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Supplementary Figure 2 from Impact of APE1/Ref-1 Redox Inhibition on Pancreatic Tumor Growth

Supplementary Methods, Figure Legends 1-3 from Impact of APE1/Ref-1 Redox Inhibition on Pancreatic Tumor Growth

Evaluation of pharmacodynamic (PD) markers in vivo.

Pancreatic cancer is especially a deadly form of cancer with a survival rate less than 2%. Pancreatic cancers respond poorly to existing chemotherapeutic agents and radiation, and progress for the treatment of pancreatic cancer remains elusive. To address this unmet medical need, a better understanding of critical pathways and molecular mechanisms involved in pancreatic tumor development, progression, and resistance to traditional therapy is therefore critical. Reduction–oxidation (redox) signaling systems are emerging as important targets in pancreatic cancer. AP endonuclease1/Redox effector factor 1 (APE1/Ref-1) is upregulated in human pancreatic cancer cells and modulation of its redox activity blocks the proliferation and migration of pancreatic cancer cells and pancreatic cancer-associated endothelial cells in vitro. Modulation of APE1/Ref-1 using a specific inhibitor of APE1/Ref-1′s redox function, E3330, leads to a decrease in transcription factor activity for NFκB, AP-1, and HIF1α in vitro. This study aims to further establish the redox signaling protein APE1/Ref-1 as a molecular target in pancreatic cancer. Here, we show that inhibition of APE1/Ref-1 via E3330 results in tumor growth inhibition in cell lines and pancreatic cancer xenograft models in mice. Pharmacokinetic studies also show that E3330 attains more than10 μmol/L blood concentrations and is detectable in tumor xenografts. Through inhibition of APE1/Ref-1, the activity of NFκB, AP-1, and HIF1α that are key transcriptional regulators involved in survival, invasion, and metastasis is blocked. These data indicate that E3330, inhibitor of APE1/Ref-1, has potential in pancreatic cancer and clinical investigation of APE1/Ref-1 molecular target is warranted. Mol Cancer Ther; 10(9); 1698–708. ©2011 AACR.

Supplemental Table S1. IC50 values for Nultin-3a, Carboplatin, and 1:1 Combination; Supplemental Material and Methods; Supplemental Figure Legends

Supplementary Figure 1 from Impact of APE1/Ref-1 Redox Inhibition on Pancreatic Tumor Growth

Peanut-induced allergy is an immunoglobulin E (IgE)–mediated type I hypersensitivity reaction that manifests symptoms ranging from local edema to life-threatening anaphylaxis. Although there are treatments for symptoms in patients with allergies resulting from allergen exposure, there are few preventive therapies other than strict dietary avoidance or oral immunotherapy, neither of which are successful in all patients. We have previously designed a covalent heterobivalent inhibitor (cHBI) that binds in an allergen-specific manner as a preventive for allergic reactions. Building on previous in vitro testing, here, we developed a humanized mouse model to test cHBI efficacy in vivo. Nonobese diabetic–severe combined immunodeficient γc-deficient mice expressing transgenes for human stem cell factor, granulocyte-macrophage colony-stimulating factor, and interleukin-3 developed mature functional human mast cells in multiple tissues and displayed robust anaphylactic reactions when passively sensitized with patient-derived IgE monoclonal antibodies specific for peanut Arachis hypogaea 2 (Ara h 2). The allergic response in humanized mice was IgE dose dependent and was mediated by human mast cells. Using this humanized mouse model, we showed that cHBI prevented allergic reactions for more than 2 weeks when administered before allergen exposure. cHBI also prevented fatal anaphylaxis and attenuated allergic reactions when administered shortly after the onset of symptoms. cHBI impaired mast cell degranulation in vivo in an allergen-specific manner. cHBI rescued the mice from lethal anaphylactic responses during oral Ara h 2 allergen–induced anaphylaxis. Together, these findings suggest that cHBI has the potential to be an effective preventative for peanut-specific allergic responses in patients.

