[Form 3] NuCana plc Initial Statement of Beneficial Ownership

Rhea-AI Filing Summary

NuCana plc filed an initial statement of beneficial ownership for officer Ian Alexander Webster, outlining multiple option grants over its Ordinary Shares. These options carry exercise prices of 0.004 Pounds Sterling or 0.0004 Pounds Sterling, with varying vesting and expiration schedules.

Some option grants over Ordinary Shares completed vesting on June 20, 2025 and January 14, 2026, and expire on June 20, 2035 and January 14, 2036, respectively. Other grants begin vesting 25% on June 20, 2026 and January 14, 2027, with the remainder vesting in three equal annual installments, subject to continued service. The filing reports holdings only, with no buy or sell transactions.

SEC 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^*

Webster Ian Alexander

(Last) (First) (Middle)

C/O NUCANA PLC

3 LOCHSIDE WAY

(Street)

EDINBURGH UNITED KINGDOM EH12 9DT

(City) (State) (Zip)

UNITED KINGDOM

(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)

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

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)

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)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Options	(1)	(1)	Ordinary Shares	49,625,635	(1)	D
Options	(2)	(2)	Ordinary Shares	81,529,196	(2)	D
Options	(3)	(3)	Ordinary Shares	12,874,360	(3)	D
Options	(4)	(4)	Ordinary Shares	20,209,396	(4)	D
Options	(5)	(5)	Ordinary Shares	54,352,798	(5)	D

Explanation of Responses:

1. The ordinary shares, nominal value 0.0004 Pounds Sterling per share (the "Ordinary Shares"), of NuCana plc (the "Company") underlying this option have an exercise price of 0.004 Pounds Sterling, completed vesting on June 20, 2025 and expire June 20, 2035.

2. The Ordinary Shares underlying this option have an exercise price of 0.0004 Pounds Sterling, completed vesting on January 14, 2026 and expire January 14, 2036.

3. The Ordinary Shares underlying this option have an exercise price of 0.004 Pounds Sterling and will vest as to 25% on June 20, 2026, with the remainder vesting in three equal annual installments thereafter, 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 0.0004 Pounds Sterling and will vest as to 25% on June 20, 2026, with the remainder vesting in three equal annual installments thereafter, subject to the Reporting Person's continued service with the Company through the applicable vesting date.

5. The Ordinary Shares underlying this option have an exercise price of 0.0004 Pounds Sterling and will vest as to 25% on January 14, 2027, with the remainder vesting in three equal annual installments thereafter, subject to the Reporting Person's continued service with the Company through the applicable vesting date.

Remarks:

Exhibit 24.1 - Power of Attorney Interim Chief Financial Officer

	/s/ Ian Webster	03/18/2026
	** 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)