Lanreotide 60 mg, a longer-acting somatostatin analog: Tumor shrinkage and hormonal normalization in acromegaly

Background: Somatostatin analogues are nowadays the milestone in the medical treatment of acromegaly. We evaluated the effects of a new 60 mg longer-acting formulation of lanreotide (LAN60) on GH/IGF-I levels and tumor size. Patients: Twenty-one acromegalics entered a prospective monocentric open study. Eight were consecutive "de novo" patients (group I). Thirteen patients sensitive to SA (GH levels <2.5 μg/l and/or IGF-I normalization on chronic LAN 30 mg (LAN30) treatment) were switched to LAN60 (group II). Protocol: LAN60 was administered IM for 6 cycles at 28 day intervals. In group I when GH/IGF-I remained pathological, the intervals were shortened to 21 days for the last three cycles. Controls: GH/IGF-I at the end of the 1st, 3rd and 6th cycle; MRI at the end of the study in all patients in group I bearing an adenoma. Results: Group I.GH (p = 0.00638, below 2.5 μg/l in two patients) and IGF-I (p = 0.0289, normalized in 5) significantly decreased. In one of two patients shortening the LAN60 schedule was more effective in suppressing GH/IGF-I. Group II. No change in GH and IGF-I levels was observed with the administration of LAN60, instead of LAN30. On LAN60 GH remained below 2.5 μg/l in 8/10 patients and IGF-I normal in 11/11 patients that had attained those values on LAN30. Tumor markedly shrank (23% to 64% vs basal), from 1400 (664-1680) mm³ to 520 (500-960) mm³ (median, interquartile, p = 0.0218) in all the 5 evaluable patients. Conclusion: LAN60 is a very effective and longer-lasting formulation for the treatment of acromegaly. A closer administration schedule might achieve greater efficacy. Its effectiveness in shrinking tumor opens new perspectives in the therapy of acromegaly.