MYC Expression Research Articles

Tucidinostat plus R-CHOP in previously untreated diffuse large B-cell lymphoma with double expression of MYC and BCL2: An interim analysis from the phase III DEB study.

LBA7003 Background: Epigenetic dysregulation is commonly correlated with the pathogenesis and development in diffuse large B-cell lymphoma (DLBCL). Tucidinostat, a subtype-selective histone deacetylase (HDAC) inhibitor, has shown promising efficacy in combination with R-CHOP in DLBCL patients with double expression of MYC and BCL2 (DE) in exploratory studies. Methods: We conducted a randomized, double-blind, placebo-controlled, phase III trial (DEB) to evaluate the efficacy and safety of tucidinostat plus R-CHOP in comparison with R-CHOP in previously untreated DLBCL patients with DE. Patients were randomly assigned in a 1:1 ratio to receive six cycles of either tucidinostat plus R-CHOP (tucidinostat group) or placebo plus R-CHOP (placebo group). Patients who achieved complete response (CR) after combination therapy received either tucidinostat or placebo as maintenance treatment with a maximum duration of 24 weeks. The primary endpoint was investigator-assessed event-free survival (EFS), and the key secondary endpoint was the complete response rate (CRR) evaluated at the end of combination treatment. An interim analysis was pre-defined to be conducted when CRR was obtained and the number of EFS events reached at least 60% of the total events required for entire study. Results: Between May 21, 2020, and July 25, 2022, 423 patients were enrolled and randomly assigned, 211 to the tucidinostat group and 212 to the placebo group. At data cutoff of this interim analysis (January 10, 2023), the median follow-up time was 13.9 months (95% CI, 12.9 - 15.4). A total of 152 EFS events (68.5% of the planned total) were observed, with 64 (30.3%) in the tucidinostat group and 88 (41.5%) in the placebo group. The 24-month EFS rate was 58.9% (95% CI, 48.9-67.6) in the tucidinostat group and 46.2% (95% CI, 35.7-56.1) in the placebo group. The hazard ratio (HR) between the two groups was 0.68 (95% CI, 0.49-0.94), with a p-value of 0.018. At the completion of combination treatment, the CRR in the tucidinostat and placebo groups were 73.0% (95% CI, 66.6-78.5) and 61.8% (95% CI, 55.1-68.1), respectively. The adjusted difference in CRR was 11.1% (95% CI, 2.3-20.0; P=0.014). The safety profiles of both groups were as expected, with no new safety findings. The incidence of ≥ grade 3 hematologic adverse events was generally higher in the tucidinostat group than the placebo group, but most patients were able to tolerate and complete the planned treatment cycles. No significant cardiac toxicity, hepatotoxicity, or nephrotoxicity were observed in both groups. Conclusion: The DEB study is the first phase III trial to show that combining tucidinostat with R-CHOP regimen is a feasible and efficacious novel approach in previously untreated DLBCL patients with DE. Tucidinostat plus R-CHOP could be a new frontline treatment option in this patient population. Clinical trial information: NCT04231448 .

Dual inhibition of the TrkA and JAK2 pathways using entrectinib and pacritinib suppresses the growth and metastasis of HER2-positive and triple-negative breast cancers

HER2-positive and triple-negative breast cancers (TNBC) are difficult to treat and associated with poor prognosis. Despite showing initial response, HER2-positive breast cancers often acquire resistance to HER2-targeted therapies, and TNBC lack effective therapies. To overcome these clinical challenges, we evaluated the therapeutic utility of co-targeting TrkA and JAK2/STAT3 pathways in these breast cancer subtypes. Here, we report the novel combination of FDA-approved TrkA inhibitors (Entrectinib or Larotrectinib) and JAK2 inhibitors (Pacritinib or Ruxolitinib) synergistically inhibited in vitro growth of HER2-positive breast cancer cells and TNBC cells. The Entrectinib-Pacritinib combination inhibited the breast cancer stem cell subpopulation, reduced expression of stemness genes, SOX2 and MYC, and induced apoptosis. The Entrectinib-Pacritinib combination suppressed orthotopic growth of HER2-positive Trastuzumab-refractory breast cancer xenografts and basal patient-derived xenograft (PDXs), reduced tumoral SOX2 and MYC, and induced apoptosis in both mouse models. The Entrectinib-Pacritinib combination inhibited overall metastatic burden, and brain and bone metastases of intracardially inoculated TNBC cells without toxicity. Together, our results demonstrate for the first time that co-inhibition of TrkA and JAK2 synergistically suppresses breast cancer growth and metastasis, thereby providing preclinical evidence that supports future clinical evaluations.

