PRESS RELEASE

Heidelberg Pharma and Partner Magenta to Present Initial Clinical Data on their Antibody Drug Conjugates at the ASH Annual Meeting 2022

• Heidelberg Pharma presents initial findings of the first in human study with ATAC^® candidate HDP-101
• Licensing partner Magenta presents initial data from Phase I/II study with ATAC^® candidate MGTA-117

Ladenburg, Germany, 10 November 2022 – Heidelberg Pharma AG (FSE: HPHA) today announced that it will present initial data from the Phase I/IIa clinical trial with HDP-101 at the 64^th Annual Meeting of the American Society of Hematology (ASH). In addition, partner Magenta Therapeutics, Cambridge, MA, USA, (Magenta) (NASDAQ: MGTA) will present data from its clinical trial with MGTA-117. The conference will take place from December 10 to 13, 2022 in New Orleans, USA.

Dr. András Strassz, Chief Medical Officer of Heidelberg Pharma AG, commented: "We are excited to present initial safety data of the first in human study with HDP-101, an Antibody Drug Conjugate with the highly potent payload Amanitin, at the ASH meeting. Up to now, HDP‑101 has shown good tolerability in late stage relapsed and/or refractory multiple myeloma patients. The study is currently enrolling patients in the third cohort and we are curious to see further safety and efficacy data.”

Poster title: HDP-101, an Anti-BCMA Antibody-Drug Conjugate with a Novel Payload Amanitin in Patients with Relapsed Multiple Myeloma, Initial Findings of the First in Human Study

Presentation details

Abstract #3219

Session: 652. Multiple Myeloma and Plasma Cell Dyscrasias: Clinical and Epidemiological: Poster II

Time and location: Sunday, December 11, 2022, 6:00pm - 8:00pm CST, Hall D (Ernest N. Morial Convention Center)

Dr. Strassz will present the poster showing initial clinical data of the ongoing open-label, multi-center Phase I/IIa trial evaluating HDP-101 in multiple myeloma. He will also be available to answer questions.

HDP-101 is a BCMA antibody-Amanitin conjugate for the treatment of relapsed or refractory multiple myeloma, a bone marrow cancer with high unmet medical need. The first part of the ongoing trial is a Phase I dose escalation study to determine an optimal and safe dose of HDP-101 for the Phase II part of the study. It is planned to treat up to 36 patients who will receive HDP‑101 intravenously every 3 weeks. During this part of the trial, tolerability of different dose levels will be evaluated.

Oral presentation from Heidelberg Pharma’s licensing partner Magenta

Presentation title: MGTA-117, an Anti-CD117 Antibody-Drug Conjugated with Amanitin, in Participants with Relapsed/Refractory Adult Acute Myeloid Leukemia (AML) and Myelodysplasia with Excess Blasts (MDS-EB): Safety, Pharmacokinetics and Pharmacodynamics Initial Findings from a Phase 1/2 Study

Presentation details

Abstract #874

Session: 701. Experimental Transplantation: Basic and Translational: Poster III

Time and location: Monday, December 12, 2022, 3.30pm CST

Poster presentations from Heidelberg Pharma’s licensing partner Magenta

Poster title: The Pharmacokinetic and Pharmacodynamic Characterization of MGTA-117, an Anti-CD117-Amanitin Antibody-Drug Conjugate for Targeted Conditioning Prior to Transplant, in Non-Human Primates

Presentation details

Abstract #4592

Session: 616. Acute Myeloid Leukemia: Novel Therapy, excluding Transplantation: Poster I

Time and location: Monday, December 12, 2022, 6:00-8:00 pm CST, Hall D (Ernest N. Morial Convention Center)

All abstracts and further information will be available online on the ASH conference website.

About Heidelberg Pharma's proprietary ATAC^® technology

Antibody drug conjugates (ADCs) combine the high affinity and specificity of antibodies with the potency of cytotoxic small molecules for the treatment of cancer. ATAC^®s are ADCs whose active ingredient is made up of amatoxin molecules. Amatoxins are small bicyclic peptides naturally occurring in the death cap mushroom. They inhibit mRNA transcription by binding to RNA polymerase II, a mechanism that is crucial for the survival of eukaryotic cells. In preclinical testing, ATAC^®s have been shown to be highly efficacious, overcoming frequently encountered resistance mechanisms and combating even quiescent tumor cells.

About Heidelberg Pharma

Heidelberg Pharma is an oncology specialist and the first company to develop the toxin Amanitin into cancer therapies using its proprietary ATAC^® technology and to advance the biological mode of action of the toxin as a novel therapeutic principle. The proprietary technology platform is being applied to develop the Company’s own therapeutic ATAC^®s as well as in third-party collaborations. The lead candidate HDP-101 is a BCMA ATAC in clinical development for multiple myeloma. HDP-102, a CD37 ATAC for Non-Hodgkin lymphoma and HDP-103, a PSMA ATAC for metastatic castration-resistant prostate cancer, are in preclinical testing.

Heidelberg Pharma AG is based in Ladenburg, Germany, and is listed on the Frankfurt Stock Exchange: ISIN DE000A11QVV0 / WKN A11QVV / Symbol HPHA. More information is available at http://www.heidelberg-pharma.com/.

ATAC^® is a registered trademark of Heidelberg Pharma Research GmbH in EU and USA.

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