The GH-receptor antagonist pegvisomant (PEG) reduces peripheral IGF-1 synthesis and is used to treat acromegaly patients resistant or intolerant to somatostatin analogues (SSA). Medical therapy is generally life-long in patients with acromegaly, since disease remission is very uncommon after SSA discontinuation and has never been reported after PEG withdrawal. Here, we report for the first time the cases of two acromegaly patients treated with PEG monotherapy for many years because of resistance to SSA, who persistently maintained normal serum IGF-1 levels after PEG withdrawal. The first patient autonomously discontinued PEG treatment after 8 years, while in the second case we stopped the treatment after 11 years, because slight hypertransaminasemia occurred. After PEG discontinuation, in both cases IGF-1 values remained persistently normal and GH during OGTT regularly suppressed. To date, both patients are still in remission. Therefore, we suggest that PEG could exert unknown antitumoral effects in pituitary tumor cells and that long-term PEG treatment can induce acromegaly remission in some patients.

GH受体拮抗剂pegvisomant（PEG）减少外周IGF-1的合成，用于治疗对生长抑素类似物（SSA）有抵抗力或不耐受的肢端肥大症患者。在肢端肥大症患者中，药物治疗通常是终生的，因为在SSA停用后疾病缓解很少见，并且在停药PEG后从未见过报道。在这里，我们首次报道了由于对SSA的抗药性而接受PEG单一疗法治疗多年的两名肢端肥大症患者的案例，他们在PEG撤药后持续维持正常的血清IGF-1水平。第一名患者在8年后自动终止PEG治疗，而第二例患者在11年后停止治疗，因为发生了轻微的高转氨血症。PEG停用后，在这两种情况下，在OGTT期间，IGF-1值始终保持正常，GH受到定期抑制。迄今为止，两名患者仍处于缓解状态。因此，我们认为PEG可能在垂体肿瘤细胞中发挥未知的抗肿瘤作用，长期的PEG治疗可以在某些患者中诱发肢端肥大症的缓解。