Mixed response to the first‐line treatment of KRAS G12C inhibitor, sotorasib, in non‐small cell lung cancer: A brief report

Key Clinical Message One Kirsten Ras (KRAS) G12C mutated non‐small cell lung cancer (NSCLC) patient had improved poor performance status and obtained mixed response with the first‐line KRAS‐targeted treatment of sotorasib. After disease progression, partial response was achieved with chemotherapy plus immunotherapy. KRAS G12C mutated immunoenvironment in NSCLC may favor the immunotherapy. Abstract KRAS is one of the most commonly mutated genes, which used to be untargetable. The phase II CodeBreak 100 trial revealed 6.8‐month median progress‐free survival (PFS) and 12.5‐month overall survival (OS) in previously treated KRAS G12C‐mutant NSCLC patients treated with KRAS inhibitor, sotorasib. The specimens of the brain, lymph node (LN), and blood from the patient were analyzed by next‐generation sequencing. Hematoxylin and eosin staining and immunohistochemistry were performed for pathological characterization. Computed tomography (CT) and magnetic resonance imaging (MRI) scan were used for treatment response evaluation. The patient was diagnosed in a bad Eastern Cooperative Oncology Group performance status (ECOG‐PS) with metastatic KRAS G12C‐mutated lung adenocarcinoma who had achieved mixed response to sotorasib as the first‐line treatment. Although 5‐month PFS of the treatment with sotorasib was not surprising, the patient achieved significantly improved ECOG‐PS score from 4 to 1. Subsequently, partial response (PR) was achieved with the treatment of pemetrexed plus pembrolizumab. This case highlights superior efficacy of first‐line treatment with sotorasib for the advance untreated KRAS G12C‐mutant patients. The high efficacy of the treatment with chemotherapy plus immunotherapy revealed that immunoenvironment of KRAS G12C‐mutated patient may favor the immunotherapy.