Eli Lilly has shared positive results from a late-stage study of its RET inhibitor Retevmo (selpercatinib) as an initial treatment for advanced or metastatic thyroid cancer.
The phase 3 LIBRETTO-531 trial has been evaluating the drug versus physicians’ choice of the multikinase inhibitors (MKIs) cabozantinib or vandetanib in patients with advanced or metastatic RET-mutant medullary thyroid cancer (MTC).
The study met its primary endpoint, the drugmaker said, with Retevmo demonstrating a statistically significant and clinically meaningful improvement in progression-free survival (PFS) compared to the MKIs.
Lilly outlined that the results build on the positive data from the late-stage LIBRETTO-001 trial, in which Retevmo was associated with clinically meaningful and durable responses across a variety of tumour types in patients with RET-driven cancers.
David Hyman, Loxo@Lilly’s chief medical officer, said: “This data from the LIBRETTO-531 trial confirms the importance of selectivity in targeting RET-driven cancers and suggest Retevmo should be considered the preferred first-line treatment for people with advanced RET-mutant MTC.
“Taken together with the recent positive Retevmo phase 3 LIBRETTO-431 announcement in lung cancer, these results underscore the importance of timely and broad-based genomic testing to ensure patients who could potentially benefit receive targeted therapies.”
More than 43,000 new cases of thyroid cancer are expected to be diagnosed in the US this year, according to the American Cancer Society.
MTC only accounts for up to 2% of thyroid cancers in the US, and RET mutations are found in approximately 60% of sporadic MTC and over 90% of hereditary MTC.
Retevmo gained its first MTC authorisation in 2020 under the US Food and Drug Administration’s accelerated approval pathway, under which the regulator may approve drugs for serious conditions where there is an unmet medical need early.
At the time, the FDA required Lilly to run a randomised trial with PFS as a key secondary endpoint in order to confirm the drug’s clinical benefit.
The latest results for Retevmo come just a few weeks after Roche said it would be withdrawing its Blueprint Medicines-partnered Gavreto (pralsetinib) from the US RET-mutant MTC market, citing that its own confirmatory trial of the drug was no longer feasible.