Spero Therapeutics : An amendment to the SC 13G filing

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. 1)*

Spero Therapeutics, Inc.

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

84833T103

(CUSIP Number)

December 31, 2019

(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)

• Rule 13d-1(c)

• 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 disclosures provided in a prior cover page.

The information required on 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. 84833T103

13G

1. NAMES OF REPORTING PERSONS Lundbeckfond Invest A/S ("Lundbeckfond")
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions)

(a) ☐ (b) ☒

1. SEC USE ONLY
2. CITIZENSHIP OR PLACE OF ORGANIZATION Denmark
   5. SOLE VOTING POWER
   877,489 shares of common stock, except that (i) Lene Skole ("Skole"), chief executive officer of Lundbeckfond, may be deemed to have sole power to vote these shares; and (ii) Casper Breum ("Breum"), senior partner of Lundbeckfond and a member of the

NUMBER OF		Board of Directors of the Issuer, may be deemed to have shared power to vote these shares.
6.	SHARED VOTING POWER
SHARES
BENEFICIALLY		See response to row 5 above.
OWNED BY
EACH	7.	SOLE DISPOSITIVE POWER
REPORTING
PERSON		877,489 shares of common stock, except that (i) Skole, chief executive officer of Lundbeckfond, may be deemed to have sole
WITH
	power to dispose of these shares; and (ii) Breum, senior partner of Lundbeckfond and a member of the Board of Directors of the
		Issuer, may be deemed to have shared power to dispose of these shares.

1. 1. 8. SHARED DISPOSITIVE POWER See response to row 7 above.

   2. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 877,489 shares of common stock
   3. CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)
      ☐
   4. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 4.6%(1)
   5. TYPE OF REPORTING PERSON (see instructions)
      FI
2. Based upon 19,128,146 shares of common stock outstanding as of October 31, 2019, as reported on the Issuer's Quarterly Report on Form10-Q as filed with the United States Securities and Exchange Commission on November 4, 2019 ("Form 10-Q").

CUSIP No. 84833T103

13G

1. NAMES OF REPORTING PERSONS Lene Skole ("Skole")
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions)

(a) ☐ (b) ☒

1. SEC USE ONLY
2. CITIZENSHIP OR PLACE OF ORGANIZATION Denmark
   5. SOLE VOTING POWER

		877,489 shares of common stock held directly by Lundbeckfond, except that Breum, senior partner Lundbeckfond and a member
NUMBER OF		of the Board of Directors of the Issuer, may be deemed to have shared power to vote these shares.
6.	SHARED VOTING POWER
SHARES
BENEFICIALLY		See response to row 5 above.
OWNED BY
EACH	7.	SOLE DISPOSITIVE POWER
REPORTING
PERSON		877,489 shares of common stock held directly by Lundbeckfond, except that Breum, senior partner of Lundbeckfond and a
WITH
	member of the Board of Directors of the Issuer, may be deemed to have shared power to dispose of these shares.

1. 1. 8. SHARED DISPOSITIVE POWER See response to row 7 above.

   2. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 877,489 shares of common stock
   3. CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)
      ☐
   4. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 4.6%(1)
   5. TYPE OF REPORTING PERSON (see instructions)
      IN
2. Based upon 19,128,146 shares of common stock outstanding as of October 31, 2019, as reported on the Issuer's Form10-Q.

CUSIP No. 84833T103

13G

1. NAMES OF REPORTING PERSONS Casper Breum ("Breum")
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions)

(a) ☐ (b) ☒

1. SEC USE ONLY
2. CITIZENSHIP OR PLACE OF ORGANIZATION Denmark
   5. SOLE VOTING POWER

		See response to row 6 below.
NUMBER OF	6.	SHARED VOTING POWER
SHARES		877,489 shares of common stock held directly by Lundbeckfond, except that Skole, chief executive officer of Lundbeckfond, may
BENEFICIALLY
OWNED BY		be deemed to have sole power to vote these shares.
EACH	7.	SOLE DISPOSITIVE POWER
REPORTING
PERSON		See response to row 8 below.
WITH
8.	SHARED DISPOSITIVE POWER

877,489 shares of common stock held directly by Lundbeckfond, except that Skole, chief executive officer of Lundbeckfond, may be deemed to have sole power to dispose of these shares.

1. 1. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 877,489 shares of common stock
   2. CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)
      ☐
   3. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 4.6%(1)
   4. TYPE OF REPORTING PERSON (see instructions)
      IN
2. Based upon 19,128,146 shares of common stock outstanding as of October 31, 2019, as reported on the Issuer's Form10-Q.

