Eli Lilly And Co (LLY  ) released topline results from the LIBRETTO-531 study evaluating Retevmo versus the physician's choice of the multikinase inhibitors (MKIs) cabozantinib or vandetanib as an initial treatment for patients with advanced or metastatic rearranged during transfection (RET)-mutant medullary thyroid cancer (MTC).

The study met its primary endpoint, demonstrating a statistically significant and clinically meaningful improvement in progression-free survival (PFS).

This result was based on a pre-specified interim efficacy analysis conducted by an independent data monitoring committee.

Adverse events observed on Retevmo were generally consistent with those identified across the previously reported Retevmo development program (LIBRETTO-001, LIBRETTO-121, LIBRETTO-321).

These results further build on the data from LIBRETTO-001, the largest clinical trial of patients with RET-driven cancers treated with a RET inhibitor, which includes more than 800 patients and spans 16 countries and 85 sites.

Retevmo demonstrated clinically meaningful and durable responses across various tumor types in patients with RET-driven cancers in this trial.

MTC accounts for 1%-2% of thyroid cancers in the U.S. RET mutations are found in approximately 60% of sporadic MTC and over 90% of hereditary MTC.

Full results from the LIBRETTO-531 trial will be presented at an upcoming medical meeting, submitted to a peer-reviewed journal, and discussed with health authorities.

Price Action: LLY shares are up 0.91% at $555.19 on the last check Tuesday.