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, 2023.

We do not control the conduct of current or any potential future investigator-initiated clinical trials, and the data from such trials is not subject to our review or quality control.

We have provided clinical data from an investigator-initiated Phase 2 clinical trial of ZYNLONTA for the treatment of relapsed/refractory marginal zone lymphoma. In the future, we may provide clinical data from this and other investigator-initiated clinical trials. We do not control the design or administration of such trials, nor the submission, approval or maintenance of any regulatory and institutional filings required to conduct such trials. Furthermore, we have limited or no rights to audit, review or apply quality control procedures to the clinical data generated from such trials. As a result, we have no control over the conduct of such trials and the timing of any data releases from such trials and we cannot be certain that such trials are or will be conducted in accordance with applicable regulatory requirements or that the clinical data provided to us by the investigators of such trials are accurate, reliable or complete.