AB Science announced on April 14, 2025, that the United States Patent Office has issued a Notice of Allowance for a patent covering the use of masitinib in treating sickle cell disease. This patent, based on preclinical data, provides intellectual property protection for the company's lead compound until November 2040, strengthening its position following a similar allowance from the European Patent Office in October 2024.
"Masitinib is quite unique in the therapeutic landscape of sickle cell disease because no other development drug targets mast cells," said Professor Olivier Hermine, President of the AB Science Scientific Committee and member of the French Academy of Sciences. "Masitinib therefore represents a promising novel strategy for treating sickle cell disease and its serious complication of acute chest syndrome, which is a common cause of hospitalization or even death."
Understanding Sickle Cell Disease and Current Treatment Limitations
Sickle cell disease (SCD) is a group of inherited red blood cell disorders affecting millions worldwide. The condition represents a significant public health challenge, with approximately 300,000 children born with SCD annually—a figure projected to reach 400,000 by 2050. In the United States alone, over 100,000 individuals are affected, while France reports approximately 26,000 patients.
Masitinib is being developed specifically for the severest forms of SCD, which account for about 65% of cases and often lead to early mortality. While curative treatments based on gene therapy exist, these options remain extremely limited due to donor scarcity, unresolved safety challenges, and prohibitive costs. Standard treatments currently include red blood cell transfusions and hydroxyurea to manage complications, but significant unmet needs persist.
Masitinib's Novel Mechanism and Promising Preclinical Results
Mast cells, which are a primary target for masitinib, appear to play a critical role in severe forms of SCD and its complications, including vaso-occlusive crises (VOC), acute chest syndrome (ACS), and pain. Masitinib functions as an inhibitor of KIT, LYN, and FYN—three major kinases involved in the activation of mast cells and basophils.
The compound has demonstrated remarkable results in preclinical studies. In an SCD mouse model, all control mice experienced VOC with 83% mortality within the first three hours. In contrast, mice pretreated with masitinib for four days experienced no VOCs and no deaths. Further analysis through lung histology and immune immunohistochemistry showed that masitinib protects against acute lung injuries and mast cell infiltration.
Clinical Development Through SICKMAST Program
Masitinib's clinical development in SCD is being conducted as part of the SICKMAST collaborative program, which has secured €9.2 million in funding. The program aims to demonstrate the efficacy of masitinib in treating both acute and chronic complications of SCD in patients identified through specific biomarkers.
The Assistance Publique-Hôpitaux de Paris (AP-HP) will sponsor the upcoming phase 2 studies, with AB Science primarily involved in supplying masitinib and monitoring pharmacovigilance data. The company maintains the freedom to pursue potential phase 3 development following successful phase 2 results.
Addressing a Significant Medical Need
The classic understanding of SCD pathophysiology involves polymerization of mutated hemoglobin (HbS) leading to red blood cell sickling, resulting in hemolytic anemia, painful vaso-occlusive crises, and acute chest syndrome. Current treatment options do not fully prevent life-threatening complications.
While allogeneic stem cell transplantation and gene therapy are available, they remain accessible to only a minority of patients due to toxicity concerns and high costs. This creates a significant medical need for new approaches to prevent both acute and chronic complications of SCD—a gap that masitinib's novel mechanism of action may help address.
Recent research has highlighted the role of inflammation mediated by innate immune cells in promoting vaso-occlusion in SCD. Clinical observations and experimental work have specifically revealed the involvement of mast cells and basophils in complications associated with the disease, providing further rationale for masitinib's potential efficacy.
As AB Science continues to develop masitinib across multiple indications, this patent allowance represents an important milestone in the company's efforts to address the significant unmet needs in sickle cell disease treatment.
