Sirion Biotech is pleased to announce that Mustang Bio is utilising its proprietary transduction enhancer, LentiBOOST™, in a pivotal Phase II clinical trial for MB-207 in X-linked severe combined immunodeficiency.

Mustang Bio (Mustang), a clinical-stage biopharmaceutical company focused on translating today’s medical breakthroughs in cell and gene therapies into potential cures for hematologic cancers, solid tumours and rare genetic diseases, has provided updates on MB-107 and MB-207, its lentiviral gene therapies for the treatment of X-linked severe combined immunodeficiency (XSCID), also known as bubble boy disease. On 28 January, the US Food and Drug Administration (FDA) removed the clinical hold on the MB-107 pivotal Phase 2 clinical trial Investigational New Drug (IND) application after reviewing a comprehensive CMC package that was submitted by Mustang in late December. Mustang will proceed with its plans to initiate the pivotal Phase 2 trial in newly diagnosed XSCID patients.

MB-207 Update

The ongoing Phase 1/2 clinical trial being conducted by the NIH is treating older XSCID patients, all of whom had previously received haploidentical HSCT as infants and were subsequently noted to be experiencing declining immune function with symptomatic infections. At the time of the most recent NIH data presentation at ASH in 2019, 8 patients had been treated without transduction enhancers (referred to as Cohort A) and had been followed for 3 to 7 years. Seven of these 8 patients experienced gradual clinical benefit in terms of clearance of chronic norovirus and associated improved abdominal complaints, malabsorption, growth and IgG production. One of these 7 patients died 27 months after gene therapy of a pulmonary bleed related to chronic bronchiectasis that predated the therapy and was deemed to be unrelated to therapy.

In an attempt to address the relatively slow resolution of chronic norovirus observed in most of these 7 patients and the delayed immune cell recovery and persistent clinical disease in the eighth patient, transduction enhancers were introduced in the cell processing for the subsequent 6 patients (referred to as Cohort B), which included retreatment of the eighth patient in Cohort A who had delayed immune recovery and persistent clinical disease. This enhanced transduction procedure achieved much greater transduction efficiencies than were observed in Cohort A, with greater than 10-fold less vector, and resulted in faster immune reconstitution and more significant clinical benefit by 3 months. As a result, Mustang has licensed Sirion Biotech’s Lentiboost™ and will include transduction enhancement in its pivotal Phase 2 clinical trial for MB-207 in this patient population.

To read the full Press Release, see here: https://ir.mustangbio.com/News/news-details/2021/Mustang-Bio-Provides-Updates-on-its-Lentiviral-Gene-Therapies-for-the-Treatment-of-X-linked-Severe-Combined-Immunodeficiency-XSCID/default.aspx