PR: Heidelberg Pharma to Present New Clinical Data on Lead ATAC Candidate Pamlectabart Tismanitin at International Myeloma Society Annual Meeting 2026

Ladenburg, Germany, 7 September 2026 – Heidelberg Pharma AG (FSE: HPHA), a clinical stage company developing innovative Antibody Drug Conjugates (ADCs), will present new data from its Phase I/IIa clinical study with lead Amanitin-based ADC candidate, pamlectabart tismanitin (HDP-101), at the 23rd International Myeloma Society (IMS) Annual Meeting, being held in Glasgow, Scotland, on 23 to 26 September 2026.

Pamlectabart tismanitin is an Anti-BCMA antibody-Amanitin drug conjugate for the treatment of relapsed or refractory multiple myeloma (RRMM), a bone marrow cancer with a high unmet medical need. Phase I of the trial was a dose escalation study to determine an optimal and safe dose level of the candidate for the Phase IIa part of the study.

Details of the presentation are as follows:

Poster title: HDP-101, a BCMA-Targeting Antibody-Drug Conjugate with a Novel Amanitin Payload, Establishes the Recommended Phase 2 Dose (RP2D) in a clinical Phase 1 trial on Relapsed/Refractory Multiple Myeloma

The Phase I part of the study including ten patient cohorts was completed in April 2026 and the recommended dose for the Phase IIa part (Recommended Phase 2 Dose; RP2D) was determined. The Phase IIa part is progressing as planned.

Pamlectabart tismanitin demonstrated consistent clinical activity with a favorable safety profile in heavily pretreated RRMM patients supporting the potential of the candidate as a novel payload BCMA-targeted ADC therapy.