Arrowhead receives $100 million milestone from Sarepta for ARO-DM1 study

Arrowhead Pharmaceuticals Inc. (NASDAQ: ARWR) received a $100 million milestone payment from Sarepta Therapeutics (NASDAQ: SRPT) after reaching the first enrollment target in a Phase 1/2 clinical study of ARO-DM1, according to a company statement.

The payment was triggered when Arrowhead reached the first of two prespecified enrollment targets and received authorization to escalate dosing in the study of ARO-DM1, an investigational RNA interference therapeutic for type 1 myotonic dystrophy. Arrowhead expects to receive the payment within 60 days under the terms of their license and collaboration agreement.

The company anticipates achieving the second enrollment target by the end of 2025, which would trigger an additional $200 million milestone payment from Sarepta.

ARO-DM1 is designed to reduce expression of the dystrophia myotonica protein kinase gene in skeletal muscle as a potential treatment for type 1 myotonic dystrophy, described as the most common adult-onset muscular dystrophy.

The milestone payment stems from a global licensing and collaboration agreement signed between Arrowhead and Sarepta in November 2024, which closed in February 2025. Under the agreement, Sarepta received rights to multiple investigational treatments using Arrowhead's Targeted RNAi Molecule platform.

The collaboration covers multiple clinical and preclinical programs in rare genetic diseases affecting muscle, central nervous system, and lungs. Sarepta can select up to six new targets for Arrowhead to conduct discovery and preclinical development activities.

Upon closing the original agreement, Arrowhead received a $500 million upfront payment and $325 million through Sarepta's purchase of Arrowhead common stock at $27.25 per share, representing a 35% premium to the 30-day volume weighted average price when the agreement was signed. Arrowhead will also receive $250 million in annual installments of $50 million over five years.

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