Dataset Information

Relugolix, an oral gonadotropin-releasing hormone (GnRH) receptor antagonist, in women with endometriosis-associated pain: phase 2 safety and efficacy 24-week results.

ABSTRACT:

Background

Relugolix is a once-daily, oral, nonpeptide, gonadotropin-releasing hormone receptor antagonist. The aim of this study was to evaluate safety of relugolix over 24 weeks in women with endometriosis-associated pain.

Methods

This phase 2, randomized, open-label, parallel-group extension study was conducted in 101 clinics in Japan. Patients (premenopausal females ≥ 20 years) who completed the preceding 12-week relugolix phase 2 study continued to receive relugolix (10 mg, 20 mg, or 40 mg), placebo, or leuprorelin (3.75 mg) for an additional 12 weeks. Relugolix was administered orally once daily, and leuprorelin subcutaneously once every 4 weeks. The primary outcome was safety, including bone mineral density (BMD) and treatment-emergent adverse events (TEAEs). Secondary endpoints included visual analog scale (VAS) scores for endometriosis-associated pain. Analysis sets were defined as all patients who were administered the study drug.

Results

Of 487 randomized patients in the preceding study, 397 enrolled in this extension study and continued to receive placebo (n = 77), relugolix 10 mg (n = 84), relugolix 20 mg (n = 78), relugolix 40 mg (n = 89), or leuprorelin (n = 69). Baseline characteristics were similar between extension study patients and patients in the preceding study. Frequency of TEAEs including metrorrhagia, menorrhagia, and hot flush was similar in the relugolix 40-mg and leuprorelin groups. Mean (SD) change in BMD from baseline at Week 24 was - 0.2 (1.99)% for placebo; - 1.6 (2.34)%, - 2.6 (2.94)%, and - 4.9 (2.91)% for the relugolix 10-mg, 20-mg, and 40-mg groups, respectively; and - 4.4 (2.16)% for leuprorelin. Mean ± SD change from baseline in mean VAS score (mm) for pelvic pain at end of treatment was - 3.2 ± 12.16 for placebo; - 6.8 ± 10.56, - 9.0 ± 11.84, and - 11.9 ± 11.26 for the relugolix 10-mg, 20-mg, and 40-mg groups, respectively; and - 12.7 ± 12.57 for leuprorelin. Estradiol levels decreased with increasing relugolix dose and remained below postmenopausal levels throughout the 24-week relugolix 40-mg treatment period.

Conclusions

Treatment with relugolix for 24 weeks was generally well tolerated and demonstrated similar pain reduction to leuprorelin in women with endometriosis. The dose-dependent loss in BMD observed with relugolix treatment was expected due to an induced hypoestrogenic state. Relugolix demonstrated a similar benefit/risk profile to injectable therapy in this phase 2 study. Trial registration NCT01452685 (ClinicalTrials.gov, registered 17/10/2011).

SUBMITTER: Osuga Y

PROVIDER: S-EPMC8218467 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Gonadotropin-releasing hormone (GnRH) regulates reproduction. The human GnRH receptor lacks a cytoplasmic carboxy-terminal tail but has amino acid sequence motifs characteristic of rhodopsin-like, class A, G protein-coupled receptors (GPCRs). This review will consider how recent descriptions of X-ray crystallographic structures of GPCRs in inactive and active conformations may contribute to understanding GnRH receptor structure, mechanism of activation and ligand binding. The structures confirmed that ligands bind to variable extracellular surfaces, whereas the seven membrane-spanning ?-helices convey the activation signal to the cytoplasmic receptor surface, which binds and activates heterotrimeric G proteins. Forty non-covalent interactions that bridge topologically equivalent residues in different transmembrane (TM) helices are conserved in class A GPCR structures, regardless of activation state. Conformation-independent interhelical contacts account for a conserved receptor protein structure and their importance in the GnRH receptor structure is supported by decreased expression of receptors with mutations of residues in the network. Many of the GnRH receptor mutations associated with congenital hypogonadotropic hypogonadism, including the Glu2.53(90) Lys mutation, involve amino acids that constitute the conserved network. Half of the ~250 intramolecular interactions in GPCRs differ between inactive and active structures. Conformation-specific interhelical contacts depend on amino acids changing partners during activation. Conserved inactive conformation-specific contacts prevent receptor activation by stabilizing proximity of TM helices 3 and 6 and a closed G protein-binding site. Mutations of GnRH receptor residues involved in these interactions, such as Arg3.50(139) of the DRY/S motif or Tyr7.53(323) of the N/DPxxY motif, increase or decrease receptor expression and efficiency of receptor coupling to G protein signaling, consistent with the native residues stabilizing the inactive GnRH receptor structure. Active conformation-specific interhelical contacts stabilize an open G protein-binding site. Progress in defining the GnRH-binding site has recently slowed, with evidence that Tyr6.58(290) contacts Tyr5 of GnRH, whereas other residues affect recognition of Trp3 and Gly10NH2. The surprisingly consistent observations that GnRH receptor mutations that disrupt GnRH binding have less effect on "conformationally constrained" GnRH peptides may now be explained by crystal structures of agonist-bound peptide receptors. Analysis of GPCR structures provides insight into GnRH receptor function.