Slowed Tumor Growth Research Articles

Vaccination Against Androgen Receptor Splice Variants to Immunologically Target Prostate Cancer

Background/Objectives: Androgen receptor (AR) expression and signaling are critical for the progression of prostate cancer and have been the therapeutic focus of prostate cancer for over 50 years. While a variety of agents have been developed to target this axis, many of these fail due to the emergent expression of AR RNA splice variants, such as AR-V7, that can signal independently of ligand binding. Other therapies, such as vaccination against prostate-specific antigens, have achieved FDA approvals but have fallen short of being incorporated as standard-of-care therapies for advanced prostate cancer. This may be due to the elevated level of immunosuppression observed in prostate cancer, which remains largely refractory to immune checkpoint blockade. Methods: We developed a vaccine targeting AR-V7, a common isoform associated with treatment resistance, and demonstrated its ability to elicit AR-V7-specific immunity and enable anti-tumor responses against AR-V7+ cancers in subcutaneous tumor models. Results: Our studies also revealed that AR-V7 expression conferred an immune suppressive phenotype that was significant in a non-AR-dependent prostate cancer model. Notably, in this model, we found that vaccination in combination with enzalutamide, an AR antagonist, suppressed these aggressive immune suppressive cancers and resulted in enhanced survival in comparison to control vaccinated and enzalutamide-treated mice. While anti-PD-1 immune checkpoint inhibition (ICI) alone slowed tumor growth, the majority of vaccinated mice that received anti-PD-1 therapy showed complete tumor elimination. Conclusions: Collectively, these results validate the importance of AR signaling in prostate cancer immune suppression and suggest the potential of AR-V7-specific vaccines as therapeutic strategies against prostate cancer, offering significant protective and therapeutic anti-tumor responses, even in the presence of androgen signaling inhibitors.

TMET-19. REWIRING OF CORTICAL GLUCOSE METABOLISM FUELS HUMAN BRAIN CANCER GROWTH

Abstract The brain avidly consumes glucose to fuel neurophysiology. Cancers of the brain, such as glioblastoma (GBM), lose aspects of normal biology and gain the ability to proliferate and invade healthy tissue. How brain cancers rewire glucose utilization to fuel these processes is poorly understood. Here we perform infusions of 13C-labeled glucose into patients and mice with brain cancer to define the metabolic fates of glucose-derived carbon in tumor and cortex. By combining these measurements with quantitative metabolic flux analysis, we find that human cortex funnels glucose-derived carbons towards physiologic processes including TCA cycle oxidation and neurotransmitter synthesis. In contrast, brain cancers downregulate these physiologic processes, scavenge alternative carbon sources from the environment, and instead use glucose-derived carbons to produce molecules needed for proliferation and invasion. In particular, we find that cortical tissue produces its own glucose-derived serine, whereas gliomas predominantly consume serine from the environment. Targeting this metabolic rewiring in mice through dietary modulation selectively alters GBM metabolism and slows tumor growth. Combining dietary serine restriction with chemoradiation reduces brain tumor growth in mice, suggesting that such a dietary intervention could improve outcomes for patients with high grade glioma.

EXTH-80. A NOVEL BISAMINOQUINOLINE DERIVATIVE NANOPARTICLE (BAQ13-NP) FOR THE TREATMENT OF GLIOBLASTOMA

Abstract Aminoquinolines, such as hydroxycholoquine, are known to inhibit autophagy and slow cancer cell growth, improving survival in preclinical models of glioblastoma. Unfortunately, they failed to demonstrate benefit in clinical trials due to a lack of sufficient potency and BBB penetration. We have developed a novel bisaminoquinoline derivative packaged in a nanoparticle (BAQ13-NP) with improved potency and intratumoral accumulation after systemic administration, confirmed by distribution and toxicity studies in animals. In this study, we evaluated the impact of BAQ13-NP on tumor cell autophagy and survival using patient-derived glioma cell lines and murine models. GBM patient-derived cell lines (n=4) and murine glioma cells (GL261, CT-2A) were treated with BAQ13-NP (1-4 µM) in culture, demonstrating growth restriction to less than 50% of control at 5-7 days (p<0.01) by MTT assay. Cells treated with BAQ13-NP also demonstrated reduced autophagy with significant increases in accumulation of LC3B and p62 (p<0.01) and reduced IL-6 dependent STAT3 phosphorylation in tumor cells, T cells, and myeloid cells (p<0.01). In addition, treatment of tumor cells with BAQ13-NP reduced IL-6 production over 50% (p<0.01). Mice with orthotopic GL261 or CT2A tumors were treated with BAQ13-NP by tail vein injection (25 mg/kg q2 days) starting 7 days post implantation. Significantly increased survival was observed in BAQ13-NP treated GL261 (HR 0.75, p=0.030) and CT2A (HR 0.78, p=0.033) bearing mice compared to vehicle control treated animals. Reduced tumor size at specific intervals was also observed with BAQ13-NP treatment, corelating with improved survival. BAQ13-NP can inhibit autophagy and slow glioma tumor growth, improving survival in preclinical models. Given the excellent distribution and low toxicity of this novel agent when delivered intravenously, we believe it has great potential to improve outcomes for GBM patients. Our drug has recently received IND approval and will soon be tested in a phase I clinical trial.

