Identification of potent biparatopic antibodies targeting FGFR2 fusion–driven cholangiocarcinoma
Saireudee Chaturantabut, Sydney Oliver, Dennie T. Frederick, Jiwan J. Kim, Foxy P. Robinson, Alessandro Sinopoli, Tian-Yu Song, Yao He, Yuan-Chen Chang, Diego J. Rodriguez, Liang Chang, Devishi Kesar, Meilani Ching, Ruvimbo Dzvurumi, Adel Atari, Yuen-Yi Tseng, Nabeel Bardeesy, William R. Sellers
Saireudee Chaturantabut, Sydney Oliver, Dennie T. Frederick, Jiwan J. Kim, Foxy P. Robinson, Alessandro Sinopoli, Tian-Yu Song, Yao He, Yuan-Chen Chang, Diego J. Rodriguez, Liang Chang, Devishi Kesar, Meilani Ching, Ruvimbo Dzvurumi, Adel Atari, Yuen-Yi Tseng, Nabeel Bardeesy, William R. Sellers
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Research Article Oncology

Identification of potent biparatopic antibodies targeting FGFR2 fusion–driven cholangiocarcinoma

Abstract

Translocations involving FGFR2 gene fusions are common in cholangiocarcinoma and predict response to FGFR kinase inhibitors. However, response rates and durability are limited due to the emergence of resistance, typically involving FGFR2 kinase domain mutations, and to suboptimal dosing, relating to drug adverse effects. Here, we develop biparatopic antibodies targeting the FGFR2 extracellular domain (ECD) as candidate therapeutics. Biparatopic antibodies can overcome drawbacks of bivalent monospecific antibodies, which often show poor inhibitory or even agonist activity against oncogenic receptors. We show that oncogenic transformation by FGFR2 fusions requires an intact ECD. Moreover, by systematically generating biparatopic antibodies targeting distinct epitope pairs in FGFR2 ECD, we identified antibodies that effectively block signaling and malignant growth driven by FGFR2 fusions. Importantly, these antibodies demonstrate efficacy in vivo, synergy with FGFR inhibitors, and activity against FGFR2 fusions harboring kinase domain mutations. Thus, we believe that biparatopic antibodies may serve as an innovative treatment option for patients with FGFR2-altered cholangiocarcinoma.

Authors

Saireudee Chaturantabut, Sydney Oliver, Dennie T. Frederick, Jiwan J. Kim, Foxy P. Robinson, Alessandro Sinopoli, Tian-Yu Song, Yao He, Yuan-Chen Chang, Diego J. Rodriguez, Liang Chang, Devishi Kesar, Meilani Ching, Ruvimbo Dzvurumi, Adel Atari, Yuen-Yi Tseng, Nabeel Bardeesy, William R. Sellers

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Figure 2

Development of candidate biparatopic antibodies directed against FGFR2.

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Development of candidate biparatopic antibodies directed against FGFR2. ...
(A) Anti-FGFR2 antibodies (Ab-A, Ab-B, Ab-C, Ab-D, Ab-E, and Ab-F) binding to SNU16 cells (FGFR2 amplification) by flow cytometry and their associated apparent Kd values. Anti-hIgG1-FITC secondary antibody was used to detect FGFR2 parental antibodies A–F (n = 3). (B) Flow cytometry analysis using anti-hIgG1-FITC secondary antibody to detect FGFR2 parental antibodies A–F. Binding epitopes of parental antibodies A–F along the FGFR2 ECD were identified using full-length, D1, D2, D3, and D2+3–deleted FGFR2-BICC1 overexpressing NIH3T3 cell lines shown in Figure 1. (C) Epitope binning through cross competition assay. BLI-Octet Epitope clustering diagrams showing cluster dendrogram with au (approximately unbiased) P values and bp (bootstrap probability) value (%). Distance represents correlations and cluster method is average. (D) α-fold predicted structure of FGFR2 ECD showing D1, D2, D3, and D1-D2 flexible linker as well as 6 FGFR2 parental antibody binding epitopes A–F. (E and F) Viability of FGFR2-PHGDH–overexpressing BaF3 cells upon treatment with increasing concentrations of antibody A–F in the presence or absence of FGF10 ligand (n = 9). All data are mean ± SEM. Data are representative of 1 out of 2 independent experiments. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 by 1-way ANOVA multiple comparisons.