CD8+ T cell tolerance: It doesn’t translate

The mechanisms that make and break CD8+ Tcell tolerance to self-antigens remain unclear. In this issue of Immunity, Van Der Byl etal. show that tolerant CD8+ Tcells rapidly adopt an epigenetically and transcriptionally distinct cell state and exhibit impaired protein translation. Breaking tolerance requires both inflammation and increased antigen exposure to augment MYC expression and restore translation.

ZDHHC20-mediated S-palmitoylation of YTHDF3 stabilizes MYC mRNA to promote pancreatic cancer progression

Post-translational modifications of proteins in malignant transformation and tumor maintenance of pancreatic ductal adenocarcinoma (PDAC) in the context of KRAS signaling remain poorly understood. Here, we use the KPC mouse model to examine the effect of palmitoylation on pancreatic cancer progression. ZDHHC20, upregulated by KRAS, is abnormally overexpressed and associated with poor prognosis in patients with pancreatic cancer. Dysregulation of ZDHHC20 promotes pancreatic cancer progression in a palmitoylation-dependent manner. ZDHHC20 inhibits the chaperone-mediated autophagic degradation of YTHDF3 through S-palmitoylation of Cys474, which can result in abnormal accumulation of the oncogenic product MYC and thereby promote the malignant phenotypes of cancer cells. Further, we design a biologically active YTHDF3-derived peptide to competitively inhibit YTHDF3 palmitoylation mediated by ZDHHC20, which in turn downregulates MYC expression and inhibits the progression of KRAS mutant pancreatic cancer. Thus, these findings highlight the therapeutic potential of targeting the ZDHHC20–YTHDF3–MYC signaling axis in pancreatic cancer.

Prognostic Significance of Double-Expresser Status in Diffuse Large B-cell lymphoma: Experience from a Tertiary Care Cancer Centre in India

Background: Diffuse large B-cell lymphoma (DLBCL) is a neoplasm of medium or large B lymphoid cells with a diffuse histopathologic growth pattern. Co-expression of MYC and BCL2 proteins in DLBCL by immunohistochemistry (IHC) is referred to as the double-expresser (DE) phenotype and is associated with inferior survival. Objectives of this study were to assess the DE status in DLBCL and to assess its utility in predicting the prognosis in DLBCL. Methods: This was a retrospective study conducted in a tertiary care cancer centre. Study population included all the cases of DLBCL, NOS diagnosed in the centre in 2012. MYC and BCL2 protein expression were analysed by immunohistochemistry. The prognostic significance of double-expressers was analysed by comparing progression free survival (PFS) and overall survival (OS) of double-expressers and non-double expressers using appropriate statistical methods. All the data were analysed using SPSS 11 software. Kaplan-Meier method was used to estimate the survival probability. A significant difference in survival between various prognostic factors was tested using the log-rank test. Prognostic factors were assessed using univariate and multivariate Cox-regression model. A P- value < 0.05 was considered to be statistically significant. Results: Double-Expresser lymphoma (DEL) constituted 22.2% (n=18) of all cases of DLBCL, NOS. DE status was associated with shorter PFS (P-value = 0.049) and OS (P-value = 0.015). Conclusion: DE status is associated with poor prognosis in DLBCL, NOS. Assessment of MYC and BCL2 by IHC represents a rapid and inexpensive approach to risk-stratify patients with DLBCL at the time of diagnosis.

GPR168 functions as a tumor suppressor in mouse melanoma by restraining Akt signaling pathway.

