UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Amendment No. 1)*

Under the Securities Exchange Act of 1934

Sigilon Therapeutics, Inc.

(Name of Issuer)

Common Stock, $0.001 par value per share

(Title of Class of Securities)

82657L206

(CUSIP Number)

Anat Hakim

Executive Vice President, General Counsel and Secretary

Eli Lilly and Company

Lilly Corporate Center

Indianapolis, Indiana 46285

Telephone: (317) 276-2000

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

Copy to:

Howard Kenny

Russell M. Franklin

Morgan, Lewis & Bockius LLP

101 Park Avenue

New York, New York 10178

(212) 309-6000

August 11, 2023

(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 to be 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 (the “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).

Explanatory Note

This Amendment No. 1 (“Amendment No. 1”) amends the Schedule 13D filed by the Reporting Persons with the SEC on July 7, 2023 (the “Original Schedule 13D”) with respect to the common stock, par value $0.001 per share (the “Common Stock”), of the Issuer. Except as set forth herein, the Original Schedule 13D is unmodified. Capitalized terms used and not otherwise defined in this Amendment No. 1 have the meanings set forth in the Original Schedule 13D.

Item 4 of the Original Schedule 13D is amended to include the following at the end thereof:

“As disclosed in the press release issued by Lilly and the Issuer on August 14, 2023 announcing the expiration and results of the Offer (which is attached hereto as Exhibit 2.3):

As a result of the Merger, Lilly received an aggregate of 100 newly issued shares of common stock, $0.0001 par value per share (the “New Shares”), of the Issuer. Consequently, Lilly became the beneficial owner of such 100 New Shares, which represent all of the Issuer’s issued and outstanding New Shares.

Following the Merger, all Shares ceased trading prior to the opening of trading on the Nasdaq Global Select Market (“Nasdaq”) on August 11, 2023, and will be delisted from Nasdaq and deregistered under the Act (the “Deregistration”).”

Item 5 of the Original Schedule 13D is hereby amended and restated in its entirety as follows:

“(a)-(b) The information relating to the beneficial ownership of the Shares by each of the Reporting Persons set forth in Rows 7 through 13 on each of the cover pages hereto is incorporated by reference herein and is as of the date hereof. This Schedule 13D shall not be construed as an admission by the Reporting Persons that the Reporting Persons are, for the purposes of Section 13(d) of the Act, the beneficial owners of any Shares covered by this statement.

(c) Except as otherwise described herein and in the Original Schedule 13D, the Reporting Persons have not engaged in any transactions with respect to the Issuer’s securities. On August 11, 2023 the Reporting Persons accepted for payment in exchange for the Offer Price (i) 683,760 Shares held of record by Flagship Ventures Fund V, L.P. and (ii) 113,960 Shares held of record by Flagship Pioneering Special Opportunities Fund II, L.P., in each case with such Shares being tendered pursuant to the Offer prior to the Expiration Time.

(d) Not applicable.

(e) Upon effectiveness of the Deregistration on November 10, 2023, the Reporting Persons will cease to have reporting obligations with regard to any beneficial ownership of the Issuer’s securities under Section 13(d) of the Act.”

Item 6 of the Original Schedule 13D is hereby amended and supplemented by adding the following at the end thereof:

“At the Effective Time, the Tender and Support Agreements terminated in accordance with their express terms.”

Item 7 of the Original Schedule 13D is hereby amended to add the following exhibits:

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.

Exhibit 2.3

Aug. 14, 2023

For Release:        Immediately

Refer to:              Jordan Bishop; jordan.bishop@lilly.com; 317-473-5712 (Media)

       Joe Fletcher; jfletcher@lilly.com; 317-296-2884 (Investors)

Lilly Completes Acquisition of Sigilon Therapeutics

INDIANAPOLIS, Aug. 14, 2023 — Eli Lilly and Company (NYSE: LLY) today announced the successful completion of its acquisition of Sigilon Therapeutics, Inc. (NASDAQ: SGTX). The acquisition allows Lilly to continue researching and developing encapsulated cell therapies, including SIG-002, for the treatment of type 1 diabetes.

“Make life better – that’s the phrase that guides everything we do at Lilly,” said Ruth Gimeno, Ph.D., group vice president, diabetes, obesity and cardiometabolic research at Lilly. “We are excited to welcome our new colleagues from Sigilon to Lilly; together, we will strive to provide solutions for people living with type 1 diabetes that absolves them of constant disease management, and advance Sigilon’s technology for patients.”

