Octreotide in insulinoma patients: efficacy on hypoglycemia, relationships with Octreoscan scintigraphy and immunostaining with anti-sst2A and anti-sst5 antibodies

Abstract

Objective: We studied the efficacy of octreotide treatment on hypoglycaemia in patients with insulinoma and its relationships with Octreoscan scintigraphy and the presence of tumoral somatostatin receptors sst2A and sst5. Design and methods: 17 patients with insulinoma were evaluated using (i) evaluation of blood glucose, insulin and C-peptide during a short 100 mg octreotide test in fasting patients and/or treatment over 8 days-8 months with octreotide, (ii) Octreoscan scintigraphy and (iii) immunostaining of the tumor with anti-sst2A and anti-sst5. Results: Octreotide was effective on hypoglycaemia in 10/17 patients. Octreoscan scintigraphy detected 4/17 insulinomas. sst2A receptor was detected in 7/17 insulinomas and sst5 in 15/17 insulinomas. Octreotide was effective on hypoglycaemia in those seven patients with sst2A receptorexpressing insulinoma, and in three patients with undetectable sst2A receptor and detectable sst5; it was ineffective in six patients whose tumor expressed the sst5 receptor with undetectable sst2A and in one patient with undetectable sst2A and sst5 receptor. Conclusions: Octreotide is an effective treatment of hypoglycaemia in more than 50% of patients with insulinoma. Detection of responsive patients was better based on a positive short test with subcutaneous octreotide than on the results of Octreoscan scintigraphy. Positive anti-sst2 receptor immunostaining is associated with efficacy of octreotide treatment, but does not account for all cases of responsiveness to octreotide. Expression of sst5 receptor does not appear to explain per se the efficacy of octreotide on sst2A-negative insulinomas.European Journal of Endocrinology 152 757-767

Molecular challenges of neuroendocrine tumors (Review)

“…Octreotide and lanreotide are somatostatin analogs proved to be useful in alleviation of of flushing and diarrhea which are associated with NETs secretion (55,56). The antitumor effect of somatostatin analogs has been established in many clinical trials (57)(58)(59).…”

Insulinoma: Literature’s Review (2)

“…The efficacy of octreotide on hypoglycemia was assessed in a study of 17 patients with insulinoma (Vezzosi et al 2005): in more than 50% of the patients, the drug was effective in hypoglycemia control. A positive subcutaneous short octreotide test (100 mg octreotide s.c. in fasting patients, with improvement in hypoglycemia) was a better marker of the therapeutic response compared with a pretreatment positive scintigraphy.…”

“…3 of the 6 malignant tumors, but none of the benign tumors expressed somatostatin receptor subtype 5. The other receptor subtypes were expressed in low numbers with no difference between benign and malignant tumors [67][68][69][70][71][72][73][74].…”

GEP-NETs update: Functional localisation and scintigraphy in neuroendocrine tumours of the gastrointestinal tract and pancreas (GEP-NETs)

“…However, as opposed to benign insulinomas, malignant insulinomas often lack GLP1R (60). Conversely, malignant insulinomas often do express sst 2 , which can be targeted using SRS (24,60,61,62,63,64,65,66). In various studies, GLP1R scintigraphy using 111 In-DOTAexendin-4 successfully detected benign insulinomas (60,67,68,69,70).…”