PAX3 and rhabdomyosarcoma: In contrast, another group’s study23 used a different dosing regimen and had notable design limitation: First, the pharmacodynamic studies were done with two alveolar rhabdomyosarcoma PDX models (Rh10 and Rh65) that lacked baseline PAX3::FOXO1 protein expression in 1 of 3 control animals for each model—drawing concerns for the authenticity of these models.