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bioRxiv2025

Multiomic profiling of a unique in-transit melanoma cohort identifies melanoma differentiation as predictor of tumor progression and therapy response

Melanoma patients with in-transit metastasis (ITM), a stage of disease where melanoma has metastasized to sites in between the primary lesion and draining lymph node, vary significantly in their clinical outcomes, but the biology driving differential outcomes in ITM is poorly understood. To elucidate the mechanisms of differential outcomes, we utilized multimodal molecular profiling (WES, RNA-seq, highly multiplexed immunofluorescence, spatial transcriptomics) in 1) evolutionary analysis of longitudinal tumor samples and 2) identifying prognostic tumor intrinsic and microenvironmental features in a unique cohort of patients with unresectable ITM. Among other findings, we observed a persistent dedifferentiated AXL/NGFR clonal lineage pre-existing and following immune checkpoint blockade in in-transit and distant metastases. Concordantly, we found that low pigmentation and high T cell exhaustion signatures were independently associated with distant progression. Our findings highlight tumor cell state and immune dysfunction as key predictors and potential biomarkers of metastatic risk in ITM. STATEMENT OF SIGNIFICANCEWhat drives distant progression in melanoma is unclear. Analyzing tumor and immune features in a rare in-transit melanoma patient cohort, we identify biological signals highlighting how immune and tumor states observable in pre-distant metastasis melanomas shape long-term outcomes, and nominate potential prognostic biomarkers.

cancer biology↗

bioRxiv2025

Single-Cell Multiomic Profiling Uncovers Radiation Dosage-Sensitive, Cluster-Specific Regulatory Dynamics in Glioblastoma

Glioblastoma (GBM) is an aggressive brain tumor that inevitably recurs after chemoradiotherapy, resulting in poor patient outcomes. Given GBMs cellular heterogeneity, we hypothesized that radiation induces sub-population specific alterations to survive and adapt to radiation stress. We performed integrated single-cell RNA-seq and ATAC-seq analyses in Glioma Stem-Like Cultures three hours after they were exposed to clinically relevant radiation doses. Radiation reshaped the cellular landscape, altering both cell type composition and GBM subtype distribution. Cluster-specific and shared transcriptional programs were induced in a dose-dependent manner, with differentially expressed genes enriching distinct biological pathways. Chromatin accessibility analyses revealed parallel cluster-specific remodeling, with both opening and closing of regulatory elements linked to functional pathway shifts. Notably, 2 Gy and 6 Gy exposures elicited conserved transcriptional profiles in RNA clusters across different radiation doses. Together, these results highlight immediate radiation-induced transcriptional and chromatin remodeling programs in GBM at single-cell resolution and identify conserved cluster-specific adaptations that may underlie therapeutic resistance.

cancer biology↗

bioRxiv2020

Genome-wide CRISPR synthetic lethality screen identifies a role for the ADP- ribosyltransferase PARP14 in replication fork stability controlled by ATR

The DNA damage response is essential to maintain genomic stability, suppress replication stress, and protect against carcinogenesis. The ATR-CHK1 pathway is an essential component of this response, which regulates cell cycle progression in the face of replication stress. PARP14 is an ADP-ribosyltransferase with multiple roles in transcription, signaling, and DNA repair. To understand the biological functions of PARP14, we catalogued the genetic components that impact cellular viability upon loss of PARP14 by performing an unbiased, comprehensive, genome-wide CRISPR knockout genetic screen in PARP14-deficient cells. We uncovered the ATR-CHK1 pathway as essential for viability of PARP14-deficient cells, and identified regulation of replication fork stability as an important mechanistic contributor to the synthetic lethality observed. Our work shows that PARP14 is an important modulator of the response to ATR-CHK1 pathway inhibitors.

cancer biology↗

bioRxiv2020

Phosphorylation of the RB C-terminus regulates condensin II release from chromatin

