Heidelberg Pharma deepens ADC alliance with Huadong

Why it matters: The companies plan to combine their technologies and development capabilities, including Heidelberg Pharma’s proprietary ATAC technology, which uses amanitin as a payload, with Huadong’s research and development capabilities.

Backstory: The relationship began in late February 2022, when Heidelberg Pharma and Huadong Medicine agreed on a strategic partnership that went well beyond a straightforward licensing deal. Huadong received exclusive development and commercialization rights to Heidelberg Pharma’s ATAC candidates HDP-101 and HDP-103 in numerous Asian markets. The deal included a $20 million upfront payment, potentially up to $449 million in milestone payments, as well as tiered royalties on sales. Additional options were agreed for further programs.

• Even more important for the long-term relationship was the second pillar of the deal: Huadong also invested in Heidelberg Pharma and became a strategic shareholder. The capital transaction envisaged a total stake of about 35%.

Yes, but: This created a structure that differs from the traditional licensor-licensee model. Huadong not only has an economic interest in individual Heidelberg Pharma programs, but also holds an equity interest in the company itself and therefore in the underlying technology platform.

• The viability of this model is now becoming evident through HDP-101, Heidelberg Pharma’s lead ATAC candidate. The BCMA-targeting ADC, now known as pamlectabart tismanitin, is being developed for multiple myeloma. While Heidelberg Pharma is advancing clinical development in Europe and the US, Huadong has taken responsibility for development in China. In March 2026, the first patient there was treated in a Phase 1 bridging study, triggering a contractually agreed development milestone and payment to Heidelberg Pharma.

Zoom in: The collaboration has since moved beyond that bridging study. At the end of August, China’s drug regulator, the NMPA, approved a Phase 1b/2 study evaluating HDP-101 in combination with established therapies in patients with relapsed or refractory multiple myeloma. Huadong will cover the development costs in China.

• At the same time, the ATAC technology is progressing beyond Heidelberg Pharma’s immediate pipeline. Heidelberg Pharma has licensed the technology to Takeda for use in its own ADC candidate. In January 2026, the start of a Phase 1/2 study of that candidate in patients with solid tumors triggered another milestone payment. At that point, three ATAC-based candidates were already in clinical development.

How it works: Heidelberg Pharma is not merely developing a single ADC. Its broader strategy is to establish a proprietary technology platform around amanitin, a deadly cyclic peptide toxin found in several poisonous mushroom species, as the active payload, advance programs to clinical proof of concept and use research and option agreements to generate longer-term licensing partnerships.

Leadership change: Particularly noteworthy is what happened at the management level of Heidelberg Pharma at the end of 2025. In November, the supervisory board revoked the appointment of Prof. Andreas Pahl as CEO and appointed Dr. Dongzhou Jeffery Liu as his successor. Pahl, who had been a member of the management board since 2016 and its chairman since February 2024, left the company and is now CEO of Swedish ADC company Simris Biologics at its Berlin research site.

• Liu did not simply arrive from another pharmaceutical company. At the time, he was chief scientific officer and president of Huadong Global Development at Huadong Medicine. Immediately before joining Heidelberg Pharma’s management board, Liu had also served on Heidelberg Pharma’s supervisory board, a position he had held since 2022. His appointment therefore effectively moved him from the company’s supervisory side to its operational leadership.

Between the lines: The personnel connection is unusually close. Heidelberg Pharma’s new CEO comes from the management team of its most important strategic partner and second-largest shareholder. Liu also remains closely linked to Huadong in terms of expertise: His background includes more than 25 years in pharmaceutical research and development, including specifically in ADC products. The collaboration has therefore reached multiple levels: capital, licensing, joint clinical development, research and now management.

What’s new: Going forward, the partners plan to jointly research and develop new ADCs against as many as six targets. These programs may use proprietary antibodies or technologies from Huadong alongside different toxin payloads from Heidelberg Pharma’s technology portfolio.

• Of particular interest is the planned development of bispecific and multispecific ADCs. The aim is to increase selectivity and biological activity by combining different targets or mechanisms of action. Rights to resulting development candidates will be divided between the partners according to their respective contributions.
• This also changes the logic of the collaboration. Whereas the 2022 agreement initially focused on licensing Heidelberg Pharma’s existing candidates for Asian markets, the two companies are now jointly working on the next generation of products.
• That also fits Heidelberg Pharma’s current situation. The company is concentrating its own resources primarily on HDP-101 while making other programs available for partnerships. At the same time, Huadong is already advancing clinical development of HDP-101 and working with Heidelberg Pharma on additional projects exploring the potential of ATAC technology in further indications.

The big picture: Heidelberg Pharma contributes a highly specialized technology platform and clinical development programs from Europe, while Huadong brings research, development and commercialization capabilities in China and Asia. For Heidelberg Pharma, the cooperation offers a way to scale its technology internationally without bearing all development and commercialization costs itself. For Huadong, it provides access to a differentiated ADC technology and new product candidates. Within four years, a single licensing agreement has therefore evolved into an increasingly dense network of equity ownership, licensing, clinical development and joint research.

What to watch: The question is how much further that integration can go. Shareholders from the Hopp family sphere, the main investor in Heidelberg Pharma, eventually intend to exit the company, something that could be difficult to achieve through the stock market given the company’s low free float and their substantial majority position. That does not mean a transaction with Huadong is inevitable. But a strategic partner that has steadily increased its involvement, invested in the company, taken responsibility for development programs and supplied its current CEO represents one possible route.

Bottom line: What began as a regional licensing agreement increasingly resembles a long-term strategic alliance and the latest expansion makes the boundaries between partner, shareholder and development collaborator thinner than ever.