A phase I and biodistribution study of ABT-806i, an 111indium-labeled conjugate of the tumor-specific anti-EGFR antibody ABT-806.

2520 Background: ABT-806 is a humanized antibody targeting a conformationally exposed epitope only available when tumor Epidermal Growth Factor Receptor (EGFR) is overexpressed or (EGFRvIII) mutated. A prior trial treated 8 patients (pts) with a chimeric homologue (single-dose 5-40 mg/kg), with a minor response in one squamous cell carcinoma of skin pt. A prior phase 1A study of ABT-806 treated 26 pts (2-24 mg/kg IV q2w), with prolonged SD in one head and neck (H&N) cancer pt. No pt had a typical EGFR-inhibitor rash. The current study gathers further ABT-806 clinical data, assesses ABT-806i dosimetry in normal and malignant tissues and examines its relationship to clinical and PK/PD data. Methods: Pts with advanced tumors likely to express EGFR, ECOG 0-2, measurable disease and adequate organ function were enrolled. ABT-806i scans comprised ABT-806i 5-7mCi injection followed by whole body and regional SPECT scans over one week. Cohort (C) 1 pts (n=6) had ABT-806i scans alone. C2 pts (n=12) had ABT-806i sc...