Meet Mustang Bio’s Breakthrough ‘Bubble Boy’ Treatment

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Mustang Bio Inc. (NASDAQ: MBIO) shares more than tripled on Thursday after the company announced a breakthrough that cured eight infants dealing with the “Bubble Boy” immune disorder.

Specifically, the data comes from a Phase 1/2 clinical trial of a lentiviral gene therapy for the treatment of newly diagnosed infants under two years old with X-linked severe combined immunodefiency (XSCID), also referred to as SCID-X1 and commonly known as bubble boy disease. Under a licensing agreement with St. Jude, Mustang will develop the lentiviral gene therapy for commercial use as MB-107.

The multicenter Phase 1/2 clinical trial is evaluating the safety and efficacy of a lentiviral vector to transfer a normal copy of the IL2RG gene to bone marrow stem cells in newly diagnosed infants under the age of two with XSCID, preceded by low exposure-targeted busulfan conditioning.

A total of 10 infants have received the therapy to date in this clinical trial. The published data covers eight infants with XSCID who were treated at St. Jude and at UCSF Benioff Children’s Hospital and followed for a median of 16.4 months.

Some quick background: The defining characteristic of SCID is usually a severe defect in both the T-lymphocyte and B-lymphocyte systems. This usually results in the onset of one or more serious infections within the first few months of life. These infections are usually serious, and may even be life-threatening. They may include pneumonia, meningitis or bloodstream infections.

Martina Sersch, M.D., Ph.D., chief medical officer of Mustang, commented:

We are extremely encouraged by the Phase 1/2 clinical data published in the New England Journal of Medicine. They underscore the potential of MB-107 as a novel approach and potentially curative treatment option for newly diagnosed infants with XSCID. We are excited to continue working with St. Jude to evaluate MB-107 in this clinical trial, and we look forward to transferring the IND to Mustang by the end of this year, after which patients’ cells from all three participating clinical trial sites will be processed in our Worcester, Mass., facility.

Shares of Mustang Bio were last seen trading up 160% at $6.91, in a 52-week range of $2.18 to $10.20. The consensus price target is $18.00.


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