Heidelberg Pharma to Present New Clinical Data of Lead ADC Candidate HDP-101 at the World ADC Congress 2025 and to Host Webinar

EQS-News: Heidelberg Pharma AG / Key word(s): Study results Heidelberg Pharma to Present New Clinical Data of Lead ADC Candidate HDP-101 at the World ADC Congress 2025 and to Host Webinar 03.11.2025 / 10:07 CET/CEST The issuer is solely responsible for the content of this announcement. PRESS RELEASE

Heidelberg Pharma to Present New Clinical Data of Lead ADC Candidate HDP-101 at the World ADC Congress 2025 and to Host Webinar

• Objective responses and promising anti-tumor activity observed in several patients across multiple cohorts in the ongoing Phase I/IIa clinical trial
• Data reinforces the therapeutic potential and safety profile of HDP-101 in relapsed or refractory multiple myeloma.
• R&D Webinar to be hosted on 11 November 2025 at 05:00 pm CET (08:00 am PST)

Ladenburg, Germany, 3 November 2025 – Heidelberg Pharma AG (FSE: HPHA), a clinical-stage developer of innovative Antibody Drug Conjugates (ADCs), today announced the presentation of new clinical data from its ongoing Phase I/IIa clinical study evaluating its lead Amanitin-based ADC candidate, HDP-101 (INN: pamlectabart tismanitin), at the 16^th Annual World ADC Congress, taking place in San Diego, California, from 3 to 6 November 2025.

HDP-101 (INN: pamlectabart tismanitin) is an anti-BCMA antibody-drug conjugate being investigated for the treatment of relapsed or refractory multiple myeloma, a bone marrow cancer with a high unmet medical need. Phase I of the ongoing study is a dose-escalation trial designed to determine the optimal and safe dose level of HDP-101 in preparation for subsequent Phase II clinical evaluation.

Professor Andreas Pahl, Chief Executive Officer of Heidelberg Pharma, will present an update from patient cohort 8 including efficacy data of the open-label, multicenter Phase I/IIa study evaluating HDP-101 in patients with relapsed or refractory multiple myeloma.

Details of the presentation at 16^th Annual World ADC Congress:

Presentation title: From Bench to Breakthrough: The Evolution of Amanitin ADCs – Insights from HDP-101 Phase I/II & the Future of Payload Differentiation

Speaker:	Professor Andreas Pahl, Chief Executive Officer
Date and time:	Wednesday, 5 November 2025, 5:00 pm (PST)
Location:	Town & Country San Diego