SC 13G/A 1 ss192044_sc13ga.htm AMENDMENT NO. 1

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION
Washington, DC 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. 1)*

Prothena Corporation Public Limited Company

(Name of Issuer)

Ordinary Shares, $0.01 par value per share

(Title of Class of Securities)

G72800108

(CUSIP Number)

December 31, 2020

(Date of Event Which Requires Filing of this Statement)

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

x Rule 13d-1(b)

o Rule 13d-1(c)

o Rule 13d-1(d)

*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.

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. G72800108

SCHEDULE 13G

Page 2 of 8 Pages


1	NAME OF REPORTING PERSONS OrbiMed Capital LLC
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) o (b) o
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 1,485,458
		6	SHARED VOTING POWER
		7	SOLE DISPOSITIVE POWER 1,485,458
		8	SHARED DISPOSITIVE POWER
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,485,458
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 3.72%
12	TYPE OF REPORTING PERSON IA

CUSIP No. G72800108

SCHEDULE 13G

Page 3 of 8 Pages


1	NAME OF REPORTING PERSONS OrbiMed Advisors LLC
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) o (b) o
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 312,000
		7	SOLE DISPOSITIVE POWER 0
		8	SHARED DISPOSITIVE POWER 312,000
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 312,000
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 0.78%
12	TYPE OF REPORTING PERSON IA

CUSIP No. G72800108

SCHEDULE 13G

Page 4 of 8 Pages

Item 1.

(a) Name of Issuer:

Prothena Corporation Public Limited Company

(b) Address of Issuer’s Principal Executive Offices:

77 Sir John Rogerson’s Quay, Block C

Grand Canal Docklands

Dublin 2, D02 T804, Ireland

Item 2.

(a) Name of Person Filing:

OrbiMed Capital LLC

OrbiMed Advisors LLC

(b) Address of Principal Business Office:

601 Lexington Avenue, 54th Floor

New York, NY 10022

(c) Citizenship:

Please refer to Item 4 on each cover page for each Reporting Person.

(d) Title of Class of Securities:

Ordinary Shares, $0.01 par value per share

(e) CUSIP No.:

G72800108

CUSIP No. G72800108

SCHEDULE 13G

Page 5 of 8 Pages

Item 3.

OrbiMed Advisors LLC (“Advisors”) and OrbiMed Capital LLC (“Capital”) are investment advisors in accordance with ss.240.13d-1(b)(1)(ii)(E).

CUSIP No. G72800108

SCHEDULE 13G

Page 6 of 8 Pages

Item 4. Ownership:

Information with respect to the Reporting Person’s ownership as of December 31, 2020 is incorporated by reference to items (5) - (9) and (11) of the cover page for the Reporting Person.

Item 5. Ownership of Five Percent or Less of a Class.

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following [X].

Item 6. Ownership of More Than Five Percent on Behalf of Another Person.

Not Applicable.

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.

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and held in the ordinary course of business and 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. G72800108

SCHEDULE 13G

Page 7 of 8 Pages

SIGNATURES

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: February 12, 2021


OrbiMed Advisors LLC


By:	/s/ Jonathan T. Silverstein
	Name:	Jonathan T. Silverstein
	Title:	Member

By:	/s/ Sven H. Borho
	Name:	Sven H. Borho
	Title:	Member

By:	/s/ Carl L. Gordon
	Name:	Carl L. Gordon
	Title:	Member


OrbiMed Capital LLC


By:	/s/ Jonathan T. Silverstein
	Name:	Jonathan T. Silverstein
	Title:	Member

By:	/s/ Sven H. Borho
	Name:	Sven H. Borho
	Title:	Member

By:	/s/ Carl L. Gordon
	Name:	Carl L. Gordon
	Title:	Member

SEC Form SC 13G/A filed