The FDA’s rejection of Telix Pharmaceuticals’ imaging agent has triggered layoffs at Heidelberg Pharma. With the regulatory setback delaying a $70 million payment, Heidelberg is reducing its workforce by 75% and narrowing its focus to extend its cash runway into the middle of next year.
Heidelberg reached the midpoint of 2025 with 33 million euros ($39 million) in the bank. While that left the biotech with a short runway, management was banking on receiving a $70 million payment tied to approval of the TLX250-CDX diagnostic at the end of August. When an FDA rejection delayed payment, Heidelberg told investors that it only had enough cash to fund operations into the first quarter of 2026.
Seeking to eke out its remaining cash, Heidelberg has outlined plans to reduce its workforce by about 75% by the middle of next year. The company had (PDF) 122 employees at the midpoint of 2025.
The workforce reduction is part of a narrowing of Heidelberg’s R&D focus. Work on lead antibody-drug conjugate HDP-101 will continue as planned. Heidelberg is pausing development of a second ADC, HDP-102, that recently entered the clinic. The biotech will create and submit a clinical trial application for a third candidate, HDP-103, as planned.
Heidelberg will stop early research activities and look into out-licensing opportunities for its preclinical programs. The company has disclosed two preclinical programs that target GCC to treat gastrointestinal tumors such as colorectal cancer.
Management is predicting the actions will extend the cash runway into mid-2026, but a longer-term fix is yet to emerge. The company is continuing the exploration of financing options it began when it learned of the delayed milestone late last month.
Heidelberg could still receive the $70 million milestone, but it is unclear whether it will arrive before the end of the company's current cash runway. Telix told investors that the concerns raised by the FDA are readily addressable when it disclosed its complete response letter. The company immediately began submission remediation work but is yet to commit to a timeline for refiling for approval.
Amid the upheaval, Heidelberg will continue advancing HDP-101 through a phase 1/2a trial in multiple myeloma. The biotech is aiming to establish the maximum dose this year, positioning it to start the phase 2 portion of the study. HDP-101 consists of an anti-BCMA antibody conjugated to an amanitin payload that differentiates the candidate from other ADCs against the target, such as GSK’s Blenrep.