UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the Month of December 2018

Commission File Number: 001-38547

Autolus Therapeutics plc

(Translation of registrant’s name into English)

Forest House

58 Wood Lane

White City

London W12 7RZ

United Kingdom

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

☒  Form 20-F                ☐  Form 40-F

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ☐

Other Events

Change in Fiscal Year

On December 19, 2018, the board of directors of Autolus Therapeutics plc, or the Company, approved a change in the Company’s fiscal year end from September 30 to December 31. The Company will file a transition report on Form 20-F to cover the transition period from October 1, 2018 to December 31, 2018.

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.