Wanted: highly selective RET inhibitor. Must sneak into the central nervous system, ignore most innocent bystander proteins, and keep microscopic lung cancer leftovers from staging a comeback tour. Liver enzyme drama may occur. Apply within.
That, in a lab-coat nutshell, is selpercatinib.
The new NEJM trial by Wu and colleagues asks a satisfying puzzle-master question: if selpercatinib works in advanced RET fusion-positive non-small-cell lung cancer, could it work earlier, after the visible tumor has already been treated with surgery or radiation? In other words, can we stop the sequel before the villain gets a post-credits scene?
The Tiny Wiring Error With Big Main Character Energy
RET is a gene that normally helps encode a receptor tyrosine kinase, basically a cellular antenna that helps transmit growth signals. That is fine when the wiring behaves. But in a RET fusion, RET gets accidentally spliced to another gene, creating a stuck-on growth signal. The cell hears "divide, divide, divide" like someone taped down the accelerator and walked away.
RET fusions show up in a small slice of non-small-cell lung cancers, often lung adenocarcinomas. Small slice, big consequences. Precision oncology lives for this kind of clue: not "lung cancer" as one giant bucket, but "lung cancer with this particular molecular fingerprint."
Selpercatinib is built to block RET. It already proved itself in advanced disease, including durable responses in LIBRETTO-001 and better progression-free survival than chemotherapy with or without pembrolizumab in the phase 3 LIBRETTO-431 trial Drilon et al., 2020, Zhou et al., 2023. This new study moves the same logic earlier in the story.
Surgery Removed the Castle. What About the Tunnels?
Early-stage lung cancer can sometimes be treated with curative intent: remove it, radiate it, add chemotherapy or immunotherapy when appropriate, then watch closely. But cancer is rude. Even when scans look clean, tiny residual cells may remain. Think of them as suspicious puzzle pieces under the couch. You do not see them, but your foot will find them later.
LIBRETTO-432 enrolled 151 patients with stage IB to IIIA RET fusion-positive NSCLC after definitive local treatment, with other adjuvant therapy if indicated. Patients received either selpercatinib or placebo. The main analysis focused on stage II to IIIA disease.
The result was not subtle. At 2 years, event-free survival was 92% with selpercatinib versus 61% with placebo in stage II to IIIA patients. The hazard ratio for recurrence, progression, or death was 0.17, meaning an 83% lower risk of an event in the selpercatinib group Wu et al., 2026. In the full stage IB to IIIA group, 2-year event-free survival was 94% versus 70%, again with a hazard ratio of 0.17.
That is the kind of symmetry a puzzle person appreciates. Same clue, same answer, fewer suspicious couch pieces.
The Pattern Is Getting Hard To Ignore
This paper fits into a broader mosaic. EGFR-mutated early-stage NSCLC has adjuvant osimertinib, which improved disease-free and overall survival in ADAURA Herbst et al., 2020, Tsuboi et al., 2023. ALK-positive resected NSCLC now has adjuvant alectinib from ALINA Wu et al., 2024. RET was the awkward empty square on the bingo card.
LIBRETTO-432 starts filling it.
The practical implication is loud: early-stage lung cancer needs molecular testing too. Not just when cancer has spread. Not just when everyone is already scrambling. At diagnosis. Otherwise, RET fusion-positive patients may miss the very clue that tells clinicians which post-treatment strategy might fit.
The Fine Print, Because Biology Charges Handling Fees
Selpercatinib was not free of side effects. The most common grade 3 or higher adverse events were elevated liver enzymes: ALT in 17% and AST in 19% of patients receiving selpercatinib. That matters because adjuvant therapy treats people who may currently have no detectable cancer. The tolerance bar is higher when you are preventing recurrence rather than shrinking obvious disease.
Also, event-free survival is not the same as overall survival. The follow-up was around 2 years, so the long-term story still needs pages: survival, late toxicity, resistance, optimal duration, cost, access, and whether every subgroup benefits equally. Cancer biology loves a red herring. Sometimes it brings snacks.
Still, this trial makes a strong case that RET is not just a metastatic-disease clue. It is an early-stage clue too.
The Aha Moment
The big takeaway is not simply "selpercatinib good." It is more elegant than that: lung cancer treatment is becoming less about where the tumor sits and more about what instruction manual the tumor is illegally using.
If this result holds up with longer follow-up and broader real-world use, early-stage RET fusion-positive NSCLC may join EGFR and ALK in the growing club of "find the driver, treat the driver, do it before the cancer gets clever."
Cancer remains a terrible puzzle. But every once in a while, a piece clicks into place loudly enough that the whole table hears it.
References
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Wu Y-L, Hochmair M, Yang Y, et al. Selpercatinib in Early-Stage RET Fusion-Positive Non-Small-Cell Lung Cancer. N Engl J Med. 2026. https://doi.org/10.1056/NEJMoa2602628
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Zhou C, Solomon BJ, Loong HH, et al. First-Line Selpercatinib or Chemotherapy and Pembrolizumab in RET Fusion-Positive NSCLC. N Engl J Med. 2023;389:1839-1850. https://doi.org/10.1056/NEJMoa2309457
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Drilon A, Oxnard GR, Tan DSW, et al. Efficacy of Selpercatinib in RET Fusion-Positive Non-Small-Cell Lung Cancer. N Engl J Med. 2020;383:813-824. https://doi.org/10.1056/NEJMoa2005653
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Drilon A, Subbiah V, Gautschi O, et al. Selpercatinib in Patients With RET Fusion-Positive Non-Small Cell Lung Cancer: Final Safety and Efficacy, Including Overall Survival, From the LIBRETTO-001 Phase I/II Trial. J Clin Oncol. 2025. PMCID: PMC12084017
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Wu Y-L, Dziadziuszko R, Ahn JS, et al. Alectinib in Resected ALK-Positive Non-Small-Cell Lung Cancer. N Engl J Med. 2024;390:1265-1276. https://doi.org/10.1056/NEJMoa2310532
Disclaimer: The image accompanying this article is for illustrative purposes only and does not depict actual experimental results, data, or biological mechanisms.