PARTICIPANTS IN THE SOLICITATION
Arsanis, X4 and their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from the holders of Arsanis
common stock in connection with the proposed transaction. Information about Arsanis directors and executive officers is set forth in Arsanis Annual Report on Form
10-K
for the year ended
December 31, 2017, which was filed with the Securities and Exchange Commission (the SEC) on March 9, 2018, and the proxy statement for Arsanis 2018 annual meeting of stockholders, which was filed with the SEC on
April 23, 2018. Other information regarding the interests of such individuals, as well as information regarding X4s directors and executive officers and other persons who may be deemed participants in the proposed transaction, will be set
forth in the proxy statement/prospectus/information statement, which will be included in Arsanis registration statement when it is filed with the SEC. Investors and security holders may obtain free copies of these documents as described in the
paragraph below.
IMPORTANT INFORMATION ABOUT THE TRANSACTION WILL BE FILED WITH THE SEC
In connection with the proposed merger, Arsanis will file with the SEC a Registration Statement on Form
S-4
that will
include a proxy statement of Arsanis, a prospectus of Arsanis and an information statement of X4 and certain of its affiliates (the X4 Parties), and the parties may file with the SEC other relevant documents concerning the proposed
transaction. Arsanis will mail the definitive proxy statement/prospectus/information statement to the Arsanis stockholders and the X4 Parties equity holders. ARSANIS STOCKHOLDERS AND X4 PARTIES EQUITY HOLDERS ARE URGED TO READ THE REGISTRATION
STATEMENT AND PROXY STATEMENT/PROSPECTUS/INFORMATION STATEMENT REGARDING THE PROPOSED TRANSACTION WHEN IT BECOMES AVAILABLE AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC, AS WELL AS ANY AMENDMENTS OR SUPPLEMENTS TO THOSE DOCUMENTS, BECAUSE
THEY WILL CONTAIN IMPORTANT INFORMATION. Investors and security holders may obtain a free copy of the proxy statement/prospectus/information statement (when available) and other filings containing information about Arsanis at the SECs website
at www.sec.gov. The proxy statement/prospectus/information statement (when available) and the other filings may also be obtained free of charge by contacting: Arsanis, Inc., 890 Winter Street, Suite 230, Waltham, Massachusetts 02451, Attention:
Investor Relations.
Additional information regarding the interests of those participants and other persons who may be deemed participants in the
transaction may be obtained by reading the proxy statement/prospectus/information statement regarding the proposed transaction when it becomes available. Free copies of this document may be obtained as described in the preceding paragraphs.
NO OFFERS OR SOLICITATIONS
This communication shall not
constitute an offer to sell or the solicitation of an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful
prior to registration or qualification under the securities laws of any such jurisdiction. No offer of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended
(the Securities Act).
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS
Certain statements in this Current Report on Form
8-K
regarding the merger, potential payments to and the option to
acquire patents from Arsanis under the License and Option Agreement, and the strategies, goals, prospects, plans, expectations, forecasts or objectives of Arsanis, X4 or the combined company constitute forward-looking statements within
the meaning of Section 27A of the Securities Act and Section 21E of the Securities Exchange Act of 1934, as amended (the Exchange Act), and are usually