(ChemotherapyAdvisor) – Patients with metastasized neuroendocrine cancers had improved efficacy and overall survival following repeated cycles of two of the most commonly used radioisotopes in somatostatin-based radiopeptide therapy, investigators reported in the Journal of Clinical Oncology published online March 5.

The radioisotope 90yttrium-labeled tetraazacyclododecane-tetraacetic acid modified Tyr-octreotide ([90YDOTA]-TOC) was administered alone (n=237) and in combination with 177lutetium-labeled DOTA-TOC ([177Lu-DOTA]-TOC) (n=249) for three or more treatment cycles to patients with neuroendocrine cancers.

Those receiving [90YDOTA]-TOC plus [177Lu-DOTA]-TOC had significantly longer survival than patients receiving [90Y-DOTA]-TOC alone (5.51 vs. 3.96 years; HR, 0.64; P=0.006). Rates of severe hematologic toxicities (6.3% vs. 4.4%) and severe renal toxicity (8.9% vs. 11.2%) were comparable in both groups.

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“Contrary to the current practice of using single-isotope radiopeptide therapy, our results suggest expanding the therapeutic options by using a combination of radioisotopes,” the investigators wrote, adding that a randomized trial is warranted to confirm these results.

Novel radiopeptides are being developed for use in various malignancies.