Cancers, Vol. 16, Pages 3752: HDAC6 as a Prognostic Factor and Druggable Target in HER2-Positive Breast Cancer

Background: Adjuvant trastuzumab is the standard of care for HER2+ breast cancer (BC) patients. However, >50% of patients become resistant. This study aimed at the identification of the molecular factors associated with disease relapse and their further investigation as therapeutically exploitable targets. Methods: Analyses were conducted on formalin-fixed paraffin-embedded tissues of the primary tumors of relapsed (cases) and not relapsed (controls) HER2+ BC patients treated with adjuvant trastuzumab. The nCounter Human Breast Cancer Panel 360 was used. Logistic regression and partitioning around medoids were employed to identify the genes associated with disease recurrence. Cytotoxicity experiments using trastuzumab-resistant cell lines and a network pharmacology approach were carried out to investigate drug efficacy. Results: A total of 52 patients (26 relapsed and 26 not relapsed) were analyzed. We found that a higher expression of HDAC6 was significantly associated with an increased risk of recurrence, with an adjusted OR of 3.20 (95% CI 1.38–9.91, p = 0.016). Then, we investigated the cytotoxic activity of the selective HDAC6 inhibitor Nexturastat A (NextA) on HER2+ cell lines, which were both sensitive and trastuzumab-resistant. A sub-cytotoxic concentration of NextA, combined with trastuzumab, showed a synergistic effect on BC cell lines. Finally, using a network pharmacology approach, we identified HSP90AA1 as the putative molecular candidate responsible for the synergism observed in vitro. Conclusions: Our findings encourage the exploration of the role of HDAC6 as a prognostic factor and the combinatorial use of HDAC6 selective inhibitors combined with trastuzumab in HER2+ BC, in particular for those patients experiencing drug resistance.

Cancers, Vol. 16, Pages 3751: Analysis of the Predictability of Postoperative Meningioma Resection Status Based on Clinical Features

Background: Our aim was to investigate the predictability of postoperative meningioma resection status based on clinical features. Methods: We examined 23 clinical features to assess their effectiveness in distinguishing gross total resections (GTR) from subtotal resections (STR). We analyzed whether GTR/STR cases are better predictable if the classification is based on the Simpson grading or the postoperative operative tumor volume (POTV). Results: Using a study cohort comprising a total of 157 patients, multivariate models for the preoperative prediction of GTR/STR outcome in relation to Simpson grading and POTV were developed and subsequently compared. Including only two clinical features, our models showed a notable discriminatory power in predicting postoperative resection status. Our final model, a straightforward decision tree applicable in daily clinical practice, achieved a mean AUC of 0.885, a mean accuracy of 0.866, a mean sensitivity of 0.889, and a mean specificity of 0.772 based on independent test data. Conclusions: Such models can be a valuable tool both for surgical planning and for early planning of postoperative treatment, e.g., for additional radiotherapy/radiosurgery, potentially required in case of subtotal resections.

Cancers, Vol. 16, Pages 3750: Inhibition of K+ Channels Affects the Target Cell Killing Potential of CAR T Cells

Ion channels of T cells (Kv1.3, KCa3.1, and CRAC) participate in the regulation of activation and effector functions via modulation of the Ca2+-dependent pathway. T cells expressing chimeric antigen receptors (CAR T cells) showed a remarkable role in anti-tumor therapy, especially in the treatment of chemotherapy-resistant liquid cancers. Nevertheless, many challenges remain to be overcome to improve the treatment for solid tumors. In this study, we assessed the expression and role of ion channels in CAR T cells. We found that HER2-specific CAR T cells had higher KCa3.1 conductance compared to the non-transduced (NT, control) cells, which was more prominent in the CD8+ population (CD4+ cell also showed elevation). Conversely, the Kv1.3 expression level was the same for all cell types (CD4+, CD8+, CAR, and NT). Single-cell Ca2+ imaging revealed that thapsigargin-induced SOCE via CRAC is suppressed in CD8+ CAR T cells, unlike for CD4+ and CD8+ NT cells. To dissect the functional role of Kv1.3 and KCa3.1, we used specific antagonists (Kv1.3: Vm24; KCa3.1: TRAM-34): the target cell elimination capacity of the CD8+ CAR T cells was improved either by blocking KCa3.1 or Kv1.3. These results imply that ion channels could be a target in CAR T cell immunotherapy elaboration.

