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 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

  1,379,177

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  1,379,177

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  1,379,177

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

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

  6.0%⁽¹⁾

  TYPE OF REPORTING PERSON

  PN

The percentage set forth in row (13) is based on the 23,163,593 outstanding shares of common stock, par value $0.001 per share, of Spruce Biosciences, 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 October 10, 2020, after giving effect to the exercise in full of the underwriters’ over-allotment option as reported by the Issuer on October 14, 2020.

  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

  73,199

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  73,199

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  73,199

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

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

  0.3%⁽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

  73,199⁽²⁾

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  73,199⁽²⁾

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  73,199⁽²⁾

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

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

  0.3%⁽¹⁾

  TYPE OF REPORTING PERSON

  OO

Represents 73,199 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

  1,452,376⁽³⁾

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  1,452,376⁽³⁾

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  1,452,376⁽³⁾

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

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

  6.3%⁽¹⁾

  TYPE OF REPORTING PERSON

  PN

Represents 1,379,177 shares of Common Stock owned by RiverVest Venture Fund III, L.P., a Delaware limited partnership (“RiverVest III”), and 73,199 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

  1,452,376⁽⁴⁾

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  1,452,376⁽⁴⁾

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  1,452,376⁽⁴⁾

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

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

  6.3%⁽¹⁾

  TYPE OF REPORTING PERSON

  OO

Represents 1,379,177 shares of Common Stock owned by RiverVest Venture Fund III, L.P., a Delaware limited partnership (“RiverVest III”), and 73,199 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 Fund IV, 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

  695,905

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  695,905

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  695,905

  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

  NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

  RiverVest Venture Partners IV, 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

  695,905⁽⁵⁾

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  695,905⁽⁵⁾

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  695,905⁽⁵⁾

  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 695,905 shares of Common Stock owned by RiverVest Venture Fund IV, L.P., a Delaware limited partnership (“RiverVest IV”). RiverVest Venture Partners IV, L.P., a Delaware limited partnership (“RiverVest Partners IV”), is the general partner of RiverVest IV.

  NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

  RiverVest Venture Partners IV, 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

  695,905⁽⁶⁾

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  695,905⁽⁶⁾

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  695,905⁽⁶⁾

  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 695,905 shares of Common Stock owned by RiverVest IV. RiverVest Venture Partners IV, LLC, a Delaware limited liability company, is the general partner of RiverVest Partners IV, which is the general partner of RiverVest IV.

  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

  2,148,281⁽⁷⁾

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  2,148,281⁽⁷⁾

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  2,148,281⁽⁷⁾

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

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

  9.3%⁽¹⁾

  TYPE OF REPORTING PERSON

  IN

Includes 1,379,177 shares of Common Stock owned by RiverVest III, 73,199 shares of Common Stock owned by RiverVest III (Ohio), and 695,905 shares of Common Stock owned by RiverVest IV.

  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

  2,148,281⁽⁸⁾

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  2,148,281⁽⁸⁾

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  2,148,281⁽⁸⁾

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

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

  9.3%⁽¹⁾

  TYPE OF REPORTING PERSON

  IN

Includes 1,379,177 shares of Common Stock owned by RiverVest III, 73,199 shares of Common Stock owned by RiverVest III (Ohio), and 695,905 shares of Common Stock owned by RiverVest IV.

  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

  1,452,376⁽⁹⁾

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  1,452,376⁽⁹⁾

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  1,452,376⁽⁹⁾

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

  ☐

  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

  6.3%⁽¹⁾

  TYPE OF REPORTING PERSON

  IN

Includes 1,379,177 shares of Common Stock owned by RiverVest III and 73,199 shares of Common Stock owned by RiverVest III (Ohio).

  NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NO. (ENTITIES ONLY)

  Niall O’Donnell, 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

  695,905⁽¹⁰⁾

  SOLE DISPOSITIVE POWER

  0

  SHARED DISPOSITIVE POWER

  695,905⁽¹⁰⁾

  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

  695,905⁽¹⁰⁾

  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

  IN

Represents 695,905 shares of Common Stock owned by RiverVest IV.

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.

In May 2016, (i) RiverVest III purchased 4,748,000 shares of Series A convertible preferred stock of the Issuer for $1.00 per share and an aggregate purchase price of approximately $4.7 million; and (ii) RiverVest III (Ohio) purchased 252,000 shares of Series A convertible preferred stock of the Issuer for $1.00 per share and an aggregate purchase price of approximately $0.3 million. The purchase price for these shares was paid by RiverVest III and RiverVest III (Ohio) from their working capital.

In February 2019, (i) RiverVest III purchased 1,899,200 shares of Series A convertible preferred stock of the Issuer for $1.00 per share and an aggregate purchase price of approximately $1.9 million; and (ii) RiverVest III (Ohio) purchased 100,800 shares of Series A convertible preferred stock of the Issuer for $1.00 per share and an aggregate purchase price of approximately $0.1 million. The purchase price for these shares was paid by RiverVest III and RiverVest III (Ohio) from their working capital.

In February 2020, (i) RiverVest III purchased 1,187,000 shares of Series B convertible preferred stock of the Issuer for $1.20 per share and an aggregate purchase price of approximately $1.4 million; (ii) RiverVest III (Ohio) purchased 63,000 shares of Series B convertible preferred stock of the Issuer for $1.20 per share and an aggregate purchase price of approximately $76,000; and (iii) RiverVest IV purchased 1,458,333 shares of Series B convertible preferred stock of the Issuer for $1.20 per share and an aggregate purchase price of approximately $1.7 million. The purchase price for these shares was paid by RiverVest III, RiverVest III (Ohio) and RiverVest IV from their working capital.

