ABSTRACT
CONTEXT: Clinical trials using 80 mg once weekly pegvisomant (pegV) in active acromegaly led to a 30% fall in serum IGF1. Subsequent studies demonstrated that daily administration of up to 40 mg/day achieved an IGF1 within reference range in 97% of patients. PegV has a half-life of >70 h suggesting weekly dosing may be possible but using higher doses than in the initial trials. OBJECTIVE: To determine the efficacy of weekly dosing of pegV. DESIGN: A two center, open-label prospective study in patients with acromegaly converted from a stable daily dose of pegV (median dose 15 mg daily (range 10-20 mg od), IGF1 normal for 3 months prior to inclusion) to twice-weekly (week 0-16) followed by once-weekly (week 16-32) administration. RESULTS: Seven patients (4M, age 57+/-7 years, 6/7 prior transsphenoidal surgery, 7/7 prior radiotherapy) were recruited. Six patients completed the twice-weekly and five patients both the twice-weekly and once-weekly administration. Headaches led to two patient withdrawals at 0+24 weeks. Mean pre-dose serum IGF1 levels remained stable with the different administration regimens (IGF1 baseline 145+/-39 ng/ml, twice-weekly 124+/-39 ng/ml and once-weekly 127+/-22 ng/ml) and all values were within age adjusted IGF1 reference range. PegV dose was reduced in two patients and five opted to continue weekly administration at trial termination. Safety and quality of life parameters remained stable. CONCLUSIONS: Twice and once-weekly administration of pegV is effective in controlling serum IGF1 levels in acromegaly and although not formally assessed, continuation of weekly dosing in five patients at study conclusion suggests patient preference for this regimen.