The retinoblastoma tumour suppressor protein (RB) plays an important role in biological processes such as cell cycle control, DNA damage repair, epigenetic regulation, and genome stability. The canonical model of RB regulation is that cyclin-CDKs phosphorylate, and render RB inactive in late G1/S, promoting entry into S phase. Recently, mono-phosphorylated RB species were described to have distinct cell-cycle independent functions, suggesting that a phosphorylation code dictates diversity of RB function. However, a biologically relevant, functional role of RB phosphorylation at non-CDK sites has remained elusive. Here, we investigated S838/T841 dual phosphorylation, its upstream stimulus, and downstream functional output. We found that mimicking T-cell receptor activation in Jurkat leukemia cells induced sequential activation of downstream kinases including p38 MAPK, and RB S838/T841 phosphorylation. This signaling pathway disrupts RB and condensin II interaction with chromatin. Using cells expressing a WT or S838A/T841A mutant RB fragment, we present evidence that deficiency for this phosphorylation event prevents condensin II release from chromatin.

cancer biology↗

bioRxiv2020

A Humanized Animal Model Predicts Clonal Evolution and Therapeutic Vulnerabilities in Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are chronic blood diseases with significant morbidity and mortality. While sequencing studies have elucidated the genetic mutations that drive these diseases, MPNs remain largely incurable with a significant proportion of patients progressing to rapidly fatal secondary acute myeloid leukemia (sAML). Therapeutic discovery has been hampered by the inability of genetically-engineered mouse models to generate key human pathologies such as bone marrow fibrosis. To circumvent these limitations, here we present a humanized animal model of myelofibrosis (MF) patient-derived xenografts (PDXs). These PDXs robustly engrafted patient cells which recapitulated the patients genetic hierarchy and pathologies such as reticulin fibrosis and propagation of MPN-initiating stem cells. The model can select for engraftment of rare leukemic subclones to identify MF patients at-risk for sAML transformation, and can be used as a platform for genetic target validation and therapeutic discovery. We present a novel but generalizable model to study human MPN biology. STATEMENT OF SIGNIFICANCEAlthough the genetic events driving myeloproliferative neoplasms (MPNs) are well-defined, therapeutic discovery has been hampered by the inability of murine models to replicate key patient pathologies. Here, we present a patient-derived xenograft (PDX) system to model human myelofibrosis that reproduces human pathologies and is amenable to genetic and pharmacological manipulation.

cancer biology↗

bioRxiv2023

A critical role for PLCG1 in RAS activation by BCR-ABL1 and FLT3-ITD

Myeloid leukemias are frequently associated with pathologically activating mutations in tyrosine kinases [BCR-ABL1 in chronic myeloid leukemia (CML); FLT3 juxtamembrane internal tandem duplication (ITD) mutations, FLT3 and KIT activation loop mutations in acute myeloid leukemia (AML)]. Mutations in these kinases activate RAS, which initiates multiple downstream signaling pathways that regulate cell proliferation, differentiation, and apoptosis. The mechanisms whereby RAS is activated by these kinases is incompletely understood, and a better understanding of the molecular mediators involved in RAS activation may uncover new therapeutic strategies. Here we identify a biologically and therapeutically important novel mechanism whereby BCR-ABL1 and FLT3-ITD activate the critical downstream effector RAS in part through phospholipase C gamma-1 (PLCG1). PLCG1 knockout decreases proliferation of CML and FLT3-ITD-expressing AML cells, reduces RAS nucleotide exchange factor activity, and increases sensitivity of CML cells to BCR-ABL1 tyrosine kinase inhibitors (TKIs). Collectively, these studies suggest that PLCG1 inhibition may augment clinical responses to BCR-ABL1 and FLT3 TKIs in CML and AML.

cancer biology↗

bioRxiv2025

A Dual-Action Liposome-Peptide Formulation Synergistically Counteracts A Gain-of-Function p53 Mutant

