Neu Direction: Testing the Efficacy of Adding HER Inhibition to Standard of Care in Metastatic MLH1-low Endocrine-resistant ER+/HER2- Breast Cancer

July 22, 2026 updated by: Asona Juwan Lui, University of California, San Diego

Neu Direction: A Single Center Phase II Randomized Clinical Trial to Assess the Efficacy of Adding HER Inhibition to Standard of Care in Patients With Metastatic MLH1-low Endocrine-resistant ER+/HER2- Breast Cancer

The goal of this clinical trial is to learn if neratinib, an FDA-approved oral pan-HER2/3/4 inhibitor, improves disease control for participants with metastatic endocrine-resistant ER+/HER2-negative breast cancer. Neratinib is already approved for the treatment of HER2-postive breast cancers. The study will also learn about the safety of adding this drug to standard of care treatments. The main questions it aims to answer are:

  1. Does adding neratinib to standard of care systemic therapy improve disease control for patients with metastatic hormone-driven breast cancer that is resistant to endocrine therapy?
  2. What side effects do participants have when adding neratinib to standard of care therapy? Researchers will compare standard of care endocrine therapy regimens with and without neratinib to see if neratinib improves control of treatment-resistant metastatic breast cancer that has continued to progress while eon first line endocrine therapy.

Participants will:

  1. Take standard of care endocrine therapy for metastatic endocrine-resistant breast cancer as determined by their medical oncologist or standard of care therapy with neratinib daily
  2. Visit the clinic every 3 months for checkups, tests and imaging studies

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

This is a prospective 2-arm Phase II study testing the efficacy of adding neratinib to standard of care therapy in patients with MLH1-low ER+/HER2- endocrine-resistant breast cancer . Patients with endocrine-resistant ER+/HER2- breast cancer who have lesions visible on CT scan will be recruited as they are seen in breast medical oncology and radiation oncology clinics at UC San Diego Health. Patients will be eligible if they have measurable persistent, recurrent, progressive or metastatic disease on imaging (including FDG PET scan) while on endocrine therapy. At least one lesion must be biopsied and confirmed ER+ by immunohistochemistry and HER2- within 6 months of study screening. Genomic mutation profile will be analyzed along with trial results to identify other potential mutations associated with MLH1 expression and/or neratinib response. Participants will be stratified by nuclear MLH1 expression on their biopsy tissue using immunohistochemistry. MLH1negative (nuclear MLH1 detectable in <5% of tumor cells) and MLH1-low patients (<50% tumor cells positive) hereafter grouped as "MLH1-low" will be randomized to standard of care without (75 participants) or with (75 participants) the addition of neratinib in Arm 1 and Arm 2 respectively . Standard of care therapy can include any endocrine therapy with or without CDK4/6 inhibitors. Prior exposure to CDK4/6 inhibitors is acceptable but not prior HER2-targeted therapy. Neratinib will be administered with a standard ramp up to therapeutic dose to minimize side effects with 120mg daily for 1 week, 160mg daily for 1 week and then 240mg daily thereafter. Treatment response will be monitored via imaging every 3 months while on study and measured using RECIST v. 1.1 criteria and/or mPERCIST criteria as appropriate using FDG-PET. Participants will remain on study until cessation due to side effects or disease progression. Biopsy at disease progression will be encouraged but not required.

Study Type

Interventional

Enrollment (Estimated)

150

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • United States
    • California
      • La Jolla, California, United States, 92037
        • UC San Diego Health Moores Cancer Center
        • Contact:
        • Principal Investigator:
          • Asona Lui, MD, PhD
        • Sub-Investigator:
          • Alyssa Beck, MD
        • Sub-Investigator:
          • Svasti Haricharan, PhD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Female over the age of 18 at the time of study enrollment
  2. Not pregnant, planning to become pregnant or breast feeding
  3. Metastatic ER+/HER2- breast cancer that has progressed on 1st line therapy including endocrine therapy +/- CDK4/6 inhibitors
  4. At least one metastatic lesion visible on imaging (including FDG-PET)
  5. At least one metastatic lesion must be biopsied and confirmed ER+ and HER2- by immunohistochemistry within 6 months of study screening (HER2 equivocal disease will be confirmed HER2- by FISH)
  6. Tumors must be MLH1-low defined by <50% tumor cells positive for nuclear MLH1 expression on immunohistochemistry
  7. Standard of care next line endocrine therapy can include any endocrine therapy
  8. Performance status ECOG > 3
  9. Life expectancy > 1 year
  10. Ability to get serial imaging studies

Exclusion Criteria:

  1. History of concurrent use of other HER2-targeted therapy
  2. Concurrent use of other targeted systemic therapy
  3. History of other cancers other than non-melanoma skin cancer
  4. Actionable mutations on tumor genomic sequencing will be ineligible, and those participants encouraged to proceed with the relevant targeted therapy
  5. Participants where there is not at least one imaging apparent lesion that has not been treated with prior targeted therapy (for example palliative radiation or cryoablation)
  6. Contraindications to Neratinib use including allergy or hypersensitivity
  7. Baseline grade 3+ diarrhea

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Standard of Care
Standard of Care 2nd or 3rd line endocrine therapy with or without CDK4/6 inhibitor
Drug: Endocrine therapy may include one of the following therapies: letrozole, anastrozole, exemestane, tamoxifen or fulvestrant
Endocrine therapy with out without CDK4/6 inhibitor
Drug: CDK4/6 + Endocrine therapy
Endocrine therapy with or without CDK 4/6 inhibitor
Experimental: Stanard of Care + Neratinib
Standard of Care 2nd or 3rd line endocrine therapy with or without CDK4/6 inhibitor + Neratinib
Drug: CDK4/6 + Endocrine therapy
Endocrine therapy with or without CDK 4/6 inhibitor
Drug: Neratinib + endocrine therapy
Neratinib 120mg daily for 1 week, 160mg daily for 1 week and then 240mg daily thereafter
Other Names:
  • neratinib

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Median Progression-Free Survival
Time Frame: From enrollment through study completion, an average of 1 year.
From enrollment through study completion, an average of 1 year.
Number of participants with treatment-related adverse events as assessed by CTCAE v4.0
Time Frame: From enrollment through study completion, an average of 1 year.
Adverse events will be quantified using the CTCAE v4.0 every 3 months
From enrollment through study completion, an average of 1 year.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of California, San Diego

Investigators

  • Principal Investigator: Asona Lui, MD, PhD, UC San Diego

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

July 1, 2027

Primary Completion (Estimated)

May 1, 2032

Study Completion (Estimated)

June 1, 2035

Study Registration Dates

First Submitted

July 14, 2026

First Submitted That Met QC Criteria

July 22, 2026

First Posted (Actual)

July 27, 2026

Study Record Updates

Last Update Posted (Actual)

July 27, 2026

Last Update Submitted That Met QC Criteria

July 22, 2026

Last Verified

July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • BC250474 (Other Grant/Funding Number: Congressionally Designated Medical Research Program (CDMRP), US ARMY MEDICAL RESEARCH ACQUISITION ACTIVITY)
  • 813310 (Other Identifier: UC San Diego Institutional Review Board (IRB))

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Only IPD used in the results publication

IPD Sharing Time Frame

Beginning 6 months and ending 3 years after publication of results

IPD Sharing Access Criteria

Proposal that describes planned analyses must be submitted and approved by the Principle Investigator, Asona Lui and data sharing agreement must be signed with the requesters institution. Evidence of IRB approval must be provided by the requestor prior to the sharing of any data.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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