Taiho and Cullinan's zipalertinib succeeds in phase 3 lung cancer trial

Taiho Pharmaceutical and Cullinan Therapeutics announced that their Phase 3 REZILIENT3 trial evaluating zipalertinib plus chemotherapy met its primary progression-free survival endpoint at an interim analysis. The study was halted early for efficacy in patients with first-line EGFR exon 20 insertion mutation non-small cell lung cancer. This success positions zipalertinib to challenge established treatments like Johnson & Johnson's Rybrevant and AstraZeneca's Zegfrovy in a highly competitive market.

REZILIENT3 phase 3 results

• ▪Taiho Pharmaceutical and Cullinan Therapeutics announced on August 12, 2026, that their investigational EGFR inhibitor zipalertinib combined with chemotherapy met its primary endpoint of progression-free survival in the Phase 3 REZILIENT3 trial.
• ▪The safety profile for the zipalertinib and chemotherapy combination arm in the REZILIENT3 trial was reported as manageable by Taiho Pharmaceutical and Cullinan Therapeutics.
• ▪An independent data committee recommended unblinding the REZILIENT3 trial at a planned interim analysis due to the statistically significant and clinically meaningful magnitude of progression-free survival improvement.

EGFR exon 20 mutations

• ▪The prevalence of EGFR exon 20 insertion mutations is estimated to be higher among patients in China, women, and non-smokers.
• ▪Epidermal growth factor receptor (EGFR) exon 20 insertion mutations account for approximately 1% to 10% of the 10% to 15% of lung tumors in the United States that harbor EGFR mutations.

Hazard ratio comparison

• ▪The REZILIENT3 trial was powered to detect a hazard ratio of 0.60 at 90% power, suggesting to analysts that the interim analysis achieved a hazard ratio below 0.60 to meet stopping criteria.
• ▪Dizal Pharmaceutical and AstraZeneca's EGFR inhibitor Zegfrovy demonstrated a hazard ratio of 0.65, representing a 35% improvement in progression-free survival, in its Phase 3 first-line trial.

Competitive EGFR inhibitor market

• ▪ArriVent BioPharma is expecting Phase 3 clinical trial data for its competing EGFR inhibitor firmonertinib in the second half of 2026.
• ▪AstraZeneca acquired global commercialization rights to Dizal Pharmaceutical's Zegfrovy for $600 million upfront and up to $1.5 billion in total payments.
• ▪If approved, zipalertinib combined with chemotherapy would compete in the first-line setting with Johnson & Johnson's Rybrevant plus chemotherapy and Dizal Pharmaceutical's Zegfrovy.

FDA regulatory review status

• ▪Taiho Pharmaceutical and Cullinan Therapeutics plan to seek regulatory approval for zipalertinib combined with chemotherapy in the first-line setting based on the REZILIENT3 results.
• ▪The Food and Drug Administration is currently reviewing zipalertinib as a second-line monotherapy for previously treated EGFR exon 20 non-small cell lung cancer, with a decision deadline of February 27, 2027.

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