Clinical Pharmacology at the Intersection of Women's Health and Regulation: Drug Development Considerations for Uterine Fibroids

Relugolix combination therapy in European women with symptomatic uterine fibroids: a subgroup analysis from the randomized phase 3 LIBERTY pivotal trials

OBJECTIVE

In the 24-week, phase 3 LIBERTY 1 (L1) and LIBERTY 2 (L2) trials, relugolix combination therapy (relugolix-CT (relugolix 40 mg, estradiol 1 mg, norethisterone acetate 0.5 mg)) reduced uterine fibroid (UF)-associated symptoms. This post hoc analysis assessed safety and efficacy of relugolix-CT in European women from L1/L2.

METHODS

Premenopausal women (aged 18-50 years) with UF-associated heavy menstrual bleeding (HMB) were randomized 1:1:1 in L1 (N = 388) and L2 (N = 382) to relugolix-CT or placebo for 24 weeks, or delayed relugolix-CT (relugolix 40 mg then relugolix-CT; 12 weeks each). Primary endpoint: proportion of responders (menstrual blood loss (MBL) <80 mL and reduction of ≥50% from baseline MBL volume) over the last 35 days of treatment. Secondary endpoints: MBL volume, amenorrhea, UF-associated pain, symptom severity, distress related to bleeding and pelvic discomfort, health-related quality of life (HRQoL). Safety endpoints included adverse event (AE) reporting and bone mineral density (BMD) assessment.

RESULTS

In European women from L1/L2 (N = 124, 16%), a significantly greater proportion of treatment responders was observed with relugolix-CT vs. placebo (85.4% vs. 19.1%, respectively; nominal p < .0001). There were statistically significant improvements with relugolix-CT vs. placebo for several secondary endpoints: reduction in MBL volume, amenorrhea rate, proportion achieving mild-to-no pain, reduction in symptom severity and distress from bleeding and pelvic discomfort, and improvement in HRQoL. Incidence of AEs and percentage changes in BMD from baseline to week 24 were similar for relugolix-CT and placebo.

CONCLUSIONS

In European women with UF and HMB, once-daily relugolix-CT vs. placebo improved UF-associated symptoms and preserved BMD.

Non-clinical studies indicating lack of interactions between iron/calcium ions and linzagolix, an orally available GnRH antagonist

Linzagolix is an orally available gonadotropin-releasing hormone antagonist used to treat sex-hormone-dependent diseases in women. This study aimed to investigate drug-drug interactions between linzagolix and iron/calcium ions in the intended clinical setting by conducting pharmacokinetic studies in vitro and in rats.Insoluble precipitate formation with metal ions was evaluated by measuring linzagolix concentrations in four types of bio-relevant dissolution media (fasted/fed state simulated gastric fluid and fasted/fed state simulated gastric fluid version 2), and chelate complex formation with metal ions was evaluated by release of linzagolix from a cellulose membrane sac. In these in vitro studies, linzagolix showed no potential for insoluble precipitate formation under fasted/fed conditions and no chelate complex formation in the presence of metal ions.In rats, the plasma concentration-time profiles of linzagolix and iron ion were similar regardless of whether they were administered with or without ferrous sulfate and linzagolix choline at clinically relevant doses. Thus, linzagolix and iron ion had no effect on each other's absorption in vivo.In conclusion, linzagolix is unlikely to cause clinically relevant drug-drug interactions by chelating metal ions according to the results of in vitro and in vivo studies.