NuCana (NCNA) Chief Medical Officer reports extensive option-based holdings

Rhea-AI Filing Summary

NuCana plc Chief Medical Officer Jeffrey D. Bloss filed a Form 3 reporting his existing ownership in the company. The filing lists multiple option awards over Ordinary Shares with exercise prices between 0.0004 and 0.004 Pounds Sterling, including grants that are fully vested and others that vest between June 2026 and January 2027, subject to continued service. Bloss also reports direct ownership of 47,136 Ordinary Shares.

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^*

Bloss Jeffrey D.

(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)

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

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	47,136	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)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Options	(1)	(1)	Ordinary Shares	73,079,440	(1)	D
Options	(2)	(2)	Ordinary Shares	87,871,006	(2)	D
Options	(3)	(3)	Ordinary Shares	146,158,880	(3)	D
Options	(4)	(4)	Ordinary Shares	73,079,440	(4)	D
Options	(5)	(5)	Ordinary Shares	87,871,006	(5)	D
Options	(6)	(6)	Ordinary Shares	175,742,012	(6)	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 0.0005 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 0.0004 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.

4. 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.

5. The Ordinary Shares underlying this option have an exercise price of 0.0005 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.

6. 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:

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 Jeffrey Bloss	03/19/2026
	** 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)

FAQ

What does the NuCana (NCNA) Form 3 for Jeffrey D. Bloss report?

The Form 3 reports Chief Medical Officer Jeffrey D. Bloss’s existing holdings in NuCana. It discloses several option awards over Ordinary Shares and a direct position of 47,136 Ordinary Shares, providing a baseline of his equity exposure as an executive.

Are there any buy or sell transactions in this NuCana (NCNA) Form 3?

No new buy or sell transactions are shown in this Form 3. The entries are classified as holdings, meaning the document records existing option and share positions rather than recent market trades or exercises that change Bloss’s ownership.

What option exercise prices are disclosed for NuCana (NCNA) Chief Medical Officer Bloss?

The filing shows options over NuCana Ordinary Shares with very low exercise prices. These options carry exercise prices of 0.0004, 0.0005, and 0.004 Pounds Sterling, indicating they are deeply in-the-money if the market price is materially higher than these nominal strike levels.

When do Jeffrey Bloss’s NuCana (NCNA) options vest according to the Form 3?

Some options were fully vested by June 20, 2025 and January 14, 2026. Other grants vest 25% on June 20, 2026 and January 14, 2027, with the remaining portions vesting in three equal annual installments, contingent on Bloss’s continued service with NuCana.

How long do the reported NuCana (NCNA) options for Jeffrey Bloss remain exercisable?

The Form 3 notes option expirations on June 20, 2035 and January 14, 2036 for certain grants. These long-dated expirations give Bloss an extended period to exercise vested options, aligning his incentives with NuCana’s long-term performance over many years.

What type of NuCana (NCNA) security does Jeffrey Bloss directly own?

In addition to options, Jeffrey Bloss directly owns NuCana Ordinary Shares. The filing reports direct ownership of 47,136 Ordinary Shares, separate from the underlying shares tied to his various option awards disclosed in the same Form 3.