for females ages 18 years and up (full criteria)
at San Francisco, California and other locations
study started
estimated completion



The purpose of phase 1 is to determine safety, tolerability and pharmacokinetics (PK) of H3B-6545 in women with locally advanced or metastatic estrogen receptor-positive, human epidermal growth factor 2 (HER2)-negative breast cancer. The purpose of phase 2 is to estimate the efficacy of H3B-6545 in terms of response rate, duration of response (DoR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS).

Official Title

A Phase I-II Multicenter, Open Label Trial of H3B-6545, a Covalent Antagonist of Estrogen Receptor Alpha, in Women With Locally Advanced or Metastatic Estrogen Receptor-positive, HER2 Negative Breast Cancer


Breast Neoplasms Breast Cancer Estrogen-receptor Positive Breast Cancer Cancer, Breast Breast Cancer Female Breast Adenocarcinoma Estrogen Receptor Positive Tumor ER Positive HER2 estrogen receptor H3B-6545 Endocrine Therapy Adenocarcinoma


You can join if…

Open to females ages 18 years and up

  1. Pre- or post-menopausal women.
  2. ER-positive, HER2-negative breast cancer that is advanced or metastatic.
  3. Progressed on prior therapy. Multiple prior lines of therapy allowed in Phase 1 and 2.
  4. Must be willing to undergo a biopsy prior to treatment and on Cycle 2 Day 1.
  5. Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1.
  6. Adequate bone marrow and organ function.

You CAN'T join if...

  1. Participant with bone-only disease (Phase I only). Note: Phase II subjects may have predominantly lytic bone only disease.
  2. Participant with inflammatory breast cancer.
  3. Participant has received more than one prior chemotherapy regimen for metastatic disease (Phase II only).
  4. Females of childbearing potential who are unable or unwilling to follow adequate contraceptive measures.


  • University of California San Francisco
    San Francisco California 94158 United States
  • University of California Los Angeles
    Los Angeles California 90404 United States


in progress, not accepting new patients
Start Date
Completion Date
H3 Biomedicine Inc.
Phase 1/2
Study Type
Last Updated