Jasper Therapeutics has announced positive results from the first 3 participants in its phase 1/2 trial of briquilimab as an addition to the bone marrow transplantation regimen in patients with sickle cell disease (SCD) and beta thalassemia. The results, announced via news release, showed improved donor myeloid chimerism 1 year after transplant.

“While stem cell infusion with healthy donor stem cells or gene-corrected cells are potentially curative options for SCD and beta thalassemia, they are both limited by the toxicity of current conditioning regimens using busulfan or melphalan,” Ronald Martell, president and chief executive officer of Jasper Therapeutics, explained.

“With briquilimab, we hope to offer a highly targeted conditioning regimen to directly address conditioning toxicity as a barrier limiting the ability of patients to access curative hematopoietic stem cell therapies.”

Successful bone marrow transplantation in patients with SCD requires adequate engraftment of donor cells, leading to the sufficient production of healthy red blood cells and reversal of the sickle cell phenotype.

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Briquilimab is an anti-c-KIT monoclonal antibody intended to be added to an existing bone marrow conditioning regimen, including alemtuzumab, sirolimus, and low-dose irradiation. It is being assessed for its potential to lead to better donor cell engraftment without added toxicity, thereby improving disease-free survival.

All 3 initial study participants in the trial achieved successful neutrophil and platelet engraftment within 17 days of the transplant, and they experienced no serious adverse events. Five months after the transplant, the first participant’s hemoglobin levels had increased from 8 to 9 g/dL at baseline to 13.3 g/dL.

In addition to its applications in SCD and beta thalassemia, briquilimab is being studied as a conditioning agent and therapeutic for several other conditions including myelodysplastic syndromes, mast cell diseases, and allergic asthma.


Jasper Therapeutics announces positive clinical data from a phase I/II trial of briquilimab as a conditioning treatment in sickle cell disease and beta thalassemia. News release. Jasper Therapeutics, Inc; January 3, 2022.