BRAF and metastatic melanoma: Because nivolumab shows higher efficacy than other anti-melanoma drugs (e.g., ipilimumab and dacarbazine) (1, 17), and induces a longer duration of anti-tumor response than BRAF/MEK inhibitors (e.g., vemurafenib, dabrafenib, trametinib) (18, 19), oncologists have been particularly interested in combining nivolumab with agents that enhance anti-tumor immune responses in patients with metastatic melanoma (1–3, 20).