CD8A and neoplasm: By studying the response to KRASG12Ci in an immune-competent model, we observed that the antitumor efficacy of dual treatment comprising an anti-HER therapy (lapatinib) and a KRASG12Ci (MRTX849 or AMG510) depends on CD8+ T cell activation, and that supplementation of the MRTX849/ lapatinib combination with anti-programmed cell death protein-1 (αPD-1) prolonged the progression-free survival of tumor-bearing mice.