Venetoclax-based Rational Combinations are Effective in Models of MYCN-amplified Neuroblastoma

Impact of BCL-2 Expression on Course of Disease in Neuroblastoma

OBJECTIVE

 The antiapoptotic BCL-2 protein has implications for maturation and differentiation of neural tissue and acts as a strong modulator of carcinogenesis in different tumors. Recent research focuses not only on its benefit as a prognostic factor, but also as a potential therapeutic target. The role of BCL-2 in neuroblastoma, the most common extracranial solid tumor in childhood, remains controversial. The aim of our study was to determine the gene expression level of BCL-2 in a large cohort of neuroblastoma patients and its correlation with clinical parameters.

METHODS

 Tumor samples and clinical data were collected from 100 neuroblastoma patients treated according to the NB2004 protocol of the German Society of Pediatric Oncology and Hematology. BCL-2 gene expression levels were measured by quantitative reverse transcription polymerase chain reaction and correlated with clinical parameters.

RESULTS

 BCL-2 expression was detected in all tumor samples. Relative BCL-2 expression levels were higher in females versus males (1.839 vs. 1.342; p = 0.0143), in patients with low versus high International Neuroblastoma Staging System stage (2.051 vs. 1.463; p = 0.0206), in nonmetastatic versus metastatic disease (1.801 vs. 1.342; p = 0.0242), as well as in patients without presurgical chemotherapy (2.145 vs. 1.402; p = 0.0016), but was not associated with overall survival and MYCN amplification.

CONCLUSION

 Our study demonstrates the ubiquitous expression of BCL-2 in neuroblastoma and suggests the possibility for targeted therapy with BCL-2 inhibitors, even in lower-stage neuroblastoma. It also underlines the need for further research on concomitant genetic alterations for a better understanding of the impact of BCL-2 on this pediatric tumor type.

Humanin Treatment Protects Against Venetoclax-Induced Bone Growth Retardation in Ex Vivo Cultured Rat Bones

Context

Recent preclinical studies reported that the BCL-2 inhibitor venetoclax can impair bone growth. A strategy to prevent such a side effect of this promising anticancer drug is highly desired. Earlier in vitro and in vivo studies suggested that the mitochondrial peptide humanin has the potential to prevent drug-induced growth impairment.

Objective

We hypothesized that co-treatment with the humanin analog HNG may prevent venetoclax-induced bone growth impairment.

Methods

Ex vivo studies were performed in fetal rat metatarsal bones and human growth plate samples cultured for 12 and 2 days, respectively, while in vivo studies were performed in young neuroblastoma mice being treated daily for 14 days. The treatment groups included venetoclax, HNG, venetoclax plus HNG, or vehicle. Bone growth was continuously monitored and at the end point, histomorphometric and immunohistochemical analyses were performed in fixed tissues.

Results

Venetoclax suppressed metatarsal bone growth and when combined with HNG, bone growth was rescued and all histological parameters affected by venetoclax monotherapy were normalized. Mechanistic studies showed that HNG downregulated the pro-apoptotic proteins Bax and p53 in cultured metatarsals and human growth plate tissues, respectively. The study in a neuroblastoma mouse model confirmed a growth-suppressive effect of venetoclax treatment. In this short-term in vivo study, no significant bone growth-rescuing effect could be verified when testing HNG at a single dose. We conclude that humanin dose-dependently protects ex vivo cultured metatarsal bones from venetoclax-induced bone growth impairment by restoring the growth plate microstructure.

Venetoclax plus cyclophosphamide and topotecan in heavily pre-treated relapsed metastatic neuroblastoma: a single center case series

The prognosis of relapsed/refractory (R/R) neuroblastoma (NB) is dismal, calling for new therapeutic strategies. Venetoclax (VEN) is a highly selective, potent, orally bioavailable, BCL-2 inhibitor small-molecule that showed a synergistic effect with cyclophosphamide and topotecan (Cy-Topo) in murine NB models. Our aim was to evaluate the feasibility of VEN plus Cy-Topo in children with R/R NB. Four patients, who had previously failed > 3 lines of treatment, were treated with VEN plus Cy-Topo based on a 28-day schedule in an outpatient setting. BCL-2 expression in immunochemistry on tumor samples at relapse and the BCL2 gene status was evaluated in all patients. The main toxicity was hematological, with grade 4 neutropenia and thrombocytopenia occurring in all courses and leading to transient VEN discontinuation. Grade 3 oral mucositis was observed in 1/8 courses. No other grade 2-4 toxicities were observed. BCL-2 was expressed in all tumors, while no molecular abnormalities in the BCL-2 genes were detected. A stable disease was observed in all patients, without any progression during the study period. VEN plus Cy-Topo is well tolerated, with encouraging results that may be improved by testing the schedule in less advanced patients.

