A case of hepatoid adenocarcinoma of the lung harboring KRAS G12C responded favorably to sotorasib.

Hepatoid adenocarcinoma of the lung is a rare variant of adenocarcinoma. We describe a case of hepatoid adenocarcinoma of the lung that harbored KRAS G12C and responded favorably to sotorasib. A man in his 70s was found to have an abnormality on his chest X-ray. He underwent right middle lobectomy, and a pathological examination of the surgical specimen showed conventional invasive adenocarcinoma with highly focal hepatoid adenocarcinoma. He received chemoradiotherapy and concurrent radiation, followed by durvalumab for postoperative recurrence. After three doses of durvalumab, he reported feeling short of breath. A computed tomography scan showed emerging broad consolidation in the right lower lobe. Transbronchial lung biopsy specimens from the consolidation showed hepatoid adenocarcinoma harboring KRAS G12C mutation. Therefore, he was started on sotorasib 960 mg daily. Eight days later, a computed tomography scan showed that the area of consolidation had reduced in size. Progressive disease was detected after 42 days of treatment with sotorasib. The patient died 1 month after cessation of sotorasib and 3 months after postoperative recurrence. We have encountered what we believe to be the first case of hepatoid adenocarcinoma of the lung with KRAS G12C mutation that responded favorably to treatment with sotorasib.