Favorable Response to Chemotherapy with Durvalumab plus Tremelimumab in Two Cases of KRAS G12C-Positive Pulmonary Sarcomatoid Carcinoma: A Case Report.

Pulmonary sarcomatoid carcinoma (PSC) and Kirsten rat sarcoma viral oncogene homologue (KRAS) mutations are poor prognostic factors in non-small cell lung cancer. We report two cases of metastatic KRAS G12C-positive PSC in men (aged 69 and 66 years). Both patients were treated with chemotherapy combined with durvalumab and tremelimumab (POSEIDON regimen). They thereafter achieved excellent clinical outcomes, including complete and partial responses, with sustained benefits. The POSEIDON regimen may represent a potent therapeutic option for this rare patient population with multiple negative prognostic factors.