TEL: (212)616-4899

Tetraphase Pharmaceuticals, Inc. (TTPH) Loss Form

The Klein Law Firm announces that a class action complaint has been filed on behalf of shareholders of Tetraphase Pharmaceuticals, Inc. (“Tetraphase”) (NASDAQ: TTPH) securities who purchased shares (1) Pursuant and/or traceable to the July 2017 Secondary Offering and/or (2) between March 8, 2017 and February 13, 2018.

The complaint alleges that (1) Tetraphase was increasing the patient enrollment in its IGNITE3 trial from 1,000 patients to 1,200 patients to meet the trial’s primary endpoints ; (2) the enrollment of more patients in the trial indicated that the existing population was inadequate to meet the trial’s primary endpoints; and (3) consequently, Defendants’ statements about Tetraphase’s business, operations, and prospects, were materially false and/or misleading and/or lacked a reasonable basis.

Shareholders have until September 25, 2018 to petition the court for lead plaintiff status. Your ability to share in any recovery does not require that you serve as lead plaintiff. You may choose to be an absent class member.

Keep Me Informed

The Klein Law Firm does not share your information with others. There is no cost or obligation. This submission does not create an attorney-client relationship. If we believe that you might be an appropriate lead plaintiff, we will contact you to discuss whether to establish an attorney-client relationship.

This letter confirms that you have retained The Klein Law Firm to represent you as a named plaintiff in a shareholder action involving Tetraphase Pharmaceuticals, Inc.

We agree to advance all expenses in the litigation, which means that you are not liable to pay any of the expenses of the lawsuit, whether attorneys' fees or costs. Regardless of the result, we will never ask you to directly pay for any attorneys' fees or costs. Should we obtain a favorable result, we may ask the court to award us compensation to be paid by the defendants or as a portion of any class benefit, but, again, we will never ask you to directly pay any of the costs of this litigation.

As the client you are entitled to direct the litigation in any way you deem proper, and may at any time order us to dismiss the case or opt-out. Should you choose to do so, we will never ask you to reimburse us directly for any legal fees or expenses. During the course of this litigation, we may employ and/or work with other law firms to prosecute your case.

We look forward to representing you and other Tetraphase Pharmaceuticals, Inc. shareholders.

Sincerely,

The Klein Law Firm

Joseph Klein

AGREED: Sign Name Clear