PRESS RELEASE

Encouraging Clinical Data from Two Antibody Drug Conjugates Based on Heidelberg Pharma’s ATAC Technology Presented at the ASH Annual Meeting 2022

Ladenburg, Germany, 14 December 2022 – Heidelberg Pharma AG (FSE: HPHA) today announced that initial clinical data from two Antibody Drug Conjugates (ADCs) based on the Company’s proprietary ATAC technology was presented at the ASH Annual Meeting 2022. Heidelberg Pharma showed preliminary safety data from the clinical trial with its candidate HDP-101 and partner Magenta Therapeutics, Cambridge, MA, USA, (Magenta) (NASDAQ: MGTA) presented in an oral session preliminary positive safety and initial efficacy data from its clinical trial with the ATAC candidate MGTA-117.

HDP-101, an ATAC targeting BCMA, is currently being evaluated in an open-label, multi-center Phase I/IIa trial in patients with multiple myeloma, a bone marrow cancer with high unmet medical need. The first part of the 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. Preliminary results from the first two patient cohorts showed good tolerability. Currently, the trial is enrolling patients in cohort 3.

MGTA-117 is being tested in a Phase I/II dose-escalation trial in relapsed/refractory (R/R) acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Patients with these conditions are deemed ineligible for transplant due to active disease characterized by high numbers of cancer blast cells present in the bone marrow and in the bloodstream. MGTA-117 is designed to deplete these cancer cells prior to a stem cell transplant or to receiving an ex vivo gene therapy product. Preliminary results from 15 patients across three dose-escalation cohorts showed target cell depletion in the blood and bone marrow, providing evidence of an active dose. Two transplant-ineligible patients became transplant-eligible due to the successful depletion of bone marrow cancer cells. MGTA-117 was well-tolerated in all participants. No serious adverse events were deemed to be related to MGTA-117; it cleared quickly as designed and no dose-limiting toxicities were observed.

Currently, the trial is enrolling patients in cohort 4; further data is expected in Q1 2023.

Prof. Andreas Pahl, Chief Scientic Officer of Heidelberg Pharma, commented: “We congratulate Magenta on their great progress with the development candidate MGTA‑117 and the preliminary but promising data from this clinical trial. We are very pleased that an ADC based on our proprietary ATAC technology has shown positive efficacy data in humans without unexpected or serious treatment-related adverse events. The presented data confirms our view that cancer therapies with ATACs can provide highly effective and well-tolerated treatment.”

MGTA-117 is an Amanitin-based ADC consisting of a CD117 antibody and Amanitin as payload. It was developed under a partnership with Heidelberg Pharma that grants Magenta exclusive worldwide development and marketing rights for antibody-drug conjugates using an Amanitin payload and targeting CD117.

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. ATACs are ADCs whose active ingredient is the mushroom toxin Amanitin. Amanitin inhibits mRNA transcription by binding to RNA polymerase II, a mechanism that is crucial for the survival of eukaryotic cells. In preclinical testing, ATACs 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 innovative 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 ATACs as well as in third-party collaborations. The lead candidate HDP-101 is a BCMA ATAC in clinical development for multiple myeloma. Further ATAC candidates are being developed against different targets such as CD37, PSMA or GCC each in the indications non-Hodgkin's lymphoma, metastatic castration-resistant prostate cancer or gastrointestinal tumors such as colorectal cancer.

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 the EU and USA.

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