Seven years after embarking on in vivo therapeutic development using CRISPR/Cas gene-editing technology with Intellia Therapeutics Inc., Regeneron Pharmaceuticals Inc. is bringing another company into the collaborative fold. Regeneron will pay Mammoth Biosciences Inc. $100 million, including $95 million as an equity investment, and an up-front payment. Mammoth also could bring in up to $370 million for each target in milestones along with royalties on net sales from products created through the collaboration.