Bone breaks from original cell therapy plan, switching endpoint and shrinking enrollment target

Needing a win to reverse its fortunes, Bone Therapeutics is rethinking an ongoing phase 2b clinical trial of its tibial fracture cell therapy. The Belgian biotech plans to change a primary endpoint and add an interim analysis as part of statistical revisions that will enable it to reduce the enrollment target by 20%.

Bone Therapeutics has been on the ropes since a phase 3 trial of its lead program in knee osteoarthritis missed the primary endpoint. Rocked by the setback, the biotech parted company with most of its executive team and threw its remaining resources behind ALLOB, an off-the-shelf therapy made from bone-forming cells. By giving the cells to patients with bone fractures, the company hopes to accelerate the healing process.

Investigators are testing that idea in a phase 2b clinical trial that got underway at the start of last year. In light of new information on the “timing and dynamics of radiological evidence of fracture resolution,” Bone Therapeutics wants to change the statistical analysis.

The plan is to convert a secondary endpoint into a primary endpoint and “provide an optimal radiological assessment of the acceleration of bone formation at three months following an intra-fracture administration of ALLOB.” As part of the changes, which are yet to be approved by regulators, Bone Therapeutics will reduce the size of the trial by 20% and add an interim analysis. 

When the trial began, Bone Therapeutics expected to have top-line results in the second half of 2022. The target later slipped to the first quarter of 2023. In the latest update, the biotech broadened its target to the first half of 2023, despite reducing the size of the trial by 20%. The interim analysis is scheduled for earlier in 2023. 

The timeline poses a problem for Bone Therapeutics. As of the end of March, the biotech had 6 million euros ($6 million) in cash. Forecasting net cash burn of 8 million euros to 10 million euros for 2022, Bone Therapeutics expects to hit the end of its cash runway in the first quarter of 2023. The biotech is talking to Medsenic about a reverse merger that could provide a way out of the tight spot.