UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 5)*

Selecta Biosciences, Inc.

(Name of Issuer)

Common Stock, $0.0001 par value per share

(Title of Class of Securities)

816212104

(CUSIP Number)

E. Peter Strand

Michael K. Bradshaw, Jr.

Nelson Mullins Riley & Scarborough LLP

101 Constitution Avenue NW, Suite 900

Washington, DC 20001

Tel: (202) 689-2800

Fax: (202) 689-2860

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

October 6, 2020

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. ☐

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are sent. 

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).

This Amendment No. 5 to the statement on Schedule 13D (this “Statement”) with respect to the shares of common stock, par value $0.0001 per share (the “Shares”), of Selecta Biosciences, Inc., a Delaware corporation (the “Issuer”), originally filed by Timothy A. Springer (“Dr. Springer”), TAS Partners LLC (“TAS”), Chafen Lu (“Dr. Lu” and, collectively, the “Reporting Persons”) and Leukon Investments, LP (“Leukon”) filed on March 27, 2019, as amended by Amendment No. 1 to the statement on Schedule 13D filed on August 23, 2019, Amendment No. 2 to the statement on Schedule 13D filed on September 16, 2019, Amendment No. 3 to the statement on Schedule 13D filed on December 17, 2019 and Amendment No. 4 to the statement on Schedule 13D filed on January 2, 2020 (such statement and amendments, as further amended herein, the “Schedule 13D”) amends the Schedule 13D as set forth below.

All capitalized terms contained herein but not otherwise defined shall have the meanings ascribed to such terms in the Schedule 13D. Except as specifically amended by this Amendment No. 5, items in the Schedule 13D are unchanged.

Item 3 of the Schedule 13D is hereby amended to be supplemented by the following:

On October 6, 2020, TAS purchased 2,000,000 Shares on the open market at a weighted average price of $1.6829 per share for an aggregate purchase price of approximately $3,365,800 (excluding commissions). TAS drew from its investment capital for such acquisition.

On October 7, 2020, TAS purchased 654,953 Shares on the open market at a weighted average price of $1.6468 per share for an aggregate purchase price of approximately $1,078,577 (excluding commissions). TAS drew from its investment capital for such acquisition.

On October 8, 2020, TAS purchased 530,441 Shares on the open market at a weighted average price of $1.88683 per share for an aggregate purchase price of approximately $1,000,852 (excluding commissions). TAS drew from its investment capital for such acquisition.

On October 9, 2020, TAS purchased 276,703 Shares on the open market at a weighted average price of $1.99659 per share for an aggregate purchase price of approximately $552,462 (excluding commissions). TAS drew from its investment capital for such acquisition.

Dr. Springer is the beneficial owner of an additional 46,410 Shares underlying options, of which 6,410 were granted on June 16, 2017 with an exercise price of $17.47 per share, 10,000 were granted on June 22, 2018 with an exercise price of $12.75 per share, 10,000 were granted on June 14, 2019 with an exercise price of $2.10 per share and 20,000 were granted on June 19, 2020 with an exercise price of $3.00 per share (collectively, the “Options”), 26,410 of which were fully exercisable as of October 9, 2020. The Options were awarded as compensation for Dr. Springer’s service as a member of the board of directors for the Issuer and Dr. Springer paid no consideration for the Options. The Options each have a term of ten years from the respective date of grant. Dr. Springer has not exercised any portion of any of the Options as of the date hereof.

Item 5 of Schedule 13D is hereby amended and restated in full as follows:

The information set forth under Item 3 and the cover page of the Schedule 13D is incorporated herein by reference into this Item 5.

(a) The percentages of beneficial ownership reported in this Item 5, and on each Reporting Person’s cover page to this Statement, are based on a total of 107,143,410 Shares issued and outstanding as of July 31, 2020, as reported on the Issuer’s Quarterly Report on Form 10-Q, dated August 6, 2020. All of the Share numbers reported below, and on each Reporting Person’s cover page to this Statement, are as of October 9, 2019.

The Reporting Persons, in the aggregate, beneficially own 18,404,586 Shares, representing approximately 17.2% of such class of securities.

Dr. Springer is the beneficial owner of a total of 18,404,586 Shares, representing approximately 17.2% of the outstanding Shares and consisting of (i) 7,293,625 Shares held directly, (ii) 79,130 Shares underlying warrants exercisable within 60 days of October 9, 2020 and held directly, (iii) 26,410 Shares issuable upon exercise of outstanding options within 60 days of October 9, 2020 and held directly, (iv) 8,948,560 Shares held by TAS, (v) 1,970,443 Shares underlying warrants exercisable within 60 days of October 9, 2020 held by TAS, and (vi) 86,418 Shares held by Dr. Lu.

TAS is the beneficial owner of a total of 10,919,003 Shares, representing approximately 10.2% of the outstanding Shares and consisting of (i) 8,948,560 Shares and (ii) 1,970,443 Shares underlying warrants exercisable within 60 days of October 9, 2020. TAS holds all such Shares directly. Dr. Springer is the sole managing member of TAS.

Dr. Lu is the beneficial owner of a total of 86,418 Shares, representing approximately 0.1% of the outstanding Shares. Dr. Lu holds all such Shares directly. Dr. Lu is the spouse of Dr. Springer.

(b) Dr. Springer exercises sole voting and dispositive power over the Shares held by him directly and the Shares held by TAS. Dr. Springer disclaims beneficial ownership of the Shares held by TAS, except to the extent of his pecuniary interest therein. Dr. Lu exercises sole voting and dispositive power over the Shares held by her directly.

(c) The Reporting Persons have not engaged in any transactions with respect to the Shares during the 60 days before the date of this filing, except as described herein and in Item 3 of Schedule 13D.

(d) No person other than the Reporting Persons is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Shares.

(e) Not applicable.

[signature page follows]

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.

Date: October 15, 2020