ObjectiveInactivation of p53 tumor suppressor functions, often through missense mutations, is essential for carcinogenesis. A sub-class of such p53 missense mutations gains new functions, including drug resistance and enhanced proliferation, in addition to its loss of function. Among the most frequent gain-of-function p53 mutants, R273H occurs in tumors of many tissue origins and imparts aggressive character and resistance to drugs to the tumor. Tumors bearing p53R273H are generally resistant to all available therapies, and need for novel interventions are urgently needed. Interaction of p53R273H with Positive Coactivator 4 (PC4), an abundant chromatin-associated protein, is essential for acquiring the gain-of-function properties. Previously, we developed a chemically modified peptide, NLS-p53(380-386), targeting PC4 that abrogated the interaction of p53R273H with PC4 and reversed many of its gain-of-function properties. We earlier demonstrated that cationic phosphatidylcholine-stearylamine (PC-SA) liposomes possess inherent anti-tumor properties. To improve efficacy, pharmacokinetics, and delivery, we entrapped the PC4-targeted peptide into PC-SA liposome. MethodsWe synthesized the NLS-p53(380-386) peptide and entrapped in PC-SA liposome. We used MTT assay, confocal microscopy, flow cytometry, qRT-PCR, and western blotting to investigate the biological effects of the p53-entrapped PC-SA. ResultsPre-treatment with the PC-SA liposome entrapped peptide enhanced the chemosensitivity of widely used anticancer drug doxorubicin in cell lines bearing p53R273H mutation. The doxorubicin-induced cell-killing effect was much more enhanced when pre- treated with the liposome-entrapped peptide than when pre-treated with either the free peptide or the liposome alone. ConclusionThe liposome-encapsulated peptide is a promising formulation for developing therapies targeting tumors bearing the p53R273H.

cancer biology↗

bioRxiv2023

Antitumor activity of intraperitoneal paclitaxel in orthotopic patient-derived xenograft models of mucinous appendiceal adenocarcinoma

Appendiceal adenocarcinomas (AAs) are a rare and heterogeneous mix of tumors for which few preclinical models exist. The rarity of AA has made performing prospective clinical trials difficult, and in part because of this AA remains an orphan disease with no chemotherapeutic agents approved by the FDA for its treatment. AA has a unique biology in which it frequently forms diffuse peritoneal metastases, but almost never spreads via a hematogenous route and rarely spreads to lymphatics. Given its localization to the peritoneal space we hypothesized that intraperitoneal (IP) delivery of chemotherapy could be an effective treatment strategy. Here we tested the efficacy paclitaxel given by IP administration using three orthotopic PDX models of AA established in NSG mice. Weekly treatment of 25.0 mg/kg of IP paclitaxel dramatically reduced AA tumor growth in TM00351 (81.9% reduction vs. control), PMP-2 (98.3% reduction vs. control), and PMCA-3 (71.4% reduction vs. control) PDX models. Comparing the safety and efficacy of intravenous (IV) to IP administration in PMCA-3, neither 6.25 nor 12.5 mg/kg of IV paclitaxel significantly reduced tumor growth. These results suggest that IP administration of paclitaxel is favorable to IV administration. Given the established safety record of IP paclitaxel in gastric and ovarian cancers, and lack of effective chemotherapeutics for AA, these data showing the activity of IP paclitaxel in orthotopic PDX models of mucinous AA support the evaluation of IP paclitaxel in a prospective clinical trial.

cancer biology↗

bioRxiv2022

On optimal temozolomide scheduling for slowly growing gliomas

BackgroundTemozolomide (TMZ) is an oral alkylating agent active against gliomas with a favorable toxicity profile. It is part of the standard of care in the management of glioblastoma, and is commonly used in low-grade gliomas. In-silico mathematical models can potentially be used to personalize treatments and to accelerate the discovery of optimal drug delivery schemes. MethodsAgent-based mathematical models fed with either mouse or patient data were developed for the in-silico studies. The experimental test beds used to confirm the results were: mouse glioma models obtained by retroviral expression of EGFR wt or EGFR vIII in primary progenitors from p16/p19 ko mice and grown in vitro and in vivo in orthotopic allografts, and human glioblastoma U251 cells immobilized in alginate microfibers. The patient data used to parametrize the model were obtained from the TCGA/TCIA databases and the TOG clinical study. ResultsSlow growth virtual murine gliomas benefited from increasing TMZ dose separation in silico. In line with the simulation results, improved survival, reduced toxicity, lower expression of resistance factors and reduction of the tumor mesenchymal component were observed in experimental models subject to long-cycle treatment, particularly in slowly-growing tumors. Tissue analysis after long-cycle TMZ treatments revealed epigenetically-driven changes in tumor phenotype, which could explain the reduction in glioma growth speed. In-silico trials provided support for methods of implementation in human patients. ConclusionsIn-silico simulations, and in-vitro and in-vivo studies show that TMZ administration schedules with increased time between doses may reduce toxicity, delay the appearance of resistances and lead to survival benefits mediated by changes in the tumor phenotype in gliomas. IMPORTANCE OF THE STUDYIn-vivo evidence is provided of improvements in survival, resistance, and toxicity from TMZ schemes with long rest periods between doses in slowly-growing GBM mouse models. The results match hypotheses generated in silico using a mathematical model incorporating the main biological features and fed with real patient data. An epigenetically-driven change in tumor phenotype was also revealed experimentally, which could explain the reduction in glioma growth speed under the long cycle scheme. To determine the extent to which our results hold for human patients, large sets of simulations were performed on virtual patients. These in-silico trials suggest different ways to bring the benefits observed in experimental models into clinical practice.