Malignant melanoma (MM) is a malignant tumor associated with high mortality rates and propensity for metastasis. Despite advancement in treatment, the incidence of MM continue to rise globally. GPR168, also known as MrgprF, is a MAS related GPR family member. The low expression of GPR168 has also been reported in many malignant tumors including MM. In the study, the statistical analysis from The Cancer Genome Atlas (TCGA) revealed a significant down regulation of GPR168 in melanoma compared to normal melanocytes, underscoring its importance in MM. The aim of the present study is to investigate the affect of GPR168 overexpression and elucidate its molecular mechanisms in MM cells. In addition, we used mouse melanoma B16-F10 cell line and xenograph tumor model to explore the function of GPR168 in melanoma. Our findings demonstrate that GPR168 overexpression could inhibit B16-F10 cell proliferation, migration, and xenografts tumor growth. Further, mechanistic studies revealed that GPR168 affected B16-F10 progress through Akt signal pathway with the decreased expression of p-Akt, p-GSK-3β, β-catenin, Myc, CyclinD1 and CDK4. In order to validate these findings, a rescue experiment was formulated employing GPR168 polyclonal antibody (Anti-GPR168 pAbs) to block GPR168 functionality. The addition of Anti-GPR168 pAbs into the culture medium restored both cell proliferation and migration. In conclusion, the overexpression of GPR168 in mouse melanoma B16-F10 cells suppressed proliferation and migration through the Akt signaling pathway. These findings collectively propose GPR168 as a promising novel tumor suppressor in MM, suggesting its potential as a therapeutic target in future interventions.

Targeting AURKA to induce synthetic lethality in CREBBP-deficient B-cell malignancies via attenuation of MYC expression.

Loss-of-function mutations in CREBBP, which encodes for a histone acetyltransferase, occur frequently in B-cell malignancies, highlighting CREBBP deficiency as an attractive therapeutic target. Using established isogenic cell models, we demonstrated that CREBBP-deficient cells are selectively vulnerable to AURKA inhibition. Mechanistically, we found that co-targeting CREBBP and AURKA suppressed MYC transcriptionally and post-translationally to induce replication stress and apoptosis. Inhibition of AURKA dramatically decreased MYC protein level in CREBBP-deficient cells, implying a dependency on AURKA to sustain MYC stability. Furthermore, in vivo studies showed that pharmacological inhibition of AURKA was efficacious in delaying tumor progression in CREBBP-deficient cells and was synergistic with CREBBP inhibitors in CREBBP-proficient cells. Our study sheds light on a novel synthetic lethal interaction between CREBBP and AURKA, indicating that targeting AURKA represents a potential therapeutic strategy for high-risk B-cell malignancies harboring CREBBP inactivating mutations.

CDK12-inactivation-induced MYC signaling causes dependency on the splicing kinase SRPK1.

Inactivation of cyclin-dependent kinase 12 (CDK12) characterizes an aggressive sub-group of castration-resistant prostate cancer (CRPC). Hyper-activation of MYC transcription factor is sufficient to confer the CRPC phenotype. Here, we show that loss of CDK12 promotes MYC activity, which renders the cells dependent on the otherwise non-essential splicing regulatory kinase SRSF protein kinase 1 (SRPK1). High MYC expression is associated with increased levels of SRPK1 in patient samples, and overexpression of MYC sensitizes prostate cancer cells to SRPK1 inhibition using pharmacological and genetic strategies. We show that Endovion (SCO-101), a compound currently in clinical trials against pancreatic cancer, phenocopies the effects of the well-characterized SRPK1 inhibitor SRPIN340 on nascent transcription. This is the first study to show that Endovion is an SRPK1 inhibitor. Inhibition of SRPK1 with either of the compounds promotes transcription elongation, and transcriptionally activates the unfolded protein response. In brief, here we discover that CDK12 inactivation promotes MYC signaling in an SRPK1-dependent manner, and show that the clinical grade compound Endovion selectively targets the cells with CDK12 inactivation.

Ajania pacifica (Nakai) K. Bremer and Humphries Extract Limits MYC Expression to Induce Apoptosis in Diffuse Large B Cell Lymphoma.

