SFEBES2022 Oral Communications Reproductive and Neuroendocrinology (6 abstracts)
Depot somatostatin receptor ligand therapy reverses tissue thyrotoxicosis in thyrotropinomas and aids microadenoma localization via 11C-Methionine PET
Olympia Koulouri 1 , James MacFarlane 1 , Waiel Bashari 1 , Daniel Gillett 1 , Russell Senanayake 1 , David Halsall 2 , Sue Oddy 2 , Andrew Powlson 1 , Laura Serban 1 , Carla Moran 1 , Nadia Schoenmakers 1 , Krishna Chatterjee 1 & Mark Gurnell 1
1Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom; 2Addenbrooke’s Hospital, Cambridge, United Kingdom
Context: Surgery is the first-line treatment option for thyrotropinomas, but medical therapy with somatostatin receptor ligands (SRL) may be used as neoadjuvant treatment and to facilitate safe surgery.
Objectives: To determine the extent to which neoadjuvant SRL (i) corrects clinical, laboratory and tissue hyperthyroidism in thyrotropinomas, (ii) induces tumour shrinkage in macroadenomas, and (iii) aids microadenoma detection by 11C-methionine PET.
Design/setting: Prospective cohort study; specialist pituitary referral center.
Patients: 20 patients with previously untreated thyrotropinomas (10 microadenomas and 10 macroadenomas).
Intervention: Depot SRL therapy for minimum of three and maximum of six injections given at 28-day intervals.
Main outcome measures: Changes in hyperthyroid symptom score (HSS), thyroid function, body composition (BC), resting energy expenditure (REE), sleeping heart rate (SHR), biomarkers of thyroid hormone action, glycaemic control, and imaging (MRI, PET) parameters. Age- and sex-matched healthy volunteers served as controls for BC, REE and SHR.
Results: Following treatment, patients had a marked improvement in thyrotoxic symptoms, thyroid function tests (median ΔFT3 -4.05 pmol/l; P=0.0001), biomarkers of thyroid hormone action (SHBG: pre-SRL 1.22xULN vs post-SRL 0.85xULN; P=0.004), with normalisation of REE [pre-SRL 0.163 MJ/kg/d vs post-SRL 0.136 MJ/kg/d (P=0.0001) vs healthy controls REE 0.135 MJ/kg/d (P=0.92)] and SHR [pre-SRL 67 bpm vs post-SRL 59 bpm (P=0.002) vs healthy controls SHR 54 bpm (P=0.05)]. Macroadenomas had a modest decrease in tumour volume (median change-14% from baseline). PET tracer uptake reduced post-SRL (Mean SUVr 3.1 prior to SRL vs 2.4 post SRL; P=0.001). Subtraction of post- from pre-SRL PET localized all microadenomas that showed biochemical response to SRL.
Conclusions: Treatment with neoadjuvant depot SRL results in marked improvements/normalisation in clinical, laboratory and tissue markers of hyperthyroidism. Tumour shrinkage and suppression of 11C-methionine tumoral uptake is observed, with the latter enhancing PET’s ability to accurately localize microthyrotropinomas.
Volume 86
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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