NSCLC with Kirsten rat sarcoma viral oncogene homolog (KRAS) or B-Raf Proto-Oncogene (BRAF) mutations have a higher TMB, whereas NSCLC with EGFR mutation or ALK fusion exhibits a lower TMB, resulting in an unfavorable response to monotherapy with PD-1/PD-L1 inhibitors. The gene discussed is BRAF; the disease is non-small cell lung carcinoma.