Clinical Data Between July 9, 2019 and February 5, 2021, 97 NSCLC patients with EGFR or HER2 mutations were dosed with DZD9008 (dose range: 50 mg to 400 mg, once daily). M/F: 44/53; 59 with EGFR exon 20. DZD9008 was well tolerated up to 400 mg (MTD) once daily. The DLTs were diarrhea and cardiac arrhythmia. The most common TEAEs were diarrhea (grade 3, 5.2%) and skin rash (grade 3, 1%). DZD9008 showed approximately dose-proportional PK, with a half-life of around 50 hours. Fifty-six patients with > 16 different EGFR exon20ins mutations had > 1 post-treatment efficacy assessment. Prior therapies: median 2 (range 1 - 10), prior chemotherapy 92.9% (52/); prior TKI 44.6% (25/56) including 1 patient had poziotinib treatment; 42.9% (24/56) with brain metastasis. Partial response was observed at ≥ 100 mg dose levels. At the RP2D dose of 300 mg once daily, the objective response rate was 48.4% (15/31), and disease control rate (DCR) was 90.3% (28/31). Responses were observed in 2 patients with prior JNJ-61186372 treatment. Anti-tumor activity was observed across different EGFR exon20ins mutation subtypes. By data cut-off, the median treatment duration was 100 days (range 1 – 422). The longest duration of response was over 6 months, and 18 out of 22 responders are still responding.