Phase I/II Open-Label Study of Autologous CD34+ Cells Transduced with G1XCGD Lentiviral Vector in X-Linked Chronic Granulomatous Disease Patients

The primary objective of this study is the **evaluation of safety and efficacy** through biochemical and functional reconstitution in the progeny of engrafted cells, as well as the stability of these cells at 12 months. This is clinically relevant as it aims to assess the potential of autologous CD34+ cells transduced with the G1XCGD lentiviral vector to provide a long-term therapeutic benefit for patients with X-linked Chronic Granulomatous Disease (X-CGD), a condition characterized by recurrent infections due to impaired immune function.

Secondary objectives include:

• Clinical efficacy and longitudinal evaluation of clinical effect in terms of improved immunity against bacterial and fungal infection.
• Transduction of CD34+ hematopoietic stem cells from X-CGD patients by ex vivo lentivirus-mediated gene transfer.
• Evaluation of engraftment kinetics and stability of gene-modified CD34+ cells.

The clinical trial focuses on the **treatment of X-linked Chronic Granulomatous Disease** (X-CGD) and involves a study population exclusively composed of male subjects. Participants are primarily aged over 23 months, although younger patients, aged between 1 month and 23 months, may be included at the discretion of the attending physician. The trial does not include female subjects. The selection criteria emphasize the absence of an HLA-matched donor after a three-month search, and participants must not have co-infections with HIV, hepatitis B, or hepatitis C. The trial population is characterized by individuals with a confirmed molecular diagnosis of X-CGD, supported by laboratory evidence of significant reduction in biochemical activity. Participants are required to have at least one severe infection or inflammatory complication that is ongoing, resistant, or at high risk of relapse, necessitating hospitalization despite conventional therapy. The sponsor has not provided information regarding the total number of participants. The trial involves a vulnerable population, and informed consent is mandatory for adult participants, with parental or guardian consent required for minors.

The clinical trial is a **phase I/II**, non-randomized, monocentric open-label study designed to evaluate the safety and efficacy of **autologous CD34+ cells transduced with the G1XCGD lentiviral vector** in patients with **X-linked Chronic Granulomatous Disease**. The primary objective is to assess safety through the incidence of adverse events related to the conditioning regimen, investigational medicinal product (IMP), or the procedure itself. Efficacy will be measured by the restoration and stability of NADPH functioning granulocytes, with a target of at least 5% expressing cells at 12 months. Secondary endpoints include the normalization of nutritional status, growth, development, and the clearing of pre-existing severe infections or chronic inflammatory lesions. The trial will also evaluate the percentage of transduced CD34+ hematopoietic stem cells at one year and the immunological reconstitution over time.

Participants will be involved in the study for an estimated duration from the recruitment start date in March 2016 to the estimated end date in June 2034. The study includes several key visits: an initial screening visit to confirm eligibility based on criteria such as age, molecular diagnosis, and absence of co-infections like HIV or hepatitis. Follow-up visits will monitor the biochemical and functional reconstitution in the progeny of engrafted cells and assess the stability of these effects at 12 months. The end-of-study visit will conclude the participant's involvement, evaluating the long-term outcomes of the treatment.

Inclusion criteria specify male patients with X-CGD over 23 months of age, with younger patients eligible at the physician's discretion. Participants must have a confirmed molecular diagnosis and meet specific clinical conditions, such as ongoing severe infections or inflammatory complications. Exclusion criteria include the presence of co-infections and the availability of an HLA-matched donor. Participants may be terminated early from the study if they experience significant adverse events or if they no longer meet the inclusion criteria. The investigational product is administered intravenously as a solution for injection, and the study is not classified as low intervention.

The clinical trial involves the administration of **G1XCGD**, a solution for injection, which consists of **autologous CD34+ cells** transduced with the G1XCGD lentiviral vector containing the human CYBB gene. This investigational product is designed for patients with X-linked chronic granulomatous disease. The pharmaceutical form of the product is a solution for injection, and it is administered via the **intravenous** route. The treatment is not a pediatric formulation and is classified as an orphan drug, indicating its use for a rare condition. The product is developed by Genethon and is identified by the sponsor product code G1XCGD.

The active substance in the investigational product is a structurally diverse substance categorized under cell therapy. The **autologous CD34+ cells** are hematopoietic stem cells that have been transduced ex vivo with the G1XCGD lentiviral vector, which includes the human gp91phox (CYBB) gene. This gene transfer product is not used in vivo and is genetically modified to enhance the therapeutic potential of the cells. The study does not include any non-experimental treatments such as standard-of-care therapy, placebo, or comparator treatment. The trial aims to evaluate the safety and efficacy of the treatment by assessing biochemical and functional reconstitution in the progeny of engrafted cells and their stability over a 12-month period.

The efficacy of the investigational product, **autologous CD34+ cells transduced with the G1XCGD lentiviral vector containing the human CYBB gene**, will be assessed in a phase I/II clinical trial involving patients with X-linked chronic granulomatous disease. The primary efficacy endpoint is the restoration and stability over time of NADPH functioning granulocytes, which will be evaluated using a DHR test. The target is to achieve at least 5% of expressing cells at 12 months post-treatment. Secondary efficacy endpoints include the normalization of nutritional status, growth, and development, as well as the resolution of pre-existing severe infections and/or chronic inflammatory lesions. Additionally, the percentage of transduced CD34+ hematopoietic stem cells at one year and the percentage of transduced mature blood cells over time will be measured. Immunological reconstitution will be assessed by evidence of restored neutrophil functionality and immunity against bacterial and fungal infections over time. These parameters will be collected and analyzed at specified time points throughout the study to determine the efficacy of the treatment.