Phase 1 letrozole SIE study compares quarterly injectable and daily oral aromatase-inhibitor exposure

ROVI Pharmaceuticals Laboratories is running an open-label, one-sequence pharmacokinetic study comparing a long-acting quarterly injectable letrozole formulation with standard daily oral letrozole. Letrozole inhibits aromatase and lowers estrogen production. Participants receive US- or EU-sourced oral letrozole 2.5 mg daily for 14 days and then switch to the injectable formulation, allowing within-patient comparisons of steady-state exposure and tolerability.

The study enrolls postmenopausal women with HR-positive early breast cancer who have completed at least 5 years of adjuvant endocrine therapy, including at least 2 years of letrozole, with an allowance for selected lower-risk patients after 4 years. Its purpose is formulation and pharmacokinetic bridging, not to show better recurrence prevention or tumor shrinkage. A quarterly formulation could reduce the burden of daily tablets, but this study must first establish its exposure profile and safety; improved adherence and equivalent long-term cancer outcomes should not be assumed from the dosing interval alone.