6-Month Subcutaneous Leuprolide Acetate Effectively Suppresses Clinical Signs of Puberty in Children With Central Precocious Puberty

Abstract

Objective: Gonadotropin-releasing hormone (GnRH) agonists, such as intramuscular leuprolide acetate, triptorelin and the subcutaneous histrelin implant, are standard treatment for central precocious puberty (CPP). Implants require surgery and sometimes anesthesia, while frequent intramuscular injections can be painful. A shift to longer acting-formulations and subcutaneous injections has been proposed for the treatment of CPP. Therapies with convenient administration, prolonged duration of action and favorable safety profile may be beneficial, improving patient adherence. 87% of subjects achieved stimulated LH suppression to <4 IU/L by Week (W) 24 in a Phase III trial evaluating the efficacy and safety of the first6-month subcutaneous injectable in situ gel leuprolide acetate for CPP. We present secondary analyses of bone age (BA) advancement, weight, BMI, and pubertal maturation from this trial. Methods: 62 children (60 girls, 2 boys) with CPP (naïve to treatment) received 2 doses of 45 mg subcutaneous leuprolide acetate at 24-week intervals, constituting the intent-to-treat population. Radiographs of the left hand and wrist were used to determine BA using the Greulich and Pyle method. BA was assessed by a blinded central reader. Rate of BA advancement was determined by the ratio of BA to chronological age (CA, BA/CA). Pubertal maturation was categorized with the Tanner staging system using breast development, external genitalia, and pubic hair. Safety outcomes were measured. Results: Mean age at onset of treatment was 7.5 ± 0.9 (SD) (range 4-9) years. BA/CA consistently declined throughout treatment, from 1.4 ± 0.2 at baseline, to 1.3 ± 0.1 at W24 and 1.3 ± 0.1 at W48. Although mean weight increased 8.7% from screening to W24 (34.8 kg vs 37.7 kg) and 16.9% from screening to W48 (40.4 kg), mean BMI remained stable throughout the study. The proportion of girls with early breast Tanner stage development (stage 1 and 2) increased from 9% at baseline to 37% at W48. The proportion of girls with late breast Tanner stage development (stage 4 and 5) decreased from 18% at baseline to 5% at W48. Both boys regressed from Tanner stage 3 to stage 2 for external genitalia development by W48. Tanner staging for pubic hair development remained stable for approximately 80% and decreased for 7% of children by W48. 52/53 treatment emergent adverse events were mild or moderate. Conclusions: 6-month 45 mg subcutaneous leuprolide acetate is a promising treatment for CPP. It effectively suppressed LH, suppressed clinical signs of pubertal maturation and demonstrated a good safety profile. It also has the beneficial features of subcutaneous administration, small injection volumeand twice a year dosing. This may be a welcome addition to the armamentarium given the proposed shift in CPP therapies towards longer-acting formulations and subcutaneous injections.