A pivotal trial of Bristol-Myers Squibb Co.'s Opdivo (nivolumab), presented at the European Society of Medical Oncology (ESMO) conference in Madrid, on Monday, heralded a potential end to chemotherapy in treating BRAF wild-type melanoma, with response rates to the programmed death-1 (PD-1) immune checkpoint inhibitor reaching 32 percent of patients vs. 11 percent on chemotherapy.