A new tumor-treating device OM-100 with low-frequency magnetic fields inhibits proliferation and metastasis in liver cancer.

This study aims to investigate a novel instrument OM-100 with low-frequency magnetic fields (LFMFs) for its potential applicability in the treatment of liver cancer. Liver cancer cell lines (HepG2 and Huh7) and normal liver cell line THLE-2 were exposed to OM-100 at LFMFs of 0, 10, 25, 50, and 100kHz for 2h in the morning, noon, and evening, respectively. The effects of LFMF on cell viability, apoptosis, migration, and invasion capabilities were examined. Additionally, impacts of LFMF on ROS production was assessed. In vivo studies were conducted to examine the safety profile of OM-100 and its effects on tumor growth. In vitro, OM-100 reduced the viability of liver cancer cells, increased cell apoptosis, and inhibited cell migration and invasion abilities in a frequency-dependent manner (P < 0.05). In vivo, OM-100significantly slowed down tumor growth and promoted apoptosis in liver tumors (P < 0.05). Moreover, OM-100 rarely affected the viability of normal liver cells, as well as the health of normal mice. Finally, we further found that OM-100 significantly increased the production of ROS in liver cancer cells (P < 0.05), a key factor in inducing autophagy, which is very important for the progression of liver cancer. Our findings reveal the safety of OM-100 and its frequency at 100kHz significantly inhibits liver cancer progression.

CSIG-04. ANTI-TUMOR RESPONSE OF ONCOMAGNETIC MONOTHERAPY IN GLIOBLASTOMA

Abstract BACKGROUND Glioblastoma (GBM) is the most lethal primary malignant brain tumor with a median survival of 15–20 months. Concurrent temozolomide (TMZ) chemotherapy and radiation (XRT) remain the current standard of care (SOC) treatment for newly diagnosed GBM. The addition of tumor treating fields (TTFs) improves median survival for newly diagnosed GBM from 16 to 20.9 months. This modest improvement underscores the urgent need to identify a new treatment modality as a safe and effective therapy. PURPOSE The noninvasive Oncomagnetic device developed in our laboratory selectively kills glioblastoma (GBM) in vitro. We studied the cellular and molecular effects of Oncomagnetic monotherapy (OMT) on GBM cell lines and investigated immune response in a syngeneic mouse model. RESULTS OMT significantly reduces cell proliferation and cell survival in vitro. OMT induces persistent ROS primarily by increasing superoxide level in cancer cells and reduces mitochondrial-membrane potential in GBM cells. It also induces DNA damage and arrests cells in G1-phase of the cell cycle. Whole-body Oncomagnetic stimulation caused a substantial retardation of tumor growth and reduction of the contrast-enhanced tumor volume in 9.4T MRI scans. OMT showed significant increase in overall survival in treated mice. We also observed upregulated immune response indicated by RNA sequencing data obtained from OMT-treated GBM cells as well as in treated GBM mouse tumor sections by imaging mass cytometry analysis. The tSNE analysis of various immune clusters suggests significant increase in immune response by activating CD4+, CD8+, murine-macrophages and M1-macrophages located at tumor site in the treated group. CONCLUSION The obtained data indicate significant anti-tumor response by inhibiting cancer signaling pathways and an increased immune response. Our findings suggest unique mechanism of action for OMT stimulation and provide a strong rationale for standalone OMT for GBM.

