ADC Therapeutics SA

Below we are providing, in supplemental form, additions to our risk factors as previously disclosed in our Annual Report on Form 10-K for the year ended December 31, 2024.

Changes in tariffs could increase our cost of sales and our operating expenses.

The U.S. government has recently announced, and is expected to continue to announce, significant changes to its trade policy, including the imposition of tariffs. Negotiations between the United States and other countries are ongoing, and the outcome of those negotiations and the scope of any tariff exemptions remain uncertain. We operate internationally and our products are manufactured outside of the United States, primarily in Europe. As a result, we may experience higher costs of sales and increased operating expenses in the future due to tariffs that may be imposed on U.S imports of our product for commercial sale in the U.S. These tariffs could adversely affect our financial condition and results of operations.

Changes in drug pricing policies of the current U.S. administration may negatively impact our product sales revenue.

The current administration has indicated that it plans to pursue additional policies aimed at lowering prescription drug costs. For example, in May 2025, the administration published an executive order regarding most favored nation (“MFN”) drug pricing, which is sometimes referred to as international reference pricing. This executive order directs the Secretary of Health and Human Services to communicate MFN price targets to pharmaceutical manufacturers, and if significant progress towards MFN pricing is not delivered, to propose a rule making plan to impose MFN pricing. The scope, timing, and potential impact of current and future policy initiatives remain uncertain, and accordingly, we cannot predict how such legal and regulatory changes may affect our business, operations, or financial condition. However, if MFN drug pricing is implemented, the U.S. list price of ZYNLONTA that is also being commercialized outside of the United States could be substantially reduced, which could negatively impact our U.S. product sale revenues and the overall U.S. market opportunity.