Here is the design of a clinical trial:

Official Title: A First in Human Feasibility Study of T Regulatory Cells (TR004) for Inflammatory Bowel Disease Using (ex Vivo) Treg Expansion

Included conditions:
- Crohn Disease

Study Armgroups:
- {'label': 'Immediate ATIMP (AP)', 'type': 'EXPERIMENTAL', 'description': 'Patients will receive Treg immunotherapy (TR004) infusion at Week 0.', 'interventionNames': ['Drug: TR004 (Treg immunotherapy)']}

Interventions:
- {'type': 'DRUG', 'name': 'TR004 (Treg immunotherapy)', 'description': 'Administered Intravenously (IV)', 'armGroupLabels': ['Immediate ATIMP (AP)'], 'otherNames': ['Autologous regulatory T cells (Tregs) expanded in vitro']}

Primary Outcomes:
- {'measure': 'Rate of dose-limiting toxicities (DLTs)', 'description': 'Pre-defined safety events occurring within 5 weeks post-infusion', 'timeFrame': 'One period will be assessed, from Week 0 to Week 5'}

Please estimate the sample size based on the assumption: 
The study was initially planned for 24 subjects but was reduced to 4 due to funding changes. Additional patients will be recruited if withdrawals occur before or during the 5-week active period without experiencing a DLT.
Sample size
        A sample size of four participants will be recruited to assess the safety and tolerability of TR004 for further investigation in a larger clinical trial. The initial plan was to recruit 24 subjects but a change in funding because of the COVID-19 pandemic required a reduction in sample size and a change to a feasibility study. The sample size was a balance between the available funding and an ability to show feasibility of recruitment and the manufacturing process.
        In situations where a patient has to be withdrawn or decides to withdraw from the study, an additional patient will be recruited and dosed if:
        
          
            They withdraw prior to the start of their 5-week active period.
          
          
            They withdraw during their 5-week active period, and have not yet experienced a DLT.