Abstract 2944: TGF-β inhibitor galunisertib combined with antiangiogenic therapies showed antitumor effects in vitro and in vivo in hepatocellular carcinoma (HCC)

Abstract

Abstract Introduction: TGF-β pathway, associated with hepatocellular carcinoma (HCC) progression, can be targeted by galunisertib, a selective ATP-mimetic TGF-β receptor (TβR)-I inhibitor in clinical trials for HCC patients. We investigated the antitumor effects of galunisertib (Galu) combined with antiangiogenic compounds (sorafenib or DC101, a fully human monoclonal antibody antagonizing VEGFR2, mimicking ramucirumab) in HCC. Methods: In vitro, we assessed proliferation (MTT assay), migration (wound healing), and invasion (boyden chambers), in a panel of HCC cell lines. Transgenic mice developing stage-defined HCC were treated from weeks (W)8 to W16 with either vehicle, sorafenib (30mg/kg), Galu (100mg/kg), sorafenib plus Galu, DC101 (40mg/kg, twice weekly, IP), or DC101 plus galunisertib. Tumor growth was evaluated by ultrasound (liver size) and by the number of macronodules at sacrifice. Angiogenesis assessed by Doppler measuring the mean blood flow in the coeliac trunk (TCm) and CD31 staining. Results: In vitro, we showed an inhibition of TGF-induced proliferation, migration and proliferation by Galu, further potentiated by sorafenib. Sorafenib-tolerant cell line SK-Sora was the most sensitive to Galu. In vivo, at W12 & W16, liver size and tumor macronodules number were significantly lower in all treatment arms compared to placebo. At W16, DC101 showed increased tumor control compared to sorafenib regarding liver weight (3,75g±0,39 vs 6,31 g±0,52, p<0.001) and macronodules number (75,7±12.0 vs 139±13,6, p<0.001). Galu/sorafenib and Galu/DC101 combinations showed increased tumor control at W16 as compared to monotherapies. Interestingly, at W16, Galu/DC101 combination showed greater effect on liver weight (3,09g±0,70 vs 3.75g±0,21, p<0.05, number of macronodules (55.1±14.8 vs 109.4±24.3, p<0.001), and micronodules surface (2.0 mm2±0.43 vs 1.43 mm2±0.33, p<0.05) as compared to Galu/sorafenib combination. Angiogenesis decreased in all treatment arms compared to placebo. At W16, we observed a TCm decrease over 50% in the combination arms compared to 24% with sorafenib, 26% with DC101 and 20% with Galu alone, respectively. These results were confirmed by CD31 staining for assessing number of vessels per field. In addition, Galu/sorafenib combination yielded an increased number of monocytes, a decreased number of neutrophils and Kuppfer cells, along with increased NK cells and decreased NKT cells. Dendritic cells as well as B and T cells population did not show particular variation except for CD4+CD25+ T cells that were strongly decreased in sorafenib-treated mice. Conclusion: The combination of galunisertib with sorafenib or DC101 showed promising antitumor activities that were associated with decreased angiogenesis, DC101 displaying increased efficacy as compared to sorafenib. Citation Format: Annemilaï Tijeras-Raballand, Christian Hobeika, Matthieu Martinet, Lucile Astorgues-Xerri, Elise Paven, Marie-Aude Le Bitoux, Anne Maillard, Clarisse Eveno, Marc Pocard, Philippe Bonnin, Alexandre Harari, Eric Raymond, Sandrine Faivre, Armand de Gramont. TGF-β inhibitor galunisertib combined with antiangiogenic therapies showed antitumor effects in vitro and in vivo in hepatocellular carcinoma (HCC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2944.