TMET-27. MACHINE LEARNING-BASED IDENTIFICATION OF METABOLIC FLUXES IN PATIENT BRAIN TUMORS

Abstract Personalized oncology aims to match effective treatments for individual cancer patients based on the biology of an individual tumor. This approach is not possible for metabolic therapies due to our inability to quantify metabolic activity in patient tumors, even when patients are infused with 13C-glucose. We overcame this challenge by generating training data with a prior knowledge of 13C-glucose infused patient data and implementing a machine learning model to predict fluxes. We trained a convolutional neural network (CNN) to predict flux ratios. To validate our model, we compared predicted flux ratios to the experimental 13C-glucose-infused mouse models to predict treatment responses for: (1) pharmacologic inhibition of de novo GMP synthesis and (2) environmental serine restriction. Our GMP synthesis model predicted elevated GMP synthesis in GBM compared to cortex in a mouse model and discriminated between sources of GMP synthesis in patients. These findings allow prediction of potential responders to mycophenolate mofetil (MMF), which inhibits de novo but not salvage GMP synthesis. Furthermore, we previously showed that circulating serine uptake is higher in GBM than normal cortex, and a serine- and glycine-restricted diet slows tumor growth in mice. While de novo serine synthesis, circulating and microenvironmental-derived serine could account for serine sources in GBM, our model can distinguish between serine sources in patients, hence potentially predict response to dietary serine depletion. Thus, we have shown that our model may identify patients who will benefit from MMF treatment or a serine- and glycine-restricted diet, potentially enabling administration of highly effective personalized metabolic treatments for GBM patients.

EXTH-41. COMBINATION TREATMENT WITH RAF/MEK AND FAK INHIBITION ENHANCES TUMOR GROWTH INHIBITION IN MENINGIOMA

Abstract BACKGROUND Patients with meningiomas who have progressed after multimodal treatments face a significant shortage of viable therapeutic options. Recent advancements in the molecular understanding of meningiomas have identified the FAK and RAF/MEK signaling pathways as potential promising targets for progressive meningiomas. METHODS In vitro, we tested two human meningioma cell lines, IOMM-Lee (NF2 wild-type and CDKN2A loss) and CH157-MN (NF2 mutant). The cells were plated in Matrigel-coated wells, treated with defactinib (FAK inhibitor), VS-6766 (RAF/MEK inhibitor, avutometinib) and the combination over a 7-day period and assessed for cell viability using the CellTiter-Glo 3D assay. In vivo, we tested the efficacy of the FAK inhibitor VS-4718 (possessing favorable pharmacokinetic properties in mice) and RAF/MEK inhibitor VS-6766, both given daily via oral gavage, in athymic nude mice bearing IOMM-Lee or CH157-MN tumors. RESULTS In the matrigel assay, VS-6766 suppressed IOMM-Lee and CH157-MN cells in a dose dependent manner. The drug combination was mostly additive in IOMM-Lee cells. However, CH157-MN cells showed a strong synergistic response across all drug concentrations tested. In the IOMM-Lee flank tumor model, VS-4718 alone had no effect, while VS-6766 alone or in combination significantly reduced tumor growth and extended median survival from 25 days to 47 days (p &amp;lt; 0.05). In the CH157 flank tumor model, VS-4718 monotherapy did not affect tumor growth or survival, but VS-6766 monotherapy slowed tumor growth and increased median survival from 10 days to 31 days (p &amp;lt; 0.001). Combining both drugs further reduced tumor growth and extended median survival to 42 days (p &amp;lt; 0.001). CONCLUSION Treatment with FAK and RAF/MEK inhibitors showed synergistic or combination effects in the NF2 mutant CH157-MN model in vitro and in vivo. RAF/MEK inhibitor monotherapy was effective for the IOMM-Lee model (NF2 wild-type), without clear benefit of combining with the FAK inhibitor. Investigations in intracranial tumor models are underway.

ASAP1 and ARF1 regulate myogenic differentiation in rhabdomyosarcoma by modulating TAZ activity.