Mechanisms of action of the BCL-2 inhibitor venetoclax in multiple myeloma: a literature review

Abnormal cellular apoptosis plays a pivotal role in the pathogenesis of Multiple Myeloma (MM). Over the years, BCL-2, a crucial anti-apoptotic protein, has garnered significant attention in MM therapeutic research. Venetoclax (VTC), a small-molecule targeted agent, effectively inhibits BCL-2, promoting the programmed death of cancerous cells. While VTC has been employed to treat various hematological malignancies, its particular efficacy in MM has showcased its potential for broader clinical applications. In this review, we delve into the intricacies of how VTC modulates apoptosis in MM cells by targeting BCL-2 and the overarching influence of the BCL-2 protein family in MM apoptosis regulation. Our findings highlight the nuanced interplay between VTC, BCL-2, and MM, offering insights that may pave the way for optimizing therapeutic strategies. Through this comprehensive analysis, we aim to lay a solid groundwork for future explorations into VTC's clinical applications and the profound effects of BCL-2 on cellular apoptosis.

Increased MCL1 dependency leads to new applications of BH3-mimetics in drug-resistant neuroblastoma

BACKGROUND

Neuroblastoma is a paediatric cancer that is characterised by poor prognosis for chemoresistant disease, highlighting the need for better treatment options. Here, we asked whether BH3-mimetics inhibiting BCL2 proteins may eliminate chemoresistant neuroblastoma cells.

METHODS

We utilised cisplatin-adapted neuroblastoma cell lines as well as patient tissues before and after relapse to study alterations of BCL2 proteins upon chemoresistance.

RESULTS

In a direct comparison of cisplatin-resistant cells we identified a prominent loss of sensitivity to BCL2/BCL-XL inhibitors that is associated with an increase in MCL1 dependency and high expression of MCL1 in patient tumour tissues. Screening of FDA-approved anti-cancer drugs in chemoresistant cells identified therapeutics that may be beneficial in combination with the clinically tested BH3-mimetic ABT263, but no synergistic drug interactions with the selective MCL1 inhibitor S63845. Further exploration of potential treatment options for chemoresistant neuroblastoma identified immunotherapy based on NK cells as highly promising, since NK cells are able to efficiently kill both parental and chemoresistant cells.

CONCLUSIONS

These data highlight that the application of BH3-mimetics may differ between first line treatment and relapsed disease. Combination of NK cell-based immunotherapy with BH3-mimetics may further increase killing of chemoresistant neuroblastoma, outlining a new treatment strategy for relapsed neuroblastoma.

Venetoclax Use in Paediatric Haemato-Oncology Centres in Poland: A 2022 Survey

Venetoclax, the best established BH3-mimetic, is a practice-changing proapoptotic drug in blood cancers in adults. In paediatrics the data are fewer but exciting results were recently presented in relapsed or refractory leukaemias demonstrating significant clinical activity. Importantly, the in-terventions could be potentially molecularly guided as vulnerabilities to BH3-mimetics were re-ported. Currently venetoclax is not incorporated into paediatric treatment schedules in Poland but it has been already used in patients that failed conventional therapy in Polish paediatric haemato-oncology departments. The aim of the study was to gather clinical data and correlates of all paediatric patients treated so far with venetoclax in Poland. We set out to gather this experience to help choose the right clinical context for the drug and stimulate further research. The questionnaire regarding the use of venetoclax was sent to all 18 Polish paediatric haemato-oncology centres. The data as available in November 2022 were gathered and analysed for the diagnoses, triggers for the intervention, treatment schedules, outcomes and molecular associations. We received response from 11 centres, 5 of which administered venetoclax to their patients. Clinical benefit, in most cases consistent with hematologic complete remission (CR), was reported in 5 patients out of ten, whereas 5 patient did not show clinical benefit from the intervention. Importantly, patients with CR included subtypes expected to show venetoclax vulnerability, such as poor-prognosis ALL with TCF::HLF fusion. We believe BH3-mimetics have clinical activity in children and should be available to pae-diatric haemato-oncology practitioners in well-selected applications.

