Jasper Therapeutics has reported positive clinical trial results from the first three subjects in a Phase I/II clinical trial of its antibody briquilimab as a conditioning therapy in sickle cell disease (SCD) and beta thalassemia patients.

The investigator-initiated trial has been designed to assess the addition of the antibody to an existing bone marrow transplantation regimen in these individuals.

These individuals are considered at high risk for complications from, or are not eligible for, standard myeloablative hematopoietic stem cell transplants.

The addition of briquilimab is being investigated as a potential way to achieve a higher, healthy donor stem cell engraftment percentage, without elevated toxicity.

The Cellular and Molecular Therapeutics Laboratory, NHLBI, director Dr John Tisdale is leading the Phase I/II trial.

Jasper Therapeutics president and CEO Ronald Martell said: “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, which are often cited as the most concerning safety risks for transplant patients and physicians.

“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.”

The trial’s primary objective is to determine if the addition of briquilimab would increase the proportion of patients with donor myeloid chimerism ≥98% after transplant at one-year.

In combination with low-dose irradiation, briquilimab, an anti-c-KIT monoclonal antibody, can improve disease-free survival as part of a transplant conditioning regimen.

At present, the trial is actively enrolling participants at NHLBI.

All three sickle cell study participants who received treatment with briquilimab successfully engrafted and no severe adverse events related to the treatment were observed.