Amendment No. 2, dated November 17, 2021 to License Agreement between Sarepta Therapeutics, Inc. and ST International Holdings Two, Inc. on the one hand and BioMarin Leiden Holding BV, BioMarin Nederlands BV and BioMarin Technologies BV on the other hand

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Exhibit 10.66

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Execution Version HIGHLY CONFIDENTIAL

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AMENDMENT NO. 2 TO LICENSE AGREEMENT

This AMENDMENT NO. 2 TO LICENSE AGREEMENT (“Amendment No. 2”) is

made and entered effective as of November 17, 2021 (the “Amendment No. 2 Effective Date”), by and between Sarepta Therapeutics, Inc., with offices at 215 First Street, Suite 415, Cambridge, MA 02142, USA and ST International Holdings Two, Inc. (the successor entity to Sarepta International C.V.), with a registered office at 251 Little Falls Drive, Wilmington, DE 19808, USA (collectively, “Sarepta”) on the one hand, and BioMarin Leiden Holding BV and its subsidiaries, BioMarin Nederlands BV and BioMarin Technologies BV (collectively, “BioMarin”), on the other hand. BioMarin and Sarepta may, from time-to-time, be individually referred to as a “Party” and collectively referred to as the “Parties”.

WHEREAS, the Parties entered into that certain License Agreement between Sarepta and BioMarin, dated as of July 17, 2017, as amended by that certain Amendment No. 1 to License Agreement dated as of April 14, 2019 (the “Current Agreement”);

WHEREAS, the Parties have been engaged in certain contract disputes and proceedings related to the Current Agreement with respect to which Sarepta formally notified BioMarin on September 7, 2021 that Sarepta viewed BioMarin to be in material breach of the Current Agreement and commenced a lawsuit against BioMarin in the United States District Court for the Southern District of New York on September 9, 2021, Docket No. 1:21-cv-7534 (the “Lawsuit”) alleging certain violations of the Current Agreement;

WHEREAS, pursuant to that certain Settlement Agreement, dated as of the Amendment No. 2 Effective Date, by and between the Parties (the “2021 Settlement Agreement”) pursuant to which the Parties have agreed to settle the Lawsuit, the Parties have agreed to simultaneously enter into this Amendment No. 2 pursuant to which, in the interest of amicably resolving the Lawsuit, BioMarin has agreed to exercise the BioMarin Co-Exclusive License Option, subject to the terms and conditions of the Current Agreement, as modified by this Amendment No. 2 (the “Agreement”);

WHEREAS, the Parties desire to amend the Current Agreement as set forth herein; and

WHEREAS, following the Amendment No. 2 Effective Date, the Agreement shall govern the relationship between the Parties with respect to the matters set forth herein and therein.

NOW, THEREFORE, in consideration of the foregoing recitals and of the conditions, covenants, and agreements set forth below and in the 2021 Settlement Agreement, the sufficiency of which is hereby acknowledged, the Parties hereto agree as follows:

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2.4.2. Co-Exclusive License. From and after the Amendment No. 2 Effective Date,

(a) the Sarepta License under Section 2.1(b) (License Grant to Sarepta) will be limited by and subject to BioMarin’s co-exclusive right (co-exclusive with Sarepta) to practice and exploit the Licensed IP in the Territory in all fields of use during the remainder of the Term, subject to the terms of this Agreement, (b) the royalties payable to BioMarin on Net Sales of Royalty Bearing Products will be reduced beginning on July 1, 2022, as set forth in Section 4.4.1 (Royalty Rates), and (c) the definitions of “Royalty Bearing Product” in Section 1.77 (Royalty Bearing Product) and “Royalty Term” in Section 1.78 (Royalty Term) will be automatically replaced by the following definitions, respectively, beginning on July 1, 2022 for all purposes of this Agreement:

“Royalty Bearing Product” means, on a country-by-country and Product- by-Product basis, all Products that are Covered by a Licensed Patent in the applicable country.

“Royalty Term” means, on a country-by-country and Royalty Bearing Product-by-Royalty Bearing Product basis, the period of time beginning on the First Commercial Sale Date and ending on the earlier of (i) the date the relevant Royalty-Bearing Product is no longer Covered by a Licensed Patent in the applicable country or (ii) March 31, 2024 in the United States and December 31, 2024 in all other countries in the Territory.

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(ii) Schedule 1.77(b) sets forth a list of all Products that have Net Sales in the Territory that the Parties agree are Covered by an issued or allowed Licensed Patent (as well as the issued or allowed Licensed Patents that the Parties agree Cover such Products) on a country-by-country basis as of the Amendment No. 2 Effective Date and thus would be Royalty Bearing Products in such country under the definition of Royalty Bearing Products that will be in effect commencing July 1, 2022 if the scope of the issued or allowed Licensed Patents does not change between the Amendment No. 2 Effective Date and July 1, 2022.

4.4.1 Royalty Rates. Subject to the terms and conditions of this Agreement and commencing upon the beginning of the first Calendar Quarter, Sarepta will pay

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to BioMarin, on a Royalty Bearing Product-by-Royalty Bearing Product and country- by-country basis, royalties on the Net Sales of Royalty Bearing Products during the applicable Royalty Term as set forth below:

If the manufacture, use, performance or sale of any Royalty Bearing Product is Covered by more than one Valid Claim or Patent of the Licensed Patents, multiple royalties will not be due as a result of being so covered. Following the expiration of the applicable Royalty Term in a country in the Territory with respect to a Royalty Bearing Product (but not following an earlier termination of this Agreement), the Sarepta License with respect to such Royalty Bearing Product in such country will be fully-paid, irrevocable, perpetual and royalty-free, on a Royalty Bearing Product-by-Royalty Bearing Product and country-by-country basis.

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1.12. [Reserved.]

“Milestone Event” means any milestone event set forth in Section 4.2 (Development Milestone Payments) corresponding to a Milestone Payment.

“Milestone Payment” means any milestone payment set forth in Section 4.2 (Development Milestone Payments) corresponding to a Milestone Event.

4.3. [Reserved.]

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13.9. Entire Agreement. This Agreement and any amendment hereto, together with its Schedules, and the Settlement Agreement, the 2021 Settlement Agreement, and the CDA together set forth the entire agreement and understanding of the Parties as to the subject matter hereof and supersede all proposals, oral or written, and all other prior communications between the Parties with respect to such subject matter. In the event of any conflict between a material provision of this Agreement and any Exhibit or Schedule hereto, the Agreement and any amendment hereto will control. The Parties hereby agree and acknowledge that the letters of correspondence from Sarepta to BioMarin or their respective counsel dated September 13, 2018, July 2, 2021, and September 7, 2021, and the letters of correspondence from BioMarin to Sarepta dated October 1, 2018 and August 18, 2021, in each case, shall have no legal binding effect, and in the event of any conflict, this Agreement and any amendment hereto shall control.

[Signatures on next page]

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IN WITNESS WHEREOF, the Parties intending to be bound have caused this Amendment No. 2 to be executed by their duly authorized representatives as of the Amendment No. 2 Effective Date.

Schedule 1.57 Licensed Patents

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Schedule 1.77(a)

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Schedule 1.77(b)

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