.79–1.31) for patients with bone metastases contrasts with the overall population benefit. Whether this reflects biology (immunosuppressive bone marrow microenvironment) or statistical noise in a subgroup analysis is unknown.

• CNS disease was excluded. Patients with untreated CNS metastases were excluded from IMpassion130. Only 6.7–6.9% of enrolled patients had brain metastases (presumably previously treated/stable). The activity of atezolizumab + nab-paclitaxel in patients with active brain metastases is unknown.

Clinical Implications

Where This Fits in the Treatment Sequence

As of 2026, atezolizumab is no longer approved for metastatic TNBC following voluntary withdrawal of the accelerated approval. Pembrolizumab plus chemotherapy (based on KEYNOTE-355) is the current preferred first-line immunotherapy option for PD-L1–positive (CPS ≥10) metastatic TNBC [3]. IMpassion130 remains historically important as the first trial to demonstrate a PFS benefit for checkpoint inhibition in this disease, and it established the biologic rationale for the immunotherapy-chemotherapy approach.

Practical Considerations

For clinicians reviewing the historical data: the PD-L1 testing platform matters. The SP142 assay (IC ≥1%) used in IMpassion130 identifies a different population than the 22C3 CPS ≥10 used for pembrolizumab eligibility. Approximately 41% of IMpassion130 patients were PD-L1–positive by SP142, while the CPS ≥10 threshold in KEYNOTE-355 identified a more restrictive population. Institutional pathology laboratories should be aware of which assay is being ordered and for which therapeutic decision.

The immune-mediated toxicity profile of atezolizumab is consistent with the PD-L1 inhibitor class. Hypothyroidism (17.3%) is the most common immune-related adverse event and is generally manageable with thyroid hormone replacement. Pneumonitis (3.1%) and hepatitis require vigilant monitoring. The treatment-related death from autoimmune hepatitis underscores the need for baseline and periodic liver function testing.

Unanswered Questions

The most practice-relevant open question is the optimal biomarker strategy for selecting patients who benefit from immunotherapy in first-line TNBC. The failure of IMpassion130 to confirm an OS benefit, contrasted with the OS benefit seen in KEYNOTE-355 (CPS ≥10), suggests that biomarker selection — and potentially the specific scoring system used — is critical. Whether composite biomarker strategies incorporating PD-L1, TILs, and genomic features can better identify benefiting patients remains an active area of investigation.

Post-Progression Options

Subsequent anticancer therapy was received by 242 patients (53.7%) in the atezolizumab arm and 272 patients (60.3%) in the placebo arm. Most received chemotherapy; only a minority (<4%) received subsequent immunotherapy. Post-progression options for metastatic TNBC include single-agent chemotherapy (gemcitabine, eribulin, capecitabine), sacituzumab govitecan (based on ASCENT), and olaparib or talazoparib for patients with germline BRCA mutations [3].

Regulatory and Guideline Status

Regulatory

• FDA: Atezolizumab received accelerated approval in combination with nab-paclitaxel for PD-L1–positive (SP142 IC ≥1%) unresectable locally advanced or metastatic TNBC in March 2019, based on IMpassion130 PFS data. This indication was voluntarily withdrawn in August 2021 after the final OS analysis did not confirm clinical benefit.
• EMA: Marketing authorization for this indication was also withdrawn.

⚠️ Regulatory status verified as of March 2026. Confirm current approval status and labeled indications before clinical use at FDA.gov. Atezolizumab is no longer indicated for metastatic TNBC.

Guidelines

• NCCN: Atezolizumab + nab-paclitaxel is no longer listed as a recommended regimen for metastatic TNBC following withdrawal of the FDA indication. Pembrolizumab + chemotherapy is the preferred first-line immunotherapy for PD-L1–positive (CPS ≥10) metastatic TNBC [3].

Companion Diagnostics

The VENTANA PD-L1 (SP142) Assay was the companion diagnostic for IMpassion130. While the assay remains commercially available, it is no longer linked to an approved therapeutic indication in metastatic TNBC. For pembrolizumab-based therapy, PD-L1 testing should be performed using the PD-L1 IHC 22C3 pharmDx assay with CPS scoring [3].

About the Author

Andrew Stevenson is the founder and systems architect of kill-cancer.com, a clinical intelligence platform delivering structured, source-traced oncology trial analysis to practicing clinicians. He holds 17 Google technical certifications in data systems, automation, and applied AI — the engineering foundation behind the extraction and verification pipeline that produces every article on this platform. Every number traces directly to its source publication. Zero calculation. Zero editorializing. Zero hallucination.

Five siblings lost to cancer built the urgency. The engineering builds the trust.

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Disclaimer

This article is intended for healthcare professionals only. It is not medical advice and should not be used as a substitute for professional clinical judgment. Treatment decisions should be made in consultation with qualified healthcare providers based on individual patient circumstances.

All trial data presented in this article are sourced directly from the published clinical trial report and its supplementary materials. Numbers are reproduced exactly as reported; no calculations, derivations, or estimates have been performed.

Trial results are presented as reported in the source publication. Updated data, label changes, or guideline revisions published after the source article may alter clinical applicability.

Comparator trial data presented in Section 8 are sourced from their respective published reports and are provided for contextual purposes only. Cross-trial comparisons have inherent limitations and should not be interpreted as direct statistical comparisons.

References

1. Schmid P, Adams S, Rugo HS, et al. Atezolizumab and nab-paclitaxel in advanced triple-negative breast cancer. N Engl J Med. 2018;379:2108-2121. doi:10.1056/NEJMoa1809615
2. Tecentriq (atezolizumab) prescribing information. U.S. Food and Drug Administration. Accessed March 2026.
3. NCCN Clinical Practice Guidelines in Oncology: Breast Cancer. Version 2.2026. Accessed March 2026.
4. Cortes J, Cescon DW, Rugo HS, et al. Pembrolizumab plus chemotherapy versus placebo plus chemotherapy for previously untreated locally recurrent inoperable or metastatic triple-negative breast cancer (KEYNOTE-355): a randomised, placebo-controlled, double-blind, phase 3 clinical trial. Lancet. 2020;396:1817-1828. doi:10.1016/S0140-6736(20)32531-9
5. Miles D, Gligorov J, André F, et al. Primary results from IMpassion131, a double-blind, placebo-controlled, randomised phase III trial of first-line paclitaxel with or without atezolizumab for unresectable locally advanced/metastatic triple-negative breast cancer. Ann Oncol. 2021;32:994-1004. doi:10.1016/j.annonc.2021.05.801