Hepatoblastoma (HB) is the most frequent childhood liver cancer. Patients with aggressive tumors have limited therapeutic options; therefore, a better understanding of HB pathogenesis is needed to improve treatment. HBs have a very low mutational burden; however, epigenetic alterations are increasingly recognized. We aimed to identify epigenetic regulators consistently dysregulated in HB and to evaluate the therapeutic efficacy of their targeting in clinically relevant models. We performed a comprehensive transcriptomic analysis of 180 epigenetic genes. Data from fetal, pediatric, adult, peritumoral (n = 72) and tumoral (n = 91) tissues were integrated. Selected epigenetic drugs were tested in HB cells. The most relevant epigenetic target identified was validated in primary HB cells, HB organoids, a patient-derived xenograft model, and a genetic mouse model. Transcriptomic, proteomic and metabolomic mechanistic analyses were performed. Altered expression of genes regulating DNA methylation and histone modifications was consistently observed in association with molecular and clinical features of poor prognosis. The histone methyltransferase G9a was markedly upregulated in tumors with epigenetic and transcriptomic traits of increased malignancy. Pharmacological targeting of G9a significantly inhibited growth of HB cells, organoids and patient-derived xenografts. Development of HB induced by oncogenic forms of β-catenin and YAP1 was ablated in mice with hepatocyte-specific deletion of G9a. We observed that HBs undergo significant transcriptional rewiring in genes involved in amino acid metabolism and ribosomal biogenesis. G9a inhibition counteracted these pro-tumorigenic adaptations. Mechanistically, G9a targeting potently repressed the expression of c-MYC and ATF4, master regulators of HB metabolic reprogramming. HBs display a profound dysregulation of the epigenetic machinery. Pharmacological targeting of key epigenetic effectors exposes metabolic vulnerabilities that can be leveraged to improve the treatment of these patients. In spite of recent advances in the management of hepatoblastoma (HB), treatment resistance and drug toxicity are still major concerns. This systematic study reveals the remarkable dysregulation in the expression of epigenetic genes in HB tissues. Through pharmacological and genetic experimental approaches, we demonstrate that the histone-lysine-methyltransferase G9a is an excellent drug target in HB, which can also be harnessed to enhance the efficacy of chemotherapy. Furthermore, our study highlights the profound pro-tumorigenic metabolic rewiring of HB cells orchestrated by G9a in coordination with the c-MYC oncogene. From a broader perspective, our findings suggest that anti-G9a therapies may also be effective in other c-MYC-dependent tumors.

Given the very poor prognosis for children with recurrent medulloblastoma, we aimed to identify prognostic factors for survival post-relapse in children with childhood medulloblastoma. We retrospectively collected clinico-biological data at diagnosis and main clinical characteristics at relapse of children newly diagnosed with a medulloblastoma between 2007 and 2017 at Gustave Roussy and Necker Hospital. At a median follow-up of 6.6 years (range, 0.4–12.3 years), relapse occurred in 48 out 155 patients (31%). The median time from diagnosis to relapse was 14.3 months (range, 1.2–87.2 months). Relapse was local in 9, metastatic in 22 and combined (local and metastatic) in 17 patients. Second-line treatment consisted of chemotherapy in 31 cases, radiotherapy in 9, SHH-inhibitor in four and no treatment in the remaining four. The 1-year overall survival rate post-relapse was 44.8% (CI 95%, 31.5% to 59.0%). While molecular subgrouping at diagnosis was significantly associated with survival post-relapse, the use of radiotherapy at relapse and time to first relapse (>12 months) might also have a potential impact on post-relapse survival.

Background: As the variable clinical outcome of patients with hepatoblastoma (HB) cannot be explained by genetics alone, the identification of drugs with the potential to effectively reverse epigenetic alterations is a promising approach to overcome poor therapy response. The gene ubiquitin like with PHD and ring finger domains 1 (UHRF1) represents an encouraging epigenetic target due to its regulatory function in both DNA methylation and histone modifications and its clinical relevance in HB. Methods: Patient-derived xenograft in vitro and in vivo models were used to study drug response. The mechanistic basis of CM-272 treatment was elucidated using RNA sequencing and western blot experiments. Results: We validated in comprehensive data sets that UHRF1 is highly expressed in HB and associated with poor outcomes. The simultaneous pharmacological targeting of UHRF1-dependent DNA methylation and histone H3 methylation by the dual inhibitor CM-272 identified a selective impact on HB patient-derived xenograft cell viability while leaving healthy fibroblasts unaffected. RNA sequencing revealed downregulation of the IGF2-activated survival pathway as the main mode of action of CM-272 treatment, subsequently leading to loss of proliferation, hindered colony formation capability, reduced spheroid growth, decreased migration potential, and ultimately, induction of apoptosis in HB cells. Importantly, drug response depended on the level of IGF2 expression, and combination assays showed a strong synergistic effect of CM-272 with cisplatin. Preclinical testing of CM-272 in a transplanted patient-derived xenograft model proved its efficacy but also uncovered side effects presumably caused by its strong antitumor effect in IGF2-driven tumors. Conclusions: The inhibition of UHRF1-associated epigenetic traces, such as IGF2-mediated survival, is an attractive approach to treat high-risk HB, especially when combined with the standard-of-care therapeutic cisplatin.