The Offer and the Merger

As previously announced, Lilly and Sigilon entered into a Merger Agreement dated as of June 28, 2023, and pursuant thereto, on July 13, 2023, Lilly and a wholly owned subsidiary (“Purchaser”) commenced a tender offer (the “Offer”) to purchase all of the issued and outstanding shares (“Shares”) of Sigilon’s common stock in exchange for (a) $14.92 per Share, net to the stockholder in cash, without interest (the “Cash Consideration”) and less any applicable tax withholding, plus (b) one non-tradable contingent value right (“CVR” and, together with the Cash Consideration, the “Offer Price”) per Share, which represents the contractual right to receive contingent payments of up to $111.64 per Share in cash, net to the stockholder in cash, without interest and less any applicable tax withholding, upon the achievement of certain specified milestones. There can be no assurance that any payments will be made with respect to the CVRs. The Offer expired as scheduled on Aug. 9, 2023, with 1,718,493 Shares validly tendered and not validly withdrawn, which together with Shares previously owned by Lilly, represented 76.61% of the issued and outstanding Shares. In accordance with the terms of the Offer, Purchaser accepted for payment all such validly tendered and not validly withdrawn Shares.

Following consummation of the Offer, on Aug. 11, 2023, Lilly completed its acquisition of Sigilon through the merger of Purchaser with and into Sigilon in accordance with Section 251(h) of the General Corporation Law of the State of Delaware), with Sigilon surviving such merger as a wholly owned subsidiary of Lilly. In connection with the merger, each Share issued and outstanding immediately prior to the effective time of the merger (other than (i) Shares held in Sigilon’s treasury or owned by Sigilon, or owned by Lilly, Purchaser or any direct or indirect wholly-owned subsidiary of Lilly or Purchaser or (ii) Shares held by any stockholder of Sigilon who was entitled to demand and properly demanded appraisal for such Shares in accordance with Section 262 of the DGCL), including each Share that was subject to vesting or forfeiture restrictions granted pursuant to a Sigilon equity incentive plan, program or arrangement, was canceled and converted into the right to receive the Offer Price, without interest, less any applicable tax withholding. Sigilon’s common stock has been delisted from the NASDAQ Global Select Market and will be deregistered under the Securities Exchange Act of 1934, as amended.

For Lilly, Morgan, Lewis & Bockius LLP is acting as legal counsel. For Sigilon, Lazard is acting as lead financial advisor and Ropes & Gray LLP is acting as legal counsel. Canaccord Genuity also acted as financial advisor to Sigilon.

About Lilly

Lilly unites caring with discovery to create medicines that make life better for people around the world. We’ve been pioneering life-changing discoveries for nearly 150 years, and today our medicines help more than 51 million people across the globe. Harnessing the power of biotechnology, chemistry and genetic medicine, our scientists are urgently advancing new discoveries to solve some of the world’s most significant health challenges, redefining diabetes care, treating obesity and curtailing its most devastating long-term effects, advancing the fight against Alzheimer’s disease, providing solutions to some of the most debilitating immune system disorders, and transforming the most difficult-to-treat cancers into manageable diseases. With each step toward a healthier world, we’re motivated by one thing: making life better for millions more people. That includes delivering innovative clinical trials that reflect the diversity of our world and working to ensure our medicines are accessible and affordable. To learn more, visit Lilly.com and Lilly.com/newsroom or follow us on Facebook, Instagram, Twitter and LinkedIn. C-LLY

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Cautionary Statement Regarding Forward-Looking Statements

This press release contains forward-looking statements regarding Lilly’s acquisition of Sigilon. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. Forward-looking statements reflect current beliefs and expectations; however, these statements involve inherent risks and uncertainties, including with respect to drug research, development and commercialization, Lilly’s evaluation of the accounting treatment of the acquisition and its impact on its financial results and financial guidance, the effects of the acquisition on Sigilon’s relationships with key third parties or governmental entities, transaction costs, risks that the acquisition disrupts current plans and operations or adversely affects employee retention, and any legal proceedings that may be instituted related to the acquisition. Actual results could differ materially due to various factors, risks and uncertainties. Among other things, there can be no guarantee that Lilly will realize the expected benefits of the acquisition, that product candidates will be approved on anticipated timelines or at all, that any products, if approved, will be commercially successful, that all or any of the contingent consideration will become payable on the terms described herein or at all, that Lilly’s financial results will be consistent with its expected 2023 guidance or that Lilly can reliably predict the impact of the acquisition on its financial results or financial guidance. For further discussion of these and other risks and uncertainties, see Lilly’s most recent Form 10-K and Form 10-Q filings with the United States Securities and Exchange Commission. Except as required by law, Lilly does not undertake any duty to update forward-looking statements to reflect events after the date of this press release.

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