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 disclosures provided in a prior cover page.

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest Venture Fund II, L.P.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

WC

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

980,693

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

980,693

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

980,693

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

2.4%⁽¹⁾

TYPE OF REPORTING PERSON

PN

The percentage set forth in row (13) is based on the 41,539,191 outstanding shares of common stock, par value $0.001 per share, of Allakos Inc., a Delaware corporation (the “Issuer”), reported by the Issuer to be outstanding immediately after the Issuer’s initial public offering on the Issuer’s prospectus filed under Rule 424(b)(4), filed with the Securities and Exchange Commission (“SEC”) on July 19, 2018, after giving effect to the exercise in full of the underwriters’ over-allotment option as reported by the Issuer on July 24, 2018.

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest Venture Fund II (Ohio), L.P.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

WC

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

266,374

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

266,374

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

266,374

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

0.6%⁽¹⁾

TYPE OF REPORTING PERSON

PN

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest Venture Partners II (Ohio), LLC

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

266,374⁽²⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

266,374⁽²⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

266,374⁽²⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

0.6%⁽¹⁾

TYPE OF REPORTING PERSON

OO

Represents 266,374 shares of Common Stock owned by RiverVest Venture Fund II (Ohio), L.P., a Delaware limited partnership (“RiverVest II (Ohio)”). RiverVest Venture Partners II (Ohio), LLC, a Delaware limited liability company (“RiverVest Partners II (Ohio)”), is the general partner of RiverVest II (Ohio).

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest Venture Partners II, L.P.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

1,247,067⁽³⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

1,247,067⁽³⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

1,247,067⁽³⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

3.0%⁽¹⁾

TYPE OF REPORTING PERSON

PN

Represents 980,693 shares of Common Stock owned by RiverVest Venture Fund II, L.P., a Delaware limited partnership (“RiverVest II”), and 266,374 shares of Common Stock owned by RiverVest II (Ohio). RiverVest Venture Partners II, L.P., a Delaware limited partnership (“RiverVest Partners II”), is the general partner of RiverVest II and the sole member of RiverVest Partners II (Ohio), which is the general partner of RiverVest II (Ohio).

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest Venture Partners II, LLC

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

1,247,067⁽⁴⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

1,247,067⁽⁴⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

1,247,067⁽⁴⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

3.0%⁽¹⁾

TYPE OF REPORTING PERSON

OO

Represents 980,693 shares of Common Stock owned by RiverVest II and 266,374 shares of Common Stock owned by RiverVest II (Ohio). RiverVest Venture Partners II, LLC, a Delaware limited liability company, is the general partner of RiverVest Partners II, which is (a) the general partner of RiverVest II and (b) the sole member of RiverVest Partners II (Ohio), which is the general partner of RiverVest II (Ohio).

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest Venture Fund III, L.P.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

WC

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

3,518,819

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

3,518,819

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

3,518,819

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

8.5%⁽¹⁾

TYPE OF REPORTING PERSON

PN

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest Venture Fund III (Ohio), L.P.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

WC

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

186,759

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

186,759

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

186,759

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

0.4%⁽¹⁾

TYPE OF REPORTING PERSON

PN

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest Venture Partners III (Ohio), LLC

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

186,759⁽⁵⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

186,759⁽⁵⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

186,759⁽⁵⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

0.4%⁽¹⁾

TYPE OF REPORTING PERSON

OO

Represents 186,759 shares of Common Stock owned by RiverVest Venture Fund III (Ohio), L.P., a Delaware limited partnership (“RiverVest III (Ohio)”). RiverVest Venture Partners III (Ohio), LLC, a Delaware limited liability company (“RiverVest Partners III (Ohio)”), is the general partner of RiverVest III (Ohio).

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest Venture Partners III, L.P.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

3,705,578⁽⁶⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

3,705,578⁽⁶⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

3,705,578⁽⁶⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

8.9%⁽¹⁾

TYPE OF REPORTING PERSON

PN

Represents 3,518,819 shares of Common Stock owned by RiverVest Venture Fund III, L.P., a Delaware limited partnership (“RiverVest III”), and 186,759 shares of Common Stock owned by RiverVest III (Ohio). RiverVest Venture Partners III, L.P., a Delaware limited partnership (“RiverVest Partners III”), is the general partner of RiverVest III and the sole member of RiverVest Partners III (Ohio), which is the general partner of RiverVest III (Ohio).

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest Venture Partners III, LLC

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

3,705,578⁽⁷⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

3,705,578⁽⁷⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

3,705,578⁽⁷⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

8.9%⁽¹⁾

TYPE OF REPORTING PERSON

OO

Represents 3,518,819 shares of Common Stock owned by RiverVest III and 186,759 shares of Common Stock owned by RiverVest III (Ohio). RiverVest Venture Partners III, LLC, a Delaware limited liability company, is the general partner of RiverVest Partners III, which is (a) the general partner of RiverVest III and (b) the sole member of RiverVest Partners III (Ohio), which is the general partner of RiverVest III (Ohio).

