Trial reportESMO open2025
Phase I study of H3B-6545 in patients with estrogen receptor-positive breast cancer.
Trial report in ESMO open, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT04568902 (A Phase 1 Study of H3B-6545 in Japanese Women With Estrogen Receptor-positive, HER2 Negative Breast Cancer), which is not on this map. Cited by 1 paper.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
A Phase 1 Study of H3B-6545 in Japanese Women With Estrogen Receptor-positive, HER2 Negative Breast Cancer
Who cites it
1 citing paper in PubMed.
- STAMBP Accelerates Progression and Tamoxifen Resistance of Breast Cancer Through Deubiquitinating ERα.Biomolecules · 2025Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
11 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundThis phase I study (NCT04568902) evaluated a novel selective estrogen receptor (ER)-α covalent antagonist (H3B-6545) at doses of 300-450 mg in Japanese women with ER-positive, human epidermal growth factor receptor 2 (HER2)-negative, advanced/metastatic breast cancer (mBC). PATIENTS AND
methodsThis study consisted of three parts. In the dose-escalation (DE) part, two dose levels [300 and 450 mg once daily (QD)] were evaluated. The next two parts (antihistamine prophylactic administration and randomization) evaluated oral antihistamines for rash occurrence. Primary endpoints were dose-limiting toxicities (DLTs) and safety; secondary endpoints included objective response rate [ORR; i.e. complete response (CR) + partial response (PR)] and clinical benefit rate [CBR; i.e. CR + PR + stable disease (SD) for ≥23 weeks].
resultsThirty-three patients were enrolled to receive H3B-6545 (300 mg, n = 3; 450 mg with antihistamine, n = 15; 450 mg without antihistamine, n = 15). Median age was 57 years. The median number of prior therapies for mBC was three including fulvestrant (78.8%) and cyclin-dependent kinase 4/6 inhibitors (72.7%). In the DE part, no DLTs were observed with H3B-6545 300 mg. One DLT (grade 3 QT interval prolonged) occurred among six patients with H3B-6545 450 mg. Overall, the most common adverse event (AE) was sinus bradycardia (93.9%); the most common grade 3 AE was anemia (15.2%). No grade 4/5 AEs were reported. Rash maculopapular or rash occurred in 10 of 15 patients (66.7%) given H3B-6545 450 mg QD with prophylactic antihistamines and in 4 of 15 patients (26.7%) not given prophylactic antihistamines. Overall, 1 patient had a PR and 19 had SD; the ORR was 3.0% and the CBR was 33.3%. Of 12 patients with mutant ESR1, the CBR was 66.7% with 1 PR.
conclusionsH3B-6545 at 450 mg QD was tolerated and showed preliminary antitumor effects in Japanese patients with ER-positive, HER2-negative mBC, particularly for those with ESR1 mutations.
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