Lilly pressures Blueprint further with positive Retevmo trial in newly diagnosed lung cancer

In their ongoing RET inhibitor rivalry, Eli Lilly is pulling further ahead of Blueprint Medicines, even as the latter company is being abandoned by Roche.

Friday, Lilly said a phase 3 trial testing Retevmo as an initial treatment for patients with RET fusion-positive advanced non-small cell lung cancer (NSCLC) has hit its primary endpoint. The RET inhibitor was better than chemotherapy—used with or without Merck’s PD-1 inhibitor Keytruda—at slowing disease progression or death, and the improvement was statistically significant and clinically meaningful, Lilly said in a release.

As Lilly pointed out, the Retevmo trial, coded LIBRETTO-431, is the first randomized study pitting a targeted therapy versus a PD-1 inhibitor plus chemotherapy in cancer patients bearing a specific biomarker.

“The results of this study provide further confirmation that RET status—like EGFR, ALK, and others in the family of lung cancer oncogenic drivers—should be known prior to initiating therapy,” David Hyman, M.D., chief medical officer of Lilly’s oncology department, said in a Friday statement.

Elsewhere, AstraZeneca’s EGFR inhibitor Tagrisso and ALK inhibitors such as Pfizer’s Lorbrena are the obvious standard first-line treatments over PD-1 inhibitors for those types of biomarker-driven NSCLC cases. EGFR and ALK mutations are more common, accounting for about 20% to 30% and 5% of all NSCLC cases, respectively. RET fusions only occur in 1% to 2% of patients with NSCLC.

Still, not all patients in LIBRETTO-431’s control arm received Keytruda. So it remains important to understand how Retevmo takers fared compared with the subgroup of patients who got both Keytruda and chemo. An independent data monitoring committee declared the positive readout at an interim analysis of the trial, and full results will be shared at an upcoming medical meeting, Lilly said.

Meanwhile, Retevmo’s positive readout adds more pressure on Blueprint Medicines’ rival RET inhibitor Gavreto, which already lags in sales and approvals.

Gavreto got its initial FDA nod in September 2020, four months behind Retevmo’s regulatory go-ahead in the U.S. Both drugs currently are approved in RET fusion-positive NSCLC and thyroid cancer. But Lilly last year converted Retevmo’s accelerated approval in NSCLC into a full nod and added a tumor-agnostic indication for RET fusion-driven solid tumors. Gavreto has yet to upgrade its accelerated approval in NSCLC, pending data from a larger pool of patients. 

In 2022, Gavreto only generated 26 million Swiss francs ($31 million), whereas Retevmo booked $192 million.

Swiss pharma giant Roche in-licensed Gavreto in 2020 before its FDA nod. However, this past February, Roche said it will return Gavreto to Blueprint and booked 663 million Swiss francs ($711 million) in impairment charges on the drug.

Then in July, Roche decided to withdraw Gavreto for the treatment of RET-mutant medullary thyroid cancer, citing an unfeasible phase 3 trial. Lilly is running the phase 3 LIBRETTO-531 trial to confirm Retevmo’s accelerated approval in that indication, and a company spokesperson told Fierce Pharma last month that the trial remained ongoing.

Gavreto is also being studied in its own phase 3 trial in first-line NSCLC. In a similar design, the AcceleRET-Lung trial is pitting Gavreto against chemo with or without Keytruda in previously untreated patients.