Integrated imaging probe and bispecific antibody development enables in vivo targeting of glypican-3-expressing hepatocellular carcinoma.

Glypican-3 (GPC3) is a proteoglycan with high sensitivity and specificity for hepatocellular carcinoma (HCC). We describe the integrated development and validation of a GPC3-targeting optical imaging probe and T-cell redirecting antibody (TRAB) as a theranostic strategy for the detection and treatment of HCC. A novel TRAB targeting GPC3 on HCC tumor cells and the CD3 T-cell receptor as well as a distinct GPC3-specific optical imaging probe were developed from a short peptide. The efficacy of GPC3/CD3 TRAB was evaluated in vitro using interferon-γ release and calcein-AM assays. Patient-derived xenografts (PDX) were used to assess the in vivo efficacy of GPC3/CD3 TRAB and the GPC3 imaging probe for the detection of GPC3+ HCC. GPC3/CD3 TRAB caused a dose-dependent escalation in interferon-γ release from inactive peripheral blood T-cells (P = 0.001) and higher tumor-cell lysis (P = 0.01) compared to controls in vitro. Intratumorally injected GPC3/CD3 TRAB resulted in significant prolongation of tumor doubling time in the GPC3+ PDX mice, with an associated reduction of tumor fluorescent signal from the HiLyte 488- conjugated GPC3 specific peptide on optical imaging. HCC cell targeting using a GPC3/CD3 TRAB derived from a small peptide resulted in effective T-cell activation and induction of a cytotoxic response toward GPC3+ HCC tumor cells both in vitro and in vivo. GPC3-specific optical imaging enabled the detection of the GPC3+ HCC cells and noninvasive monitoring of tumor response to adoptive immunotherapy. The integrated development of a targeted therapeutic and molecular imaging probe provides a novel paradigm for developing cancer theranostics.