 The deal gives JJs Janssen unit access to Momentas experimental therapy, nipocalimab, being tested for myasthenia gravis, a neuromuscular disease that causes weakness in muscles, and other diseases where the immune system attacks the body. JJ hopes to get the drug approved to treat several conditions and eventually bring in blockbuster sales, as the company bulks up its pharmaceuticals unit, its largest business. Shares of Cambridge, Massachusetts-based Momenta were up 69.3 at 52.15 before the bell, just a hairs breadth away from the offer price of 52.50. 