Despite aggressive, multimodal therapies, the prognosis of patients with refractory or recurrent rhabdomyosarcoma (RMS) has not improved in four decades. Because RMS resembles skeletal muscle precursor cells, differentiation-inducing therapy has been proposed for patients with advanced disease. In RAS-mutant PAX fusion-negative RMS (FN-FMS) preclinical models, MEK1/2 inhibition (MEKi) induces differentiation, slows tumor growth, and extends survival. However, the response is short-lived. A better understanding of the molecular mechanisms regulating FN-RMS differentiation could improve differentiation therapy. Here, we identified a role in FN-RMS differentiation for ASAP1, an ARF GTPase-activating protein (ARF GAP) with both pro-invasive and tumor suppressor functions. We found that ASAP1 knockdown inhibited differentiation in FN-RMS cells. Interestingly, knockdown of the GTPases ARF1 or ARF5, targets of ASAP1 GAP activity, also blocked differentiation of FN-RMS. We discovered that loss of ARF pathway components blocked myogenic transcription factor expression. Therefore, we examined the effects on transcriptional regulators. MEKi led to the phosphorylation and inactivation of WWTR1 (TAZ), a homolog of the pro-proliferative transcriptional co-activator YAP1 regulated by the Hippo pathway. However, loss of ASAP1 or ARF1 blocked this inactivation, which inhibits MEKi-induced differentiation. Finally, MEKi-induced differentiation was rescued by dual knockdown of ASAP1 and WWTR1. This study shows that ASAP1 and ARF1 are necessary for myogenic differentiation, providing a deeper understanding of differentiation in FN-RMS and illuminating an opportunity to advance differentiation therapy. Implications: ASAP1 and ARF1 regulate MEKi-induced differentiation of FN-RMS cells by modulating WWTR1 (TAZ) activity, supporting YAP1/TAZ inhibition as a FN-RMS differentiation therapy strategy.

Quercetin inhibits endothelial & hepatocellular carcinoma cell crosstalk via reducing extracellular vesicle-mediated VEGFR2 mRNA transfer.

This study aims to investigate the regulatory effects of quercetin extracellular vesicles (EVs)-mediated expression of vascular endothelial growth factor receptor 2 (VEGFR2) in hepatocellular carcinoma (HCC)-derived circulating tumor cells (CTCs) and the underlying mechanisms. CTCs were isolated from patients with pathologically diagnosed HCC, with VEGFR2 expression visualized by fluorescence in situ hybridization (FISH). The human HCC cell line Huh-7 and SK-HEP-1 were used for in vitro studies to assess EVs uptake, VEGFR2 mRNA transfer, invasion, migration, cancer stem cell (CSC) properties, and VEGF secretion. Results showed that VEGFR2 mRNA was commonly expressed in HCC-CTCs, with a higher incidence in biphenotypic CTCs. Its expression was limited in HCC cell lines, but present in certain liver cells. In vitro experiments confirmed that VEGFR2 mRNA could be transferred to HCC cells via EVs from primary tumor endothelial cells (PTECs), which was impaired by quercetin treatment. Quercetin significantly reduced VEGFR2 mRNA and protein expression in HCC cells, weakened their invasive and metastatic capacities, and diminished VEGFR2-mediated CSC properties. In vivo, quercetin reduced VEGF secretion, impaired angiogenesis, slowed tumor growth, and decreased the number and proportion of VEGFR2-positive CTCs. In summary, VEGFR2 mRNA is present in HCC-CTCs, potentially sourced from PTECs-derived EVs. Quercetin effectively inhibits VEGFR2 expression, impacting HCC cell invasion, metastasis, and CSC characteristics. Besides, it reduces VEGFR2-positive CTCs in vivo. These effects support its therapeutic potential in HCC treatment by targeting the angiogenesis and tumor dissemination pathway.

Engineered protein destabilization reverses intrinsic immune evasion for candidate vaccine pan-strain KSHV and SARS-CoV-2 antigens.

Both Kaposi sarcoma herpesvirus LANA and SARS coronavirus 2 RdRp/nsp12 are highly conserved replication proteins that evade immune processing. By deleting the LANA central repeat 1 domain (LANA ΔCR1 ) or by dividing RdRp into two separated fragments (RdRp Frag ) to maximize nascent protein mis-folding, cis peptide presentation was increased. Native LANA or RdRp SIINFEKL fusion proteins expressed in MC38 cancer cells were not recognized by activated OT-1 CD8 + cells against SIINFEKL but cytotoxic recognition was restored by expression of the corresponding modified proteins. Immunocompetent syngeneic mice injected with LANA- or RdRp-SIINFEKL MC38 cells developed rapidly-growing tumors with short median survival times. Mice injected with LANA ΔCR1 - or RdRp Frag -SIINFEKL had partial tumor regression, slower tumor growth, longer median survival, as well as increased effector-specific tumor-infiltrating lymphocytes. These mice developed robust T cell responses lasting at least 90 days post-injection that recognized native viral protein epitopes. Engineered vaccine candidate antigens can unmask virus-specific CTL responses that are typically suppressed during native viral infection.

