Ligand Pharmaceuticals Incorporated today announced that it has earned a $500,000 milestone payment from SAGE Therapeutics relating to the treatment of the first patient in SAGE's Phase 3 open-label expanded access protocol, designated Study 302. Study 302 is designed to offer SAGE-547 to patients affected by super-refractory status epilepticus and to evaluate the safety of SAGE-547 in patients with SRSE.