Mustang Bio has received orphan drug designation from the US Food and Drug Administration (FDA) for MB-108, a herpes simplex virus type 1 oncolytic virus and a component of MB-109, designed to treat malignant glioma.

MB-109 is Mustang's regimen that combines MB-101, a chimeric antigen receptor (CAR)-T-cell therapy targeting interleukin 13 receptor alpha 2, with MB-108, which is licenced from Nationwide Children’s Hospital.

Preclinical data has suggested that the combination therapy could potentially optimise outcomes for patients with recurrent glioblastoma multiforme (GBM).

By converting immunologically 'cold' tumours into 'hot' ones, MB-108 may enhance the efficacy of the MB-101 CAR-T cell therapy.

Separately, data on MB-101 and MB-108 indicated that both therapies were well-tolerated in patients with recurrent GBM.

Notably, two patients treated with MB-101 alone, who had 'hot' tumours with high levels of cluster of differentiation 3+ T cells, achieved complete responses lasting over seven and 31+ months.

These remarkable outcomes were observed in the two patients with the most immunologically active tumours among the 53 participants in the City of Hope Phase I trial.

The ongoing Phase I clinical trials for MB-101 at City of Hope and MB-108 at the University of Alabama at Birmingham, US, are continuing to enrol patients.

The future development of the MB-109 programme for recurrent GBM and high-grade astrocytomas is dependent on securing additional funding or forming strategic partnerships.

Additionally, the company is planning to request MB-101’s ODD from the FDA for treating malignant gliomas.

Mustang Bio president and CEO Manuel Litchman said: “The orphan drug designation for MB-108 is significant for Mustang, as it could provide additional market exclusivity and we hope to advance MB-108, in combination with MB-101, as a potential treatment option for patients living with malignant glioma, including patients with recurrent glioblastoma and high-grade astrocytomas, where there is historically a median overall survival of six months.

“Our novel therapeutic strategy, combining our MB-108 oncolytic virus with MB-101 CAR-T-cell therapy, could be the first-ever industry-sponsored trial of its kind for the treatment of malignant glioma.”