KEYNOTE-B49

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Screened window

May 20, 2021 → Oct 30, 2026

Cited window

Jul 5, 2023 → Oct 30, 2026

Retrieved

Oct 31, 2026

Title

A Randomized, Double-blind, Placebo-controlled, Phase 3 Study of Pembrolizumab Plus Chemotherapy Versus Placebo Plus Chemotherapy for the Treatment of Chemotherapy-Candidate Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative (HR+/HER2-) Locally Recurrent Inoperable or Metastatic Breast Cancer (KEYNOTE-B49)

Registry

NCT04895358

Study IDs

3475-B49 · MK-3475-B49 (MSD) · KEYNOTE-B49 (MSD) · 2023-506752-24-00 (EU CT) · U1111-1294-3354 (UTN) · jRCT2051210049 (Japan Registry of Clinical Trials (jRCT)) · PHRR210721-003751 (Philippine Health Research Registry (PHRR)) · 2020-005407-38

Sponsor

Merck Sharp & Dohme LLC

Design

Phase 3 · Interventional, randomized, parallel

Status

Active, not recruiting

Enrollment

342 actual

Registered

2021-05-20

Start

2021-06-18 actual

Primary completion

2026-04-24 actual

Primary endpoint

Progression-free Survival (PFS) per Response Evaluation Criteria in Solid Tumors 1.1 (RECIST 1.1) by Blinded Independent Central Review (BICR) in Participants With Combined Positive Score (CPS) ≥1

Interventions

7 registered

This report does not judge efficacy, estimate HCP prevalence or consensus or give treatment advice.

• –Discussion that does not name the trial may be missing from this edition.
• –Not yet captured in this edition: a view on overall survival, CPS-specific progression-free survival and chemotherapy distribution with pembrolizumab plus chemotherapy.
• –Some clinician views in the sources used in this report are not yet captured as evidence in this edition.
• –Some passages in the sources used in this report were not fully assessed for clinician views, so a view there may be missing from this edition.
• –70 statements in the sources reviewed for this edition are about other patients or topics, or only mention the trial, and are not counted.
• –Further source limits: discussion that describes the trial without naming it may be incomplete; some discussion that describes the trial without naming it may be missing; sources about other trials are not included.
• –The sources reviewed for this edition are not a representative sample of HCP opinion. Reposts, quotations and repeated posts cannot be counted as additional independent speakers.
• –Some passages and organizational commentary were not fully assessed, so additional interpretations or qualifications may be absent.
• –Some speakers' identities or clinical roles are not established in the sources used in this report; each statement is attributed only as far as its source shows.
• –A full study protocol was not available for assessment, limiting independent evaluation of amendments and planned analyses.
• –Drug-label review was incomplete, including no exact nab-paclitaxel label. The Japan approval statement applies to October 2026 and cannot establish current or international availability.
• –The publication excerpt supports methods. Efficacy and safety figures in this report are attributed to the commentators who reported them, not independently reconstructed from results tables.
• –Higher-CPS observations include small numbers and secondary-endpoint qualifications. CPS greater than ten and CPS ≥10 are preserved as stated, and a speaker's subgroup label rendered as 19 remains uncertain.
• –Late-tail percentages and terminology differ across authors and have not been harmonized. A speaker's remaining-on wording is not assumed to be a specified PFS rate.
• –OS maturity is described differently by two speakers. The sources do not justify silently reconciling pending mature OS with final OS.
• –The interview's three deaths during the study lack arm and causality information and must not be equated with a reported treatment-related fatal-event rate.
• –Earlier-stage I-SPY 2 evidence, prior metastatic studies and personal treatment experience explain views but are not KEYNOTE-B49 outcomes.

How reports are built and checked: Methods.

Last checked for new commentary Oct 31, 2026. A new or changed finding gets a new version number; added evidence alone is a smaller update. No corrections.

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Help me decide whether to buy the Erudio report "KEYNOTE-B49" (NCT04895358), and buy it for me if I ask. Erudio reports cover what clinicians say in public about one clinical trial, with every verified statement linked to its source.

1. Use the free Erudio MCP server at https://mcp.erudio.com/free; it needs no sign-in. Nothing needs installing: if it is not connected in this app and you can make HTTP requests, call it directly with JSON-RPC POSTs to that URL (initialize, then tools/call), sending "Accept: application/json, text/event-stream". Call get_report_card with slug "keynote-b49-04895358". If you cannot make requests, read https://www.erudio.com/reports/keynote-b49-nct04895358.md instead.
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4. Once it is paid, call get_order with the status_url: it returns my license key. Then use the Erudio MCP server at https://mcp.erudio.com/mcp with the header "Authorization: Bearer <key>". Call read_report with report_id erudio-nct04895358 and sections ["all"], and summarize the findings for me with their sources. The full report is large (about 500 KB): save the response to a file and work from it rather than printing it. If you cannot, read sections ["narratives"] first, the executive summary and analysis.

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get_report_card({ "slug": "keynote-b49-04895358" })