Study of 18FET PET in Functional Pituitary Adenomas With Indeterminate MRI Findings

Condition(s) studied

Investigational drug(s) / intervention(s)

fluoroethyl-L tyrosine (18F): The protocol consists of a single arm involving the administration of the radiopharmaceutical 18FET (IASOglio). This will be administered once during the study, directly intravenously with an activity of 200 +/- 15MBq, as recommended by the European EANM/EANO/RANO guidelines and used in retrospective studies investigating the contribution of 18FET in AP. Included patients will have fasted for at least 4 hours beforehand. PET image acquisition will begin as soon as the radiopharmaceutical is injected.

Study summary

Pituitary adenomas (PAs) are common benign tumors, but their potential for tumor aggression and hormone secretion make them serious tumors. In particular, patients with secreting tumors \[prolactinomas (prolactin secretion), acromegaly (growth hormone), Cushing's disease (ACTH), thyrotropic adenomas (TSH)\] have increased morbidity and mortality. They may be small and/or undetectable by magnetic resonance imaging (MRI), the current gold standard for morphological evaluation of pituitary lesions. The diagnosis of recurrence in a patient who has already undergone surgery also raises the problem of distinguishing between a lesion and postoperative remodeling. The detection of these tumors therefore represents a significant challenge in guiding therapeutic management.Nuclear medicine could solve this challenge, particularly radiopharmaceuticals (MRPs) used in PET (positron emission tomography) combined with CT scans. A few studies have evaluated MRPs in the context of APs, with those targeting amino acid metabolism proving to be the most promising, particularly carbon-11-labeled methionine (11C-MET). In retrospective studies only, 11C-MET PET has shown excellent performance in all situations where MRI fails (detection rate \>80%), but the extremely short half-life of 11C requires heavy infrastructure, limiting its access in routine clinical practice.18Fluoroethyl-Tyrosine (18FET) is also a PET MRP targeting amino acid metabolism used in France in neuro-oncology with performance equivalent to 11C-MET, and which has the advantage of being available daily in all nuclear medicine centers.

The performance of 18FET in APs is almost unknown, with only two retrospective studies recently published, including 22 patients with Cushing's disease on the one hand and 17 patients with prolactinoma on the other: The detection rates were particularly interesting (82% and 100% respectively), but it is imperative to confirm these data prospectively and to evaluate the performance of this MRP in other functional types, which is therefore the purpose of this study.

Eligibility

Primary outcome measure(s)

• Describe the ability of 18FET PET to detect functional pituitary adenomas in patients with de novo, recurrent, or persistent functional AP when pituitary MRI is non-contributive. — 2 months +/- 2 months
  Frequency of patients for whom PET would be useful among patients with a positive 18FET PET result.The gold standard will be defined by the pathological examination of the surgical specimen in the case of surgery, or by the possibility of stopping or gradually reducing medical treatment while maintaining normalized hormone secretion in the case of radiotherapy.

Trial sites (1)

More University Hospital, Lille trials in France