BOOST Pharma has announced unprecedented two-year follow-up results from its landmark BOOSTB4 Phase I/II clinical trial, demonstrating that stem cell therapy achieved a nearly 78% reduction in bone fractures among children with severe osteogenesis imperfecta (OI). The data, presented at the 15th International Conference on Osteogenesis Imperfecta in Hong Kong, represents a significant milestone in treating this devastating genetic disorder.
Sustained and Improved Therapeutic Benefits
The long-term data revealed that more than 50% of treated patients experienced zero bone fractures in the second year after their last dose, with fracture counts ranging from 0-5 across the patient population. This improvement built upon the previously reported ~70% reduction in fractures during the first year of follow-up, indicating that the therapeutic effect of BT-101 stem cell therapy not only sustained but continued to improve over time.
"For families living with OI, every fracture is a major strain. Seeing that more than half of the treated children had no fractures at all during the second year is tremendously encouraging. It gives us the strength to continue developing the treatment," said Dr. Cecilia Götherström, docent at the Department of Clinical Science, Intervention and Technology at Karolinska Institutet and coordinator of the study.
First-in-Class Disease-Modifying Approach
The BOOSTB4 trial represents the world's first clinical study to evaluate postnatal and prenatal allogeneic stem cell therapy for OI. The therapy leverages mesenchymal stem cells with high bone-forming capability, aiming to address the genetic cause of OI rather than merely providing supportive care. This approach suggests that BT-101 has the potential to be a disease-modifying cellular therapy that may effectively prevent new bone fractures in patients with severe OI.
"BOOSTB4 is the result of a unique multidisciplinary European collaboration where research, clinical practice and advanced cell therapy come together. It demonstrates that when research and clinic work hand in hand, we can change the lives of our patients," Götherström noted.
Addressing Critical Unmet Medical Need
Osteogenesis imperfecta, also known as brittle bone disease, is a rare and devastating genetic condition estimated to affect 1 in 15,000 people globally. The disease is characterized by fragile bones and reduced bone mass resulting in bones that break easily, loose joints, and weakened teeth. In severe cases, patients may experience hundreds of fractures in a lifetime, along with muscle weakness, early hearing loss, fatigue, curved bones, scoliosis, respiratory problems, and short stature.
Currently, there are no FDA or EU approved treatments that address the root cause of OI. Treatment remains purely supportive, focusing on minimizing fractures and maximizing mobility, leaving a significant gap in therapeutic options for patients and families affected by this condition.
Clinical Trial Design and Collaboration
The "Boost Brittle Bones Before Birth" (BOOSTB4) study is an exploratory, open-label, multiple-dose, multicenter Phase I/II trial evaluating the safety and efficacy of postnatal, or prenatal and postnatal administration of allogeneic expanded human stem cells compared with historical and untreated prospective controls. The study began in 2020 and is currently in its follow-up phase, conducted at Karolinska University Hospital.
The cells used in the trial were produced at Vecura, a GMP-certified manufacturing facility for advanced therapy medicinal products and a central component of the Karolinska ATMP Center. This center, established in 2023 as a joint initiative between Karolinska Institutet and Karolinska University Hospital, coordinates research, production, and clinical application of advanced therapies to accelerate new treatment development.
The study received funding from the European Union's Horizon 2020 Research and Innovation Program and the Swedish Research Council, with Karolinska Institutet serving as the study sponsor.
"Demonstrating such a dramatic reduction in fracture rates over a two-year period marks an extraordinary milestone and supports our mission to significantly improve the lives of children born with this severe genetic disorder," said Ingelise Saunders, Chairman of BOOST Pharma.
