UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-Q/A

(Amendment No. 1)

(Mark One)

For the quarterly period ended March 31, 2020

OR

Commission File Number: 001-38630

Aridis Pharmaceuticals, Inc.

(Exact Name of Registrant as Specified in its Charter)

(408) 385-1742

(Registrant’s telephone number, including area code)

(Former name, former address and former fiscal year, if changed since last report)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes x No ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ¨ No x

The number of shares of the registrant’s common stock, $0.0001 par value per share, outstanding at April 30, 2020 was 8,923,374.

EXPLANATORY NOTE

This Amendment No. 1 (the “Amendment”) to the Quarterly Report on Form 10-Q of Aridis Pharmaceuticals, Inc. (the “Company”) for the fiscal quarter ended March 31, 2020, originally filed with the Securities and Exchange Commission (the “SEC”) on May 12, 2020 (the “Original Filing”), is being filed solely to include revised Exhibits 31.1 and 31.2, which include certain statements required by Item 601(b)(31) of Regulation S-K inadvertently omitted by the Company when originally filed. This Amendment contains only the cover page, this explanatory note, the exhibit index, the signature page and the revised certifications.

Except for the foregoing, this Amendment does not alter or update any information contained in the Original Filing. The Original Filing continues to speak as of the date of the Original Filing, and the Company has not updated the disclosures contained therein to reflect any events that have occurred as of a date subsequent to the date of the Original Filing. Accordingly, this Amendment should be read in conjunction with the Original Filing, and the Company’s filings made with the SEC subsequent to the filing of the Original Filing.

PART II — OTHER INFORMATION

Item 6. Exhibits

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.