Heidelberg Pharma AG will present promising preclinical data for its antibody-drug conjugate HDP-103 targeting metastatic castration-resistant prostate cancer at the American Association of Cancer Research Annual Meeting 2026 in San Diego. The presentation, scheduled for April 21, will detail findings from patient-derived xenograft models that demonstrate the compound's efficacy even in tumors with heterogeneous PSMA expression and those harboring a del(17p) genetic alteration.
The data shows HDP-103 demonstrates target-specific binding in human tissues and robust, durable antitumor activity in models representative of metastatic castration-resistant prostate cancer. In these challenging models, the amanitin-based ADC was superior to an anti-PSMA Exatecan ADC, showing particular promise for patients with del(17p) who currently have limited treatment options. The abstract detailing these findings is available at https://www.abstractsonline.com/pp8/#!/21436/presentation/5438.
Adverse events observed in non-human primate studies were restricted to known off-target effects of amanitin-based ADCs, primarily affecting the liver and kidney. These effects were transient and can be readily monitored in clinical settings. HDP-103 serum levels demonstrated stability in circulation with no evidence of drug accumulation, no differences between sexes, and dose-linearity, contributing to a favorable pharmacokinetic profile.
The combination of potent anti-tumor efficacy with manageable safety and favorable half-life results in a therapeutic index for HDP-103 that falls within the range of other ADCs approved or in development for solid tumor indications. This therapeutic profile supports further clinical development of HDP-103 as a novel treatment option for metastatic castration-resistant prostate cancer, particularly for patients with del(17p) who represent a population with high unmet medical need.
Heidelberg Pharma's ATAC technology platform utilizes amanitin, a compound derived from the green death cap mushroom, representing a novel therapeutic modality in cancer treatment. The company's approach differs from conventional ADC technologies through its unique mechanism of action, which may provide advantages over existing treatment modalities. More information about the company's technology and pipeline is available at https://www.heidelberg-pharma.com.
The presentation at AACR represents a significant milestone in the development of HDP-103, as the data suggests the compound could address critical gaps in prostate cancer treatment. Metastatic castration-resistant prostate cancer remains a challenging disease with limited effective options, particularly for patients with specific genetic alterations like del(17p). The preclinical success of HDP-103 in these difficult-to-treat models indicates potential for meaningful clinical impact if these results translate to human trials.
These findings warrant continued investigation of HDP-103 as it progresses toward clinical development. The data presentation at one of oncology's premier scientific meetings provides validation of Heidelberg Pharma's ATAC platform and highlights the potential of amanitin-based ADCs to address unmet needs in solid tumor oncology. The company's approach represents an innovative direction in ADC development that could expand treatment options for patients with limited alternatives.
