Follow-up of pituitary tumor volume in patients with acromegaly treated with pegvisomant in clinical trials.
OBJECTIVE
We examined pituitary tumor volumes in patients treated with pegvisomant for 18 months or longer, and in whom the tumors were monitored for at least 3 years. We present details on 9 of 304 patients in clinical trials with pegvisomant who experienced tumor growth within the first year of treatment.


METHODS
Magnetic resonance images prior to start of pegvisomant and at last follow-up were examined in 43 patients (14% of participating patients). Twenty-nine had received prior radiation therapy (18% of irradiated patients) and all but five received somatostatin analogs between periods of pegvisomant treatment.


RESULTS
At follow-up, the median tumor volume was 0.6 cc (range 0.0-19.7 cc), in comparison with 1.6 cc (0.0-19.7 cc) at baseline (P<0.001). Twenty-five patients, of which 23 received radiation therapy, had tumor volume reduction. Seventeen patients had no significant change. One patient, who had not received radiation therapy, had an increase in tumor volume from 1.61 to 1.93 cc. Of the nine patients with tumor growth, six had progressive growth before initiating pegvisomant. Two patients with stable tumors while on octreotide experienced enlargement after octreotide discontinuation but remained stable on long-term pegvisomant therapy.


CONCLUSIONS
The present data indicate that pegvisomant does not promote tumor growth and suggest that the nine observed cases of tumor progression, which occurred within 8 months after commencing pegvisomant, are likely rebound expansions after discontinuation of somatostatin analogs and/or the natural history of aggressively growing pituitary tumors. Continued long-term surveillance of tumor volume, particularly in non-irradiated patients, is recommended.
Jimenez
Camilo
C
Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
Burman
Pia
P
Abs
Roger
R
Clemmons
David R
DR
Drake
William M
WM
Hutson
Kent R
KR
Messig
Michael
M
Thorner
Michael O
MO
Trainer
Peter J
PJ
Gagel
Robert F
RF
D000172:Acromegaly / Q000188:drug therapy* / Q000473:pathology* / Q000532:radiotherapy; D000236:Adenoma / Q000188:drug therapy* / Q000473:pathology* / Q000532:radiotherapy; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D002986:Clinical Trials as Topic; D003131:Combined Modality Therapy; D004359:Drug Therapy, Combination; D005260:Female; D005500:Follow-Up Studies; D019382:Human Growth Hormone / Q000031:analogs & derivatives* / Q000097:blood / Q000627:therapeutic use; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000627:therapeutic use; D010902:Pituitary Gland / Q000473:pathology*
D018931:Antineoplastic Agents, Hormonal; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; C406545:pegvisomant; D015282:Octreotide