ADC Therapeutics SA美股招股说明书(2026-04-15版)

This prospectus supplement updates ADC Therapeutics SA’s (the “Company”) prospectus dated July 9, 2025 relating tothe offer and sale from time to time by the selling shareholders of 27,726,052 common shares. This prospectussupplement should be read in conjunction with the prospectus and is not complete without, and may not be used ordelivered except in connection with, the prospectus. Point72 Associates, LLC, a selling shareholder named in the prospectus, has informed the Company that it transferred1,383,144 common shares registered pursuant to the prospectus to SILV Fund Ltd. This prospectus supplement updatesthe table contained in the “Selling Shareholders” section of the prospectus by (i) reducing the number of common sharesthat may be offered and sold by Point72 Associates, LLC by 1,383,144 common shares and (ii) adding SILV Fund Ltd. asa selling shareholder as set forth below to register the offer and sale by SILV Fund Ltd. of the 1,383,144 common sharesthat it received from Point72 Associates, LLC. This prospectus supplement does not change the aggregate number ofshares registered pursuant to the prospectus. (1)Sirenia Capital Management LP (“Sirenia”) is the investment manager of SILV Fund, Ltd. and as such has investment and votingpower with respect to the securities held by SILV Fund, Ltd. Sirenia Capital Management GP LLC (“Sirenia GP”) is the general partnerof Sirenia. Alex Silverstein is the managing member of Sirenia GP. Each of SILV Fund, Ltd., Sirenia GP and Mr. Silverstein disclaimsbeneficial ownership over such securities. The address for the selling shareholder is 1674 Meridian Ave, Suite 320, Miami Beach, FL33139. Prospectus supplement dated April 15, 2026.