Risk Factors Update Summary

• Market and data exclusivity for biological product candidates may be shortened due to legislative action.
• Increased expenses for ongoing activities, including clinical development and manufacturing efforts.
• Evaluating a limited number of ADC product candidates, including XMT-1660 and XMT-2056.
• Obtained marketing approval instead of receiving could materially harm business, results, and financial condition.
• The Pediatric Research Equity Act requires data on pediatric populations for certain biological products.
• Losses of $204.2 million in 2022, with accumulated deficit of $826.7 million as of December 31, 2023.
• Facing setbacks, such as the UPLIFT Phase 2 trial failure, impacting profitability.
• Laws allowing drug importation from Canada and FDA approvals could affect drug pricing and availability.
• Litigation and legislation over the ACA and CPACA could lead to uncertain results impacting the company.
• Potential market acceptance challenges due to competition and uncertainties in addressable markets.
• Potential competition from biosimilars could impact business due to increased competition and pricing pressure.
• Changes in Medicare payments due to Consolidated Appropriations Act and CARES Act could impact financials.
• Changes in Health Technology Assessment regulations in the EU could impact cooperation and assessments.
• Need substantial additional financing, with cash of $209 million as of December 31, 2023.
• New regulations in the EU and US impact clinical trial authorization and diversity action plans.
• Borrowed up to $25 million under the New Credit Facility, with available borrowings through June 30, 2023.
• Changes in marketing approval policies, including diversity action plans and new Clinical Trials Regulation in the EU.
• Delay in Medicare sequester reductions through fiscal year 2032 could affect financial results.
• Brexit impacts marketing authorization in the UK and EU, with changes in regulatory responsibilities.
• The Windsor Framework changes the regulatory system in the UK, affecting MHRA responsibilities.
• Litigation challenging FDA approval of mifepristone may impact product development and approval.