The FDA has approved Eli Lilly’s RET inhibitor Retevmo (selpercatinib) for three types of RET-driven cancer. The company acquired the first-in-class agent last year, in an $8 billion acquisition of Loxo Oncology that broadened Lilly’s oncology focus.
Around 2% of cancers carry mutations or abnormalities in the receptor tyrosine kinase RET. In the phase 1/2 LIBRETTO-001 trial of Retevmo, the sponsors enrolled patients with advanced, RET-aberrant solid cancers. The data from this trial have now supported the FDA’s approvals for Retevmo in non-small-cell lung cancer (NSCLC), one of the most prevalent forms of cancer, and in two forms of thyroid cancer, in which RET alterations are particularly common. The overall response rates to treatment were 64–85% in patients with RET-fusion-positive NSCLC, 69–73% in patients with RET-mutant medullary thyroid cancer, and 75–79% in patients with RET-fusion-positive thyroid cancer.
Lilly has not developed a companion diagnostic for Retevmo, and recommends next-generation sequencing or other approaches to identify patients who are most likely to respond to treatment. A tissue-agnostic approval — in which the drug is available for all patients with RET alterations, regardless of where the cancer started — could still be on the horizon for Retevmo. “Regulatory interactions are planned to understand what the registration path would be for a tissue-agnostic indication,” a Lilly spokesperson told Nature Biotechnology. The LIBRETTO-001 trial is still enrolling patients with RET-driven tumors beyond the lung and thyroid, she added. Loxo and partner Bayer secured a landmark tissue-agnostic approval in 2019 for the NTRK inhibitor Vitrakvi (larotrectinib).
Others are also looking to compete in the RET inhibitor space. Blueprint Medicines submitted its pralsetinib for RET-fusion-positive NSCLC earlier this year, paving the way for a possible approval by year end. Turning Point Therapeutics’ dual RET and SRC inhibitor TPX-0046 is in phase 1/2 testing.
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FDA approves first RET inhibitor. Nat Biotechnol 38, 662 (2020). https://doi.org/10.1038/s41587-020-0568-2