Several studies have reported the development of scFvs targeting tumor cell surface antigens, such as mesothelin, a surface antigen in ovarian cancer and mesothelioma; hence, these specific scFvs have also been fused with toxins such as Pseudomonas Endotoxin A and the administration of this specific scFv showed a high-binding affinity of the immunotoxin to mesothelin and it was stable for up to 40 h. This evidence concerns the gene MSLN and ovarian cancer.