Material Agreement (Form 8-K)

Item 1.01. Entry into a Material Definitive Agreement.

On September 23, 2026, REGENXBIO Inc. (the "Company") and The Trustees of the University of Pennsylvania ("UPenn") entered into a Settlement Agreement (the "Settlement Agreement") with Sarepta Therapeutics, Inc. and Sarepta Therapeutics Three, LLC (together with Sarepta Therapeutics, Inc., "Sarepta") and Catalent, Inc. to resolve all patent infringement litigation alleging infringement of U.S. Patent No. 10,526,617 (the "617 patent") and U.S. Patent No. 11,680,274 (the "274 patent") (together with the 617 patent, "the Patents-in-Suit") related to Sarepta's manufacture, use, offer to sell and sale of SRP-9001 (also known as ELEVIDYS® in the U.S.).

Pursuant to the terms of the Settlement Agreement, Sarepta will make a payment of $39.0 million to the Company within 10 days of the effective date of the Settlement Agreement. Thereafter, the parties will terminate with prejudice all ongoing patent litigation regarding the Patents-in-Suit. The Settlement Agreement includes the release by the Company and UPenn of all current claims of infringement and a covenant not to sue for future claims relating to any Sarepta gene therapy product that uses an AAVrh74-based capsid, including ELEVIDYS, relating to the Patents-in-Suit, U.S. Patent No. 9,198,984, and related patents and patent applications. In addition, the Company agreed not to sue Sarepta or its affiliates, licensees or commercial partners over any Company patents or patent applications that cover the existing form of ELEVIDYS or the AAVrh74-based capsid sequence; but does not extend to patents or patent applications that cover other aspects of gene therapy products.

The foregoing description of the terms of the Settlement Agreement does not purport to be complete and is qualified in its entirety by the full text of such agreement. The Company intends to file a copy of the Settlement Agreement with its Quarterly Report on Form 10-Q for the quarter ending September 30, 2026.