cancer biology↗

bioRxiv2020

Imaging the Transmembrane and Transendothelial Sodium Gradients in Gliomas

High sodium (Na+) in extracellular (Na+e) and blood (Na+b) compartments and low Na+ in intracellular milieu (Na+i) produce strong transmembrane ({Delta}Na+mem) and weak transendothelial ({Delta}Na+end) gradients respectively, which reflect cell membrane potential (Vm) and blood-brain barrier (BBB) integrity. We developed a sodium (23Na) magnetic resonance spectroscopic imaging (MRSI) method using an intravenously-administered paramagnetic contrast agent to measure {Delta}Na+mem and {Delta}Na+end. In vitro 23Na-MRSI established that the 23Na signal is strongly shifted by the agent compared to biological factors. In vivo 23Na-MRSI showed Na+i remained unshifted and Na+b was more shifted than Na+e, and these together created weakened {Delta}Na+mem and enhanced {Delta}Na+end in rat gliomas. Specifically, RG2 and U87 tumors maintained weakened {Delta}Na+mem (i.e., depolarized Vm) implying an aggressive state for proliferation, and RG2 tumors displayed elevated {Delta}Na+end suggesting altered BBB integrity. 23Na-MRSI will allow explorations of perturbed Na+ homeostasis in vivo for the tumor neurovascular unit.

cancer biology↗

bioRxiv2020

Tumor edge architecture in glioblastoma is constructed by inter-cellular signals from vascular endothelial cells

One of the hallmarks of glioblastoma (GBM) is extensive neovascularization. In addition to supplying blood and nutrients, vascular endothelial (VE) cells provide trophic support to GBM cells via paracrine signaling, the precise mechanisms of which are being unraveled. Here, using patient-derived GBM and VE cells as well as orthotopic GBM mouse models, we report that Endocan (ESM1), an endothelial-secreted proteoglycan, confers enhanced proliferative, migratory, and angiogenic properties to GBM cells and regulates their spatial identity. Mechanistically, Endocan exerts at least part of its functions via direct binding and activation of the PDGFRA receptor. Subsequent downstream signaling enhances chromatin accessibility of the Myc promoter and upregulates Myc expression inducing highly stable phenotypic changes in GBM cells. Furthermore, Endocan confers a radioprotection phenotype in GBM cells, both in vitro and in vivo. Inhibition of Endocan-PDGFRA signaling with ponatinib increases survival in the Esm1 wild-type but not in the Esm1 knock-out mouse GBM model. Our findings identify Endocan and its downstream signaling axis as a potential target to subdue the recurrence of GBM and further highlight the importance of vascular to tumor cell signaling for GBM biology. Significance statementIdentification of the Endocan/PDGFRA/Myc axis demonstrates an important role of VE cells in GBM malignancy. The contribution of Endocan to the development of GBM cell populations with different phenotypes reveal an additional pathway underlying the origin of GBM intratumoral heterogeneity. Targeting Endocan-mediated crosstalk may enhance the efficacy of GBM treatment.

cancer biology↗

bioRxiv2022

Genomic heterogeneity and ploidy identify patients with intrinsic resistance to PD-1 blockade in metastatic melanoma