The proto-oncogene MYC is frequently dysregulated in patients with diffuse large B-cell lymphoma (DLBCL) and plays a critical role in disease progression. To improve the clinical outcomes of patients with DLBCL, the development of strategies to target MYC is crucial. The use of medicinal plants for developing anticancer drugs has garnered considerable attention owing to their diverse mechanisms of action. In this study, 100 plant extracts of flora from the Republic of Korea were screened to search for novel agents with anti-DLBCL effects. Among them, Ajania pacifica (Nakai) K. Bremer and Humphries extract (APKH) efficiently suppressed the survival of DLBCL cells, while showing minimal toxicity toward normal murine bone marrow cells. APKH suppressed the expression of anti-apoptotic BCL2 family members, causing an imbalance between the pro-apoptotic and anti-apoptotic BCL2 members. This disrupted mitochondrial membrane potential, cytochrome c release, and pro-caspase-3 activation and eventually led to DLBCL cell death. Importantly, MYC expression was markedly downregulated by APKH and ectopic expression of MYC in DLBCL cells abolished the pro-apoptotic effects of APKH. These results demonstrate that APKH exerts anti-DLBCL effects by inhibiting MYC expression. Moreover, when combined with doxorubicin, an essential component of the CHOP regimen (cyclophosphamide, doxorubicin, vincristine, and prednisone), APKH synergistically enhanced the therapeutic effect of doxorubicin. This indicates that APKH may overcome drug resistance, which is common in patients with refractory/relapsed DLBCL. To identify compounds with anti-DLBCL activities in APKH, the chemical profile analysis of APKH was performed using UPLC-QTOF/MSe analysis and assessed for its anticancer activity. Based on the UPLC-QTOF/MSe chemical profiling, it is conceivable that APKH may serve as a novel agent targeting MYC and sensitizing drug-resistant DLBCL cells to CHOP chemotherapy. Further studies to elucidate how the compounds in APKH exert tumor-suppressive role in DLBCL are warranted.

Regulation of Myc transcription by an enhancer cluster dedicated to pluripotency and early embryonic expression

MYC plays various roles in pluripotent stem cells, including the promotion of somatic cell reprogramming to pluripotency, the regulation of cell competition and the control of embryonic diapause. However, how Myc expression is regulated in this context remains unknown. The Myc gene lies within a ~ 3-megabase gene desert with multiple cis-regulatory elements. Here we use genomic rearrangements, transgenesis and targeted mutation to analyse Myc regulation in early mouse embryos and pluripotent stem cells. We identify a topologically-associated region that homes enhancers dedicated to Myc transcriptional regulation in stem cells of the pre-implantation and early post-implantation embryo. Within this region, we identify elements exclusively dedicated to Myc regulation in pluripotent cells, with distinct enhancers that sequentially activate during naive and formative pluripotency. Deletion of pluripotency-specific enhancers dampens embryonic stem cell competitive ability. These results identify a topologically defined enhancer cluster dedicated to early embryonic expression and uncover a modular mechanism for the regulation of Myc expression in different states of pluripotency.

Exploring the effects of Hippo signaling pathway on rumen epithelial proliferation

BackgroundThe current understanding to the mechanism of rumen development is limited. We hypothesized that the Hippo signaling pathway controlled the proliferation of rumen epithelium (RE) during postnatal development. In the present study, we firstly tested the changes of the Hippo signaling pathway in the RE during an early growing period from d5 to d25, and then we expanded the time range to the whole preweaning period (d10-38) and one week post weaning (d45). An in vitro experiment was also carried out to verify the function of Hippo signaling pathway during RE cell proliferation.ResultsIn the RE of lambs from d5 to d25, the expression of baculoviral IAP repeat containing (BIRC3/5) was increased, while the expressions of large tumor suppressor kinase 2 (LATS2), TEA domain transcription factor 3 (TEAD3), axin 1 (AXIN1), and MYC proto-oncogene (MYC) were decreased with rumen growth. From d10 to d38, the RE expressions of BIRC3/5 were increased, while the expressions of LATS2 and MYC were decreased, which were similar with the changes in RE from d5 to d25. From d38 to d45, different changes were observed, with the expressions of LATS1/2, MOB kinase activator 1B (MOB1B), and TEAD1 increased, while the expressions of MST1 and BIRC5 decreased. Correlation analysis showed that during the preweaning period, the RE expressions of BIRC3/5 were positively correlated with rumen development variables, while LAST2 was negatively correlated with rumen development variables. The in vitro experiment validated the changes of LATS2 and BIRC3/5 in the proliferating RE cells, which supported their roles in RE proliferation during preweaning period.ConclusionsOur results suggest that the LATS2-YAP1-BIRC3/5 axis participates in the RE cell proliferation and promotes rumen growth during the preweaning period.

Trisomy 8 Defines a Distinct Subtype of Myeloproliferative Neoplasms Driven by the MYC-Alarmin Axis.

