PMON69 Effective Suppression of Gonadotropins and Gonadal Steroids Following Oral Administration of Leuprolide

A platform designed to enable systemic delivery of peptides via the oral-GI route was employed to deliver low doses of leuprolide --- 4 mg qd (Treatment A, n=9), 4 mg bid (Treatment B, n=9), and 10 mg bid (Treatment D, n=12) --- daily for 28 days to regularly-menstruating, healthy female volunteers. Pharmacodynamic (PD) effects on LH, FSH, estradiol, and progesterone, along with leuprolide drug levels, were assessed weekly and compared to those following a single intramuscular injection of leuprolide acetate 3.75 mg (Treatment C, n=5) in a parallel-group design. The primary PD endpoint was the subject incidence of E(2) suppression to ≤40 pg/mL on Treatment Day 29; additional endpoints --- E2 suppression rates on Treatment Days 8, 15 and 22, incidence of 'ovulation' defined as progesterone level ≥3 ng/mL, and suppression of LH and FSH levels --- were assessed on Treatment Days 8, 15, 22, and 29. Safety and tolerability of the test drugs was also assessed. Dose-dependent suppression of E(2) was seen, with 66.7%, 87.5%, 100% and 100% of subjects in Treatments A, B, C and D, respectively, achieving E(2) ≤40 pg/mL. Median E(2) levels on days 15, 22, and 29 were <40 pg/mL after 4 mg bid po, and <20 pg/mL after both 10 mg bid po and the 3.75 mg injection. 'Ovulation rates’ on days 22 and 29 were 0% after both 10 mg bid po and 3.75 mg im. Because of the initial burst following injection of the monthly depot, leuprolide Cmax was greater in Treatment C (17.5 ±2.7 ng/mL) on Dosing Day 1 than for oral leuprolide (3.7 ±3.2 ng/mL for 4 mg qd, 4.1 ±5.1 ng/mL for 4 mg bid), though by Day 29, Css in Treatment C (1.7 ±1.2 ng/mL) was lower than that day's Cmax for oral leuprolide (2.7 ±3.6 ng/mL for 4 mg qd, 4.8 ±6.2 ng/mL for 4 mg bid). Cmax and AUC0-24h were dose-dependent but not strictly dose-proportional. Leuprolide "trough" levels prior to oral dosing were frequently below LLQ (25 pg/mL) in subjects treated with 4 mg qd; this occurred in only 6% of samples on 10 mg bid, and 0% on 4 mg bid, thus confirming reliability of oral delivery of leuprolide. There were no Serious or severe Adverse Events, nor changes in laboratory values of concern. One subject discontinued the study due to a transient episode of nausea, vomiting, and headache during her initial dose of 4 mg po. A total of 80 AEs were treatment-emergent, generally mild in intensity, and spread relatively evenly across all 4 treatment groups. This investigation confirms effective suppression of gonadal steroids via oral administration of leuprolide, comparable to that of injectable leuprolide, and to some marketed doses of GnRH antagonists (historical data). Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.