SAN FRANCISCO, CA—Tumor growth may be substantially slowed by the novel therapy 177Lutetium-DOTATATE (Lutathera), according to early results from a phase III study of patients with previously treated, advanced midgut neuroendocrine tumors. The risk of disease progression or death was 79% lower for patients treated with the experimental drug compared with patients who received octreotide LAR 60 mg every 4 weeks. These findings were presented at the 2016 Gastrointestinal Cancers Symposium.

177Lutetium-DOTATATE is a member of a new class of drugs known as peptide receptor radionuclide therapy (PRRT), a combination of hormone therapy and radiotherapy. This particular drug has a somatostatin analog attached to a radioactive molecule that allows targeted delivery of radiation to kill cancer tumors.

Midgut neuroendocrine tumors begin in the small intestine and proximal colon. The typical treatment is hormone therapy with a somatostatin analog, such as octreotide or lanreotide. Currently, no effective systemic second-line treatment options exist for patients whose tumors stop responding to somatostatin analogs.

In this study, designed to evaluate the efficacy of 177Lutetium-DOTATATE in patients with advanced midgut neuroendocrine tumors, the 230 patients enrolled had advanced tumors that worsened despite first-line somatostatin analog therapy. Participants were randomly assigned to treatment with 177Lutetium-DOTATATE or high-dose octreotide LAR. The trial included 15 sites in the United States and 36 in Europe.

“Our results indicate that Lutathera appears to be a safe and effective treatment option. On average, tumors responded to the drug for several years before they began growing again,” said Jonathan R. Strosberg, MD, a medical oncologist at the Moffitt Cancer Center in Tampa, Florida, and lead author of the study. “The new therapy is also more convenient. It requires only 4 treatments, as opposed to medications that patients have to take daily over long periods of time.”

Trial enrollment was completed in February 2015. Preliminary findings suggest that 177Lutetium-DOTATATE may extend patients survival. The median progression-free survival was not yet reached for 177Lutetium-DOTATATE; it was 8.4 months for high-dose octreotide LAR.

The data was too early to analyze overall survival. Initial results suggest that 177Lutetium-DOTATATE may extend patient survival, as substantially fewer deaths occurred in the 177Lutetium-DOTATATE group vs the high-dose octreotide LAR group (13 vs 22).

The number of responses, including both complete and partial responses, was 19 (18.8%) in the 177Lutetium-DOTATATE group and 3 (3.0%) in the high-dose octreotide LAR group.

Both treatment groups had similar rates of adverse events and serious adverse events. 177Lutetium-DOTATATE can cause low blood cell counts that are typically transient.

This study received funding from Advanced Accelerator Applications (AAA), a radiopharmaceutical company that specializes in molecular nuclear medicine.