Despite advances in understanding the genetic abnormalities in myeloproliferative neoplasms (MPN) and the development of JAK2 inhibitors, there is an urgent need to devise new treatment strategies, particularly for patients with triple-negative (TN) myelofibrosis (MF) who lack mutations in the JAK2 kinase pathway and have very poor clinical outcomes. Here we report that MYC copy number gain and increased MYC expression frequently occur in TN-MF and that MYC-directed activation of S100A9, an alarmin protein that plays pivotal roles in inflammation and innate immunity, is necessary and sufficient to drive development and progression of MF. Notably, the MYC-S100A9 circuit provokes a complex network of inflammatory signaling that involves numerous hematopoietic cell types in the bone marrow microenvironment. Accordingly, genetic ablation of S100A9 or treatment with small molecules targeting the MYC-S100A9 pathway effectively ameliorates MF phenotypes, highlighting the MYC-alarmin axis as a novel therapeutic vulnerability for this subgroup of MPNs. Significance: This study establishes that MYC expression is increased in TN-MPNs via trisomy 8, that a MYC-S100A9 circuit manifest in these cases is sufficient to provoke myelofibrosis and inflammation in diverse hematopoietic cell types in the BM niche, and that the MYC-S100A9 circuit is targetable in TN-MPNs.

MYC and NCAPG2 as molecular targets of colorectal cancer and gastric cancer in nursing.

Colorectal cancer is a common malignant tumor in intestinal tract, the early symptoms are not obvious. Gastric cancer is a malignant tumor originating from the gastric mucosal epithelium. However, the role of MYC and non-SMC condensin II complex subunit G2 (NCAPG2) in colorectal cancer and gastric cancer remains unclear. The colorectal cancer datasets GSE49355 and gastric cancer datasets GSE19826 were downloaded from gene expression omnibus database. Differentially expressed genes (DEGs) were screened and weighted gene co-expression network analysis (WGCNA) was performed. Functional enrichment analysis, gene set enrichment analysis (GSEA) and immune infiltration analysis was performed. Construction and analysis of protein-protein interactions (PPI) network. Survival analysis and comparative toxicogenomics database (CTD) were performed. A heat map of gene expression was drawn. A total of 751 DEGs were obtained. According to the gene ontology (GO) analysis, in Biological process (BP) analysis, they are mainly enriched in cell differentiation, cartilage development, and skeletal development. In cellular component (CC) analysis, they are mainly enriched in the cytoskeleton of muscle cells and actin filaments. In molecular function (MF) analysis, they are mainly concentrated in Rho GTPase binding, DNA binding, and fibronectin binding. In Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis, they are mainly enriched in the MAPK signaling pathway, apoptosis, and cancer pathways. The soft threshold power for WGCNA analysis was set to 9, resulting in the generation of 40 modules. Ultimately, 2 core genes (MYC and NCAPG2) were identified. The heatmap of core gene expression showed high expression of MYC and NCAPG2 in colorectal cancer tissue samples and low expression in normal tissue samples, while they were core molecules in gastric cancer. Survival analysis indicated that MYC and NCAPG2 were risk factors, showing an upregulation trend with increasing risk scores. CTD analysis revealed associations of MYC and NCAPG2 with colorectal cancer, gastric cancer, inflammation, and immune system diseases. MYC and NCAPG2 are highly expressed in colorectal cancer. The higher the expression of MYC and NCAPG2, the worse the prognosis. MYC and NCAPG2 are core molecules in gastric cancer.

Abstract PO4-18-07: A dose escalation and cohort expansion study of the CDK9 inhibitor KB-0742 in triple negative breast cancer and transcriptionally addicted relapsed or refractory solid tumors

