Deerfield Mgmt IV Form 3 Cabaletta Bio / James E Flynn ownership change

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^*

Flynn James E

(Last) (First) (Middle)

780 THIRD AVENUE, 37TH FLOOR

(Street)

NEW YORK NY 10017

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
10/24/2019

3. Issuer Name and Ticker or Trading Symbol
Cabaletta Bio, Inc. [ CABA ]

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

	Director	X	10% Owner
	Officer (give title below)	X	Other (specify below)
Possible Member of 10% Group

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

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

	Form filed by One Reporting Person
X	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
Series B Preferred Stock	(1)	(1)	Common Stock	464,253(1)	(1)	I	Through Deerfield Private Design Fund IV, L.P.(2)(3)
Series B Preferred Stock	(1)	(1)	Common Stock	464,253(1)	(1)	I	Through Deerfield Special Situations Fund, L.P.(2)(3)

1. Name and Address of Reporting Person^*

Flynn James E

(Last) (First) (Middle)

780 THIRD AVENUE, 37TH FLOOR

(Street)

NEW YORK NY 10017

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Deerfield Mgmt IV, L.P.

(Last) (First) (Middle)

780 THIRD AVENUE, 37TH FLOOR

(Street)

NEW YORK NY 10017

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C)

(Last) (First) (Middle)

780 THIRD AVENUE, 37TH FLOOR

(Street)

NEW YORK NY 10017

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Deerfield Private Design Fund IV, L.P.

(Last) (First) (Middle)

780 THIRD AVENUE 37TH FLOOR

(Street)

NEW YORK NY 10017

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Deerfield Mgmt L.P.

(Last) (First) (Middle)

780 THIRD AVENUE

37TH FLOOR

(Street)

NEW YORK NY 10017

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Deerfield Special Situations Fund, L.P.

(Last) (First) (Middle)

780 THIRD AVENUE

37TH FLOOR

(Street)

NEW YORK NY 10017

(City) (State) (Zip)

Explanation of Responses:

1. Each share of Series B Preferred Stock is convertible into 0.66666667 shares of the Issuer's common stock upon the closing of the Issuer's initial public offering (on an adjusted basis, after giving effect to the 1-for-1.5 reverse stock split of the Issuer's common stock effected by the Issuer on October 16, 2019). Shares of Series B Preferred Stock will automatically convert into shares of the Issuer's common stock upon the closing of the Issuer's initial public offering of common stock.

2. This Form 3 is being filed by the undersigned as well as the entities listed on the Joint Filer Information Statement attached as an exhibit hereto (the "Reporting Persons"). Deerfield Mgmt IV, L.P. is the general partner of Deerfield Private Design Fund IV, L.P. ("Fund IV"). Deerfield Mgmt, L.P. is the general partner of Deerfield Special Situations Fund, L.P. (collectively with Fund IV, the "Funds"). Deerfield Management Company, L.P. is the investment manager of the Funds. James E. Flynn is the sole member of the general partner of each of Deerfield Mgmt IV, L.P., Deerfield Mgmt, L.P. and Deerfield Management Company, L.P.

3. In accordance with Instruction 5 (b)(iv) to Form 3, the entire amount of the Issuer's securities held by the Funds is reported herein. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, each Reporting Person disclaims beneficial ownership of any such securities, except to the extent of his/its indirect pecuniary interest therein, if any, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or otherwise.

Remarks:

Please see Joint Filer Information Statement attached as Exhibit 99 hereto. Jonathan Isler, Attorney-in-Fact: Power of Attorney, which is hereby incorporated by reference to Exhibit 24 to a Form 3 with regard to Proteon Therapeutics, Inc. filed with the Securities and Exchange Commission on August 4, 2017 by Deerfield Special Situations Fund, L.P., Deerfield Partners, L.P., Deerfield International Master Fund, L.P., Deerfield Private Design Fund III, L.P., Deerfield Private Design Fund IV, L.P., Deerfield Mgmt, L.P., Deerfield Mgmt III, L.P., Deerfield Mgmt IV, L.P., Deerfield Management Company, L.P., and James E. Flynn.

	/s/ Jonathan Isler, Attorney-in-Fact	10/24/2019
	** Signature of Reporting Person	Date
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