Core Insights - Cullinan Therapeutics, Taiho Pharmaceutical, and Taiho Oncology announced positive results from the Phase 2b cohorts of the REZILIENT1 trial for zipalertinib in patients with advanced or metastatic non-small cell lung cancer (NSCLC) with EGFR exon 20 insertion mutations [1][2] Efficacy Results - A total of 244 patients were enrolled in the REZILIENT1 trial, with 176 patients included in the overall efficacy population, showing a confirmed overall objective response rate (ORR) of 35% and a median duration of response (mDOR) of 8.8 months [3][7] - In patients who had received prior platinum-based chemotherapy, the ORR was 40% with an mDOR of 8.8 months [7] - For patients with prior chemotherapy and amivantamab, the ORR was 30% with an mDOR of 14.7 months [7] - Patients with brain metastases had an ORR of 31% with an mDOR of 8.3 months [7] Safety and Tolerability Results - Zipalertinib demonstrated a manageable safety profile, with the most common treatment-related adverse events (TRAEs) being paronychia (38.5%), rash (30.3%), and dermatitis acneiform (24.6%) [4][5] - The majority of TRAEs were grade 1 or 2, with grade ≥3 TRAEs including anemia (7%) and pneumonitis (2.5%) [5][4] About Zipalertinib - Zipalertinib is an orally available small molecule targeting EGFR mutations, specifically designed to inhibit EGFR variants with exon 20 insertion mutations while sparing wild-type EGFR [7][8] - It has received Breakthrough Therapy Designation from the FDA and is currently investigational [8] About EGFR Exon 20 Insertion Mutations - EGFR exon 20 insertions account for up to 4% of all NSCLC cases, making them the third most common EGFR mutation subtype [9]