Patient-derived models: Advanced tools for precision medicine in neuroblastoma

Neuroblastoma is a childhood cancer derived from the sympathetic nervous system. High-risk neuroblastoma patients have a poor overall survival and account for ~15% of childhood cancer deaths. There is thus a need for clinically relevant and authentic models of neuroblastoma that closely resemble the human disease to further interrogate underlying mechanisms and to develop novel therapeutic strategies. Here we review recent developments in patient-derived neuroblastoma xenograft models and in vitro cultures. These models can be used to decipher mechanisms of metastasis and treatment resistance, for drug screening, and preclinical drug testing. Patient-derived neuroblastoma models may also provide useful information about clonal evolution, phenotypic plasticity, and cell states in relation to neuroblastoma progression. We summarize current opportunities for, but also barriers to, future model development and application. Integration of patient-derived models with patient data holds promise for the development of precision medicine treatment strategies for children with high-risk neuroblastoma.

Drug sensitivity profiling of 3D tumor tissue cultures in the pediatric precision oncology program INFORM

The international precision oncology program INFORM enrolls relapsed/refractory pediatric cancer patients for comprehensive molecular analysis. We report a two-year pilot study implementing ex vivo drug sensitivity profiling (DSP) using a library of 75-78 clinically relevant drugs. We included 132 viable tumor samples from 35 pediatric oncology centers in seven countries. DSP was conducted on multicellular fresh tumor tissue spheroid cultures in 384-well plates with an overall mean processing time of three weeks. In 89 cases (67%), sufficient viable tissue was received; 69 (78%) passed internal quality controls. The DSP results matched the identified molecular targets, including BRAF, ALK, MET, and TP53 status. Drug vulnerabilities were identified in 80% of cases lacking actionable (very) high-evidence molecular events, adding value to the molecular data. Striking parallels between clinical courses and the DSP results were observed in selected patients. Overall, DSP in clinical real-time is feasible in international multicenter precision oncology programs.

Venetoclax cooperates with ionizing radiation to attenuate Diffuse Midline Glioma tumor growth

PURPOSE

Tumor relapse after radiation therapy (RT) is a major hurdle in treating pediatric H3K27M-mutant diffuse midline gliomas (DMGs). RT-induced stress increases association of BCL2 family of proteins with BH3 pro-apoptotic activators preventing apoptosis. We hypothesized that inhibition of RT-induced BCL2 with a clinically relevant inhibitor, venetoclax, will block BCL2 activity leading to increased apoptosis. BCL2 has never been implicated in DMG as a RT-induced resistant mechanism.

EXPERIMENTAL DESIGN

We performed an integrated genomic analysis to determine genes responsible for radioresistance and a targeted drug screen to identify drugs that synergize with radiation in DMG. Effect of venetoclax on radiation-na�ve and 6Gy radiation on cells was evaluated by studying cell death, changes in BCL2 phosphorylation, reactive oxygen species (ROS), and apoptosis, as well as BCL2 association with BH3 apoptosis initiators. The efficacy of combining venetoclax with radiation was evaluated in vivo using orthotopic xenograft models.

RESULTS

BCL2 was identified as a key regulator of tumor growth after radiation in DMGs. Radiation sensitizes DMGs to venetoclax treatment independent of p53 status. Venetoclax as a monotherapy was not cytotoxic to DMG cells. Post-radiation venetoclax treatment significantly increased cell death, reduced BCL2-BIM association and augmented mitochondrial ROS leading to increased apoptosis. Combining venetoclax with RT significantly enhanced the survival of mice with DMG tumors.

CONCLUSIONS

This study shows that venetoclax impedes the anti-apoptotic function of radiation-induced BCL2 in DMG leading to increased apoptosis. Results from these pre-clinical studies demonstrate the potential use of the BCL2 inhibitor, venetoclax, combined with RT for pediatric DMG.

MYCN in Neuroblastoma: "Old Wine into New Wineskins"

MYCN Proto-Oncogene, BHLH Transcription Factor (MYCN) has been one of the most studied genes in neuroblastoma. It is known for its oncogenetic mechanisms, as well as its role in the prognosis of the disease and it is considered one of the prominent targets for neuroblastoma therapy. In the present work, we attempted to review the literature, on the relation between MYCN and neuroblastoma from all possible mechanistic sites. We have searched the literature for the role of MYCN in neuroblastoma based on the following topics: the references of MYCN in the literature, the gene's anatomy, along with its transcripts, the protein's anatomy, the epigenetic mechanisms regulating MYCN expression and function, as well as MYCN amplification. MYCN plays a significant role in neuroblastoma biology. Its functions and properties range from the forming of G-quadraplexes, to the interaction with miRNAs, as well as the regulation of gene methylation and histone acetylation and deacetylation. Although MYCN is one of the most primary genes studied in neuroblastoma, there is still a lot to be learned. Our knowledge on the exact mechanisms of MYCN amplification, etiology and potential interventions is still limited. The knowledge on the molecular mechanisms of MYCN in neuroblastoma, could have potential prognostic and therapeutic advantages.