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Filing Details

Accession Number:: 0000902664-24-001056
Form Type:: 13G Filing
Publication Date:: 2024-02-04 19:00:00

Filed By:: Adage Capital Management
Company:: Mereo Biopharma Group Plc
Filing Date:: 2024-02-05
SEC Url:: 13G Filing

Ownership Summary

Please notice the below summary table is generated without human intervention and may contain errors. Please refer to the complete filing displayed below for exact figures.

Name	Shared Voting Power	Shared Dispositive Power	Aggregate Amount Owned Power	Percent of Class
Adage Capital Partners	50,250,000	50,250,000	50,250,000	7.17%
Adage Capital Partners GP	50,250,000	50,250,000	50,250,000	7.17%
Adage Capital Management	50,250,000	50,250,000	50,250,000	7.17%
Robert Atchinson	50,250,000	50,250,000	50,250,000	7.17%
Phillip Gross	50,250,000	50,250,000	50,250,000	7.17%

Filing

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No. )*

Mereo Biopharma Group Plc.
(Name of Issuer)

Ordinary Shares, nominal value £0.003 per share
(Title of Class of Securities)

589492107**
(CUSIP Number)

January 24, 2024
(Date of Event Which Requires Filing of This Statement)


Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

¨	Rule 13d-1(b)
ý	Rule 13d-1(c)
¨	Rule 13d-1(d)

(Page 1 of 11 Pages)

______________________________

*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

**There is no CUSIP number assigned to the Ordinary Shares. The CUSIP number 589492107 has been assigned to the American Depositary Shares ("ADSs") of the Company, which are quoted on Nasdaq under the symbol "MREO." Each ADS represents 5 Ordinary Shares.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 589492107

13G

Page 2 of 11 Pages

1	NAME OF REPORTING PERSON Adage Capital Partners, L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	5	SOLE VOTING POWER 0
	6	SHARED VOTING POWER 50,250,000 (represented by 10,050,000 ADSs)
	7	SOLE DISPOSITIVE POWER 0
	8	SHARED DISPOSITIVE POWER 50,250,000 (represented by 10,050,000 ADSs)
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 50,250,000 (represented by 10,050,000 ADSs)
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			¨
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 7.17%
12	TYPE OF REPORTING PERSON PN

CUSIP No. 589492107

13G

Page 3 of 11 Pages

1	NAME OF REPORTING PERSON Adage Capital Partners GP, L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	5	SOLE VOTING POWER 0
	6	SHARED VOTING POWER 50,250,000 (represented by 10,050,000 ADSs)
	7	SOLE DISPOSITIVE POWER 0
	8	SHARED DISPOSITIVE POWER 50,250,000 (represented by 10,050,000 ADSs)
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 50,250,000 (represented by 10,050,000 ADSs)
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			¨
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 7.17%
12	TYPE OF REPORTING PERSON OO

CUSIP No. 589492107

13G

Page 4 of 11 Pages

1	NAME OF REPORTING PERSON Adage Capital Management, L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	5	SOLE VOTING POWER 0
	6	SHARED VOTING POWER 50,250,000 (represented by 10,050,000 ADSs)
	7	SOLE DISPOSITIVE POWER 0
	8	SHARED DISPOSITIVE POWER 50,250,000 (represented by 10,050,000 ADSs)
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 50,250,000 (represented by 10,050,000 ADSs)
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			¨
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 7.17%
12	TYPE OF REPORTING PERSON PN, IA

CUSIP No. 589492107

13G

Page 5 of 11 Pages

1	NAME OF REPORTING PERSON Robert Atchinson
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	5	SOLE VOTING POWER 0
	6	SHARED VOTING POWER 50,250,000 (represented by 10,050,000 ADSs)
	7	SOLE DISPOSITIVE POWER 0
	8	SHARED DISPOSITIVE POWER 50,250,000 (represented by 10,050,000 ADSs)
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 50,250,000 (represented by 10,050,000 ADSs)
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			¨
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 7.17%
12	TYPE OF REPORTING PERSON IN

