Jordi Abril-Fornaguera

Hepatoblastoma (HB), the most frequent pediatric liver cancer (2.16 cases/million), has surgery and perioperative chemotherapy as primary treatment, with severe lifelong side effects. This study evaluates the efficacy of the Wnt/ CTNNB1 inhibitor WNTinib as a potential HB treatment, since CTNNB1 mutations occur in 70–90% of HBs. WNTinib's efficacy was assessed in three animal models ( n = 48): (a) patient‐derived xenograft (PDX) HB tumors ( n = 5 CTNNB1‐ mutant, n = 1 CTNNB1 wild‐type) implanted in NSG mice; (b) PDX‐derived TT001‐ and (c) HepG2‐HB cells subcutaneously implanted in Fox1 ^nu mice; and in two patient‐derived organoids from CTNNB1 ‐mutant HBs. WNTinib delayed tumor growth in n = 4/5 CTNNB1 ‐mutant PDX models and significantly improved survival versus controls ( P = 0.03), with no effect in the wild‐type model. Further, in the TT001 and HepG2 models, WNTinib reduced tumor growth ( P < 0.05 and P = 0.002) and extended survival ( P = 0.03 and P = 0.008), respectively. In HB organoids, WNTinib demonstrated greater efficacy than standard‐of‐care cisplatin ( P = 0.009, org‐1), and its antitumor effect was further enhanced when combined with chemotherapy ( P = 0.01, org‐1; P = 0.007, org‐22). WNTinib delays tumor progression and increases survival in CTNNB1 ‐mutated HB models, providing rationale to explore its use in human HB.

Supplementary Figures and Tables

Purpose: Aberrant activation of β-catenin (CTNNB1) occurs in ∼30% of hepatocellular carcinomas (HCC) and is associated with immune evasion and limited response to immunotherapy. However, it remains an undruggable target. In this study, we studied the antitumor and antiangiogenic activity of combining E7386 [an oral protein–protein interaction inhibitor targeting CREB-binding protein (CBP)/β-catenin] with lenvatinib and elucidated a novel mechanism of action of E7386 that boosts the antitumor response. Experimental Design: We generated a genetically engineered CTNNB1-mutant murine HCC model and randomized the animals to receive vehicle, E7386, lenvatinib, or the combination (n = 22–23/arm). We evaluated survival and analyzed the tumors transcriptomically and by IHC. Also, we analyzed five patient-derived organoids, four HCC cell lines, and seven paired pre-/on-treatment specimens from patients with HCC receiving E7386 in combination with lenvatinib in the context of a phase Ib/II trial (NCT04008797). Results: E7386 in combination with lenvatinib significantly prolonged mouse survival compared with monotherapy. Cell lines and patient-derived organoid data corroborated that sensitivity to E7386 involves processes beyond CBP/β-catenin interaction blockade. Mechanistically, E7386 promoted activating transcription factor 4 (ATF4) activation, triggering the integrated stress response in preclinical models of HCC. In vivo, E7386 concomitantly potentiated the antiangiogenic effects of lenvatinib, resulting in increased antitumor efficacy. Upregulation of ATF4 gene expression signatures was confirmed in four of seven E7386 + lenvatinib–treated patients with HCC, three of whom exhibited tumor diameter shrinkage >30%. Conclusions: E7386 sensitized tumors to lenvatinib, thereby enhancing survival in mice compared with either monotherapy. In patients, E7386 combined with lenvatinib promoted tumor shrinkage and, in parallel, activated ATF4 signaling.

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths worldwide. β-Catenin (CTNNB1)-mutated HCC represents 30% of cases of the disease with no precision therapeutics available. Using chemical libraries derived from clinical multi-kinase inhibitor (KI) scaffolds, we screened HCC organoids to identify WNTinib, a KI with exquisite selectivity in CTNNB1-mutated human and murine models, including patient samples. Multiomic and target engagement analyses, combined with rescue experiments and in vitro and in vivo efficacy studies, revealed that WNTinib is superior to clinical KIs and inhibits KIT/mitogen-activated protein kinase (MAPK) signaling at multiple nodes. Moreover, we demonstrate that reduced engagement on BRAF and p38α kinases by WNTinib relative to several multi-KIs is necessary to avoid compensatory feedback signaling—providing a durable and selective transcriptional repression of mutant β-catenin/Wnt targets through nuclear translocation of the EZH2 transcriptional repressor. Our studies uncover a previously unknown mechanism to harness the KIT/MAPK/EZH2 pathway to potently and selectively antagonize CTNNB1-mutant HCC with an unprecedented wide therapeutic index.

Supplementary Figures and Tables

Supplementary Figures and Tables

Management of hepatoblastoma (HB), the most frequent pediatric liver cancer, is based on surgical resection and perioperative chemotherapy regimens. In this study, we aimed to identify actionable targets in HB and assess the efficacy of molecular therapies in preclinical models of HB. Paired tumor and adjacent tissues from 31 HBs and a validation set of 50 HBs were analyzed using RNA-seq, SNP, and methylation arrays. IGF2 overexpression was identified as the top targetable HB driver, present in 71% of HBs (22/31). IGF2high tumors displayed progenitor cell features and shorter recurrence-free survival. IGF2 overexpression was associated in 91% of cases with fetal promoter hypomethylation, ICR1 deregulation, 11p15.5 loss of heterozygosity or miR483-5p overexpression. The antitumor effect of xentuzumab (a monoclonal antibody targeting IGF1/2) alone or in combination with the conventional therapeutic agent cisplatin was assessed in HB cell lines, in PDX-derived HB organoids and in a xenograft HB murine model. The combination of xentuzumab with cisplatin showed strong synergistic antitumor effects in organoids and in IGF2high cell lines. In mice (n = 55), the combination induced a significant decrease in tumor volume and improved survival compared with cisplatin alone. These results suggest that IGF2 is an HB actionable driver and that, in preclinical models of HB, the combination of IGF1/2 inhibition with cisplatin induces superior antitumor effects than cisplatin monotherapy. Overall, our study provides a rationale for testing IGF2 inhibitors in combination with cisplatin in HB patients with IGF2 overexpression.