Tetraphase Announces Receipt of Amended Melinta Proposal, Determination of Superior Offer and Notice to AcelRx

Tetraphase Pharmaceuticals, Inc. (Nasdaq:TTPH), a biopharmaceutical company focused on commercializing its novel tetracycline XERAVA (eravacycline for injection) to treat serious and life-threatening infections, today announced that its Board of Directors has received a revised proposal from Melinta Therapeutics, Inc. (“Melinta”) amending its prior proposal to acquire the Company (the “Amended Melinta Proposal”), and has determined that the Amended Melinta Proposal is a “Superior Offer” under the terms of the Agreement and Plan of Merger, dated March 15, 2020 and amended on May 27, 2020 and on May 29, 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 the Amended Melinta Proposal, the Superior Offer 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 Wednesday, June 3, 2020 that, if accepted, would result in the Amended Melinta Proposal ceasing to be a Superior Offer.

Under the AcelRx Merger Agreement, as amended, Tetraphase stockholders would receive, for each share of Tetraphase common stock, (1) $0.5872 in cash and 0.7409 of a share of AcelRx common stock, representing approximately $1.70 in upfront per share value, based on the closing price of AcelRx’s common stock as of the close of trading on May 28, 2020, in each case subject to downward adjustment in the event that the Company’s closing net cash is less than $5.0 million, and (2) one contingent value right (“CVR”), which would entitle the holders to receive potential aggregate payments of up to $16.0 million in cash upon the achievement of certain future XERAVA net sales milestones starting in 2021. Based on the closing price of AcelRx common stock on June 1, 2020, the total upfront consideration to be received by Tetraphase equityholders under the AcelRx Merger Agreement at closing is valued at approximately $33.3 million, with approximately $16.8 million of this amount allocated to the Company’s outstanding common stock warrants.