In August 2020, (i) RiverVest III purchased 1,187,000 shares of Series B convertible preferred stock of the Issuer for $1.20 per share and an aggregate purchase price of approximately $1.4 million; (ii) RiverVest III (Ohio) purchased 63,000 shares of Series B convertible preferred stock of the Issuer for $1.20 per share and an aggregate purchase price of approximately $76,000; and (iii) RiverVest IV purchased 1,458,333 shares of Series B convertible preferred stock of the Issuer for $1.20 per share and an aggregate purchase price of approximately $1.7 million. The purchase price for these shares was paid by RiverVest III, RiverVest III (Ohio) and RiverVest IV from their working capital.

On October 2, 2020, the Issuer effected a 1-for-6.541 reverse stock split of its Common Stock. Following this reverse stock split, the conversion price of RiverVest III, RiverVest III (Ohio) and RiverVest IV’s shares of Series A convertible preferred stock and Series B convertible preferred stock was adjusted so that each share of convertible preferred stock was convertible into Common Stock on a 6.541-for-1 basis at any time at the shareholder’s election and automatically upon the closing of the IPO.

RiverVest III acquired an aggregate of 1,379,177 shares of Common Stock, RiverVest III (Ohio) acquired an aggregate of 73,199 shares of Common Stock, and RiverVest IV acquired an aggregate of 445,905 shares of Common Stock, in each case upon the automatic conversion of the convertible preferred stock that occurred upon the closing of the IPO; and

RiverVest IV purchased 250,000 shares of Common Stock from the underwriters (the “IPO Shares”) at $15.00 per share for an aggregate purchase price of $3.75 million pursuant to the provisions of the Underwriting Agreement among the Issuer and the several underwriters for the IPO. The purchase price of the IPO Shares was paid by RiverVest IV from its working capital.

Following these purchases in the IPO, RiverVest III held a total of 1,379,177 shares of Common Stock, (ii) RiverVest III (Ohio) held a total of 73,199 shares of Common Stock, and (iii) RiverVest IV held a total of 695,905 shares of Common Stock.

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 III, L.P.

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

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

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

RiverVest Venture Partners III, LLC⁽³⁾

RiverVest Venture Fund IV, L.P.

RiverVest Venture Partners IV, L.P. ⁽⁴⁾

RiverVest Venture Partners IV, LLC⁽⁵⁾

John P. McKearn, Ph.D.⁽⁶⁾

Jay Schmelter⁽⁷⁾

Thomas C. Melzer⁽⁸⁾

Niall O’Donnell⁽⁹⁾

Based on the 23,163,593 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 October 10, 2020, after giving effect to the exercise in full of the underwriters’ over-allotment option as reported by the Issuer on October 14, 2020.

RiverVest Partners III (Ohio) is the general partner of RiverVest III (Ohio), and as a result, may be deemed to beneficially own the 73,199 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 1,379,177 shares of Common Stock owned by RiverVest III and the 73,199 shares of Common Stock owned by RiverVest III (Ohio).

RiverVest Venture Partners III, LLC 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 1,379,177 shares of Common Stock owned by RiverVest III and the 73,199 shares of Common Stock owned by RiverVest III (Ohio).

RiverVest Partners IV is the general partner of RiverVest IV, and as a result, may be deemed to beneficially own the 695,905 shares of Common Stock owned by RiverVest IV.

RiverVest Venture Partners IV, LLC is the general partner of RiverVest Partners IV, which is the general partner of RiverVest IV, and as a result, may be deemed to beneficially own the 695,905 shares of Common Stock owned by RiverVest IV.

Dr. McKearn is a member of RiverVest Venture Partners III, LLC, which is the general partner of RiverVest Partners III. RiverVest Partners III 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). As a result, Dr. McKearn may be deemed to beneficially own the 1,379,177 shares of Common Stock owned by RiverVest III and the 73,199 shares of Common Stock owned by RiverVest III (Ohio).

Mr. Schmelter is a member of RiverVest Venture Partners III, LLC, which is the general partner of RiverVest Partners III. RiverVest Partners III 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). As a result, Mr. Schmelter may be deemed to beneficially own the 1,379,177 shares of Common Stock owned by RiverVest III and the 73,199 shares of Common Stock owned by RiverVest III (Ohio).

Mr. Melzer is a member of RiverVest Venture Partners III, LLC, which is the general partner of RiverVest Partners III. RiverVest Partners III 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). As a result, Mr. Melzer may be deemed to beneficially own the 1,379,177 shares of Common Stock owned by RiverVest III and the 73,199 shares of Common Stock owned by RiverVest III (Ohio).

Mr. O’Donnell is a member of RiverVest Venture Partners IV, LLC, which is the general partner of RiverVest Partners IV. RiverVest Partners IV is the general partner of RiverVest IV. As a result, Mr. O’Donnell may be deemed to beneficially own the 695,905 shares of Common Stock owned by RiverVest IV.

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ John P. McKearn, Ph.D

/s/ Jay Schmelter

/s/ Thomas C. Melzer

/s/ Niall O’Donnell, Ph.D.

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ Jay Schmelter

/s/ John P. McKearn, Ph.D.

/s/ Jay Schmelter

/s/ Thomas C. Melzer

/s/ Niall O’Donnell, Ph.D.