- Prior Treatment. 1. Less than 1 week since the last treatment of lapatinib, less than 2 weeks since the last treatment of vemurafenib, less than 4 weeks since the last treatment of chemotherapy, biological therapy, immunotherapy and systemic radiotherapy (except palliative radiation delivered to <20% of bone marrow), less than 8 weeks for cranial radiotherapy, and less than 6 weeks for nitrosoureas and mitomycin C.