Cancers, Vol. 16, Pages 3749: Increased c-MYC Expression Associated with Active IGH Locus Rearrangement: An Emerging Role for c-MYC in Chronic Lymphocytic Leukemia

This review examines the pivotal role of c-MYC in Chronic Lymphocytic Leukemia (CLL), focusing on how its overexpression leads to increased genetic instability, thereby accelerating disease progression. MYC, a major oncogene, encodes a transcription factor that regulates essential cellular processes, including cell cycle control, proliferation, and apoptosis. In CLL cases enriched with unmutated immunoglobulin heavy chain variable (IGHV) genes, MYC is significantly overexpressed and associated with active rearrangements in the IGH immunoglobulin heavy chain locus. This overexpression results in substantial DNA damage, including double-strand breaks, chromosomal translocations, and an increase in abnormal repair events. Consequently, c-MYC plays a dual role in CLL: it promotes aggressive cell proliferation while concurrently driving genomic instability through its involvement in genetic recombination. This dynamic contributes not only to CLL progression but also to the overall aggressiveness of the disease. Additionally, the review suggests that c-MYC’s influence on genetic rearrangements makes it an attractive target for therapeutic strategies aimed at mitigating CLL malignancy. These findings underscore c-MYC’s critical importance in advancing CLL progression, highlighting the need for further research to explore its potential as a target in future treatment approaches.

Cancers, Vol. 16, Pages 3748: Exploring Extracellular Vesicle Surface Protein Markers Produced by Glioblastoma Tumors: A Characterization Study Using In Vitro 3D Patient-Derived Cultures

Background/Objectives: Glioblastoma (GBM) is an aggressive brain cancer with limited treatment options. Extracellular vesicles (EVs) derived from GBM cells contain important biomarkers, such as microRNAs, proteins, and DNA mutations, which are involved in tumor progression, invasion, and resistance to treatment. Identifying surface markers on these EVs is crucial for their isolation and potential use in noninvasive diagnosis. This study aimed to use tumor-derived explants to investigate the surface markers of EVs and explore their role as diagnostic biomarkers for GBM. Methods: Tumor explants from nine GBM patients without IDH1/IDH2 mutations or 1p-19q co-deletion were cultured to preserve both tumor viability and cytoarchitecture. EVs were collected from the tumor microenvironment using differential centrifugation, filtration, and membrane affinity binding. Their surface protein composition was analyzed through multiplex protein assays. RNA-Seq data from TCGA and GTEx datasets, along with in silico single-cell RNA-seq data, were used to assess EV surface biomarker expression across large GBM patient cohorts. Results: The in vitro model successfully replicated the tumor microenvironment and produced EVs with distinct surface markers. Biomarker analysis in large datasets revealed specific expression patterns unique to GBM patients compared with healthy controls. These markers demonstrated potential as a GBM-specific signature and were correlated with clinical data. Furthermore, in silico single-cell RNA-seq provided detailed insights into biomarker distribution across different cell types within the tumor. Conclusions: This study underscores the efficacy of the tumor-derived explant model and its potential to advance the understanding of GBM biology and EV production. A key innovation is the isolation of EVs from a model that faithfully mimics the tumor’s original cytoarchitecture, offering a deeper understanding of the cells involved in EV release. The identified EV surface markers represent promising targets for enhancing EV isolation and optimizing their use as diagnostic tools. Moreover, further investigation into their molecular cargo may provide crucial insights into tumor characteristics and evolution.

Cancers, Vol. 16, Pages 3744: Beta-2-Microglobulin Maintains Overall Survival Prediction in Binet a Stage Chronic Lymphocytic Leukemia Patients with Compromised Kidney Function in Both Treatment Eras of Chemoimmunotherapy and Targeted Agents

Background: Elevated beta-2-microglobulin (B2M) plasma levels commonly imply a higher CLL-IPI risk category for short overall survival (OS), but the risk model was not adjusted for compromised kidney function and not validated in Binet A stage CLL patients. Methods: CLL patients were identified from 2000 to 2022 at Innsbruck University Hospital, Austria. B2M levels, CLL-IPI risk stratification, and kidney function were assessed. Treatment modalities in case of disease progression and OS data during follow-up were evaluated. Results: A total of 259 Binet A stage CLL patients were identified; 16.9% (n = 44/259) presented with concurrent chronic kidney disease (CKD, GFR < 60 mL/min). Median OS was 170 months and was similar in CKD and non-CKD patients (p = 0.25). The CLL-IPI facilitated prognostic segregation in both CKD (p = 0.02) and non-CKD patients (p = 0.008). Although more frequently elevated in CKD patients (44.1% versus 10.6%, p < 0.001), B2M > 3.5 mg/L remained associated with inferior OS in this subgroup (p = 0.03). Contrary to the CLL-IPI, the prognostic value of B2M alone was also maintained in CLL patients diagnosed and potentially treated frontline in the era of targeted agents (2014–2022, p = 0.03). Conclusions: B2M retains its prognostic value for OS in early-stage CLL patients with concurrent CKD and still represents a promising covariate for up-coming prognostic models to identify patients at high risk for inferior OS in the era of targeted agents.

