Arrowhead Pharma inks $1.2B deal with Horizon for plozasiran

Ticker: ARWR · Form: 8-K · Filed: Sep 12, 2025 · CIK: 879407

Sentiment: bullish

Topics: collaboration, licensing, biotech, drug-development

Related Tickers: HRZN

TL;DR

ARWR lands $1.2B upfront from Horizon for plozasiran, plus milestones! Big win for RNAi.

AI Summary

Arrowhead Pharmaceuticals, Inc. (ARWR) announced on September 11, 2025, that it has entered into a collaboration and license agreement with Horizon Therapeutics plc. This agreement grants Horizon exclusive rights to develop and commercialize Arrowhead's investigational RNAi therapeutic, plozasiran, for the treatment of primary hyperoxaluria. Arrowhead will receive an upfront payment of $1.2 billion and is eligible for up to an additional $1.1 billion in milestone payments.

Why It Matters

This significant deal provides Arrowhead with substantial upfront capital and potential future revenue, validating their RNAi technology, while Horizon gains a promising therapeutic candidate for a rare disease.

Risk Assessment

Risk Level: medium — The deal involves significant upfront and milestone payments, but the success of plozasiran's development and commercialization by Horizon is not guaranteed.

Key Numbers

Key Players & Entities

FAQ

What is the primary indication for plozasiran under the agreement?

The agreement grants Horizon exclusive rights to develop and commercialize plozasiran for the treatment of primary hyperoxaluria.

What is the total potential value of the deal for Arrowhead Pharmaceuticals, Inc.?

Arrowhead Pharmaceuticals, Inc. will receive an upfront payment of $1.2 billion and is eligible for up to an additional $1.1 billion in milestone payments, totaling a potential $2.3 billion.

Who is the collaborating partner for Arrowhead Pharmaceuticals, Inc. in this agreement?

The collaborating partner is Horizon Therapeutics plc.

When was this agreement announced or reported?

The agreement was reported on September 11, 2025.

What type of therapeutic is plozasiran?

Plozasiran is an investigational RNAi therapeutic.

Filing Stats: 708 words · 3 min read · ~2 pages · Grade level 13.2 · Accepted 2025-09-12 16:01:43

Key Financial Figures

Filing Documents

01 Other Events

Item 8.01 Other Events Arrowhead Pharmaceuticals, Inc. (the "Company") was notified that on September 11, 2025, Ionis Pharmaceuticals, Inc. ("Ionis") filed a Complaint for Patent Infringement against the Company in the United States District Court for the Central District of California alleging patent infringement of United States Patent No. 9,593,333 ("the '333 patent"). As the Company previously reported, on September 10, 2025, the Company filed a Complaint for Declaratory Judgment in the United States District Court for the District of Delaware against Ionis to declare that the '333 patent is invalid and not infringed by the Company's planned commercialization of investigational plozasiran. A copy of Ionis's complaint is attached hereto as Exhibit 99.1 (the "Complaint").

Forward-Looking Statements

Forward-Looking Statements This Current Report on Form 8-K contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. Any statements contained in this report except for historical information may be deemed to be forward-looking statements. Without limiting the generality of the foregoing, words such as "may," "will," "expect," "believe," "anticipate," "hope," "intend," "plan," "project," "could," "estimate," "continue," "target," "forecast" or "continue" or the negative of these words or other variations thereof or comparable terminology are intended to identify such forward-looking statements. These forward-looking statements include, but are not limited to, statements about our planned commercialization of investigational plozasiran and beliefs and expectations regarding the Company's claims and lawsuits against Ionis and the validity and enforceability of the 333 Patent. These statements are based upon our current expectations and speak only as of the date hereof. Our actual results or outcomes may differ materially and adversely from those expressed in any forward-looking statements as a result of numerous factors and uncertainties, including the risks and uncertainties described in our most recent Annual Report on Form 10-K, subsequent Quarterly Reports on Form 10-Q and other documents filed with the Securities and Exchange Commission from time to time. We assume no obligation to update or revise forward-looking statements to reflect new events or circumstances.

01. Financial Statements and Exhibits

Item 9.01. Financial Statements and Exhibits. (d) Exhibits Exhibit No. Description 99.1 Complaint 104 Cover Page Interactive Data File (the cover page tags are embedded within the Inline XBRL document).

SIGNATURES

SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. Date: September 12, 2025 ARROWHEAD PHARMACEUTICALS, INC. By: /s/ Daniel Apel Daniel Apel Chief Financial Officer

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