NCT07401381

A Study to Compare the Steady-State Bioavailability of Injectable Letrozole SIE and Oral Letrozole in Post-Menopausal Women With Hormone Receptor Positive Early Breast Cancer

An Open-Label, One-Sequence Study to Evaluate the Steady-State Comparative Bioavailability of Quarterly Letrozole SIE and Once Daily 2.5 mg Oral Letrozole (Femara®) in Post-Menopausal Women Treated With Endocrine Therapy for Hormone Receptor-Positive Early Breast Cancer. (SIE-1)

• Status: Not Yet Recruiting
• Phase: Phase 1
• Study type: Interventional
• Enrollment: 120 (estimated)
• Sponsor: Rovi Pharmaceuticals Laboratories · Industry
• Sex: Female
• Age: 18 Years – 80 Years
• Healthy volunteers: Not accepted

Summary

The study aims to compare the amount of the drug letrozole that gets into the bloodstream after multiple doses of the quarterly injection Letrozole SIE, versus multiple doses of the standard oral daily tablet of letrozole (Femara®), in women who have gone through menopause and have received treatment for hormone receptor-positive early breast cancer. Participants must have completed at least five years of hormone therapy with at least two of those years with letrozole before starting their participation in the study. Women who have completed four years of hormone therapy are also eligible if their doctor considers them at low risk of cancer returning.

Detailed description

The primary objective of the study is to evaluate the steady-state comparative bioavailability of quarterly injectable Letrozole SIE compared to United States (US)-sourced oral Femara® in the US-sourced arm and of quarterly injectable Letrozole SIE compared to European Union (EU)-sourced oral Femara® in the EU-sourced arm, in post-menopausal women treated with endocrine therapy for hormone-receptor positive (HR+) early breast cancer (EBC). The study also aims to characterize the elimination phase of Letrozole SIE after multiple doses. The study consists of four periods: Screening, Treatment Period 1 (TP1), Treatment Period 2 (TP2) and Extension Period. After the Screening Period, participants will be randomized to two different arms: US-sourced oral Femara® or EU-sourced oral Femara® for 14 days to achieve the steady-state concentrations of letrozole in TP1. After receiving the latest oral letrozole dose, participants from both arms will start TP2. In TP2, quarterly injectable Letrozole SIE will be administered to achieve steady-state. After TP2, a subset of participants (up to 60 participants, regardless of which study arm they belong to) will continue in the study for the assessment of the elimination phase of Letrozole SIE after multiple doses during the Extension Period. It is estimated that approximately 120 subjects should be randomized.

Conditions

• Hormone Receptor Positive Early Breast Cancer

Interventions

Type	Name	Description
DRUG	US-sourced oral Femara® + Letrozole SIE	US-sourced Femara® 2.5 mg/day oral for 14 days (treatment period 1) + quarterly injectable Letrozole SIE (treatment period 2)
DRUG	EU sourced oral Femara® + Letrozole SIE	EU-sourced oral Femara® 2.5 mg/day for 14 days (treatment period 1) + quarterly injectable Letrozole SIE (treatment period 2)

Timeline

• Start date: 2026-03-01
• Primary completion: 2028-05-01
• Completion: 2028-10-01
• First posted: 2026-02-10
• Last updated: 2026-02-10

Regulatory

• FDA-regulated drug study