Topline Findings
- $100 Million Milestone Achieved: Sarepta triggered a $100 million milestone payment to Arrowhead after the first enrollment target in the Phase I/II ARO-DM1 trial for type 1 myotonic dystrophy.
- Equity Sale and Funding Strategy: Sarepta sold over 9.2 million Arrowhead shares in a private block trade, generating at least $174 million. The company will transfer an additional 2.66 million shares to satisfy $50 million of the milestone payment.
- Future RNA interference (RNAi) Development: Arrowhead anticipates reaching the second enrollment target by the end of 2025, which could trigger an additional $200 million milestone payment and support ongoing advancement of multiple RNAi therapeutic programs.
Sarepta Therapeutics and Arrowhead Pharmaceuticals announced that they have finalized a transaction related to Sarepta’s RNA interference (RNAi) collaboration and milestone obligations. The $100 million milestone was triggered after Arrowhead met the first of two prespecified enrollment targets in its Phase I/II trial of ARO-DM1, an RNAi therapeutic for the treatment of type 1 myotonic dystrophy (DM1).
Sarepta sold more than 9.2 million Arrowhead shares in a private block trade, securing at least $174 million in gross proceeds. The company will also transfer an additional 2.66 million shares to cover $50 million of the previously announced milestone payment.1,2
How Does this Milestone Reshape the Sarepta–Arrowhead Partnership?
“We are very pleased with the progress of our potentially best-in-class siRNA programs, including the advancement of our SRP-1003 program for DM1, triggering the $100 million milestone payment to our partner, Arrowhead,” said Doug Ingram, CEO, Sarepta, in a press release. “The sale of our equity investment is a strategic decision to help fund this milestone but does not change our conviction in the utility of the siRNA approach and our confidence in the work Arrowhead is doing to apply this technology across several disease states. We look forward to sharing early data from our FSHD and DM1 programs in the second half of this year.”
Details of the Original Agreement
- Sarepta first announced the deal with Arrowhead in November 2024.
- The agreement granted Sarepta exclusive rights to several Arrowhead candidates, including ARO-DM1, ARO-DUX4 for facioscapulohumeral muscular dystrophy, ARO-MMP7 for idiopathic pulmonary fibrosis, and ARO-ATXN2 for spinocerebellar ataxia 2.
- All programs leverage Arrowhead’s TRiM platform for precise siRNA delivery.
- At the outset of the agreement, Arrowhead secured a substantial $500 million upfront payment from Sarepta, coupled with a $325 million equity investment in Arrowhead common stock.
- The shares were purchased at a 35% premium to the 30-day volume-weighted average price preceding the announcement, reflecting Sarepta’s confidence in the partnership’s long-term potential.
- The deal also included an additional $250 million commitment to Arrowhead, structured as five annual installments of $50 million, providing a steady flow of capital to support ongoing RNAi therapeutic development.
- Arrowhead is responsible for conducting the Phase I/II trials.3
Arrowhead’s Perspective
“We are committed to supporting our broad and long-term collaboration and we are thrilled with the great progress we’ve made on multiple important clinical, preclinical, and discovery stage siRNA programs,” said Christopher Anzalone, PhD, president, CEO, Arrowhead Pharmaceuticals, in a press release. “While we remain confident that Sarepta will meet its financial obligations to Arrowhead, we believe reducing our outstanding shares by receiving approximately half of the $100 million due from Sarepta in cash and half in Arrowhead stock to be returned to treasury is a compelling opportunity.”
Looking Ahead
Last week, Arrowhead reported in its Q3 financial results that it anticipates reaching the second enrollment target by the end of 2025, which would unlock an additional $200 million milestone payment from Sarepta.4
“With a strong balance sheet anticipated to fund our company into fiscal 2028, we believe this direct stock buyback of Arrowhead shares from Sarepta is an attractive option, given Arrowhead’s current stock price and the significant growth potential, both near- and longer-term, as we pursue multiple commercial launches of wholly-owned and partnered candidates in the coming quarters and years,” concluded Anzalone, in the press release.
References
- Sarepta Therapeutics Announces Advancement of siRNA Collaboration and Sale of Arrowhead Equity Investment. BuisnessWire. August 13, 2025. Accessed August 14, 2025. https://www.businesswire.com/news/home/20250813527219/en/Sarepta-Therapeutics-Announces-Advancement-of-siRNA-Collaboration-and-Sale-of-Arrowhead-Equity-Investment
- Arrowhead Pharmaceuticals Redeems Approximately $50 Million of Arrowhead Stock and Will Receive Approximately $50 Million in Cash in Satisfaction of Milestone from Sarepta Therapeutics. BusinessWire. August 13, 2025. Accessed August 14, 2025. https://www.businesswire.com/news/home/20250813886473/en/Arrowhead-Pharmaceuticals-Redeems-Approximately-%2450-Million-of-Arrowhead-Stock-and-Will-Receive-Approximately-%2450-Million-in-Cash-in-Satisfaction-of-Milestone-from-Sarepta-Therapeutics
- Sarepta, Arrowhead Strike Global Collaboration Deal to Develop Treatments for Rare Genetic Diseases Affecting Muscles. PharmExec. November 27, 2024. Accessed August 14, 2025. https://www.pharmexec.com/view/sarepta-arrowhead-strike-global-collaboration-deal-develop-treatments-rare-genetic-diseases-affecting-muscles
- Arrowhead Pharmaceuticals Reports Fiscal 2025 Third Quarter Results. Arrowhead. August 7, 2025. Accessed August 14, 2025. https://ir.arrowheadpharma.com/news-releases/news-release-details/arrowhead-pharmaceuticals-reports-fiscal-2025-third-quarter?utm_source=chatgpt.com