CUSIP No. 589492107

13G

Page 6 of 11 Pages

1	NAME OF REPORTING PERSON Phillip Gross
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	5	SOLE VOTING POWER 0
	6	SHARED VOTING POWER 50,250,000 (represented by 10,050,000 ADSs)
	7	SOLE DISPOSITIVE POWER 0
	8	SHARED DISPOSITIVE POWER 50,250,000 (represented by 10,050,000 ADSs)
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 50,250,000 (represented by 10,050,000 ADSs)
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			¨
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 7.17%
12	TYPE OF REPORTING PERSON IN

CUSIP No. 589492107

13G

Page 7 of 11 Pages

Item 1(a).	NAME OF ISSUER
	The name of the issuer is Mereo Biopharma Group Plc., (the “Company”).

Item 1(b).	ADDRESS OF ISSUER’S PRINCIPAL EXECUTIVE OFFICES
	The Company’s principal executive offices are located at 4th Floor, One Cavendish Place, London, W1G 0QF, United Kingdom.

Item 2(a).	NAME OF PERSON FILING
	This statement is filed by:

	(i)	Adage Capital Partners, L.P., a Delaware limited partnership (“ACP”) with respect to the Ordinary Shares represented by ADSs directly owned by it;

	(ii)	Adage Capital Partners GP, L.L.C., a limited liability company organized under the laws of the State of Delaware (“ACPGP”), as general partner of ACP with respect to the Ordinary Shares represented by ADSs directly owned by ACP;

	(iii)	Adage Capital Management, L.P., a Delaware limited partnership (“ACM”), as the investment manager of ACP, with respect to the Ordinary Shares represented by ADSs directly owned by ACP;

	(iv)	Robert Atchinson (“Mr. Atchinson”), as (1) managing member of Adage Capital Advisors, L.L.C., a limited liability company organized under the laws of the State of Delaware (“ACA”), managing member of ACPGP and (2) managing member of Adage Capital Partners LLC, a Delaware limited liability company (“ACPLLC”), general partner of ACM, with respect to the Ordinary Shares represented by ADSs directly owned by ACP; and

	(v)	Phillip Gross (“Mr. Gross”), as (1) managing member of ACA, managing member of ACPGP and (2) managing member of ACPLLC, general partner of ACM, with respect to the Ordinary Shares represented by ADSs directly owned by ACP.

	The foregoing persons are hereinafter sometimes collectively referred to as the “Reporting Persons.” Any disclosures herein with respect to persons other than the Reporting Persons are made on information and belief after making inquiry to the appropriate party.

	The filing of this statement should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of the securities reported herein.

Item 2(b).	ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE
	The address of the business office of each of the Reporting Persons is 200 Clarendon Street, 52nd Floor, Boston, Massachusetts 02116.

Item 2(c).	CITIZENSHIP
	ACP and ACM are limited partnerships organized under the laws of the State of Delaware. ACPGP is a limited liability company organized under the laws of the State of Delaware. Messrs. Gross and Atchinson are citizens of the United States.

Item 2(d).	TITLE OF CLASS OF SECURITIES
	Ordinary Shares, par value £0.0003 per share (the “Ordinary Shares”).

CUSIP No. 589492107

13G

Page 8 of 11 Pages

Item 2(e).	CUSIP NUMBER
	There is no CUSIP number assigned to the Ordinary Shares. The CUSIP number 589492107 has been assigned to the American Depositary Shares ("ADSs") of the Company, which are quoted on Nasdaq under the symbol "MREO." Each ADS represents 5 Ordinary Shares.

Item 3.	IF THIS STATEMENT IS FILED PURSUANT TO Rules 13d-1(b), OR 13d-2(b) OR (c), CHECK WHETHER THE PERSON FILING IS A:
	(a)	¨	Broker or dealer registered under Section 15 of the Act;
	(b)	¨	Bank as defined in Section 3(a)(6) of the Act;
	(c)	¨	Insurance company as defined in Section 3(a)(19) of the Act;
	(d)	¨	Investment company registered under Section 8 of the Investment Company Act of 1940;
	(e)	¨	An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E);
	(f)	¨	An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F);
	(g)	¨	A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G);
	(h)	¨	A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act;
	(i)	¨	A church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act;
	(j)	¨	A non-U.S. institution in accordance with Rule 13d-1(b)(1)(ii)(J);
	(k)	¨	Group, in accordance with Rule 13d-1(b)(1)(ii)(K).

