🏛️ Verified NIH Record • Updated 2026-06-24

Phase III Study to Assess AZD9833+ CDK4/6 Inhibitor in HR+/HER2-MBC With Detectable ESR1m Before Progression (SERENA-6) (NCT04964934)

A Phase III, Double-blind, Randomised Study to Assess Switching to AZD9833 (a Next Generation, Oral SERD) + CDK4/6 Inhibitor vs Continuing Aromatase Inhibitor (Letrozole or Anastrozole)+ CDK4/6 Inhibitor in HR+/HER2-MBC Patients With Detectable ESR1Mutation Without Disease Progression During 1L Treatment With Aromatase Inhibitor+ CDK4/6 Inhibitor- A ctDNA Guided Early Switch Study

🔵 Active, Not Recruiting Phase3 💊 Investigational Drug / Biologic Sponsor: AstraZeneca

🩺 Plain-English Summary (8th-Grade Level)

The study is intended to show superiority of AZD9833 in combination with CDK4/6 inhibitor (palbociclib, abemaciclib or ribociclib) versus aromatase inhibitors (anastrozole or letrozole) in combination with CDK4/6 inhibitor in patients with hormone receptor-positive (HR-positive), human epidermal growth factor receptor 2-negative (HER2-negative) metastatic breast cancer with detectable ESR1 mutation.

Who can join: To join this study, participants generally need to meet the listed inclusion criteria (15 items) and avoid the listed exclusions (11 items).

Location: Research Site — Phoenix, Arizona

Age range: 18 Years to 130 Years

🧪 Interventions in This Study

📋 "Do I Qualify?" — 1-Minute Self Screener

Instant Checklist

Check every box below. If you can check all of them, you may meet the study's basic screening requirements (final eligibility is confirmed by the site team).

Usually NOT eligible if any of the following apply:

  • EXCLUSION CRITERIA: INFORMATION FOR TRIAL PARTICIPANTS - Participants cannot join the trial if they:
  • Had certain types of tumors in the past that may come back;
  • Are currently taking any other treatments for their cancer or other conditions including hormone replacements, medications, or supplements that could interfere with the trial treatment;
  • Have or have had any major health problem, infection, or recent surgery that could make it difficult or dangerous to participate in this trial. Full list of exclusion criteria:
  • Advanced, symptomatic, visceral spread, that are at risk of life-threatening complications in the short term;
  • Known active uncontrolled or symptomatic CNS metastases, carcinomatous meningitis, or leptomeningeal disease;
  • Any evidence of severe or uncontrolled systemic diseases which, in the investigator's opinion, makes it undesirable for the participant to participate in the study or that would jeopardize compliance with the protocol;
  • Patient with known or family history of severe heart disease;
  • Previous treatment with AZD9833, investigational SERDs or fulvestrant;
  • Currently pregnant (confirmed with positive pregnancy test) or breastfeeding;
  • Persistent non-haematological toxicities (CTCAE Grade \> 2) caused by CDK4/6 inhibitor and/or AI treatment.

🔍 Extracted verbatim from the official NIH eligibility criteria. Always confirm with the study coordinator.

📍 All Participating Trial Locations (264 Sites)

Showing the first 25 of 264 sites.

  • Research Site — Phoenix, Arizona
  • Research Site — Hot Springs, Arkansas
  • Research Site — Little Rock, Arkansas
  • Research Site — Long Beach, California
  • Research Site — San Diego, California
  • Research Site — Santa Rosa, California
  • Research Site — Grand Junction, Colorado
  • Research Site — Lone Tree, Colorado
  • Research Site — Fort Myers, Florida
  • Research Site — Jacksonville, Florida
  • Research Site — Jacksonville, Florida
  • Research Site — St. Petersburg, Florida
  • Research Site — Atlanta, Georgia
  • Research Site — Atlanta, Georgia
  • Research Site — Atlanta, Georgia
  • Research Site — Park Ridge, Illinois
  • Research Site — Fort Wayne, Indiana
  • Research Site — Indianapolis, Indiana
  • Research Site — Baltimore, Maryland
  • Research Site — Boston, Massachusetts
  • Research Site — Fairhaven, Massachusetts
  • Research Site — Foxborough, Massachusetts
  • Research Site — Milford, Massachusetts
  • Research Site — South Weymouth, Massachusetts
  • Research Site — Detroit, Michigan

💰 Cost, Insurance & Patient Rights

  • 100% Free Items: The investigational treatment and protocol-required procedures are supplied at zero cost by the sponsor.
  • Routine Patient Care: Under federal law (ACA § 2709) and many state statutes, routine care costs are covered during participation.
  • Voluntary Participation: You may withdraw at any time without affecting your standard medical care.

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💡 How to Participate

  1. Check the checklist above to see if you may qualify.
  2. Review the official NIH record below to find the coordinating site.
  3. Ask about the visit schedule, what is covered at no cost, and any travel support.
  4. Confirm with your own doctor before making a decision.
🏛️ View Official NIH Record ↗