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AVZO-023 alone or with AVZO-021 and hormone therapy for advanced HR+/HER2- breast cancer

A Phase 1/2, First-in-human Study to Assess the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Antitumor Activity of AVZO-023 as a Single Agent, and in Combination With AVZO-021 and/or Endocrine Therapy in Patients With Advanced Solid Tumors

PHASE1; PHASE2 · Avenzo Therapeutics, Inc. · NCT06998407

This will test whether the oral drug AVZO-023, given alone or with AVZO-021 and hormone therapy, is safe and can help control advanced HR+/HER2- breast cancer.

Quick facts

PhasePHASE1; PHASE2
Study typeInterventional
Enrollment380 (estimated)
Ages18 Years and up
SexAll
SponsorAvenzo Therapeutics, Inc. (industry)
Drugs / interventionsimmunotherapy, radiation
Locations14 sites (Los Angeles, California and 13 other locations)
Trial IDNCT06998407 on ClinicalTrials.gov

What this trial studies

AVZO-023 is an oral, selective CDK4 inhibitor being given for the first time in humans to patients with HR+/HER2- locally advanced or metastatic breast cancer. Phase 1 uses dose escalation to define safety, tolerability, pharmacokinetics, pharmacodynamics, and a recommended Phase 2 dose for AVZO-023 alone and in combination with AVZO-021 with or without endocrine therapy. Phase 2 will test antitumor activity and confirm the recommended dose in combination regimens. Key requirements include measurable disease, adequate organ function, ECOG 0-1, and no prior selective investigational CDK inhibitor exposure.

Who should consider this trial

Good fit: Adults with HR+/HER2- locally advanced or metastatic breast cancer who have ECOG 0-1, measurable disease, adequate organ function, and no prior selective CDK inhibitor therapy are ideal candidates.

Not a fit: Patients with active untreated brain metastases, prior exposure to selective CDK2/4/6 inhibitors, or inadequate organ function are unlikely to benefit or be eligible.

Why it matters

Potential benefit: If successful, this approach could provide a new oral targeted option that better controls tumor growth in HR+/HER2- advanced breast cancer.

How similar studies have performed: Approved CDK4/6 inhibitors combined with endocrine therapy have improved outcomes in HR+/HER2- breast cancer, but AVZO-023 is a first-in-human agent and its specific effects are untested.

Eligibility criteria

Show full inclusion / exclusion criteria 
Key Inclusion Criteria:

* Male or female aged ≥ 18 years old at screening with Eastern Cooperative Oncology Group (ECOG) 0-1 and life expectancy \> 3 months
* Patients with histologically or cytologically proven advanced malignancies of preferred indications
* Measurable disease (as assessed by investigator using RECIST v1.1) is preferred in Phase 1 dose escalation, unless otherwise specified in the protocol, and in all patients in Phase 2. Bone only disease is allowed in dose escalation.
* Agree to provide molecular test report results to confirm eligibility and archival tumor samples and/or fresh biopsy, as applicable
* Adequate renal, liver, and bone marrow function

Key Exclusion Criteria:

* Patients should not have received any prior selective investigational CDK (CDK2, CDK4, CDK2/4, CDK2/4/6) inhibitors
* Has known active brain metastasis (have either previously untreated intracranial CNS metastasis or previously treated intracranial central nervous system (CNS) metastasis with radiologically documented new or progressing CNS lesions) or leptomeningeal disease
* Other concurrent invasive malignancy or a prior invasive malignancy for which treatment was completed within 3 years before the first dose on study except for adequately treated basal cell or squamous cell skin cancer, carcinoma in situ, or colorectal adenomatous polyps
* Last anticancer treatment within 2 weeks (4 weeks for biologic, immunotherapy or ADC) or 5 half-lives of the drug, whichever is shorter, prior to first dose on study
* Major surgery within 4 weeks prior to first dose on study
* Have received radiotherapy with a limited field of radiation for palliation within 7 days of the first dose of study treatment, except for patients receiving whole brain radiotherapy, which must be completed at least 4 weeks prior to the first dose of study treatment. Patients must have recovered from all radiation-related toxicities, not require corticosteroids, and not have active radiation pneumonitis
* Strong or moderate CYP3A4 inhibitors or inducers within 2 weeks or 5 half-lives of the drug, whichever is shorter, prior to first dose on study
* History of serious cardiovascular conditions within 6 months prior to first dose on study
* Unresolved toxicities from prior therapy greater than Grade 1 (per CTCAE version 5.0) (with exceptions of alopecia, vitiligo, and ≤ Grade 2 peripheral neuropathy) prior to the first dose on study
* History of drug-induced pneumonitis/interstitial lung disease
* Confirmed loss of function mutation or deletion of Rb1 gene

Where this trial is running

Los Angeles, California and 13 other locations

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: HR+/HER2- Breast Cancer, HR+, HER2-, Advanced Breast Cancer

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.