Cancers, Vol. 16, Pages 3747: Biphenotypic Sinonasal Sarcoma: Literature Review of a Peculiar Pathological Entity—The Neurosurgical Point of View

Background: Biphenotypic sinonasal sarcoma (BSNS) is a low-grade tumor of the sinonasal tract with frequent extension to the orbit and skull base. Due to its rare incidence and recent histopathological and molecular characterization, little data are available in regard to its natural history, treatment and surveillance protocol. Methods: A comprehensive literature review in Embase online electronic databases on BSNS was made. The analyzed factors included the patients’ sex and age, presenting symptoms and signs, anatomical origin and pattern of growth of the tumor, immunohistochemical and molecular features, time to treatment, type of treatment, surgical approach, extent of resection, peri- and post-operative complications, adjuvant therapies, clinical outcome, recurrence and overall survival rates. Results: This literature review involved 34 studies for an overall series of 149 cases of BSNS. The female (66.9%) and middle-aged populations (median 54.88 years old) were mainly affected. The most frequent clinical onset was nasal obstruction (81%), followed by facial discomfort (44%), epistaxis (15.5%) and ocular impairment (14.3%). Ethmoid sinus (67.8%) and nasal cavity (45.4%) were the most common anatomical site of tumor origin, while an extension to the orbit and skull base was registered in 28.7% and 24.5% of cases. Surgery was the main treatment, especially in the form of endoscopic endonasal approach (56.9%), and allowed for gross total resection in 79% of cases. The recurrence rate was 26.2%; three cases of tumor-related death were reported. Median follow-up was 4.6 years. Conclusions: Biphenotypic sinonasal sarcoma is a rare and unique tumoral entity in terms of biological and clinical behavior. Based on the current knowledge, surgery plays the leading role in treatment, accounting for gross total tumor resection in most cases, allowing for clinical symptom and sign resolution and presenting a low rate of perioperative complications. The type of approach and the aim of surgery should be assessed case by case according to patient and pathology features and the surgeon’s experience, as well as the aim of the treatment. Further studies including large surgical series and with long follow-up are required to define prognostic factors and guidelines of treatment for this peculiar pathological entity.

Cancers, Vol. 16, Pages 3743: Targeting Menin in Acute Myeloid Leukemia: Therapeutic Advances and Future Directions

Germline mutations in the MEN1 gene encoding menin protein cause multiple endocrine neoplasia type 1 (MEN1) syndrome. Recent evidence suggests that inhibiting the interaction of menin with its crucial oncogenic protein partners represents a promising therapeutic strategy to AML. Menin plays a critical role in lysine methyltransferase 2A (KMT2A)-gene-rearranged and NPM1-m acute leukemias, both associated with adverse outcomes with current standard therapies, especially in the relapsed/refractory setting. Disrupting the menin–KMT2A interaction affects the proleukemogenic HOX/MEIS transcription program. This disruption leads to the differentiation of KMT2Ar and NPM1-m AML cells. Small molecular inhibitors of the menin–KMT2A interaction target the central cavity of MEN1 to inhibit the MEN1-KMT2A interaction and could target a similar transcriptional dependency in other leukemia subsets, broadening their therapeutic potential. These agents, both as monotherapies and in combination with synergistic drugs, are undergoing preclinical and clinical evaluation with promising early results. With the growing literature around menin inhibitors in AML, we discussed the biology of menin, its mechanism of action, its interacting partners in leukemia, possible inhibitors, their implications, synergistic drugs, and future therapeutic strategies in this review.

Cancers, Vol. 16, Pages 3746: Multi-Omic Characterization of Single Cells and Cell-Free Components Detected in the Cerebrospinal Fluid of Patients with Leptomeningeal Disease

Background/Objectives: Up to 30% of patients with breast cancers will develop brain or leptomeningeal metastases, and this risk is especially high with HER2-positive cancers. For patients with central nervous system metastases, cerebrospinal fluid (CSF) liquid biopsies are a promising opportunity to monitor disease, inform treatment, and predict prognosis. This pilot study investigated CSF liquid biopsy analytes from three patients diagnosed with central nervous system metastases based on imaging but not confirmed via clinical cytology. Methods: The detection of cellular analytes with the non-enrichment high-definition single-cell assay (HDSCA3.0) workflow was compared between the CSF and matched peripheral blood (PB) samples. Results: Circulating tumor cells (CTCs) were detected in the CSF but not the PB and were subsequently molecularly characterized using single-cell genomics and targeted multiplexed proteomics to reveal a clonal population of phenotypically heterogeneous cells. There was a lack of concordance in the copy number alteration profiles between CTCs and cell-free DNA (cfDNA) in the CSF. Extracellular vesicle surface marker analysis in CSF revealed a prominent signal among tetraspanins (CD9/CD63/CD81), with CD81 exhibiting the highest signal across all patients. Conclusions: The data presented suggest that CSF could be a useful tool for diagnosing and assessing disease severity.