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Pearl
Neuroendocrine tumors (NETs) are rare cancers in neuroendocrine cells anywhere in the body - they are most often found in the pancreas (the type of cancer Steve Jobs had), GI tract, appendix, and lungs
NETs are an odd group of tumors - they can be fast or slow growing, they may secrete hormones or they may not
For tumors that secrete hormones, you might be familiar with somatostatin analogs (SSAs) but are likely less familiar with PRRT (peptide receptor radionuclide therapy)
PRRT is akin to our antibody drug conjugates (ADCs). It combines a protein that targets and binds tumor cells and a payload - in PRRT, the payload is radiation versus cytotoxic chemotherapy with ADCs.
The PRRT drug available in the US is Lutathera (Lutetium Lu 177 dotatate) which combines the synthetic somatostatin dotatate with lutetium-177, the radioactive component
Somatostatin is an endogenous hormone that prevents hormone secretion and we can also administer it exogenously with SSAs (octreotide LAR or lanreotide)
Most patients with NETs who receive PRRT treatment will have had disease progression on a first-line SSA but they may continue treatment with SSAs for management of carcinoid syndrome if they have hormonally functional tumors. So can a patient receive PRRT while getting an SSA?
Yes and no. Since PRRT is a radiolabeled SSA, long-acting SSAs should not be administered for 4 weeks prior to each PRRT dose
If an SSA is needed for carcinoid symptom control prior to treatment, short acting octreotide PRN can be used but should be discontinued at least 24 hours prior to administering Lutathera
Patients may still remain on long-acting SSAs throughout Lutathera treatments, but careful coordination is required to ensure there’s at least 4 weeks between the injection and the next Lutathera dose. Long- or short-acting SSAs can be resumed as soon as 4-24 hours after PRRT treatment. |
