IFNA1 and Decreased total neutrophil count: During treatment with vemurafenib 960 mg b.i.d. + PEG-IFN-α-2b 1 μg/kg once weekly, 65.3% of the AEs observed were of mild severity, 28.6% moderate, and 4.1% were life-threatening (neutropenia and leukopenia grade 4).