Conference Coverage

Lentiviral gene therapy appears effective in X-CGD



Lentiviral gene therapy appears safe and was potentially effective in a rare primary immunodeficiency disease known as X-linked chronic granulomatous disease, said Donald B. Kohn, MD, of the University of California, Los Angeles.

Dr. Donald B. Kohn of UCLA

Dr. Donald B. Kohn

Seven of nine patients treated were “alive and well” at 12 months’ follow-up after receiving lentiviral vector transduced CD34+ cells, Dr. Kohn reported in a late-breaking clinical trial session at the Transplantation & Cellular Therapy Meetings.

Most patients were able to discontinue antibiotic prophylaxis for this disease, which is associated with severe, recurrent, and prolonged life-threatening infections, he said.

Results of the small study provide “proof of concept” for use of the gene therapy in the disease, though additional studies are needed to formally assess the clinical safety and efficacy of the approach, he said.

The estimated incidence of chronic granulomatous disease is 1 in 200,000 births in the United States, and the X-linked form is most common, occurring in about 60% of patients, Dr. Kohn told attendees of the meeting held by the American Society for Blood and Marrow Transplantation and the Center for International Blood and Marrow Transplant Research.

Most of these patients are treated with antibacterial or antifungal prophylaxis. While allogeneic hematopoietic stem cell transplantation is also an option, according to Dr. Kohn, the approach is limited by a lack of matched donors and graft-versus-host disease.

Dr. Kohn reported results for nine patients in the United States and the United Kingdom who were treated with the same G1XCGD lentiviral vector. The patients, who ranged in age from 2 to 27 years, underwent CD34+ cell mobilization or bone marrow isolation, transduction with the lentiviral vector, busulfan conditioning, and autologous transplantation.

All patients had confirmed X-linked chronic granulomatous disease, and had had at least one severe infection or inflammatory complication requiring hospitalization.

There were no infusion-related adverse events, and one serious adverse event, which was an inflammatory syndrome that resolved with steroids. Two patients died from complications unrelated to gene therapy, Dr. Kohn reported.

“The other patients are basically doing quite well,” he said.

Of the seven patients alive at the 12-month follow up, six were reported as “clinically well” and off antibiotic prophylaxis, according to Dr. Kohn, while the seventh patient was clinically well and receiving antimicrobial support.

Dr. Kohn is a scientific advisory board member for Orchard Therapeutics, which licensed the lentiviral gene therapy for X-CGD discussed in his presentation. He is also an inventor of intellectual property related to the therapy that UCLA has licensed to Orchard.

At its meeting, the American Society for Blood and Marrow Transplantation announced a new name for the society: American Society for Transplantation and Cellular Therapy (ASTCT).

SOURCE: Kohn DB et al. TCT 2019, Abstract LBA1.

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