Genetically-informed therapy for advanced ER+ breast cancer after CDK4/6 inhibitors

Genetically-informed Therapy for ER+ Breast Cancer in a Post-CDK4/6 Inhibitor Setting: a Phase II Umbrella Study (GERTRUDE)

PHASE2 · Dartmouth-Hitchcock Medical Center · NCT05933395

This study is testing different drug combinations to see if they can help post-menopausal women with advanced ER+/HER2- breast cancer who have already been treated with certain medications.

Quick facts

PhasePHASE2
Study typeInterventional
Enrollment135 (estimated)
Ages18 Years and up
SexFemale
SponsorDartmouth-Hitchcock Medical Center (other)
Drugs / interventionsdenosumab, chemotherapy
Locations1 site (Lebanon, New Hampshire)
Trial IDNCT05933395 on ClinicalTrials.gov

What this trial studies

This study aims to evaluate the effectiveness of specific drug combinations in treating post-menopausal women with advanced ER+/HER2- breast cancer who have previously been treated with CDK4/6 inhibitors such as palbociclib, ribociclib, or abemaciclib. The interventions include Fulvestrant, Neratinib, Alpelisib, Everolimus, and Abemaciclib, focusing on patients with metastatic or locally recurrent disease not suitable for curative treatment. The study will assess the response to these therapies to determine their potential benefits in this patient population.

Who should consider this trial

Good fit: Ideal candidates are post-menopausal women aged 18 and older with metastatic ER+ breast cancer or locally recurrent ER+ disease not amenable to curative therapy.

Not a fit: Patients with non-ER+ breast cancer or those who have not been treated with a CDK4/6 inhibitor may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide new effective treatment options for patients with advanced ER+ breast cancer who have limited alternatives after CDK4/6 inhibitor therapy.

How similar studies have performed: Other studies have shown promise in using targeted therapies for ER+ breast cancer, suggesting potential success for this approach.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. Post-menopausal women ≥18 years of age with metastatic ER+ breast cancer, or with locally recurrent ER+ disease not amenable to therapy for curative intent.
2. Patient must be post-menopausal per NCCN guidelines.
3. Patient must have been treated with a CDK4/6i (either palbobclib, ribociclib, or abemaciclib) alone or in combination with an endocrine agent in the advanced disease setting.

   * Up to 3 lines of therapy following CDK4/6i are permissible.
   * Any number of prior lines of endocrine-containing therapy is permissible.
   * Up to 1 prior line of chemotherapy is permissible.
4. Histologic documentation of ER+ breast cancer by core needle biopsy, fine needle aspiration, incisional biopsy, or surgical biopsy of ≥1 site(s) of metastatic or locally recurrent disease performed as standard of care.

   * Exceptions: patients with bone-dominant metastatic disease, or non-bone metastatic disease in whom a safe and accurate biopsy of recurrent/metastatic disease cannot be readily obtained, with a history of ER+ breast cancer are eligible, and biopsy is not required, providing their primary cancer is consistent with the ER criteria described below.
5. ER+ status defined as ER staining by immunohistochemistry in ≥1% of malignant cell nuclei.
6. Tumor must be HER2-non-amplified as defined by an immunohistochemistry score of 0-1+, or with a FISH ratio \<2 if IHC is 2+ or if IHC has not been done (as per ASCO/CAP definitions). In cases of borderline or equivocal HER2 status, eligibility will be determined by the PI.
7. Genetic profiling of a tumor or plasma specimen acquired after disease progression on a CDK4/6i must have been performed in a CAP-accredited, CLIA-certified laboratory using clinically validated methods. Profiling must minimally include analysis of study-relevant alterations in ERBB2, PIK3CA, AKT1, MTOR, PTEN, and RB1.

   * If not done: Profiling of a tumor (preferable) or plasma specimen will be performed as part of the study in the DHMC Pathology Laboratory. A plasma specimen may be obtained for study-specific genetic profiling to direct treatment assignment. Tumor specimens must be obtained outside of this study (e.g., by biopsy).
8. If available, archived tumor tissue must be accessible for research purposes, sufficient to make ≥10 five-micron sections; more tumor tissue is preferred.
9. Radiographic staging performed as standard of care, including specifically either PET/CT, or contrast CT (CAP) and bone scan.
10. Patient must be capable and willing to provide informed written consent for study participation.

Exclusion Criteria:

1. Treatment with abemaciclib in the most recent or current line of therapy.
2. During the study Treatment Phases, no concurrent anti-cancer therapies are allowed with the following exception: anti-resorptive bone therapies (e.g., bisphosphonates, denosumab) are permitted.
3. Any investigational cancer therapy in the last 3 weeks.
4. Known untreated CNS disease, unless clinically stable for ≥ 3 months.

Where this trial is running

Lebanon, New Hampshire

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Advanced Breast Cancer, locally recurrent, metastatic, ER+, ER+/HER2-

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.