15. Commitments and Contingencies

Legal Proceedings

From time to time, the Company is a party to various legal proceedings arising in the ordinary course of business. In addition, the Company has in the past been, and may in the future be, subject to investigations by governmental and regulatory authorities, which expose it to greater risks associated with litigation, regulatory or other proceedings, as a result of which the Company could be required to pay significant fines or penalties. The costs and outcome of litigation, regulatory or other proceedings cannot be predicted with certainty, and some lawsuits, claims, actions or proceedings may be disposed of unfavorably to the Company and could have a material adverse effect on the Company’s business, financial condition, results of operations and cash flows. In addition, intellectual property disputes often have a risk of injunctive relief which, if imposed against the Company, could materially and adversely affect its financial condition or results of operations. If a matter is both probable to result in material liability and the amount of loss can be reasonably estimated, the Company estimates and discloses the possible material loss or range of loss. If such loss is not probable or cannot be reasonably estimated, a liability is not recorded in its condensed consolidated financial statements.

On January 26, 2024, the Company was sued in the United States District Court for the District of Delaware (the “District Court”) by Advanced Accelerator Applications USA, Inc. and Advanced Accelerator Applications SA (collectively known as “ADACAP” in the court proceedings), each a Novartis entity, for patent infringement in response to the filing of our Abbreviated New Drug Application and Paragraph IV certification in connection with PNT2003, consistent with the process established by the Hatch-Waxman Act. In December 2025, the court conducted its trial. On June 17, 2026, the District Court issued an opinion in Lantheus’ favor; specifically, the District Court determined that all the patents asserted by ADACAP are invalid. On June 23, 2026, ADACAP appealed the District Court’s decision to the Court of Appeals for the Federal Circuit (“CAFC”) and moved for an emergency injunction to stay Lantheus’ launch of PNT2003 pending appeal. On July 2, 2026, the CAFC denied ADACAP’s motion to stay Lantheus from launching PNT2003 during the appeal process. As of the date of this Form 10-Q, the Company is waiting for final FDA approval and participating in the appeal briefing process on an expedited basis which will culminate in an oral hearing before the CAFC currently scheduled for December 14, 2026. The timing of the oral hearing and the final decision of the CAFC on ADACAP’s appeal is not known. Because the outcome of litigation is uncertain, the Company cannot predict how or when this matter will ultimately be resolved.

On September 9, 2025, an alleged stockholder initiated a putative securities class action against the Company in the United States District Court for the Southern District of New York, styled Margolis v. Lantheus Holdings, Inc., et al. The operative complaint also asserts claims against certain of the Company’s named executives. A related action, styled Indiana Pub. Ret. Sys. v. Lantheus Holdings, Inc., et al., was filed in the same court on November 5, 2025. Those actions are now consolidated into a single putative securities class action (captioned In re Lantheus Holdings, Inc. Secs. Litig.), the theory of which is that the defendants made materially false or misleading statements (or omitted

material facts) in violation of the Exchange Act. The lead plaintiff filed an amended complaint on March 13, 2026. The Company and its executives filed a motion to dismiss the amended complaint on May 11, 2026, and under the operative scheduling order, that motion will be fully briefed by August 10, 2026. Additionally, on December 17, 2025, another alleged stockholder of the Company filed a shareholder derivative action in the same court, styled Lelchuk v. Heino et al., nominally on behalf of the Company and naming as defendants the current directors of the Board and the same officers named in the consolidated securities class action described above (a similar derivative complaint styled Jones v. Markison et al., was previously filed on October 31, 2025 but was voluntarily withdrawn without prejudice). The derivative complaint largely repeats the allegations asserted in the consolidated securities class action, and asserts claims for alleged breaches of fiduciary duties, aiding and abetting breach of fiduciary duty, unjust enrichment, waste of corporate assets, and violations of the Exchange Act. The plaintiff seeks damages and other relief on behalf of the Company. The derivative action is stayed pending one or more of the following events: (i) a public announcement of any settlement of the putative securities class action; (ii) a ruling on the defendants’ motion to dismiss; or (iii) a dismissal with prejudice of the putative securities class action and exhaustion of all related appeals. Because the outcome of litigation is uncertain, the Company cannot predict how or when these matters will ultimately be resolved.

As of June 30, 2026, the Company was not a party to any other material ongoing legal proceedings and has determined that the aforementioned matters are not expected to have a material adverse effect on its business or consolidated financial results.

Technology License and Other Commitments

The Company has licensed from third parties the rights to use certain technologies in its research and development (“R&D”) processes as well as in other products it may develop, commercialize, or sell. In accordance with the related license or sublicense agreements, the Company is contractually required to make certain future payments to these third parties contingent upon (i) the achievement of specified regulatory, development and/or commercialization milestones and (ii) future sales of specified products in the form of royalty payments. Milestone payments are generally recognized in the period in which the achievement of the underlying milestone becomes probable, which is generally the period in which it is actually achieved. Royalty payments are generally recognized in the period in which the associated revenue is recognized.

Repurchase of License

In June 2026, the Company entered into a repurchase agreement (the “Repurchase Agreement”) with its distributor in China pursuant to which the Company repurchased from the distributor the license to DEFINITY in China along with the related materials, approvals and clinical trial research that had been accumulated since the original Distribution and Supply Agreement between the same parties (the “Supply Agreement”), which was executed in April 2012. The Company’s repurchase right was in accordance with the Supply Agreement. The total consideration to be paid as part of the Repurchase Agreement is $30.0 million, which is expected to be paid in three tranches by the end of the first quarter of 2027 upon satisfaction of certain conditions.

The Company accrued $30.0 million related to the Repurchase Agreement. The amount is recorded in accrued expenses and other current liabilities on the Company’s condensed consolidated balance sheet as of June 30, 2026 and was fully expensed to sales and marketing expenses on the Company’s condensed consolidated statements of operations for the three and six months ended June 30, 2026.