Abstract Background: MYC deregulation is a hallmark of triple negative breast cancer (TNBC) and is associated with aggressive tumors and poor clinical outcomes. Although MYC remains undrugged, targeting of its cofactors has emerged as an attractive strategy to inhibit MYC oncogenic activity. Cyclin-dependent kinase 9 (CDK9) is a critical regulator of oncogenic MYC expression and an important MYC cofactor. KB-0742 is an oral CDK9 inhibitor that demonstrates promising preclinical activity against TNBC. In a real-world cohort, TNBCs have higher MYC expression and higher rates of MYC genomic amplification than other breast cancer subtypes. In primary patient-derived cell lines, KB-0742 treatment results in stronger cytotoxic effects in TNBC as compared to other subtypes. In patient-derived organoids and patient-derived xenografts, CDK9 inhibition by KB-0742 drives antiproliferative and anti-tumor growth effects, including in models that are resistant to standard of care. KB-0742 strongly downregulates MYC protein levels at doses that only partially inhibit CDK9 activity, suggesting a therapeutic window for tumor-specific activity (Saffran, D.C. et al, 2021). KB-0742 is currently being evaluated in a phase 1/2 dose escalation and cohort expansion study in patients with TNBC and other transcriptionally addicted tumors (NCT04718675). Trial design: This phase 1/2 study includes two parts: dose escalation (part 1) and cohort expansion (part 2). Part 2 includes cohort A (solid tumors with high prevalence of MYC overexpression including TNBC, non-small cell lung cancer and ovarian) and cohort B (other transcriptionally addicted tumor types including sarcomas, adenoid cystic carcinoma, nut midline carcinoma and small cell lung cancer). KB-0742 is dosed orally once daily for 3 consecutive days, followed by 4 days, off on a weekly basis in 28-day cycles until unacceptable toxicity or disease progression. Eligibility criteria: Part 1 dose escalation is open to patients with relapsed or refractory solid tumors. Part 2 is defined by tumor indications in cohorts A and B. Eligibly criteria include age > 18 years (≥ 12 years old and with a body weight ≥ 40 kg part 2 for cohort B), acceptable organ function, and ECOG PS < 2. Specific aims: Primary objectives include evaluation of pharmacokinetics (PK), pharmacodynamics (PD), safety, tolerability, preliminary anti-tumor activity, and identifying a maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). PK measurements include Cmax, tmax, AUC0-last, accumulation ratio (Racc) and t1/2. Safety data will be evaluated per the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) v5.0. The Modified Continuous Reassessment Method (mCRM) (Goodman et al., Stat Med 1995) will guide dose escalation and MTD. RP2D nomination is informed by PD in peripheral blood mononuclear cells using assays to evaluate phosphorylation of the CDK9 substrate serine 2 on the RNA Polymerase II C-terminal domain (pSER2) and CDK9-responsive gene expression. Radiographic tumor response to KB-0742 in patients is assessed every other cycle starting from cycle two after treatment using RECIST 1.1 criteria. Target accrual: Targeted total enrollment is 170 patients. For additional information, contact clinicaltrials@kronosbio.com Citation Format: Monica Mita, Alain Mita, Miguel Villalona-Calero, Noah Federman, Drew Rasco, David Spigel, Jia Luo, Gregory Cote, Richard Cutler, Pavan Kumar, Crystal MacKenzie, Charles Lin, Jorge DiMartino, Elizabeth Olek, Brian Van Tine. A dose escalation and cohort expansion study of the CDK9 inhibitor KB-0742 in triple negative breast cancer and transcriptionally addicted relapsed or refractory solid tumors [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-18-07.

Abstract PS14-07: Exploring Circulating Leukocyte RNA Expression: Implications for Treatment Outcomes and Immune-Related Adverse Events in Patients with Triple Negative Breast Cancer Enrolled in the GeparNuevo Trial

