Checkmate, and/or their collaborators or licensees may be replicated in other studies and/or lead to advancement of product candidates to clinical trials, therapeutic applications, or regulatory
approval; the potential of the Toll-like receptor 9 (TLR9) agonist technology discussed in this communication; uncertainty of the utilization, market acceptance, and commercial success of Regenerons Products, Regenerons Product
Candidates, and vidutolimod and the impact of studies (whether conducted by Regeneron, Checkmate or others and whether mandated or voluntary) on any of the foregoing or any potential regulatory approval of Regenerons Products, Regenerons
Product Candidates, and vidutolimod; the likelihood, timing, and scope of possible regulatory approval and commercial launch of Regenerons Product Candidates and vidutolimod and new indications for Regenerons Products; the ability of
Regenerons and Checkmates collaborators, licensees, suppliers, or other third parties (as applicable) to perform manufacturing, filling, finishing, packaging, labeling, distribution, and other steps related to Regenerons Products,
Regenerons Product Candidates, and vidutolimod; the ability of Regeneron and/or its collaborators to manufacture and manage supply chains for multiple products and product candidates; safety issues resulting from the administration of
Regenerons Products, Regenerons Product Candidates, and vidutolimod in patients, including serious complications or side effects in connection with the use of Regenerons Products, Regenerons Product Candidates, and
vidutolimod in clinical trials; determinations by regulatory and administrative governmental authorities which may delay or restrict Regenerons ability to continue to develop or commercialize Regenerons Products, Regenerons Product
Candidates, or Checkmates ability to continue to develop or commercialize vidutolimod; and competing drugs and product candidates that may be superior to, or more cost effective than, Regenerons Products, Regenerons Product
Candidates, or vidutolimod. A more complete description of these and other material risks can be found in Regenerons and Checkmates filings with the U.S. Securities and Exchange Commission, including their Forms 10-K for the year ended December 31, 2021 as well as the Schedule TO and related tender offer documents to be filed by Regeneron and Scandinavian Acquisition Sub, Inc., and the Schedule 14D-9 to be filed by Checkmate, and, if applicable, the proxy statement referenced below. Any forward-looking statements are made based on the current beliefs and judgments of Regenerons and Checkmates
management, and the reader is cautioned not to rely on any forward-looking statements made by Regeneron or Checkmate. Regeneron and Checkmate do not undertake any obligation to update (publicly or otherwise) any forward-looking statement, including
without limitation any financial projection or guidance, whether as a result of new information, future events, or otherwise.
Additional Information
and Where to Find It
The tender offer referenced in this communication has not yet commenced. This communication is for informational purposes only
and is neither an offer to purchase nor a solicitation of an offer to sell securities of Checkmate, nor is it a substitute for the tender offer materials that Checkmate, Regeneron or its acquisition subsidiary, Scandinavian Acquisition Sub, Inc.,
will file with the Securities and Exchange Commission (SEC). 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. CHECKMATES STOCKHOLDERS AND
OTHER INVESTORS ARE URGED TO READ CAREFULLY THE TENDER OFFER MATERIALS (INCLUDING AN OFFER TO PURCHASE, A RELATED LETTER OF TRANSMITTAL AND CERTAIN OTHER TENDER OFFER DOCUMENTS), THE SOLICITATION/RECOMMENDATION STATEMENT ON SCHEDULE 14D-9, AND, IF APPLICABLE, THE PROXY STATEMENT BECAUSE THEY WILL EACH CONTAIN IMPORTANT INFORMATION THAT HOLDERS OF CHECKMATE SECURITIES AND OTHER INVESTORS SHOULD CONSIDER BEFORE MAKING ANY DECISION REGARDING WITH
RESPECT TO THE TENDER OFFER, OR, IF APPLICABLE, VOTING ON THE TRANSACTION. The Offer to Purchase, the related Letter of Transmittal, certain other tender offer documents, as well as the Solicitation/Recommendation Statement, and if applicable, the
proxy statement will be made available to all stockholders of Checkmate at no expense to them and will also be made available for free at the SECs website at www.sec.gov. Additional copies may be obtained for free by contacting either
Regeneron or Checkmate. Copies of the documents filed with the SEC by Checkmate will be available free of charge on Checkmates website at https://ir.checkmatepharma.com or by contacting Checkmates Investor Relations Department at (617) 682-3625. Copies of the documents filed with the SEC by Regeneron will be available free of charge on Regenerons website at https://investor.regeneron.com or by contacting Regenerons Investor Relations
Department at invest@regeneron.com or (914) 847-7741.