Eligible patients (≥18 years) had advanced, histologically confirmed solid tumors associated with EGFR overexpression (centralized testing)...preliminary antitumor activity at the recommended phase II dose (RP2D) is reported only for patients with glioblastoma (n = 24)....Responses in patients with glioblastoma included 1 partial response (~33 months), 6 stable disease....Ser-T monotherapy at doses up to 50 μg/kg initial dose, followed by 25 μg/kg Q4W demonstrated a tolerable safety profile with minimal antitumor activity observed in patients with glioblastoma.