While the introduction of immune checkpoint blockade (ICB) has dramatically improved clinical outcomes for patients with advanced melanoma, a significant proportion of patients develop resistance to therapy, and mechanisms of resistance are poorly elucidated in most cases. Further, while combination ICB has higher response rates and improved progression free survival compared to single agent therapy in the front line setting, there is significantly increased toxicity with combination ICB, and biomarkers to identify patients who would disproportionately benefit from combination therapy vs aPD-1 ICB are poorly characterized. To understand resistance mechanisms to single vs combination ICB therapy, we analyze whole-exome-sequencing (WES) of pre-treatment tumor and matched normals of 4 cohorts (n=140) of previously ICB-naive aPD-1 ICB treated patients. We find that high intratumoral genomic heterogeneity and low ploidy identify patients with intrinsic resistance to aPD-1 ICB. Comparing to a melanoma cohort from a pre-targeted therapy and ICB time period ("untreated" cohort), we find that genomic heterogeneity specifically predicts response and survival in the ICB treated cohorts, but not in the untreated cohort, while ploidy is also prognostic of overall survival in the "untreated" (by targeted therapy or ICB) group. To establish clinically actionable predictions, we optimize a simple decision tree using genomic ploidy and heterogeneity to identify with high confidence (90% PPV) a subset of patients with intrinsic resistance to and significantly worse survival on aPD1 ICB treatment. We then validate this model in independent cohorts, and further show that a significant proportion of patients predicted to have intrinsic resistance to single agent aPD-1 ICB respond to combination ICB, which suggests that nominated patients may benefit disproportionately from combination ICB. We further show that the features and predictions of the model are independent of known clinical features and previously nominated molecular biomarkers. These findings highlight the clinical and biological importance of genomic heterogeneity and ploidy, and sets a concrete framework towards clinical actionability, broadly advancing precision medicine in oncology.

cancer biology↗

bioRxiv2023

Targeting Acute Myeloid Leukemia Stem Cells Through Perturbation of Mitochondrial Calcium

We previously reported that acute myeloid leukemia stem cells (LSCs) are uniquely reliant on oxidative phosphorylation (OXPHOS) for survival. Moreover, maintenance of OXPHOS is dependent on BCL2, creating a therapeutic opportunity to target LSCs using the BCL2 inhibitor drug venetoclax. While venetoclax-based regimens have indeed shown promising clinical activity, the emergence of drug resistance is prevalent. Thus, in the present study, we investigated how mitochondrial properties may influence mechanisms that dictate venetoclax responsiveness. Our data show that utilization of mitochondrial calcium is fundamentally different between drug responsive and non-responsive LSCs. By comparison, venetoclax-resistant LSCs demonstrate a more active metabolic (i.e., OXPHOS) status with relatively high steady-state levels of calcium. Consequently, we tested genetic and pharmacological approaches to target the mitochondrial calcium uniporter, MCU. We demonstrate that inhibition of calcium uptake sharply reduces OXPHOS and leads to eradication of venetoclax-resistant LSCs. These findings demonstrate a central role for calcium signaling in the biology of LSCs and provide a therapeutic avenue for clinical management of venetoclax resistance. SignificanceWe identify increased utilization of mitochondrial calcium as distinct metabolic requirement of venetoclax-resistant LSCs and demonstrate the potential of targeting mitochondrial calcium uptake as a therapeutic strategy.

cancer biology↗

bioRxiv2018

Study on tumor cell RNA cross-anticancer mechanism in non-tumor mice experimental model

To report the experiments of fractal structure and self-similar function in biological coupled oscillation brings life system waving growth in life organism. At the same time by self-organization the system openness come into being to maintain stability features of growth survival. From this, the orderly oscillation of tumor cell RNA was recognized that this process could lead to system sequentiality openness. According to waving growth of basic research the procedure could be sure to turn into a model as out of control of growing in tumor. Then in complete contrast that derived from the same component which have cross resistance effect. It shows that its biological behavior is converted as only a single physical power to play action by inactivated processing. Subsequent further confirms the essential roles whether essential roles link up with recovery of physiological function. The result in that it could exhibit feature of anticancer owing to be endowed tissue embryonization response. So that it also exerts preventing on senile chronic diseases. In theory, the concept of this tissue response in life organism closely link up with the single physical power of RNA component so as to bring up specific procedure of growing and subsisting that deal with keeping life vigor generalized explanatory.