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

3x5 RiverVest Fund II, L.P.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

WC

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

2,331,987

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

2,331,987

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

2,331,987

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

5.6%⁽¹⁾

TYPE OF REPORTING PERSON

PN

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

3x5 RiverVest Fund II-B, L.P.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

WC

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

86,620

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

86,620

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

86,620

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

0.2%⁽¹⁾

TYPE OF REPORTING PERSON

PN

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

3x5 RiverVest Partners II, LLC

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

2,418,607⁽⁸⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

2,418,607⁽⁸⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

2,418,607⁽⁸⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

5.8%⁽¹⁾

TYPE OF REPORTING PERSON

OO

Represents 2,331,987 shares of Common Stock owned by 3x5 RiverVest Fund II, L.P., a Delaware limited partnership (“3x5 RiverVest II”), and 86,620 shares of Common Stock owned by 3x5 RiverVest Fund II-B, L.P., a Delaware limited partnership (“3x5 RiverVest II-B”). 3x5 RiverVest Partners II, LLC, a Delaware limited liability company (“3x5 RiverVest Partners”), is the general partner of 3x5 RiverVest II and 3x5 RiverVest II-B.

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest 3x5 Managers II, L.P.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

2,418,607⁽⁹⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

2,418,607⁽⁹⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

2,418,607⁽⁹⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

5.8%⁽¹⁾

TYPE OF REPORTING PERSON

PN

Represents 2,331,987 shares of Common Stock owned by 3x5 RiverVest II, and 86,620 shares of Common Stock owned by 3x5 RiverVest II-B. RiverVest 3x5 Managers II, L.P., a Delaware limited partnership (“RiverVest 3x5 Managers”), is one of two members of 3x5 RiverVest Partners, which is the general partner of 3x5 RiverVest II and 3x5 RiverVest II-B.

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

RiverVest 3x5 Managers II, LLC

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware, USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

2,418,607⁽¹⁰⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

2,418,607⁽¹⁰⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

2,418,607⁽¹⁰⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

5.8%⁽¹⁾

TYPE OF REPORTING PERSON

OO

Represents 2,331,987 shares of Common Stock owned by 3x5 RiverVest II, and 86,620 shares of Common Stock owned by 3x5 RiverVest II-B. RiverVest 3x5 Managers II, LLC, a Delaware limited liability company (“RiverVest 3x5 Managers II”), is the general partner of RiverVest 3x5 Managers, which is one of two members of 3x5 RiverVest Partners. 3x5 RiverVest Partners is the general partner of 3x5 RiverVest II and 3x5 RiverVest II-B.

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

John P. McKearn, Ph.D.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

7,374,385.33 ⁽¹¹⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

7,374,385.33 ⁽¹¹⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

7,374,385.33 ⁽¹¹⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

17.8%⁽¹⁾

TYPE OF REPORTING PERSON

IN

Includes 980,693 shares of Common Stock owned by RiverVest II, 266,374 shares of Common Stock owned by RiverVest II (Ohio), 3,518,819 shares of Common Stock owned by RiverVest III, 186,759 shares of Common Stock owned by RiverVest III (Ohio), 2,331,987 shares of Common Stock owned by 3x5 RiverVest II, and 86,620 shares of Common Stock owned by 3x5 RiverVest II-B.

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

Jay Schmelter

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

7,371,252⁽¹²⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

7,371,252⁽¹²⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

7,371,252⁽¹²⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

17.7%⁽¹⁾

TYPE OF REPORTING PERSON

IN

Represents 980,693 shares of Common Stock owned by RiverVest II, 266,374 shares of Common Stock owned by RiverVest II (Ohio), 3,518,819 shares of Common Stock owned by RiverVest III, 186,759 shares of Common Stock owned by RiverVest III (Ohio), 2,331,987 shares of Common Stock owned by 3x5 RiverVest II, and 86,620 shares of Common Stock owned by 3x5 RiverVest II-B.

NAME OF REPORTING PERSON

I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

Thomas C. Melzer

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)  ☐        (b)  ☐

SEC USE ONLY

SOURCE OF FUNDS

AF

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e)

☐

CITIZENSHIP OR PLACE OF ORGANIZATION

USA

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

0

SHARED VOTING POWER

7,371,252⁽¹³⁾

SOLE DISPOSITIVE POWER

0

SHARED DISPOSITIVE POWER

7,371,252⁽¹³⁾

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

7,371,252⁽¹³⁾

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES

☐

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

17.7%⁽¹⁾

TYPE OF REPORTING PERSON

IN

Represents 980,693 shares of Common Stock owned by RiverVest II, 266,374 shares of Common Stock owned by RiverVest II (Ohio), 3,518,819 shares of Common Stock owned by RiverVest III, 186,759 shares of Common Stock owned by RiverVest III (Ohio), 2,331,987 shares of Common Stock owned by 3x5 RiverVest II, and 86,620 shares of Common Stock owned by 3x5 RiverVest II-B.

