CellProthera Prepares Phase III Cardiac Stem Cell Trial, Acquires Delivery Catheter

CellProthera is set to begin a Phase III study exploring the potential of its stem cell therapy in patients with heart failure post-myocardial infarction in Q1 2027. For this study, CellProthera hopes to enrol between 300 and 400 patients at around 50 sites across the US and Europe – though the company is also looking into running a part of the study in an Asian country too.

The trial will assess the efficacy and safety of CellProthera's ProtheraCytes, which are designed to repair, protect and promote the regeneration and revascularisation of damaged cardiac tissue without the need for immunosuppressants. The therapy was also created to reduce the level of scar tissue formation on the heart. This can help stop the organ's expansion, while allowing the previously damaged tissue to become contractile again.

According to the trial protocol design prepared with key opinion leaders in the heart failure and post-myocardial infarction space, the study has already received positive feedback from US regulators. A treatment option like this could be particularly beneficial for the 5-10% of patients who experience extensive cardiac tissue damage post-heart attack due to a delay in receiving treatment.

CellProthera recently acquired a transendocardial catheter from Celyad Oncology to facilitate the direct delivery of the CD34+ stem cells to the damaged cardiac tissue in the Phase III study. Under the terms of the agreement, CellProthera will pay €5 million ($5.93 million) in milestone-based installments, plus future royalties on net sales.

The transendocardial catheter will allow the company to precisely and accurately inject the stem cells around the scar of the heart. For the ProtheraCytes to exhibit their therapeutic effect, they must be administered to the right location. While this will add a layer of complexity to CellProthera's regulatory proceedings, the catheter constitutes a highly important part of the trial.

The autologous treatment is derived from CD34+ cells harvested from a patient's peripheral blood. Although CellProthera did not use the catheter during Phase I/II clinical trials, the company performed equivalence and compatibility testing to ensure suitability for its therapeutic approach, and the device itself has already been used in other clinical studies, demonstrating safety and performance in patients.

If CellProthera were to secure regulatory approval for its ProtheraCytes, the catheter would be part of the therapy's final approval – though the company will need to obtain a CE mark for the catheter first. As this novel catheter is not routinely used when treating heart failure, CellProthera is planning to fully train operators on how to use the medical device before it is applied in the clinical or commercial setting.

The acquisition grants CellProthera further control of its process from manufacturing through delivery, reducing the firm's reliance on third-party device availability. The catheter will be integrated into a delivery platform rather than being treated as a standalone tool. Ownership enables the company to tailor the catheter and its associated procedures to CellProthera's delivery equipment. The company can standardize how the therapy is administered across centers, improve procedural reproducibility, and implement consistent training and quality controls.

Transendocardial administration is relevant for a broad range of therapeutic agents that require precise, localized delivery into cardiac tissue, including other regenerative cell therapies, biologics, and potentially gene-based treatments.