cancer biology↗

bioRxiv2024

Multi-omics reveals AKR1B1-regulated galactose metabolic as a driver of gastrointestinal stromal tumor progression

The underlying mechanism of malignant progression in gastrointestinal stromal tumors (GISTs) is not fully understood. Despite recent advancements, a comprehensive profile of metabolome, transcriptome, and proteome of GISTs is lacking. This study conducted an integrated multi-omics analysis of GISTs across different risk classifications. By integrating metabolomics, transcriptomics, and proteomics, we identify distinct metabolic patterns and associated biological pathways implicated in the malignant progression of GISTs. Moreover, we identified galactose metabolism and the pivotal rate-limiting enzyme AKR1B1 is dysregulated in GISTs progression. AKR1B1 was upregulated and predicted poor prognosis in GISTs. In addition, AKR1B1 knockdown resulted in trehalose accumulation in GIST cells, thereby inhibiting cell proliferation and mitosis. These findings not only enhance our comprehension of the underlying mechanisms governing GIST progression from a metabolic reprogramming standpoint but also furnish prognostic biomarkers and potential therapeutic targets for GISTs.

cancer biology↗

bioRxiv2026

Disentangling the Crabtree and Warburg effects across syngeneic non-tumor and tumor cells.

Oxidative phosphorylation (OxPhos) and substrate-level phosphorylation (SLP) are the primary biochemical mechanisms for ATP generation in mammalian cells. Increased dependency on SLP can arise from either transient (e.g., Crabtree effect) or chronic (e.g., Warburg effect) suppression of OxPhos. We evaluated the steady-state bioenergetics of quiescent and proliferating mouse cells matched in genetic background and cell biology, including primary thioglycollate-elicited peritoneal macrophages, malignant VM-M3 glioma with macrophage characteristics, and malignant CT-2A astrocytoma. Data are presented showing: 1) OxPhos insufficiency was the primary bioenergetic hallmark of proliferating malignant cells. 2) Dysregulated proliferation was associated with lower metabolic flexibility under nutrient stress than was growth arrest or regulated proliferation. 3) The Crabtree effect was present in macrophages and involved a glucose- and time-dependent suppression of OxPhos coupled to ATP production through SLP and resistance to mitochondrial inhibitors; lowering glucose concentration or substituting glucose with respiratory fuels increased OxPhos and restored sensitivity to mitochondrial inhibitors. 4) The Warburg effect in tumor cells involved a persistent SLP dependency and resistance to mitochondrial inhibitors under equivalent glucose-replete conditions. 5) OxPhos could sustain the regulated proliferation of non-tumor cells in the absence of a Warburg effect. Collectively, our findings emphasize that comparisons between normal and cancer cell metabolism require long-term experimental endpoints that ensure steady-state ATP sufficiency.

cancer biology↗

bioRxiv2024

Multi-pronged analysis of pediatric low-grade glioma reveals a unique tumor microenvironment associated with BRAF alterations

