NCT05607004Phase 2Active not recruiting

(Z)-Endoxifen for the Treatment of Premenopausal Women With ER+/HER2- Breast Cancer

Study sponsor: Atossa Therapeutics, Inc. · ATOS

Compare the available registry edits below. Primary completion is the date data collection ends for the main study measures; it does not tell you when results will be published.

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Primary completion2026-11Estimated

Enrollment · participants87Estimated

Source updated2026-07-08Last update listed in the registry record

Version history

Changes to this trial

Last 12 months

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Posted 2026-07-08 · 1 field changed

Recruitment status

Recorded edit

− Previous value

Recruiting

+ Updated value

Active not recruiting

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Posted 2025-10-08 · 3 fields changed

Primary outcomes · main study measures

Text edit · unverified significance

− Previous value

measure: PK Cohort - (Z)-endoxifen steady-state plasma concentrations; measure: Treatment Cohort Part 2a - Endocrine sensitive disease rate based on Ki-67 percent after 4 weeks of treatment; measure: Treatment Cohort Part 2b - Endocrine sensitive disease rate based on Ki-67 percentage after 24 weeks of treatment.

+ Updated value

measure: PK Cohort - (Z)-endoxifen steady-state plasma concentrations; measure: For Analysis of Cohort A (Treatment Cohort): determine whether the week 4 Ki-67≤10% rate is at least 65%; measure: For analysis Cohort B (Treatment Cohort): determine the objective tumor response rate at 24 weeks

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Enrollment · participant count

Recorded edit

− Previous value

count: 214; type: ESTIMATED

+ Updated value

count: 87; type: ESTIMATED

Primary completion date

Recorded edit

− Previous value

2026-02

+ Updated value

2026-11

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Study details

Conditions studied

Breast Neoplasms; Invasive Breast Cancer; Estrogen-receptor-positive Breast Cancer; HER2-negative Breast Cancer

Treatments or interventions studied

(Z)-endoxifenDrugAlso known as endoxifen
goserelinDrugAlso known as Zoladex

Primary outcomes · main study measures

Read the study measures

measure: PK Cohort - (Z)-endoxifen steady-state plasma concentrations; description: (Z)-endoxifen steady-state plasma concentrations (Css) of evaluable subjects who completed at least one cycle of treatment (28 +/- 3 days); timeFrame: After 4 weeks of treatment; measure: For Analysis of Cohort A (Treatment Cohort): determine whether the week 4 Ki-67≤10% rate is at least 65%; description: For analysis Cohort A (subjects that have a baseline Ki-67\>10%): the primary objective is to determine whether the Week 4 Ki-67 ≤ 10% rate is at least 65% among premenopausal women with primary estrogen receptor positive (ER+), Human Epidermal Growth Factor Receptor 2 negative (HER2-) breast cancer.; timeFrame: After 4 weeks of treatment; measure: For analysis Cohort B (Treatment Cohort): determine the objective tumor response rate at 24 weeks; description: For analysis Cohort B (subjects have baseline Ki-67≤ 10%): the primary objective is to determine the objective tumor response rate at 24 weeks among premenopausal women with ER+, HER2-, Ki-67 ≤ 10% breast cancer receiving (Z) endoxifen plus goserelin.; timeFrame: After 24 weeks of treatment

History coverage

Research sample: selected versions from May 2023 onward plus a preceding baseline where available. Only selected fields were retained; endpoint measures were truncated to 300 characters. This is not complete trial or sponsor history. Daily snapshots begin when collection starts.

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