If filing as a non-U.S. institution in accordance with Rule 13d-1(b)(1)(ii)(J), please

specify the type of institution: Not applicable.

Item 4.	OWNERSHIP
	The information required by Items 4(a) – (c) is set forth in Rows (5) – (11) of the cover page for each Reporting Person hereto and is incorporated herein by reference for each such Reporting Person.

	The percentage set forth in this Schedule 13G is calculated based upon 701,217,089 Ordinary Shares outstanding as of November 16, 2023, as reported in Exhibit 99.1 attached to the Company’s Report of Foreign Private Issuer on Form 6-K filed with the Securities and Exchange Commission on November 16, 2023.

Item 5.	OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS
	Not applicable.

Item 6.	OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON
	Not applicable.

CUSIP No. 589492107

13G

Page 9 of 11 Pages

Item 7.	IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY OR CONTROL PERSON
	Not applicable.

Item 8.	IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP
	Not applicable.

Item 9.	NOTICE OF DISSOLUTION OF GROUP
	Not applicable.

Item 10.	CERTIFICATION
	Each of the Reporting Persons hereby makes the following certification:

	By signing below each Reporting Person certifies that, to the best of his or its knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

CUSIP No. 589492107

13G

Page 10 of 11 Pages

SIGNATURES

After reasonable inquiry and to the best of his or its knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

DATE: February 5, 2024

	ADAGE CAPITAL PARTNERS, L.P.
	By: Adage Capital Partners GP, L.L.C.,
	its general partner

	By: Adage Capital Advisors, L.L.C.,
	its managing member

	/s/ Robert Atchinson
	Name: Robert Atchinson
	Title: Managing Member

	ADAGE CAPITAL PARTNERS GP, L.L.C.
	By: Adage Capital Advisors, L.L.C.,
	its managing member

	/s/ Robert Atchinson
	Name: Robert Atchinson
	Title: Managing Member

	ADAGE CAPITAL MANAGEMENT, L.P.
	By: Adage Capital Partners LLC,
	its general partner

	/s/ Robert Atchinson
	Name: Robert Atchinson
	Title: Managing Member

	/s/ Robert Atchinson
	ROBERT ATCHINSON, individually

	/s/ Phillip Gross
	PHILLIP GROSS, individually

CUSIP No. 589492107

13G

Page 11 of 11 Pages

EXHIBIT 1

JOINT FILING AGREEMENT
PURSUANT TO RULE 13d-1(k)

The undersigned acknowledge and agree that the foregoing statement on Schedule 13G is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13G shall be filed on behalf of each of the undersigned without the necessity of filing additional joint filing agreements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained herein and therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate.

DATE: February 5, 2024

	ADAGE CAPITAL PARTNERS, L.P.
	By: Adage Capital Partners GP, L.L.C.,
	its general partner

	By: Adage Capital Advisors, L.L.C.,
	its managing member

	/s/ Robert Atchinson
	Name: Robert Atchinson
	Title: Managing Member

	ADAGE CAPITAL PARTNERS GP, L.L.C.
	By: Adage Capital Advisors, L.L.C.,
	its managing member

	/s/ Robert Atchinson
	Name: Robert Atchinson
	Title: Managing Member

	ADAGE CAPITAL MANAGEMENT, L.P.
	By: Adage Capital Partners LLC,
	its general partner

	/s/ Robert Atchinson
	Name: Robert Atchinson
	Title: Managing Member

	/s/ Robert Atchinson
	ROBERT ATCHINSON, individually

	/s/ Phillip Gross
	PHILLIP GROSS, individually