Mustang Bio and St. Jude Children’s Research Hospital to Work on Gene Therapy Together

Mustang Bio and St. Jude Children’s Research Hospital have signed an exclusive worldwide license deal to develop a first-in-class lentiviral gene therapy for X-linked severe combined immunodeficiency (X-SCID).

Mustang Bio, Inc., located in New York City, and St. Jude Children’s Research Hospital, in Memphis, Tennessee, have signed an exclusive worldwide license deal to develop a first-in-class lentiviral gene therapy for X-linked severe combined immunodeficiency (X-SCID).

Mustang Bio, a Fortress Biotech company, focuses on immunotherapies based on proprietary chimeric antigen receptor engineered T-cell (CAR-T) technology. The company’s business model is based on licensing or acquiring an ownership interest in the technologies of interest.

X-SCID is better known as bubble boy disease. The body produces few if any T cells and NK cells, which results in defective B cells. This causes a severely impaired immune system. It affects about one in 50,000 to 100,000 newborns worldwide. Mustang and St. Jude state there may be as many as 1,000 to 1,500 X-SCID patients in the U.S, and a similar number in Europe, who still have immune problems despite receiving allogeneic stem cell transplants and who would be eligible for gene therapy.

“X-SCID is a devastating genetic disorder of the immune system that occurs in infant males who, without treatment, do not live beyond infancy,” said Brian Sorrentino, director of the division of Experimental Hematology at St. Jude, in a statement. “We have seen compelling clinical data in which this X-SCID gene therapy enabled immune system reconstitution and the resolution of disseminated infections. We look forward to working with Mustang Bio to continue to advance the clinical development of this promising and potentially first-in-class gene therapy.”

The gene therapy includes a low dose of busulfan before reinfusion of the patients’ own gene-modified blood stem cells. It is currently being evaluated in a Phase I/II multicenter clinical trial in children under the age of two years at St. Jude, UCSF Benioff Children’s Hospital San Francisco, and Seattle Children’s Hospital. It is the world’s first lentiviral gene therapy trial for infants with X-SCID. It is being led by Ewelina Mamcarz, Assistant Member at St. Jude.

The gene therapy is also being evaluated in patients older than two years of age in another Phase I/II clinical trial at the National Institutes of Health (NIH).

So far, eight patients under the age of two with X-SCID have been treated and the results were released at the 21st Annual Meeting of the American Society of Gene & Cell Therapy in May. The therapy was well tolerated and six of the eight patients treated showed reconstituted immune systems within three to four months after treatment. The remaining two patients are progressing favorably. Two of the six patients ended intravenous immunoglobulin (immune) therapy, while the remaining four continue to progress. Three patients who had disseminated infections before therapy had those infections completely resolved.

“Our therapy has been well tolerated thus far, and none of the infants required any blood product support after low dose of busulfan,” Mamcarz said in a statement. “Most importantly, we observed recovery of all cells of the immune system, which is truly an achievement over prior gene therapy trials, where B cell reconstitution did not occur, and patients required intravenous immunoglobulin for life.”

Mustang Bio also released their second-quarter financial report yesterday. In a statement, the company’s president and chief executive officer, Manuel Litchman, said, “In the second quarter of 2018 we achieved multiple significant milestones that advance our goal of developing and commercializing safe and effective therapies in-house for patients in areas of unmet need. In June, we were thrilled to open our cell therapy manufacturing facility at UMass Medicine Science Park in Worcester, Mass. The facility will enable us to differentiate our product candidates through innovation in cell processing and allow the efficient in-house evaluation of immuno-oncology technologies, like checkpoint antibodies and oncolytic viruses, with our CAR Ts, potentially speeding up development timelines. We expect to be ready to process personalized cell therapies for use in clinical trials by the end of the year.”