Clinical Variability And Limited Sample SizeSubstantial variability in patient responses and small early sample sizes increase uncertainty about treatment effectiveness and make it harder to build conviction ahead of pivotal trials.
Regulatory Uncertainty From Agency FeedbackA complete response letter highlighting uncertainty in target population definition, control comparability and surrogate endpoint relevance has created a regulatory overhang and complicates approval pathways.
Safety Findings And Clinical HoldsDetection of a brain tumor in a related program and evidence of viral vector integration near cancer-related genes prompted clinical holds, creating material safety uncertainty for linked programs.