ITM Isotope Technologies has provided more detail on how its lead radiotherapy bested the standard of care in a recent phase 3 study while revealing that the candidate was unable to prove a statistically significant benefit in median overall survival.
The therapy, dubbed ITM-11, consists of a therapeutic β-emitting radioisotope called lutetium-177 along with a somatostatin receptor (SSTR) agonist called edotreotide. ITM already announced in January that a phase 3 study of 309 patients with SSTR-positive neuroendocrine tumors of the stomach or pancreas had shown that ITM-11 met the primary endpoint of prolonging progression-free survival (PFS) when compared to everolimus.
Now, ITM is providing details of that phase 3 win—while acknowledging that another survival endpoint wasn’t quite as successful.
Median PFS was “significantly longer” for ITM-11, at 23.9 months, compared to 14.1 months seen by the everolimus cohort, the radiopharma explained. Everolimus, which has been sold by Novartis as Afinitor, is a targeted molecular therapy approved for advanced neuroendocrine tumors and other indications.
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But when it came to the secondary endpoint of interim overall survival (OS), the ITM-11 cohort reached 63.4 months while the everolimus group was not far behind at 58.7 months. This gap was “numerically higher” but not statistically significant, the company admitted in its data release.
To help explain this finding, ITM pointed out that patients had been permitted to start an alternative therapy after disease progression, which “potentially confound[ed] the overall survival data.”
When it came to safety, 82.5% of the ITM-11 cohort experienced treatment-emergent adverse events compared to 97% of those who received everolimus. One grade 2 serious event of myelodysplastic syndrome was reported as related to ITM-11, the company said.
After 20 years of building radioisotope expertise as a manufacturer and supplier, the German company has been pushing its own therapies into the clinic, with ITM-11 leading the charge. The company also has a phase 1 trial in children with SSTR-positive tumors ongoing, as well as a phase 3 study in lung and thymus neuroendocrine tumors.
“These successful results validate our decision to design a pivotal phase 3 trial directly comparing a targeted radiopharmaceutical against a targeted molecular therapy … underscoring our commitment to improving the lives of people living with this challenging cancer,” ITM’s CEO Andrew Cavey, M.D., Ph.D., said in a release.
“With this successful readout, [ITM-11] becomes the first drug candidate in ITM’s broad portfolio of early- to late-stage radiopharmaceuticals to deliver positive phase 3 results and progress towards NDA submission and commercial launch preparations,” Cavey added.