PRMT5 maintains tumor stem cells to promote pediatric high-grade glioma tumorigenesis.

Pediatric high-grade gliomas (PHGG) are aggressive, undifferentiated CNS tumors with poor outcomes, for which no standard-of-care drug therapy currently exists. Through a knockdown screen for epigenetic regulators, we identified PRMT5 as essential for PHGG cell growth. We hypothesized that, similar to its effect in normal cells, PRMT5 promotes self-renewal of stem-like PHGG tumor initiating cells (TICs) essential for tumor growth. We conducted in vitro analyses, including limiting dilution studies of self-renewal, to determine the phenotypic effects of PRMT5 KD. We performed ChIP-Seq to identify PRMT5-mediated epigenetic changes and performed gene set enrichment analysis to identify pathways that PRMT5 regulates. Using an orthotopic xenograft model of PHGG, we tracked survival and histological characteristics resulting from PRMT5 KD or administration of a PRMT5 inhibitor ± radiation therapy (RT). In vitro, PRMT5 KD slowed cell cycle progression, tumor growth and self-renewal, and altered chromatin occupancy at genes associated with differentiation, tumor formation and growth. In vivo, PRMT5 KD increased survival and reduced tumor aggressiveness; however, pharmacological inhibition of PRMT5 with or without RT did not improve survival. PRMT5 KD epigenetically reduced TIC self-renewal, leading to increased survival in preclinical models. Pharmacological inhibition of PRMT5 enzymatic activity may have failed in vivo due to insufficient reduction of PRMT5 activity by chemical inhibition, or this failure may suggest that non-enzymatic activities of PRMT5 are more relevant. Implications: PRMT5 maintains and promotes the growth of stemlike cells that initiate and drive tumorigenesis in pediatric high grade glioma.

Catabolism of extracellular glutathione supplies amino acids to support tumor growth.

Restricting amino acids from tumors is an emerging therapeutic strategy with significant promise. While typically considered an intracellular antioxidant with tumor-promoting capabilities, glutathione (GSH) is a tripeptide of cysteine, glutamate, and glycine that can be catabolized, yielding amino acids. The extent to which GSH-derived amino acids are essential to cancers is unclear. Here, we find that GSH catabolism promotes tumor growth. We show that depletion of intracellular GSH does not perturb tumor growth, and extracellular GSH is highly abundant in the tumor microenvironment, highlighting the potential importance of GSH outside of tumors. We find supplementation with GSH can rescue cancer cell survival and growth in cystine-deficient conditions, and this rescue is dependent on the catabolic activity of γ-glutamyltransferases (GGTs). Finally, pharmacologic targeting of GGTs' activity prevents the breakdown of circulating GSH, lowers tumor cysteine levels, and slows tumor growth. Our findings indicate a non-canonical role for GSH in supporting tumors by acting as a reservoir of amino acids. Depriving tumors of extracellular GSH or inhibiting its breakdown is potentially a therapeutically tractable approach for patients with cancer. Further, these findings change our view of GSH and how amino acids, including cysteine, are supplied to cells.

Cancer-associated Fibroblasts-derived Exosomes with HOXD11 Overexpression Promote Ovarian Cancer Cell Angiogenesis Via FN1.

Cancer-associated fibroblasts (CAFs) represent a critical stromal component of metastatic niche and promote metastasis in patients with ovarian cancer (OC). Here, we try to further understand the mechanism by which CAFs-derived exosomes (CAFs-Exo) promoted angiogenesis in OC. We intersected differentially expressed genes in OC cells after CAFs-Exo treatment in the GSE147610 dataset with a list of transcription factors to identify homeobox protein hox-D11 (HOXD11) as a possible cargo of CAFs-Exo. HOXD11 encapsulated by CAFs-Exo enhanced colony formation, migration, and invasion of OC cells. HOXD11 bound to the promoter of fibronectin (FN1) and promoted its transcription. HOXD11 knockdown from CAFs-Exo significantly repressed the VEGF and CD31 protein expression and tube formation, viability, and migration of human umbilical vein endothelial cells (HUVEC) and slowed angiogenesis and tumor growth in mice. Furthermore, we found that overexpression of FN1 increased the expression of angiogenic factors and activity of HUVEC in the presence of HOXD11 knockdown. These results verify the significant contribution of CAFs-Exo to angiogenesis in OC, which could be partially due to the promotion of FN1 mediated by HOXD11.