Abstract Abstract Exploring Circulating Leukocyte RNA Expression: Implications for Treatment Outcomes and Immune-Related Adverse Events in Patients with Triple Negative Breast Cancer Enrolled in the GeparNuevo Trial Background: Significant research has been conducted on the influence of immune checkpoint inhibitor therapy on tumor microenvironment, particularly with regard to tumor-infiltrating immune cells. Nevertheless, our understanding of the circulating immune repertoire and its association with treatment outcomes remains limited. Consequently, our subproject of the GeparNuevo trial aimed to explore the RNA phenotype of circulating leukocytes and its impact on overall survival (OS), and adverse events of patients enrolled in the GeparNuevo trial (Loibl S et al. Annals Oncol 2022). Methods: The GeparNuevo phase II trial focused on the effects of neoadjuvant nab-paclitaxel followed by epirubicin/cyclophosphamide (nabP-EC) chemotherapy combined with the anti-PD-L1 immune checkpoint inhibitor durvalumab versus placebo in patients with non-metastatic triple-negative breast cancer. RNA-stabilizing PAXgene tubes were used to collect blood samples prior to treatment initiation. RNA was extracted from circulating leukocytes of 117 patients and analyzed using a custom NanoString nCounter CodeSet, including 290 immune-related target genes. The associations between 16 immune cell scores, 26 immune signaling scores, 31 individual gene expression patterns, OS, and immune-related adverse events (irAEs) were analyzed. Results: Univariate Cox regression analysis using continuous scores revealed a significant correlation between PIP3 activates AKT signaling, T cells, CDK2, and TIMP1 expression with OS in the placebo arm. Higher expression of PIP3 activates AKT signaling, T cells, and CDK2, as well as lower expression of TIMP1, were associated with prolonged survival. Notably, T cell scores and CDK2 expression exhibited a significant interaction with the treatment arm (p=0.0489 and 0.0210, respectively). Multivariate Cox regression analysis demonstrated a significant association of DPP4, ICOS and MYC expression with OS. Additionally, CDK2, CDKN2A, F5 and HLA-DRA expression were linked to the presence of irAEs. In the durvalumab arm, TNFR2 non canonical NFkB pathway signaling, CDK2 and CDKN2A expression showed an inverse association with the occurrence of irAEs. Conclusions: Our study provides preliminary evidence that RNA derived from circulating leukocytes may serve as a potential biomarker for predicting treatment outcomes and identifying patients prone to develop side effects during standard-of-care chemotherapy or immune checkpoint therapy. These findings highlight the potential utility of peripheral immune cell RNA profiling in improving treatment strategies and patient management. Further research and validation are necessary to fully comprehend the clinical significance and broader implications of these findings. Citation Format: Hanna Hübner, Matthias Ruebner, Andreas Schneeweiss, Carsten Denkert, Hans-Peter Sinn, Michael Braun, Thomas Karn, Bruno V. Sinn, Dirk-Michael Zahm, Jörg Thomalla, Jens Huober, Claus Hanusch, Michael Untch, Christine Solbach, Theresa Link, Natalie Filmann, Julia Rey, Johannes Holtschmidt, Sibylle Loibl, Peter A. Fasching. Exploring Circulating Leukocyte RNA Expression: Implications for Treatment Outcomes and Immune-Related Adverse Events in Patients with Triple Negative Breast Cancer Enrolled in the GeparNuevo Trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS14-07.

642: Characterization of radiation response of pancreatic tumor cells in correlation with MYC expression

642: Characterization of radiation response of pancreatic tumor cells in correlation with MYC expression

The regulatory role of the transcription factor HEB in Myc-overexpressing T-cell Acute Lymphoblastic Leukemia

Abstract Acute Lymphoblastic Leukemia (ALL) is the most common cancer among children in the US. Approximately 5% of T-cell ALL (T-ALL) cases involve acquired focal chromosomal duplications encompassing a region downstream of the Myc oncogene, characterized as a Notch1-dependent Myc enhancer (N‑Me). The lack of mouse models with such N‑Me duplications has limited our ability to study the molecular mechanisms of the disease. We found that mouse leukemias resulting from conditional aberrant activation of β-catenin with simultaneous ablation of the transcription factor HEB in CD4+CD8+ double positive thymocytes bear N‑Me duplications. The ablation of HEB fundamentally changes the mechanism of leukemogenesis induced by the simple activation of β-catenin, which is characterized by TCRα-Myc/Pvt1 reciprocal translocations. Based on the finding that HEB binds N-Me at a site that overlaps Notch-1 binding and the conserved motifs of other regulators, we propose that HEB has a central regulatory role in the oncogenic process. We hypothesize that HEB binding regulates the access of transcription regulators to N-Me, rationing Myc expression. Loss of HEB in the context of activated β-catenin enables access of these regulators to N-Me, and triggers super-enhancer properties and changes in chromatin conformation, leading to excessive Myc expression and leukemogenesis. Ultimately, the proposed study aspires to determine the role of HEB in the initiation, progression, and treatment of human T-ALL

