biomarkersBiomarker

Somatostatin receptor expression by PET (SSTR-positive)

aka SSTR PET positive, somatostatin receptor-positive, SSTR-positive, DOTATATE PET positive, Krenning score, SSTR2 expression, octreoscan positive

Somatostatin receptor-positive means a neuroendocrine tumour takes up a DOTATATE tracer on PET. It is the requirement for lutetium-177 dotatate and the marker that predicts response to octreotide and lanreotide.

Gallium-68 or copper-64 DOTATATE PET (Netspot, Detectnet) images SSTR2; the Lutathera label covers somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumours, including foregut, midgut and hindgut, in adults and children 12 and over, with the NETTER-1 trial requiring uptake at least equal to liver (Krenning score 2 or higher) on every lesion. The Krenning scale (0 to 4, from no uptake to greater than spleen or kidney) is the historic scintigraphy score carried over to PET. Actinium-225 DOTATATE and other radioligands in trials use the same selection.

Part ofSomatostatin receptor 2· SSTR2 All readouts

Somatostatin receptor 2: what it is and how drugs act on it · animated schematic, not to scale

Target · the protein and the cell it sits on
Drug · antibody, small molecule, cell or radioligand
Effect · signal, damage or kill

In plain words · Somatostatin receptor 2 is a hormone receptor densely present on neuroendocrine tumours, and was the first theranostic target to reach routine care.

PET 1 approval threshold

What it means for a patient

A DOTATATE PET scan that lights up your tumour at least as brightly as your liver makes it somatostatin receptor-positive, which is needed for lutetium-177 dotatate and predicts benefit from the monthly somatostatin injections. Tumours that do not take up the tracer, often the fast-growing ones, need a different plan.

Written only from the label or guideline text cited on this page. Not medical advice; your own report and the reading your team gives it come first.

Scoring rule

Tumour uptake of a somatostatin receptor PET tracer at least equal to normal liver (Krenning score 2 or higher) in target lesions; the Lutathera label states 'somatostatin receptor-positive' without a numeric cut-off.

“LUTATHERA is indicated for the treatment of adult and pediatric patients 12 years and older with somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumors (GEP-NETs), including foregut, midgut, and hindgut neuroendocrine tumors.”
Lutathera prescribing information

Thresholds used in approvals

Threshold	Drug	Cancer	Regulator	Source
Somatostatin receptor-positive by SSTR imaging	Lutetium-177 dotatate	Neuroendocrine tumours	FDA	label

Drugs whose label names it

Lutetium-177 dotatate

Trials that name this readout

Matched on the name and aliases of the readout in the title, setting and summary of each trial; a match is a mention, not proof the readout was an entry criterion.