Integrated bioinformatics analysis and experimental validation on malignant progression and immune cell infiltration of LTBP2 in gliomas

BackgroundGliomas are the highly aggressive brain tumor and also the most devastating human tumors. The latent TGF binding proteins (LTBP) had been found to be involved in malignant biological process and could be used as potent biomarkers in several solid tumors. While the role of LTBP family in human glioma remain to be elucidated.MethodsNormalized gene expression and corresponding clinical data of 2407 gliomas samples in public datasets were downloaded from Gliovis. Kaplan–Meier methods and Cox regression analysis was used for survival analyses.Western blot (WB) and Immunohistochemical (IHC) testing were employed to test LTBPs protein level in 154 gliomas samples. Correlation between LTBP2 expression and immune infiltration was evaluated by immunofluorescence (IF) and IHC in glioma tissues. CCK8 and flow cytometric analysis were used to detect the effect of LTBP2 on glioma cells. Orthotopic glioma- mouse models were utilized to evaluate effects in vivo.ResultsLTBP2 mRNA level was dramatically higher in glioma samples compared with non-tumor brain tissues in XENA-TCGA_GTEx, Gill and Gravendeel datasets (all P < 0.01), and its expression positively correlated with glioma WHO grade, IDH1/2 wildtype and mesenchymal subtypes. These results were confirmed by In-house cohort which was detected by WB and IHC. We found that gliomas patients with high LTBP2 level had shorter OS than those with low LTBP2 level. LTBP2 expression significantly associated with glioma immune score (Spearman r = 0.68, P < 0.01)) and strongly correlated with infiltration degreee of macrophages both in lower grade gliomas (LGG) and GBM. Knocking down LTBP2 obviously reduced proliferation and enhanced sensitivity to temozolomide in U87 and U251 cells. Nude mice with lower expression of LTBP2 had slower tumor growth, and accompanied by less tumor-associated macrophages (TAMs) infiltration detected by IHC staining in vivo. Finally, low LTBP2 expression glioma patients who received chemotherapy survived longer than patients with high LTBP2 expression.ConclusionLTBP2 could be used as a prognostic marker, and high LTBP2 expression related to abundant TAMs infiltration and with a worse response to chemotherapy.

Reviewing the efficiency of photobiomodulation therapy in oncological treatment.

The aim of the present systematic review is to evaluate the effects of different photobiomodulation therapy (PBMT) approaches in oncological treatment practices. The review follows the PRISMA guidelines. Specifically, the review is composed of laser PBMT and LED PBMT. A total of 23 studies were included, 14 investigating laser PBMT and 9 examining LED PBMT. In vitro studies demonstrated laser PBMT's potential to induce apoptosis and cytotoxicity in various cancer cell lines while enhancing sensitivity to chemotherapeutics and natural compounds. However, some studies highlighted divergent effects between in vitro (promoted proliferation) and in vivo xenograft models (slowed tumor growth) for certain laser wavelengths. LED PBMT studies showed blue light inhibited melanoma and pancreatic cancer cell growth, potentially via ROS generation, while red light raised concerns about enhancing oral cancer invasiveness. Both modalities mitigated treatment side effects like oral mucositis, xerostomia, peripheral neuropathy, and improved quality of life. While promising, the outcomes varied based on light parameters, cancer type, and experimental setting, necessitating further optimization of PBMT protocols through well-designed studies to establish long-term safety and efficacy across clinical scenarios.

Preclinical Evaluation of 226Ac as a Theranostic Agent: Imaging, Dosimetry, and Therapy.