Dependence of lymphopoiesis on efficient β-catenin degradation

Abstract Wnt/β-catenin pathway is tightly controlled by β-catenin destruction complex to regulate lineage specification and differentiation. Compared to epithelial lineage, lymphoid cells display higher rates of β-catenin degradation to achieve constitutively low levels of β-catenin. Emphasizing the reliance of lymphoid cells on β-catenin degradation, expression of degradation resistant form of β-catenin or deletion of APC or CK1 suppressed lymphoid development. Similarly, small molecules inhibiting GSK3β mediated phosphorylation or proteasomal degradation of β-catenin induced higher toxicity selectively in lymphoid cells compared to other lineages. Our interactome and CHIP-seq analysis highlighted that the unique dependency of lymphoid cells on efficient degradation of β-catenin is mediated by Ikaros zinc finger (IKZF) proteins and nucleosome remodeling and deacetylase (NuRD) complexes. Unlike activating TCF/β-catenin complexes in epithelial cells, recruitment of repressive β-catenin/IKZF/NuRD complexes to MYC superenhancer (SE) regions lead to suppression of Myc expression and induced cell death. Deletion of both IKZF1 and IKZF3 or mutation of Ikaros binding motifs within the Myc-SE subverted the β-catenin mediated toxicity. Upon loss of Ikaros factors, β-catenin interaction with TCF-factors resulted in de novo activation of epithelial specific genes. Our findings suggest that β-catenin degradation is an evolutionary requirement for Ikaros mediated protection of lymphoid identity.

Effect of MYC and PARP Inhibitors in Ovarian Cancer Using an In Vitro Model.

The 8q24 chromosomal region, which contains the MYC and PVT1 candidate oncogenes, is amplified in carcinomas. Both genes have been involved in the etiopathogenesis of ovarian cancer (OC). In this study, we used an in vitro OC model with a known 8q24 copy number increase and in silico tools to investigate the expression of MYC/PVT1 loci and copy number variation in OC. We also assessed the effects of rucaparib (a PARP inhibitor) in the presence or absence of 10058F4 (a MYC inhibitor) on the expression of MYC/linear PVT1/circular PVT1. Tissue culture, chromosome preparation, RNA extraction, RT-qPCR, FISH, and wound healing assays were employed. OncoDB, cBioportal, UALKAN, and ROC Plotter in silico tools were also utilized. Although PVT1 and MYC expression levels remained unaltered in OC, putative copy number alterations across all cancers showed a marked difference between the two genes, particularly in gain and amplification for MYC. PVT1 expression demonstrated prognostic value for the treatment of patients with serous and endometrioid OC. Both genes correlated with PARP10, FAM83H, and DEPTOR. The use of rucaparib in the presence or absence of the MYC inhibitor (10058F4) in vitro, led to a significant down-regulation in the expression of MYC, linear, and circular PVT1. Our data provide a novel insight into the potential interactions of MYC and PVT1 with other genes. Moreover, we identified a new PARP inhibition mechanism down-regulating MYC, as well as the linear and circular PVT1 transcripts. Future work should expand on clinical studies to better understand the prognostic role of PVT1 in OC.

Mining and exploration of rehabilitation nursing targets for colorectal cancer.

There are often subtle early symptoms of colorectal cancer, a common malignancy of the intestinal tract. However, it is not yet clear how MYC and NCAPG2 are involved in colorectal cancer. We obtained colorectal cancer datasets GSE32323 and GSE113513 from the Gene Expression Omnibus (GEO). After downloading, we identified differentially expressed genes (DEGs) and performed Weighted Gene Co-expression Network Analysis (WGCNA). We then undertook functional enrichment assay, gene set enrichment assay (GSEA) and immune infiltration assay. Protein-protein interaction (PPI) network construction and analysis were undertaken. Survival analysis and Comparative Toxicogenomics Database (CTD) analysis were conducted. A gene expression heat map was generated. We used TargetScan to identify miRNAs that are regulators of DEGs. 1117 DEGs were identified. Their predominant enrichment in activities like the cellular phase of the cell cycle, in cell proliferation, in nuclear and cytoplasmic localisation and in binding to protein-containing complexes was revealed by Gene Ontology (GO). When the enrichment data from GSE32323 and GSE113513 colon cancer datasets were merged, the primary enriched DEGs were linked to the cell cycle, protein complex, cell cycle control, calcium signalling and P53 signalling pathways. In particular, MYC, MAD2L1, CENPF, UBE2C, NUF2 and NCAPG2 were identified as highly expressed in colorectal cancer samples. Comparative Toxicogenomics Database (CTD) demonstrated that the core genes were implicated in the following processes: colorectal neoplasia, tumour cell transformation, inflammation and necrosis. High MYC and NCAPG2 expression has been observed in colorectal cancer, and increased MYC and NCAPG2 expression correlates with worse prognosis.