EQS-News: Heidelberg Pharma Significantly Reduces Operating Costs and Focuses on Lead ADC Candidate HDP-101 Due to Delayed Milestone Payment

PRESS RELEASE

Heidelberg Pharma Significantly Reduces Operating Costs and Focuses on Lead ADC Candidate HDP-101 Due to Delayed Milestone Payment

• Milestone payment of USD 70 million from royalty financing agreement with HealthCare Royalty delayed as payment condition has not yet been met
• Clinical Phase I/IIa trial with HDP-101 in Multiple Myeloma will continue as planned; further pipeline programs will be adapted
• Significant reduction in the workforce by approx. 75%
• Cash reach extended until mid-2026

Ladenburg, Germany, 25 September 2025 – Heidelberg Pharma AG (FSE: HPHA), a clinical stage biotech company developing innovative Antibody Drug Conjugates (ADCs), today resolved with the approval of the Supervisory Board to implement extensive cost-saving measures and consequently, to focus all development activities exclusively on lead ADC candidate HDP-101 to extend the Company’s cash reach. This is due to the delay of an expected milestone payment of USD 70 million from the royalty financing agreement with HealthCare Royalty (HCRx), as the payment condition has not yet been met.

Professor Andreas Pahl, Chief Executive Officer of Heidelberg Pharma, commented: "Over the past few weeks, we intensively discussed with the Supervisory Board various options and strategies that would ensure the continuation of our clinical and operational activities in their current form. In this situation we need to prioritize projects. The decision to focus on our main project HDP-101 and the cost-saving measures are a necessary step to maintain our liquidity and will result in a significant reduction in workforce. We deeply regret this decision. We would like to thank all employees for their long-standing commitment and their professional contribution in advancing our unique ADC technology through research and development to patients. We will provide the colleagues affected with the best possible support during this professional transition.”

The clinical development of HDP-101, an Amanitin-based ADC that is currently in a Phase I/IIa trial in Multiple Myeloma, will continue as planned. A second clinical program, HDP-102, will temporarily be paused. Clinical Trial Application for HDP-103 will be prepared for submission as planned.

Early research activities will be discontinued stepwise, and Heidelberg Pharma will explore outlicensing options for its preclinical programs.

The Executive Management Board plans to reduce the workforce companywide by approximately 75% by mid-2026.

The Executive Management Board continues to evaluate alternative financing options together with the Supervisory Board. Cash as of 31 August 2025 was EUR 22.9 million and is expected to be sufficient to continue operations until mid-2026 after implementation of the aforementioned measures. The financial guidance published on 21 March 2025 will be reviewed in light of the measures just adopted and adjusted in a timely manner if necessary.

For further details on the background to the measures, please refer to the ad hoc announcement dated 28 August 2025 (Ad hoc announcement as of 28 August 2025).

Invitation to the webcast

On Thursday, 25 September 2025, Heidelberg Pharma will hold a conference call for media, analysts, and investors in English at 3:00 pm CEST/9:00 am EDT. Please register at least 10 minutes in advance using the following link:

https://us06web.zoom.us/webinar/register/WN_eyvcBX7VTD2HjhlLYDmHdg

You will receive an e-mail with your registration confirmation, which contains the link to participate in the audio webcast as well as dial-in numbers for participation by phone. Please note that asking oral questions is only possible for online participants.

About Heidelberg Pharma

Heidelberg Pharma is a biopharmaceutical company working on a new treatment approach in oncology and developing novel drugs based on its ADC technologies for the targeted and highly effective treatment of cancer. ADCs are antibody-drug conjugates that combine the specificity of antibodies with the efficacy of toxins to fight cancer. Selected antibodies are loaded with cytotoxic compounds, the so-called payloads, that are transported into diseased cells. Inside the cells, the toxins then unleash their effect and kill the diseased cells.

Heidelberg Pharma is the first company to use the compound Amanitin from the green death cap mushroom in cancer therapy. The biological mechanism of action of the toxin represents a new therapeutic modality and is used as a compound in the Amanitin-based ADC technology, the so-called ATAC technology.

The lead candidate HDP-101 is a BCMA ATAC in clinical development for multiple myeloma. A second ATAC candidate, HDP-102, has recently started clinical development in Non-Hodgkin Lymphoma. HDP-103 against metastatic castration-resistant prostate cancer and HDP-104 targeting gastrointestinal tumors such as colorectal cancer have completed preclinical development. Heidelberg Pharma is open for partnering.

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

ATAC^® is a registered trademark of Heidelberg Pharma Research GmbH.

This communication contains certain forward-looking statements relating to the Company's business, which can be identified by the use of forward-looking terminology such as "estimates", "believes", "expects", "may", "will" "should" "future", "potential" or similar expressions or by a general discussion of the Company's strategy, plans or intentions. Such forward-looking statements involve known and unknown risks, uncertainties and other factors, which may cause our actual results of operations, financial condition, performance, or achievements, or industry results, to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. Given these uncertainties, prospective investors and partners are cautioned not to place undue reliance on such forward-looking statements. We disclaim any obligation to update any such forward-looking statements to reflect future events or developments.