Pediatric low-grade gliomas (pLGG) comprise 35% of all brain tumors. Despite favorable survival, patients experience significant morbidity from disease and treatments. A deeper understanding of pLGG biology is essential to identify novel, more effective, and less toxic therapies. We utilized single cell RNA sequencing (scRNA-seq), spatial transcriptomics, and cytokine analyses to characterize and understand tumor and immune cell heterogeneity across pLGG. scRNA-seq revealed tumor and immune cells within the tumor microenvironment (TME). Tumor cell subsets revealed a developmental hierarchy with progenitor and mature cell populations. Immune cells included myeloid and lymphocytic cells. There was a significant difference between the prevalence of two major myeloid subclusters between pilocytic astrocytoma (PA) and ganglioglioma (GG). Bulk and single-cell cytokine analyses evaluated the immune cell signaling cascade with distinct immune phenotypes among tumor samples. KIAA1549-BRAF tumors appeared more immunogenic, secreting higher levels of immune cell activators and chemokines, compared to BRAF V600E tumors. Spatial transcriptomics revealed the differential gene expression of these chemokines and their location within the TME. A multi-pronged analysis of pLGG demonstrated the complexity of the pLGG TME and differences between genetic drivers that may influence their response to immunotherapy. Further investigation of immune cell infiltration and tumor-immune interactions is warranted. Key pointsO_LIThere is a developmental hierarchy in neoplastic population comprising of both progenitor-like and mature cell types in both PA and GG. C_LIO_LIA more immunogenic, immune activating myeloid population is present in PA compared to GG. C_LIO_LIFunctional analysis and spatial transcriptomics show higher levels of immune mobilizing chemokines in KIAA1549-BRAF fusion PA tumor samples compared to BRAF V600E GG samples. C_LI Importance of the StudyWhile scRNA seq provides information on cellular heterogeneity within the tumor microenvironment (TME), it does not provide a complete picture of how these cells are interacting or where they are located. To expand on this, we used a three-pronged approach to better understand the biology of pediatric low-grade glioma (pLGG). By analyzing scRNA-seq, secreted cytokines and spatial orientation of cells within the TME, we strove to gain a more complete picture of the complex interplay between tumor and immune cells within pLGG. Our data revealed a complex heterogeneity in tumor and immune populations and identified an interesting difference in the immune phenotype among different subtypes.

cancer biology↗

bioRxiv2018

A second generation IL-2 receptor-targeted diphtheria fusion toxin exhibits anti-tumor activity and synergy with anti-PD-1 in melanoma

Denileukin diftitox (DAB1-389-IL-2, Ontak(R)) is a diphtheria toxin-based fusion protein that depletes CD25-positive cells including regulatory T cells (Tregs) and was approved for the treatment of persistent or recurrent cutaneous T cell lymphoma. However, the clinical use of denileukin diftitox was limited by vascular leak toxicity and production issues related to drug aggregation and purity. We found that a single amino acid substitution (V6A) in a motif associated with vascular leak induction yields a fully active, second-generation biologic, s-DAB1-386-IL-2(V6A), which elicits 50-fold less HUVEC monolayer permeation and is 3.7-fold less lethal to mice by LD50 analysis than s-DAB1-386-IL-2 Additionally, to overcome aggregation problems, we developed a novel production method for the fusion toxin using Corynebacterium diphtheriae that secretes fully-folded, biologically active, monomeric s-DAB1-386-IL-2 into the culture medium. Using the poorly immunogenic mouse B16F10 melanoma model, we initiated treatment 7 days after tumor challenge and observed that, while both s-DAB1-386-IL-2(V6A) and s-DAB1-386-IL-2 are inhibitors of tumor growth, the capacity to treat with higher doses of s-DAB1-386-IL-2(V6A) could provide a superior activity window. In a sequential dual therapy study in tumors that have progressed for 10 days both s-DAB1-386-IL-2(V6A) and s-DAB1-386-IL-2 given prior to checkpoint inhibition with anti-PD-1 antibodies inhibited tumor growth, while either drug given as monotherapy had less effect. s-DAB1-386-IL-2(V6A), a fully monomeric protein with reduced vascular leak, is a second-generation diphtheria toxin-based fusion protein with promise as a cancer immunotherapeutic both alone and in conjunction with PD-1 blockade.\n\nSignificance StatementRegulatory T cells (Tregs) infiltrate tumors in various cancers and promote an immunosuppressive microenvironment that hinders anti-tumor immunity. Denileukin diftitox, a diphtheria toxin-based fusion protein that depletes Tregs, was approved for the treatment of T cell malignancies, but its clinical use was limited due to the presence of protein aggregates and toxicity associated with vascular leakage. Here we report the production of a second generation IL-2 receptor-targeted, fully-folded, monomeric diphtheria fusion toxin, and a V6A mutant variant which showed reduced vascular leak in vitro and reduced lethality in mice. In a mouse model of melanoma, we found significant decrease in tumor growth associated with reduction in Tregs when the protein was tested as monotherapy or in combination with checkpoint blockade.

cancer biology↗