San Diego-based Ambrx has garnered an undisclosed upfront payment from Merck KGaA in a deal to co-develop ARX424, a new therapy for multiple sclerosis. Ambrx also gets an undisclosed equity investment and milestones. Xconomy's Luke Timmerman correctly notes that undisclosed payments are typically a sign that the deal involves small figures. But he speculates that in this case the principals may be more interested in keeping the details secret from the competition. Release l Report