NuCana (NCNA) 6-K Current report (foreign)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN ISSUER

PURSUANT TO RULE13a-16 OR15d-16

OF THE SECURITIES EXCHANGE ACT OF 1934

For the month of December 2019

(Commission FileNo. 001-38215)

NUCANA PLC

(Translation of registrant’s name into English)

3 Lochside Way

Edinburgh EH12 9DT

United Kingdom

(Address of registrant’s principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under coverForm 20-F orForm 40-F.

Form 20-F  ☒             Form40-F  ☐

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

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

Other Events

On November 13, 2019, NuCana plc (the “Company”) announced that it was prioritizing resources on its two key programs, Acelarin in biliary tract cancer andNUC-3373 in colorectal cancer. Further to that announcement, the Company has determined not to proceed with Part II of itsPRO-105 study.PRO-105 is the Company’s Phase II study of single-agent Acelarin for patients with platinum-resistant ovarian cancer and had atwo-part design. Part I was designed to compare a 500mg/m2 dose of Acelarin versus a 750mg/m2 dose of Acelarin in platinum resistant ovarian cancer in heavilypre-treated patients (patients who have received at least 3 prior lines of chemotherapy). Part II was designed to then investigate the optimal dose identified in Part I in an expansion cohort. The Company expects to report data from Part I of thePRO-105 study in the first half of 2020.

The information above shall be deemed to be incorporated by reference into the registration statements onForm F-3 (File Number333-227624) andForm S-8 (FileNumber 333-223476), and related prospectuses, as such registration statements and prospectuses may be amended from time to time, and to be a part thereof from the date on which this report is filed, to the extent not superseded by documents or reports subsequently filed or furnished.

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.

NuCana plc
By:	/s/ Donald Munoz
Name:	Donald Munoz
Title:	Chief Financial Officer

Date: December 27, 2019