Thirty-four people with a neuroendocrine cancer that the big trials mostly skipped received a radioactive peptide. In four out of five, the tumor shrank or at least stopped growing.
That 80 percent disease-control figure comes from a single-center study published online June 3 in Annals of Nuclear Medicine ↗. It is small and retrospective, one hospital's decade of records, but it answers a question the large trials largely left open: does this treatment work in the neuroendocrine tumors that were never the headliners?
The peptide that carries a radioactive payload
The treatment is peptide receptor radionuclide therapy, or PRRT, and the name describes the mechanism. The peptide is 177Lu-DOTATATE, sold as Lutathera: a lab-made copy of the hormone somatostatin, re-engineered to carry a radioactive atom of lutetium-177. Neuroendocrine tumors tend to coat their surfaces with somatostatin receptors. The peptide locks onto those receptors, and the lutetium it is carrying then irradiates the tumor cell from point-blank range, sparing most of the healthy tissue around it. The peptide is the guidance. The isotope is the warhead.
Neuroendocrine tumors get sorted by where in the developing gut they first formed. Midgut tumors, the ones in the small intestine, dominated the studies that won PRRT its approval, including the landmark NETTER-1 trial. Foregut tumors (stomach, lung, thymus) and hindgut tumors (colon, rectum, anus) were thin on the ground in those cohorts. The authors put it plainly: these groups are "sparse and underrepresented" in the trials. So they built a study out of exactly those patients, 16 foregut and 18 hindgut, treated between 2014 and 2024.
What the decade of records showed
Patients received up to four cycles of 177Lu-DOTATATE at 7.4 gigabecquerels each, the standard regimen, with kidney protection. The objective response rate, the share whose tumors measurably shrank, was 45 percent. The disease-control rate, which adds in the patients whose tumors held steady, was 80 percent. Median progression-free survival, the time before the cancer started advancing again, was 29.7 months, close to two and a half years. Just over half the group, 53.6 percent, was still alive at five years.
The safety side carried the other half of the story. Serious (grade 3) side effects showed up in only 5 of the 34 patients. For a therapy that delivers targeted radiation to people with metastatic cancer, that is a light toxicity footprint, and it is the reason PRRT is given when older options have run out.
What this study cannot do is prove the point. There was no comparison group, no randomization, and the 34 patients came from a single institution that chose who to treat. The numbers are real-world observation, not a controlled trial, so they read as a strong signal that PRRT travels beyond the midgut, not as final proof of it. The authors say as much, calling for prospective trials in larger cohorts.
The cold cousins on the platform
PRRT sits at one end of a family. peptidemodel hosts the other end: the cold, non-radioactive somatostatin analogs that aim at the same receptor. Lanreotide ↗ and octreotide ↗ bind the somatostatin receptor SSTR2 ↗ to slow hormone-driven neuroendocrine tumors without any radiation at all. DOTATATE is a molecule from that same lineage, fitted with a chelator and a radioactive isotope so that it does more than occupy the receptor.
That is the quiet lesson in the geometry. The difference between a peptide that merely quiets a tumor and one that irradiates it can come down to a single radioactive atom bolted onto the same receptor-homing backbone. The receptor does the targeting either way. What you hang off the peptide decides what happens when it arrives.