Name of Person Filing (each a “Reporting Person” and collectively, the “Reporting Person”)

Residence or Business Address

Present Principal Occupation or Employment

During the last five years, none of the Reporting Persons has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

During the last five years, none of the Reporting Persons has been named as a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

Each of the Reporting Persons who is a natural person is a citizen of the United States of America.

RiverVest II purchased an aggregate of 954,494 shares of Series A preferred stock of the Issuer (“Series A Preferred Stock”) and an aggregate of 26,199 shares of Series B preferred stock of the Issuer (“Series B Preferred Stock”) in a series of private placement transactions for an aggregate purchase price of $2,501,083;

RiverVest II (Ohio) purchased an aggregate of 259,258 shares of Series A Preferred Stock and an aggregate of 7,116 shares of Series B Preferred Stock in a series of private placement transactions for an aggregate purchase price of $679,338;

RiverVest III purchased an aggregate of 3,234,069 shares of Series A Preferred Stock and an aggregate of 284,750 shares of Series B Preferred Stock in a series of private placement transactions for an aggregate purchase price of $11,161,211;

RiverVest III (Ohio) purchased an aggregate of 171,647 shares of Series A Preferred Stock and an aggregate of 15,112 shares of Series B Preferred Stock in a series of private placement transactions for an aggregate purchase price of $592,381;

3x5 RiverVest II purchased 1,795,434 shares of Series A Preferred Stock and aggregate of 428,071 shares of Series B Preferred Stock in a series of private placement transactions for an aggregate purchase price of $9,814,508;

3x5 RiverVest II-B 67,822 shares of Series A Preferred Stock and aggregate of 16,169 shares of Series B Preferred Stock in a series of private placement transactions for an aggregate purchase price of $370,742; and

the Issuer granted Dr. McKearn, as a non-employee director of the Issuer, an option to purchase 37,600 shares of Common Stock at a per share exercise price equal to $16.00, which option vests as to 1/36th of the shares subject to the option each month following July 2018, subject to continued service through each applicable vesting date.

The acquisition by any person of additional securities of the Issuer, or the disposition of securities of the Issuer;

An extraordinary corporate transaction, such as a merger, reorganization or liquidation, involving the Issuer or any of its subsidiaries;

A sale or transfer of a material amount of assets of the Issuer or any of its subsidiaries;

Any change in the present board of directors or management of the Issuer, including any plans or proposals to change the number or term of directors or to fill any existing vacancies on the board;

Any material change in the present capitalization or dividend policy of the Issuer;

Any other material change in the Issuer’s business or corporate structure;

Changes in the Issuer’s charter, bylaws or instruments corresponding thereto or other actions which may impede the acquisition of control of the Issuer by any person;

Causing a class of securities of the Issuer to be delisted from a national securities exchange or to cease to be authorized to be quoted in an inter-dealer quotation system of a registered national securities association;

A class of equity securities of the Issuer becoming eligible for termination of registration pursuant to Section 12(g)(4) of the Securities Exchange Act of 1934, as amended (the “Act”); or

Any action similar to any of those enumerated above.

Entity or Individual

RiverVest Venture Fund II, L.P.

RiverVest Venture Fund II (Ohio), L.P.

RiverVest Venture Partners II (Ohio), LLC⁽¹⁾

RiverVest Venture Partners II, L.P. ⁽²⁾

RiverVest Venture Partners II, LLC⁽³⁾

RiverVest Venture Fund III, L.P.

RiverVest Venture Fund III (Ohio), L.P.

RiverVest Venture Partners III (Ohio), LLC⁽⁴⁾

RiverVest Venture Partners III, L.P. ⁽⁵⁾

RiverVest Venture Partners III, LLC⁽⁶⁾

3x5 RiverVest Fund II, L.P.

3x5 RiverVest Fund II-B, L.P.

3x5 RiverVest Partners II, LLC⁽⁷⁾

RiverVest 3x5 Managers II, L.P. ⁽⁸⁾

RiverVest 3x5 Managers II, LLC⁽⁹⁾

John P. McKearn, Ph.D. ⁽¹⁰⁾

Jay Schmelter⁽¹¹⁾

Thomas C. Melzer ⁽¹²⁾

Based on the 41,539,191 outstanding shares of Common Stock reported by the Issuer to be outstanding immediately after the IPO on the Issuer’s prospectus filed under Rule 424(b)(4), filed with the SEC on July 19, 2018, after giving effect to the exercise in full of the underwriters’ over-allotment option as reported by the Issuer on July 24, 2018.

