Insights into the design of inhibitors of the EGFR family with anticancer activity overcoming resistance: A case of optimizing thieno[2,3-d]pyrimidine-based EGFR inhibitors

•Thieno[2,3-d]pyrimidine-based dual EGFR/HER2 inhibitors were designed.•12 compounds were prepared and tested against EGFR, HER2 and T790M/L858R.•Their anti-proliferative activities were assessed against relevant cancer cell lines.