Analysis of tumor biomarkers in patients (pts) with advanced hepatocellular carcinoma (HCC) from a phase 1b study of E7386, a CREB-binding protein/β-catenin interaction inhibitor, in combination with lenvatinib.
Authors: Kudo Masatoshi , Kato Naoya , Kondo Shunsuke , Inaba Yoshitaka , Ueshima Kazuomi , Sasaki Mitsuhito , Ogasawara Sadahisa , Sahara Takatoshi , Li Shuyu D , Shen Jialing , Kimura Takayuki , Dutta Lea , Tamai Toshiyuki , Ikeda Masafumi 
Published: January 2024

535 Background: E7386, a novel oral anticancer agent, inhibits β-catenin binding to its transcriptional co-activator CREB-binding protein, thus modulating Wnt/β-catenin signaling. Lenvatinib is a multikinase inhibitor that targets VEGFR 1–3, FGFR 1–4, PDGFRα, RET, and KIT. We previously reported the safety/tolerability, pharmacokinetics, biomarkers, and preliminary efficacy of E7386 plus lenvatinib in 25 pts with HCC in the dose escalation part of a phase 1b study1 (NCT04008797). Here, we present the results of exploratory tumor biomarker analyses from this study. Methods: Pts with HCC were treated with E7386 10–80 mg QD and 60–120 mg BID plus lenvatinib (bodyweight < 60 kg: 8 mg QD; ≥ 60 kg: 12 mg QD). Archival or fresh tumor samples were collected at baseline and post-treatment; tumor tissue was assessed for genetic alteration, immunohistochemistry (IHC), and gene expression. Gene signature scores of interest were calculated using obtained gene expression data. The preliminary association between biomarker status and efficacy was investigated. Results: Of the 25 pts enrolled, 22 had baseline tumor samples available for the gene mutation analysis. TERT (6 pts: 27%), CTNNB1 (5 pts: 23%), and TP53 (4 pts: 18%) mutations were detected. CTNNB1 mutation was confirmed in 3 of 7 responders and 2 of 13 non-responders. Nuclear β-catenin expression was confirmed by IHC analysis in 5 of 16 pts; it was expressed in 3 of 5 pts with CTNNB1 MUT and 2 of 11 pts with CTNNB1 WT. Pts with expression of nuclear β-catenin had 2 partial responses (PRs) among 5 pts; those without β-catenin expression had 2 PRs among 11 pts. Additionally, IHC analysis of tumor microvessel density (MVD; number of CD31+ vessels) at baseline suggested that greater maximum tumor shrinkage (MTS) tended to be observed in the MVD-high population compared to the MVD-low population. 7 Pts had evaluable baseline and post-baseline tumor samples and were included in the gene signature analysis. Despite the small sample size, preliminary results indicated that MTS may be associated with a decrease in Wnt signaling and angiogenesis gene signature scores (spearman r [r]=0.61 for both) and attenuation of hypoxic induction and glycolysis gene signature scores (r=0.79 and 0.68, respectively). Conclusions: These exploratory tumor biomarker analyses suggest that E7386 in combination with lenvatinib may affect the tumor microenvironment in HCC pts through effects on Wnt signaling, angiogenesis, hypoxic response, and glycolysis pathways. This concept is the basis for treatment with this combination. However, given the small sample size, further investigation is needed to confirm these effects on the tumor microenvironment. Enrollment of pts with HCC to the expansion part of Study 102 is ongoing. 1. Ikeda et al. ASCO 2023. Clinical trial information: NCT04008797 .