RiverVest Partners II (Ohio), as the general partner of RiverVest II (Ohio), may be deemed to beneficially own the 266,374 shares of Common Stock owned by RiverVest II (Ohio).

RiverVest Partners II is the general partner of RiverVest II and the sole member of RiverVest Partners II (Ohio), which is the general partner of RiverVest II (Ohio), and as a result,, may be deemed to beneficially own the 980,693 shares of Common Stock owned by RiverVest II and the 266,374 shares of Common Stock owned by RiverVest II (Ohio).

RiverVest Venture Partners II, LLC, a Delaware limited liability company, is the general partner of RiverVest Partners II, which is (a) the general partner of RiverVest II and (b) the sole member of RiverVest Partners II (Ohio), which is the general partner of RiverVest II (Ohio), and as a result, may be deemed to beneficially own the 980,693 shares of Common Stock owned by RiverVest II and the 266,374 shares of Common Stock owned by RiverVest II (Ohio).

RiverVest Partners III (Ohio) is the general partner of RiverVest III (Ohio), and as a result, may be deemed to beneficially own the 186,759 shares of Common Stock owned by RiverVest III (Ohio).

RiverVest Partners III is the general partner of RiverVest III and the sole member of RiverVest Partners III (Ohio), which is the general partner of RiverVest III (Ohio), and as a result, may be deemed to beneficially own the 3,518,819 shares of Common Stock owned by RiverVest III and the 186,759 shares of Common Stock owned by RiverVest III (Ohio).

RiverVest Venture Partners III, LLC, a Delaware limited liability company, is the general partner of RiverVest Partners III, which is (a) the general partner of RiverVest III and (b) the sole member of RiverVest Partners III (Ohio), which is the general partner of RiverVest III (Ohio), and as a result, may be deemed to beneficially own the 3,518,819 shares of Common Stock owned by RiverVest III and the 186,759 shares of Common Stock owned by RiverVest III (Ohio).

3x5 RiverVest Partners is the general partner of 3x5 RiverVest II and 3x5 RiverVest II-B, and as a result, may be deemed to beneficially own the 2,331,987 shares of Common Stock owned by 3x5 RiverVest II and the 86,620 shares of Common Stock owned by 3x5 RiverVest II-B.

RiverVest 3x5 Managers is one of two members of 3x5 RiverVest Partners, which is the general partner of 3x5 RiverVest II and 3x5 RiverVest II-B, and as a result, may be deemed to beneficially own the 2,331,987 shares of Common Stock owned by 3x5 RiverVest II and the 86,620 shares of Common Stock owned by 3x5 RiverVest II-B.

RiverVest 3x5 Managers II is the general partner of RiverVest 3x5 Managers, which is one of two members of 3x5 RiverVest Partners. 3x5 RiverVest Partners is the general partner of 3x5 RiverVest II and 3x5 RiverVest II-B. As a result, RiverVest 3x5 Managers II may be deemed to beneficially own the 2,331,987 shares of Common Stock owned by 3x5 RiverVest II and the 86,620 shares of Common Stock owned by 3x5 RiverVest II-B.

Dr. McKearn is an authorized person of RiverVest Venture Partners II, LLC, a Delaware limited liability company, which is the general partner of RiverVest Partners II. RiverVest Partners II is (a) the general partner of RiverVest II and (b) the sole member of RiverVest Partners II (Ohio), which is the general partner of RiverVest II (Ohio). As a result, Dr. McKearn may be deemed to beneficially own the 980,693 shares of Common Stock owned by RiverVest II and the 266,374 shares of Common Stock owned by RiverVest II (Ohio).

Mr. Schmelter is a member of RiverVest Venture Partners II, LLC, a Delaware limited liability company, which is the general partner of RiverVest Partners II. RiverVest Partners II is (a) the general partner of RiverVest II and (b) the sole member of RiverVest Partners II (Ohio), which is the general partner of RiverVest II (Ohio). As a result, Mr. Schmelter may be deemed to beneficially own the 980,693 shares of Common Stock owned by RiverVest II and the 266,374 shares of Common Stock owned by RiverVest II (Ohio)

Mr. Melzer is a member of RiverVest Venture Partners II, LLC, a Delaware limited liability company, which is the general partner of RiverVest Partners II. RiverVest Partners II is (a) the general partner of RiverVest II and (b) the sole member of RiverVest Partners II (Ohio), which is the general partner of RiverVest II (Ohio). As a result, Mr. Melzer may be deemed to beneficially own the 980,693 shares of Common Stock owned by RiverVest II and the 266,374 shares of Common Stock owned by RiverVest II (Ohio).