CUSIP No. 84833T103

13G

Item 1.

1. Name of Issuer
   Spero Therapeutics, Inc.
2. Address of Issuer's Principal Executive Offices

675 Massachusetts Avenue, 14th Floor Cambridge, MA 02139

Item 2.

1. Name of Each Person Filing

This joint statement on Schedule 13G is being filed on behalf of each of the following persons: Lundbeckfond Invest A/S (the "Lundbeckfond")

Lene Skole ("Skole") Casper Breum ("Breum")

The foregoing entities and individuals are collectively referred to as the "Reporting Persons."

Skole is the chief executive officer of Lundbeckfond. The directors of Lundbeckfond have delegated voting and dispositive power with respect to shares of the Issuer held by Lundbeckfond to Skole. Breum is a senior partner of Lundbeckfond and a member of the Board of Directors of the Issuer.

1. Address or the Principal Office or, if none, residence of each Person FilingThe principal business address for each Reporting Person is:

c/o Lundbeckfond Invest A/S Scherfigsvej 7

DK-2100 Copenhagen, Denmark

1. Citizenship

Lundbeckfond is a private Danish corporation.

Each of Skole and Breum are citizens of Denmark.

1. Title of Class of SecuritiesCommon Stock, par value $0.001 per share

CUSIP No. 84833T103

13G

1. CUSIP Number
   84833T103

Item 3. If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

Not applicable.

Item 4. Ownership.

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

1. Amount beneficially owned: See row 9 of cover page for each Reporting Person.
2. Percent of class: See row 11 and corresponding footnote on the cover page for each Reporting Person.
3. Number of shares as to which the person has:

1. Sole power to vote or to direct the vote:

See row 5 of cover page for each Reporting Person.*

1. Shared power to vote or to direct the vote:

See row 6 of cover page for each Reporting Person.*

1. Sole power to dispose or to direct the disposition of:

See row 7 of cover page for each Reporting Person.*

1. Shared power to dispose or to direct the disposition of: See row 8 of cover page for each Reporting Person.*

* Each of the Reporting Persons, except Lundbeckfond, disclaims beneficial ownership of the shares owned by Lundbeckfond, except to the extent of their respective pecuniary interests therein.

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 5% of the class of securities, check the following: ☒

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

Under certain circumstances set forth in the governing documents of Lundbeckfond, the stockholders of Lundbeckfond may be deemed to have the right to receive dividends from, or the proceeds from, the sale of shares of the Issuer.

Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company.

Not applicable.

CUSIP No. 84833T103

13G

Item 8. Identification and Classification of Members of the Group.

Not applicable.

Item 9. Notice of Dissolution of Group.

Not applicable.

Item 10. Certification.

Not applicable.

Material to be Filed as Exhibits.

Exhibit 1 - Agreement regarding filing of joint Schedule 13G.

CUSIP No. 84833T103

13G

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.

Date: January 31, 2020

LUNDBECKFOND INVEST A/S

By: /s/ Lene Skole

Name: Lene Skole

Title: Chief Executive Officer & Attorney-in-Fact*

By: /s/ Mette Kirstine Agger

Name: Mette Kirstine Agger

Title: Attorney-in-Fact*

LENE SKOLE

/s/ Lene Skole

CASPER BREUM

/s/ Casper Breum

• This Schedule 13G was executed by Lene Skole and Mette Kristine Agger on behalf of the entity listed above, as indicated, pursuant to that certain Power of Attorney, a copy of which is already on file with the appropriate agencies.

EXHIBIT 1

Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, the undersigned hereby agree that only one statement containing the information required by Schedule 13G need be filed with respect to the ownership by each of the undersigned of shares of Common Stock of Spero Therapeutics, Inc.

Date: January 31, 2020

LUNDBECKFOND INVEST A/S

By: /s/ Lene Skole

Name: Lene Skole

Title: Chief Executive Officer & Attorney-in-Fact*

By: /s/ Mette Kirstine Agger

Name: Mette Kirstine Agger

Title: Attorney-in-Fact*

LENE SKOLE

/s/ Lene Skole

CASPER BREUM

/s/ Casper Breum

This Schedule 13G was executed by Lene Skole and Mette Kristine Agger on behalf of the entity listed above, as indicated, pursuant to that certain Power of Attorney, a copy of which is already on file with the appropriate agencies.