The latest safety and efficacy data of patients treated with Pegvisomant
I Schreiber, K Forssmann, M Buchfelder, M Droste, K Mann, B Saller & CJ Strasburger
The German Acrostudy is at present the largest database on acromegalics (n=184) treated with pegvisomant (Somavert®). 91% pts underwent pituitary surgery, 45% received radiation therapy, and previous medical therapy included dopamine agonists (56%), octreotide (90%) and/or lanreotide (10%). Common concomitant diseases at baseline were hypertension (47.0%), diabetes mellitus (31.7%), and gallstone disease (25.6%). Efficacy analysis was performed in 134 pts with a follow-up after 6 months, in 99 pts after 12 months and in 22 pts after 2 years. Mean duration of pegvisomant therapy was 42.2±30.0 wks. IGF-I was normalized in 65.4% at 6 months with a median dose of 15.0 mg/d and in 90.2% of pts treated for at least 2 years. The fasting glucose levels improved significantly from 117.3±49.5 mg/dl to 105.0±44.9 mg/dl after 6 months and 100.7±34.0 mg/ml after 12 months respectively. General physical condition measured by specific sign and symptom score improved significantly. Elevated liver function tests (LFTs) >3 times above normal occurred in 9 pts receiving octreotide before. In 6/9 pts, LFTs spontaneously normalized during continued treatment, in 3 pts (1.6%), levels normalized after discontinuation. With exception of one patient with transient LFT elevation due to alcohol excess, ALT was the enzyme most prominently elevated. Progression of remnant pituitary adenoma was reported in a total of 9 pts. 7 cases were re-evaluated by a independent neurosurgeon. In 3 pts tumor progression could not be verified at re-evaluation. In 2 pts, the tumor continuously grew already on somatostatin analogues. In one case, a slight and clinically non-significant growth was confirmed during pegvisomant therapy and one case showed a tumor growth due to rebound from somatostatin-induced shrinkage. In conclusion, Pegvisomant is generally well tolerated with a safety profile similar to that reported in clinical trials, and can effectively reduce IGF-I in pts refractory to conventional therapy.