Regeneron Pharmaceuticals, Inc. entered an agreement to acquire Checkmate Pharmaceuticals, Inc., a clinical stage biopharma company focused on technology to harness the immune system to combat cancer, for approximately $250 million in cash.   Checkmate’s lead investigational candidate is vidutolimod, an advanced generation CpG-A oligodeoxynucleotide Toll-like receptor 9 (TLR9) agonist delivered in a virus-like particle.   “As we continue to advance and expand our research efforts...