226Ac (t½ = 29.37 h) has been proposed as a theranostic radioisotope leveraging both its diagnostic γ-emissions and therapeutic α-emissions. 226Ac emits 158 and 230 keV γ-photons ideal for quantitative SPECT imaging and acts as an invivo generator of 4 high-energy α-particles. Because of these nuclear decay properties, 226Ac has potential to act as a standalone theranostic isotope. In this proof-of-concept study, we evaluated a preclinical 226Ac-radiopharmaceutical for its theranostic efficacy and present the first 226Ac-targeted α-therapy study. Methods: 226Ac was produced at TRIUMF and labeled with the chelator-peptide bioconjugate crown-TATE. [226Ac]Ac-crown-TATE was selected to target neuroendocrine tumors in male NRG mice bearing AR42J tumor xenografts for SPECT imaging, biodistribution, and therapy studies. A preclinical SPECT/CT scanner acquired quantitative images reconstructed from both the 158 and the 230 keV emissions. Mice in the biodistribution study were euthanized at 1, 3, 5, 24, and 48 h after injection, and internal radiation dosimetry was derived for the tumor and organs of interest to establish appropriate therapeutic activity levels. Mice in the therapy study were administered 125, 250, or 375 kBq treatments and were monitored for tumor size and body condition. Results: We present quantitative SPECT images of the invivo biodistribution of [226Ac]Ac-crown-TATE, which showed agreement with ex vivo measurements. Biodistribution studies demonstrated high uptake (>30%IA/g at 5 h after injection) and retention in the tumor, with an estimated mean absorbed dose coefficient of 222 mGy/kBq. [226Ac]Ac-crown-TATE treatments significantly extended the median survival from 7 d in the control groups to 16, 24, and 27 d in the 125, 250, and 375 kBq treatment groups, respectively. Survival was prolonged by slowing tumor growth, and no weight loss or toxicities were observed. Conclusion: This study highlights the theranostic potential of 226Ac as a standalone therapeutic isotope in addition to its demonstrated diagnostic capabilities to assess dosimetry in matched 225Ac-radiopharmaceuticals. Future studies will investigate maximum dose and toxicity to further explore the therapeutic potential of 226Ac-radiopharmaceuticals.

Local Sustained Dinutuximab Delivery and Release From Methacrylated Chondroitin Sulfate.

Neuroblastoma (NB) is the most common pediatric extracranial solid tumor. High-risk NB is a subset of the disease that has poor prognosis and requires multimodal treatment regimens, with a 50% rate of recurrence despite intervention. There is a need for improved treatment strategies to reduce high-risk patient mortality. Dinutuximab is an anti-GD2 antibody ideal for targeting GD2 expressing NB cells, but binding of the antibody to peripheral nerve fibers leads to severe pain during systemic administration. Intratumoral delivery of the anti-GD2 antibody would allow for increased local antibody concentration, without increasing systemic toxicity. Chondroitin Sulfate (CS) is a biocompatible glycosaminoglycan that can be methacrylated to form CSMA, a photocrosslinkable hydrogel that can be loaded with therapeutic agents. The methacrylation reaction time can be varied to achieve different degrees of substitution, resulting in different release and degradation profiles. In this work, 4 and 24 h reacted CSMA was used to create hydrogels at 10% and 20% CSMA. Sustained in vitro release of dinutuximab from these formulations was observed over a 24-day period, and 4 h reacted 10% CSMA hydrogels had the highest overall dinutuximab release over time. An orthotropic mouse model was used to evaluate in vivo response to dinutuximab loaded 4 h methacrylated 10% CSMA hydrogels as compared to bolus tail vein injections. Tumor growth was monitored, and there was a statistically significant increase in the days to reach specific tumor size for tumors treated with intratumoral dinutuximab-loaded hydrogel compared to those treated with dinutuximab solution through tail vein injection. This supports the concept that locally delivering dinutuximab within the hydrogel formulation slowed tumor growth. The CSMA hydrogel-only treatment slowed tumor growth as well, an interesting effect that may indicate interactions between the CSMA and cell adhesion molecules in the tumor microenvironment. These findings demonstrate a potential avenue for local sustained delivery of dinutuximab for improved anti-tumoral response in high-risk NB.

Impact on Prognosis of Stage I Non-Small Cell Lung Cancer Secondary to Delays in Diagnostic Workup.

