Bloomsbury Genetic Therapies: Clinical Trial for OTC

Who are Bloomsbury Genetic Therapies?

Bloomsbury is a clinical-stage biotechnology company developing potentially curative treatments for patients suffering from rare neurological and metabolic diseases based on clinically proven gene therapy technologies. Incorporated in August 2021 and launched in October 2022, Bloomsbury is a UK-based spin-out from University College London (UCL).

Bloomsbury’s four academic founders from UCL combine world-leading clinical insights and preclinical development expertise and it is building a team of industry leaders and subject matter experts with extensive experience in developing and registering gene therapies and rare disease treatments

What work is Bloomsbury Genetic Therapies doing?

BGT-OTCD is a liver-targeted AAV gene therapy designed to provide a potentially curative solution to OTCD patients following a one-time intravenous injection. The approach is to deliver a functioning copy of the OTC gene to the cells in the liver of OTCD patients by using a certain harmless virus type called AAV as a delivery mechanism.

Once the virus has delivered its genetic cargo to the liver, normal urea cycle function would be restored, and patients wouldn’t need to control their diet or to take ammonia scavengers anymore. This benefit would be achieved following a single injection, and the effect may be sustained for many years, if not decades. This approach has been successfully pioneered in other rare diseases such as in haemophilia, where gene therapy treatments with potentially curative effect have recently been approved, including in the UK.

BGT-OTCD was initially developed by Prof Ian Alexander and Associate Prof Leszek Lisowski of Children’s Medical Research Institute (CMRI) in Westmead, Australia, in collaboration with Prof Paul Gissen from UCL. This treatment candidate is currently evaluated in a Phase 1/2 clinical trial called HORACE (Halting Ornithine transcarbamylase deficiency with Recombinant AAV in ChildrEn). The trial is taking place at the Great Ormond Street Hospital in London, and will recruit about six children and young persons living with OTC deficiency aged between 6 and 16 in the first part and about six aged between 0 and 16 in the second part.


Costs and reimbursement
Bloomsbury is providing financial support to UCL for the trial. There are no costs to families for their child to participate in the trial.

Participating sites in the UK
The HORACE trial will be sponsored by University College London under the supervision of the primary investigator Dr Anupam Chakrapani, consultant in Metabolic Medicine at the Great Ormond Street Hospital (GOSH), where the trial will take place. Three other UK hospitals will collaborate with GOSH: Evelina London Children’s Hospital, Royal Manchester Children’s Hospital and Birmingham Children’s Hospital.

More information
For more information on the Phase 1/2 HORACE trial of BGT-OTCD for the treatment of OTCD, please visit: and for more information about participation to the trial, please contact

Following HORACE, Bloomsbury intends to evaluate BGT-OTCD in larger clinical trials in both children and adult with OTCD, and in countries beyond the UK, as required for its ultimate approval as a treatment option.

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