Dive Brief:

  • Taiho Oncology and its partner Cullinan Therapeutics announced that their investigational targeted therapy has succeeded in a Phase 3 trial for first-line lung cancer, with investigators stopping the study at an interim analysis due to clearly positive results.
  • The companies are testing zipalertinib in combination with chemotherapy in patients whose lung tumors harbor an EGFR exon 20 insertion mutation. While detailed data were not released, on Wednesday they reported that the combination "demonstrated a statistically significant and clinically meaningful improvement" in progression-free survival, meeting a pre-specified threshold for unblinding.
  • The U.S. Food and Drug Administration is currently reviewing zipalertinib as a second-line treatment, with a decision expected by Feb. 27. If approved, the drug would enter a highly competitive arena. Johnson & Johnson's Rybrevant and AstraZeneca/Dizal's Zegfrovy are already on the market, and ArriVent BioPharma anticipates Phase 3 data for its candidate later this year.

Dive Insight:

EGFR exon 20 insertion mutations occur in a small subset of lung cancers. EGFR mutations broadly account for about 10% to 15% of lung tumors in the U.S., and exon 20 insertions are seen in 1% to 10% of those cases, according to the American Lung Association. Some estimates indicate a higher prevalence among people in China, women, and non-smokers.

Despite the relatively small patient population, targeted therapies for these tumors represent substantial commercial opportunities. AstraZeneca's Tagrisso, which targets different EGFR mutations, surpassed $7 billion in sales last year. J&J's Rybrevant franchise, used for exon 20 insertions and other EGFR mutations, generated more than $700 million in 2025. AstraZeneca recently committed up to $1.5 billion to China-based Dizal for Zegfrovy rights, while Taiho in 2022 repurchased partial rights to zipalertinib for up to $405 million.

Taiho and Cullinan's regulatory submission for second-line use is based on a Phase 2 trial in which zipalertinib shrank or eliminated tumors in more than one-third of treated patients. The Phase 3 trial in first-line disease compares zipalertinib plus chemotherapy against chemotherapy plus placebo, with the goal of delaying disease progression or death.

Although detailed results were not disclosed, William Blair analyst Matt Phipps noted that the trial was designed to detect a 40% reduction in the relative risk of tumor progression or death at the final analysis. He suggested that the interim halt implies an even larger observed effect.

Phipps also pointed out that, as a monotherapy versus chemotherapy, Zegfrovy has reduced the risk of progression by 35%.

The readout "raises the competitive bar" for ArriVent, which expects pivotal data for its drug firmonertinib in the coming months, according to Cantor Fitzgerald analyst Li Watsek. ArriVent shares fell as much as 7% in morning trading, but Watsek cautioned that it is "premature to assess the magnitude of the competitive threat."

Watsek further argued that the relative safety profiles of each drug may be the key differentiator for patients and physicians. ArriVent is evaluating firmonertinib monotherapy versus chemotherapy in its Phase 3 trial, which, if successful, could offer an alternative with fewer side effects, she added.