Lilly's rare cancer drug Retevmo looks to broaden reach with adjuvant trial win

 Some six years after the FDA approved Eli Lilly’s Retevmo to treat lung and thyroid cancers that have a mutation or fusion to the RET gene, the Indianapolis drugmaker is laying groundwork to move the treatment into the adjuvant setting.

Lilly has reported a successful phase 3 trial in which Retevmo demonstrated “highly statistically significant and clinically meaningful” improvement in event-free survival in patients with early-stage (II-IIIA) RET fusion-positive non-small cell lung cancer (NSCLC). The twice-daily oral medication was tested against placebo in patients who have had surgery or radiation therapy. 

Lilly isn’t declaring complete victory in the study yet, however. As a secondary endpoint, overall survival trended positively in Retevmo's favor, but the data were immature with few events observed at the time of the drugmaker's analysis. Lilly said it will present detailed results from the trial at an upcoming medical conference and discuss them with global regulators. 

“We have consistently observed that cancer medicines can deliver their greatest impact when administered early in the course of a patient’s treatment journey,” Jacob Van Naarden, Lilly’s oncology chief, said in a release, adding that the results show “an effect size in line with the most striking data for targeted adjuvant therapy in lung cancer.”

The trial, which enrolled 151 participants, is the first randomized phase 3 study to evaluate the safety and efficacy of a selective RET kinase inhibitor as adjuvant therapy in the patient population, Lilly said.

NSCLC accounts for about 85% of all lung cancer diagnoses in the U.S., with half of those having actionable biomarkers, Lilly said, including 1% to 2% with RET fusions. 

“Building on the adoption of targeted therapies for early-stage patients with EGFR- and ALK-driven lung cancer, we hope these results further accelerate the use of genomic testing for all people diagnosed with early-stage disease,” Van Naarden added. 

Two years after the FDA originally approved Retevmo on an accelerated basis, the U.S. regulator signed off on the RET inhibitor to treat all tumor types that bear the relevant biomarker. The nod covered patients with locally advanced or metastatic solid tumors who have tried prior systemic treatment, as well as those with no other treatment alternatives. 

The approval was based on Retevmo showing that it shrunk various tumor types by 44% and provided benefits for a median of 24.5 months. 

Retevmo generated sales of $364 million in 2024 and $456 million last year. Lilly acquired Retevmo in its $8 billion buyout of Loxo Oncology in 2019. Two years ago, the company scrapped a next-generation RET inhibitor gained in the buyout which was designed to overcome acquired resistance to Retevmo. 

The only other RET inhibitor on the market, Rigel’s Gavreto, has struggled to gain traction, achieving sales of $32 million in the first three quarters of 2025. 

The FDA originally approved Gavreto in 2020, four months after signing off on Retevmo. It was developed by Blueprint, with Roche paying $675 million upfront to become commercial partner on the drug in 2020. The Swiss pharma giant exited the collaboration three years later, and Rigel picked up the product from Blueprint in early 2024. 

https://www.fiercepharma.com/pharma/lilly-scores-rare-cancer-drug-retevmo-adjuvant-therapy