Prognosis of children with high-risk hepatoblastoma (HB), the most common pediatric liver cancer, remains poor. In this study, we found ribonucleotide reductase (RNR) subunit M2 (RRM2) was one of the key genes supporting cell proliferation in high-risk HB. While standard chemotherapies could effectively suppress RRM2 in HB cells, they induced a significant upregulation of the other RNR M2 subunit, RRM2B. Computational analysis revealed distinct signaling networks RRM2 and RRM2B were involved in HB patient tumors, with RRM2 supporting cell proliferation and RRM2B participating heavily in stress response pathways. Indeed, RRM2B upregulation in chemotherapy-treated HB cells promoted cell survival and subsequent relapse, during which RRM2B was gradually replaced back by RRM2. Combining an RRM2 inhibitor with chemotherapy showed an effective delaying of HB tumor relapse in vivo. Overall, our study revealed the distinct roles of the two RNR M2 subunits and their dynamic switching during HB cell proliferation and stress response.

Background: An average time to diagnosis of 7 years is commonly described for endometriosis; diagnostic delay for adenomyosis is unknown. This cross-sectional study aimed to describe diagnostic delay for endometriosis and adenomyosis and to investigate the factors associated with this delay. Methods: Community of Patients for Research (ComPaRe)-Endometriosis is a prospective e-cohort of women with endometriosis and/or adenomyosis in France. About 6,949 participants were included. We used linear regression modeling to assess factors associated with diagnostic delay, after adjustment for age, education level, body mass index, number of comorbidities, and family history of the disease or of chronic pelvic pain (CPP). Results: The average diagnostic delay was 10 years for endometriosis and 11 years for adenomyosis. Factors associated with a significantly longer diagnostic delay were year of diagnosis (+0.34 years, p < 0.0001), unemployment (+0.7 years, p = 0.01), number of comorbidities (+0.3 years, p < 0.0001), family history of the disease or of CPP (+1.1 years, p < 0.0001), severe dysmenorrhea before diagnosis (numeric-rating scale: +0.8 years, p < 0.0001), number of health professionals consulted before diagnosis (+0.3 years, p < 0.0001), and presence of multiple symptoms leading to first consultation (+1.6 years, p < 0.0001). In contrast, factors associated with a shorter delay were a financial position perceived as comfortable (-1.4 years, p < 0.0001), age at menarche (-0.6 years, p < 0.0001), and age at first symptoms (-0.8 years, p < 0.0001). Conclusions: This study highlights several factors associated with diagnostic delay among women with self-reported endometriosis and/or adenomyosis and provides new insights to improve care by informing both clinicians and patients. Attention to these profiles may improve disease management.

Netrin-1 signaling is an essential prototypical neuronal guidance mechanism during embryonic development that also regulates tumor cell survival in a variety of adult cancer entities. In line with these data, a monoclonal netrin-1 blocking antibody (anti-netrin-1 mAb/NP137) has been preclinically developed and netrin-1 blockade has recently been investigated in phase 1 and 2 clinical trials in several adult cancers. Here, we investigate the role of netrin-1 in the most common malignant pediatric brain cancer, Medulloblastoma. Interestingly, we find that netrin-1 is upregulated in medulloblastoma subgroups associated with developmental dysregulation, in particular in medulloblastoma with Sonic Hedgehog (SHH) activation. First, we demonstrate that genetic deletion of netrin-1 or systemic treatment with the clinical-stage anti-netrin-1 blocking antibody significantly reduces tumor growth in vivo in various orthotopic models of SHH medulloblastomas. Second, in vitro and in vivo, we unexpectedly uncover that SHH medulloblastomas treated with an SHH-inhibitor targeting Smoothened (SMO) increase netrin-1 expression, paving the way for combinatorial therapy. In line with that, we next show that netrin-1 blockade potentiates the efficacy of SMO inhibitor therapy in vivo. Together, our data indicate that, netrin-1 blockade, used as monotherapy or in combination with SMO inhibitors, is a promising therapeutic strategy in SHH medulloblastomas.