The solicitation and offer to buy Checkmate stock will only be made pursuant to an Offer to Purchase and related tender offer materials that Regeneron intends to file with the SEC. At the time the tender offer is commenced, Regeneron and its acquisition subsidiary will file a Tender Offer Statement on Schedule TO and thereafter Checkmate will file a Solicitation/Recommendation Statement on Schedule 14D-9 with the SEC with respect to the tender offer. Under certain circumstances described in the definitive transaction documents, Regeneron may determine to instead to terminate or withdraw the offer and effect the transaction through a merger only, in which case the relevant documents to be filed with the SEC will include a proxy statement for the solicitation of votes of Checkmate stockholders to approve the merger.