SEC FORM 3

SEC FORM 3SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

Mellish Martin C.B.

(Last)

(First)

(Middle)

C/O NUCANA PLC

3 LOCHSIDE WAY

(Street)

EDINBURGH

EH12 9DT

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Date of Event Requiring Statement (Month/Day/Year)
03/18/2026

3. Issuer Name and Ticker or Trading Symbol
NuCana plc [ NCNA ]

3a. Foreign Trading Symbol

5. If Amendment, Date of Original Filed (Month/Day/Year)

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
	Officer (give title below)	Other (specify below)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Ordinary Shares	28	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
American Depositary Shares	⁽¹⁾	⁽¹⁾	Ordinary Shares	7	⁽¹⁾	D
Options	⁽²⁾	⁽²⁾	Ordinary Shares	35,231,753	⁽²⁾	D
Options	⁽³⁾	⁽³⁾	Ordinary Shares	35,231,753	⁽³⁾	D
Options	⁽⁴⁾	⁽⁴⁾	Ordinary Shares	42,362,799	⁽⁴⁾	D
Options	⁽⁵⁾	⁽⁵⁾	Ordinary Shares	42,362,799	⁽⁵⁾	D

Explanation of Responses:

1. Each American Depositary Share ("ADS") represents 5,000 ordinary shares, nominal value 0.0004 Pounds Sterling per share (the "Ordinary Shares"), of NuCana plc (the "Company"). ADSs have no expiration date.

2. The Ordinary Shares underlying this option have an exercise price of 0.004 Pounds Sterling, completed vesting on June 20, 2025 and expire June 20, 2035.

3. The Ordinary Shares underlying this option have an exercise price of 0.0004 Pounds Sterling and will vest in full on June 20, 2026, subject to the Reporting Person's continued service with the Company through the applicable vesting date.

4. The Ordinary Shares underlying this option have an exercise price of 0.0005 Pounds Sterling, completed vesting on January 14, 2026 and expire January 14, 2036.

5. The Ordinary Shares underlying this option have an exercise price of 0.0004 Pounds Sterling and will vest in full on January 14, 2027, subject to the Reporting Person's continued service with the Company through the applicable vesting date.

Remarks:

This Form 3 is being filed late due to unanticipated delays in receiving the Reporting Person's EDGAR codes, which delays the Reporting Person understands were due to the high volume of applications at the time. Exhibit 24.1 - Power of Attorney

	/s/ Ian Webster, Attorney-in-Fact for Martin Mellish	03/20/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 3: SEC 1473 (03-26)

SEC Form 3 filed by new insider Mellish Martin C.B.