Item 8.01. Other Events.
On May 21, 2020, Tetraphase Pharmaceuticals, Inc. (Tetraphase) announced that its Board of Directors has determined that the latest proposal
from Melinta Therapeutics, Inc. (Melinta) to acquire the Company is a Superior Offer under the terms of the Agreement and Plan of Merger, dated March 15, 2020, to which the Company is a party with AcelRx Pharmaceuticals,
Inc. (AcelRx) and its merger subsidiary (the AcelRx Merger Agreement). In connection with this determination and in accordance with the terms of the AcelRx Merger Agreement, the Company has given notice to AcelRx of such
determination and of its intention to consider changing its recommendation of the AcelRx Merger Agreement or terminating the AcelRx Merger Agreement unless AcelRx proposes revisions to the terms of the AcelRx Merger Agreement or makes another
proposal on or prior to Friday, May 29, 2020 that, if accepted, would result in the Melinta proposal ceasing to be a Superior Offer. A copy of the press release is attached as Exhibit 99.1 hereto and is incorporated herein by reference.
Additional Information and Where to Find it
In
connection with the proposed transaction between Tetraphase and AcelRx Pharmaceuticals, Inc. (AcelRx), AcelRx filed with the Securities and Exchange Commission (the SEC) the Registration Statement containing a document
constituting a prospectus of AcelRx and a proxy statement of Tetraphase. The Registration Statement was declared effective by the SEC on April 24, 2020, and Tetraphase commenced mailing the definitive proxy statement/prospectus to stockholders
of Tetraphase on April 28, 2020. Tetraphase and AcelRx also plan to file other relevant documents with the SEC regarding the proposed transaction. Investors and security holders are urged to read the definitive proxy statement/prospectus and
other relevant documents filed with the SEC carefully and in their entirety because they contain important information.
Investors and security
holders can obtain free copies of the proxy statement/prospectus and other documents filed with the SEC by Tetraphase, AcelRx and/or Melinta Therapeutics, Inc. (Melinta) through the web site maintained by the SEC at www.sec.gov. In
addition, investors and security holders can obtain free copies of the proxy statement/prospectus from Tetraphase by written request to Tetraphase Pharmaceuticals, Inc., 480 Arsenal Way, Watertown, Massachusetts 02472, Attn: Secretary or by calling
(617) 715-3600.
No Offer or Solicitation
This communication does not constitute an offer to sell, or the solicitation of an offer to buy, any securities, nor a solicitation of any vote or approval,
with respect to the proposed transaction or otherwise. No offering 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, and otherwise in accordance with
applicable law. If a negotiated transaction between Tetraphase and Melinta is agreed, Tetraphase and Melinta will prepare filing(s) related to the proposed transaction (including a tender offer statement on Schedule TO, including an offer to
purchase, a related letter of transmittal and other tender offer documents related to the transaction and any amendments thereto, and Tetraphase would file a recommendation statement on Schedule 14D-9 with the
SEC and any amendments thereto), and Tetraphase will provide the filing(s) to its stockholders. Tetraphase, and possibly Melinta, may also file other documents with the SEC regarding the proposed transaction. This document is not a substitute for
any tender offer document or any other document which Tetraphase or Melinta may file with the SEC in connection with the proposed transaction. If a negotiated transaction between Tetraphase and Melinta is agreed, investors and security holders
are urged to read the filing(s) and the other relevant materials with respect to the proposed transaction with Melinta carefully in their entirety when they become available before making any voting or investment decision with respect to any
proposed transaction with Melinta, because they will contain important information about any proposed transaction with Melinta.
Participants in
the Solicitation
Tetraphase and its directors and executive officers may be deemed to be participants in the solicitation of proxies from Tetraphase
stockholders in respect of the transactions contemplated by the merger agreement, dated as of March 15, 2020 (the AcelRx Merger Agreement) with AcelRx and Consolidation Merger Sub, Inc. or the Melinta proposal. Information about
Tetraphases directors and executive officers is included in Tetraphases Annual Report on Form 10-K for the year ended December 31, 2019, which was filed with the SEC on March 12, 2020.
Other