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Long-term treatment of somatostatin analog-refractory growth hormone-secreting pituitary tumors with pegvisomant alone or combined with long-acting somatostatin analogs: a retrospective analysis of clinical practice and outcomes

Antonio Bianchi1*, Ferdinando Valentini2, Raffaella Iuorio3, Maurizio Poggi4, Roberto Baldelli5, Marina Passeri6, Antonella Giampietro1, Linda Tartaglione1, Sabrina Chiloiro1, Marialuisa Appetecchia5, Patrizia Gargiulo3, Andrea Fabbri6, Vincenzo Toscano4, Alfredo Pontecorvi1 and Laura De Marinis1

Author Affiliations

1 Department of Endocrinology, Catholic University, School of Medicine, Largo A. Gemelli 8, 00168, Rome, Italy

2 Endocrinology Section, San Camillo-Forlanini Hospital, Via Portuense, 332A, 00151, Rome, Italy

3 Endocrinology Section, University “La Sapienza”, Viale R. Elena, 324, 00185, Rome, Italy

4 Endocrinology Section, St. Andrea Hospital, University “La Sapienza”, 2nd Faculty, Via di Grottarossa, 1035/1039, 00189, Rome, Italy

5 Endocrinology Unit, Regina Elena Cancer Institute – IFO, Via Elio Chianesi 53, Rome, 00144, Rome, Italy

6 Endocrinology Unit, St. Eugenio and CTO Andrea Alesini Hospital, University of Tor Vergata, Via San Nemesio, 21, 00145, Rome, Italy

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Journal of Experimental & Clinical Cancer Research 2013, 32:40  doi:10.1186/1756-9966-32-40

Published: 21 June 2013

Abstract

Background

Pegvisomant (PEGV) is widely used, alone or with somatostatin analogs (SSA), for GH-secreting pituitary tumors poorly controlled by SSAs alone. No information is available on specific indications for or relative efficacies of PEGV?+?SSA versus PEGV monotherapy. Aim of our study was to characterize real-life clinical use of PEGV vs. PEGV?+?SSA for SSA-resistant acromegaly (patient selection, long-term outcomes, adverse event rates, doses required to achieve control).

Methods

A retrospective analysis of data collected in 2005–2010 in five hospital-based endocrinology centers in Rome was performed. Sixty-two adult acromegaly patients treated ≥6 months with PEGV (Group 1, n?=?35) or PEGV?+?SSA (Group 2, n?=?27) after unsuccessful maximal-dose SSA monotherapy (≥12 months) were enroled. Groups were compared in terms of clinical/biochemical characteristics at diagnosis and before PEGV or PEGV?+?SSA was started (baseline) and end-of-follow-up outcomes (IGF-I levels, adverse event rates, final PEGV doses).

Results

Group 2 showed higher IGF-I and GH levels and sleep apnea rates, higher rates residual tumor tissue at baseline, more substantial responses to SSA monotherapy and worse outcomes (IGF-I normalization rates, final IGF-I levels). Tumor growth and hepatotoxicity events were rare in both groups. Final daily PEGV doses were similar and significantly increased with treatment duration in both groups.

Conclusions

PEGV and PEGV?+?SSA are safe, effective solutions for managing SSA-refractory acromegaly. PEGV?+?SSA tends to be used for more aggressive disease associated with detectable tumor tissue. With both regimens, ongoing monitoring of responses is important since PEGV doses needed to maintain IGF-I control are likely to increase over time.