Background Diagnostic workup of small pulmonary nodules often requires follow-up CT scans to confirm nodule growth before invasive diagnostics or treatment. Purpose To confirm prior results from the International Early Lung Cancer Action Program (I-ELCAP) on quantifying decreases in lung cancer prognosis by using two large databases, the National Lung Screening Trial (NLST) and International Association for the Study of Lung Cancer (IASLC). Materials and Methods In this retrospective study, a model was developed to predict cure rates based on size of solid nodules using the NLST (August 2002 to summer 2007) and IASLC (January 2011 to December 2019) databases, focusing on stage I non-small cell lung cancer (NSCLC). Kaplan-Meier methods were used to calculate 10-year lung cancer-specific survival and 5-year overall survival rates for different tumor sizes. Tumor diameter increases after 90-, 180-, and 365-day delays were estimated using volume doubling times (VDTs) of 60, 120, and 240 days corresponding to fast, moderate, and slow tumor growth. Initial and delayed lung cancer cure rates were assessed across nine scenarios of time delays and tumor growth rates and compared with the previous results of the I-ELCAP database. Results Using regression models based on 166 NLST and 22 590 IASLC patients with NSCLC, 10-year lung cancer-specific survival and 5-year overall survival, respectively, for tumors 4.0-20.0 mm in diameter were estimated. For a 20.0-mm tumor with a 60-day VDT in the NLST database, the lung cancer-specific survival decreased from 83.4% to 76.5%, 66.8%, and 32.3% after 90, 180, and 365 days, respectively. The IASLC database showed similar decreases in 5-year overall survival, from 81.2% to 73.4%, 62.4%, and 23.3% after 90, 180, and 365 days, respectively. Comparison across NLST, IASLC, and I-ELCAP databases revealed minor variations in lung cancer cure rates between 79.9% and 83.4%, with reductions of 6.9%-8.3% after a 180-day delay with a 120-day VDT. Conclusion The NLST and IASLC databases confirmed prior estimates from the I-ELCAP database for the decrease in lung cancer prognosis due to diagnostic delays. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Park and Lee in this issue.

N6-methyladenosine-mediated upregulation of LNCAROD confers radioresistance in esophageal squamous cell carcinoma through stabilizing PARP1.

Radiotherapy is a primary therapeutic modality for esophageal squamous cell carcinoma (ESCC), but its effectiveness is still restricted due to the resistance of cancer cells to radiation. Long non-coding RNAs (lncRNAs) and N6-methyladenosine (m6A) have been shown to play significant roles in tumour radioresistance. However, the precise manifestation and role of m6A-modified lncRNAs in ESCC radioresistance remain unclear. Bioinformatics analysis was conducted to identify m6A-modified lncRNAs implicated in the radioresistance of ESCC. A series of functional experiments were performed to investigate the function of LNCAROD in ESCC. Methylated RNA immunoprecipitation, chromatin isolation by RNA purification-mass spectrometry, RNA immunoprecipitation, and co-immunoprecipitation experiments were performed to explore the mechanism of m6A-mediated upregulation of LNCAROD expression and the downstream mechanism enhancing the radioresistance of ESCC. The efficacy of LNCAROD in vivo was assessed using murine xenograft models. Herein, we identified LNCAROD as a novel METTL3-mediated lncRNA that enhanced radioresistance in ESCC cells and was post-transcriptionally stabilised by YTHDC1. Moreover, we confirmed that LNCAROD prevented ubiquitin-proteasome degradation of PARP1 protein by facilitating PARP1-NPM1 interaction, thereby contributing to homologous recombination-mediated DNA double-strand breaks repair and enhancing the radiation resistance of ESCC cells. Silencing LNCAROD in a nude mouse model of ESCC in vivo resulted in slower tumour growth and increased radiosensitivity. Our findings enhance the understanding of m6A-modified lncRNA-driven machinery in ESCC radioresistance and underscore the significance of LNCAROD in this context, thereby contributing to the development of a potential therapeutic target for ESCC patients.

Selective and Orally Bioavailable c-Met PROTACs for the Treatment of c-Met-Addicted Cancer.

c-Met is an attractive therapeutic target in multiple tumors. Previous studies have discovered some effective proteolysis-targeting chimeras (PROTACs) able to degrade c-Met; however, the structure-activity relationship (SAR), degradation selectivity, and pharmacokinetic profiles of c-Met PROTACs have, to date, remained largely unknown. Herein, through extensive SAR studies on various warheads, linkers, and E3 ligase ligands, a novel potent c-Met PROTAC Met-DD4 was identified. Our results suggested that Met-DD4 could induce robust c-Met degradation with excellent selectivity (DC50 = 6.21 nM), substantially killing the c-Met-addicted cancer cells (IC50 = 4.37 nM). Furthermore, in vivo studies showed that Met-DD4 could achieve excellent oral bioavailability and c-Met degradation, strongly retarding tumor growth with minute organ toxicity. Overall, this study reveals that targeted degradation of c-Met is a promising strategy for the treatment of c-Met-addicted cancers and provides novel lead compounds for the clinical translation of c-Met PROTACs.