NGF and neoplasm: To address potential neurotoxicity given CD24 expression in immature neural tissue, we performed focused safety assays: H&E staining of coronal brain sections showed no overt neuropathology (Fig. S10A), and NGF-differentiated PC12 neuron-like cells (CD24+, lower than tumor lines) exhibited right-shifted dose–response curves with selectivity indices of ∼3.7 (vs. SK-N-DZ) and ∼4.7 (vs. SH-SY5Y) (Fig. S10B–H).