Lead multiple myeloma candidate enters Cohort 8; second asset dosed in lymphoma trial as platform momentum builds

Heidelberg Pharma is reporting steady progress across its antibody-targeted amanitin conjugate (ATAC) platform.

Its lead candidate, HDP-101, has advanced to cohort 8 of a Phase 1/2a trial in multiple myeloma, while HDP-102—its second ATAC asset—is now in clinical development for non-Hodgkin lymphoma (NHL).

The German biotech, which uses amanitin payloads to develop next-generation ADCs, confirmed safety and tolerability up to a 112.5 µg/kg dose in HDP-101, with no signs of pulmonary or ocular toxicity. Five patients remain on treatment, and dose escalation continues with a higher 140 µg/kg regimen in Cohort 8. One patient from Cohort 5 has reportedly achieved sustained molecular remission.

Meanwhile, HDP-102, which targets CD37 on B-cell malignancies, has now dosed its first patient in a multinational Phase I trial. The study will assess safety, pharmacokinetics, and optimal dosing across EU countries, Israel, and Moldova.

“Moving our second ATAC program, HDP-102, into clinical development in patients with non-Hodgkin lymphoma is a significant milestone,” said Dr. András Strassz, chief medical officer at Heidelberg Pharma.

“Building on the encouraging safety and efficacy data we have seen with HDP-101 in multiple myeloma, we are optimistic that HDP-102 will deliver similarly promising results. Our goal is to bring new therapies with favorable safety profiles to patients facing these devastating and challenging cancers.”

Alongside scientific progress, the company also strengthened its financial position, securing a $20 million payment from HealthCare Royalty in March via an amended agreement tied to the TLX250-CDx diagnostic, developed in partnership with Telix. A further $70 million milestone is expected upon regulatory approval, potentially as early as Q3 2025.

Preclinical work on a third candidate, HDP-201, was also showcased at AACR, with data suggesting high tumour specificity using an Exatecan-based multimer linker. The company is also exploring novel NAMPT inhibitors as future ADC payloads, using in silico modelling to enhance selectivity.

Based on current cash and the expected milestone, Heidelberg says it is now funded into early 2027.