Pediatric gliomas are the most common type of pediatric brain tumors representing wide range of molecularly and clinically heterogenous subtypes. The hyperactivity of mitogen-activated protein kinases (MAPK) pathway has been identified in the majority of pediatric glioma suggesting its therapeutic potential. However, pharmacologic targeting single MAPK pathway’s component is limited due to the development of drug resistance and differential response associated with tumor molecular landscape. Therefore, effective combination strategy in the framework of precision medicine is needed. Here we report combination benefit and molecular underpinning therapeutic response of brain penetrant MEK inhibitor (mirdametinib) and SHP2 inhibitor (SHP099) in a pediatric patient derived xenograft (PDX) and xenoline developed at our institution. Our model was derived from a pediatric patient who was diagnosed with rare high-grade subtype of glioma, anaplastic pleomorphic xanthoastrocytoma, and did not respond to MEK inhibitor, trametinib. Integrative multi-omics revealed molecular fidelity between our model and its patient tumor counterpart including the presence of 7q35 fusion, CDC52SE2-BRAF, CDKN2A/B loss, and MAPK pathway hyperactivation. In vitro studies using our xenoline IU-X128 demonstrated synergy between SHP099 and mirdametinib to curtail cell proliferation (p Citation Format: Nur P. Damayanti, Anthony Alfonso, Josue D. Ordaz, Erika Dobrota, M. Reza Saadatzadeh, Pankita Pandya, Barbara J. Bailey, Khadijeh Bijangi-Vishehsaraei, Harlan E. Shannon, Kathy Coy, Melissa Trowbridge, Anthony L. Sinn, Rosa Gallager, Julia Wulfkuhle, Emanuel Petricoin, Amber Mosley, Mark S. Marshall, Alex Lion, Michael J. Fergusson, Karl Balsara, Karen E. Pollok. SHP2 inhibition enhances antitumor effect of mirdametinib in a pediatric brain tumor model bearing CDC42SE2BRAF fusion by rewiring the proteome and phosphoproteome landscape. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5498.

Wilms Tumor (WT) is an embryonal renal tumor that accounts for more than 90% of kidney tumors in children. Significant advances in multidisciplinary therapeutic approaches have increased survival rates up to 90%. However, approximately 15% of patients with favorable histology and 50% of patients with anaplastic WT experience recurrence of disease. Thus, there is still a critical need to develop therapies that are effective and safe for these patients with progressive disease. To address this, we have developed a pipeline of patient derived xenograft (PDX) models from single academic institution patients with metastatic and aggressive cancers. Among these we have developed 3 xenograft models derived from patients with WT. To gain a detailed understanding of the complex array of mutations and identify therapeutic targets, molecular signatures were obtained at the DNA and protein levels via whole genome sequencing and reverse phase protein array analyses respectively. While PDX derived from encapsulated WT specimens exhibited basal levels of PI3K and MAPK pathway activation, which are well-known for promoting tumor survival, growth, and metastasis, no mutations that drive hyperactivation of these pathways were identified in these PDX. In contrast, a rare WT xenograft (PDX120) was established from a female patient with recurrent disease and metastatic cancer in the liver. -OMICS data indicated hyperactivation of PI3K (PIK3CA p.H1047R) and MAPK (KRAS p.G12_G10ins) which was validated by qPCR and immunoblotting in original tumor sample and serially passaged PDX120 xenografts. -OMICS data also confirmed the fidelity of the molecular signature between the original tumor sample and the serially passaged PDX120. The metastatic WT model was screened with two FDA approved drugs as single agents: Trametinib (MAPK pathway inhibitor; BID M-F 1mg/kg PO Day 1-35) or Alpelisib (PI3K pathway inhibitor; QD M-F 50mg/kg PO: Mice were dosed Day 1-29, followed by a gap period, and then dosing re-initiated, Day 86-103). Trametinib therapy did not effectively attenuate PDX120 tumor growth. In contrast, the PI3K inhibitor Alpelisib was well tolerated and significantly decreased PDX120 growth and prolonged survival compared to the vehicle control (Two-way ANOVA, Holm-Sidak, p Citation Format: Mohammad Reza Saadatzadeh, Khadijeh Bijangi Vishehsaraei, Erika A. Dobrota, Barbara J. Bailey, Lauren E. Hein, Kathryn L. Coy, Melissa A. Trowbridge, Anthony L. Sinn, Troy A. Markel, Michael J. Ferguson, Pankita H. Pandya, Karen E. Pollok. Effective anti-tumor effect in a rare metastatic Wilms tumor xenograft by inhibition of RAS/PI3K hyperactivation. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4487.

Osteosarcoma (OS) is an aggressive cancer of the bone with high metastatic potential in pediatric as well as adolescent and young adults. The survival rate for metastatic and relapsed OS patients is Citation Format: Niknam Riyahi, Pankita H. Pandya, Barbara J. Bailey, Erika A. Dobrota, Courtney Young, Harlan E. Shannon, Farinaz Barghi, Rada Malko, Khadijeh Bijangi-Vishehsaraei, Melissa A. Trowbridge, Kathy Coy, Felicia M. Kennedy, Anthony L. Sinn, Steve Angus, Michael J. Ferguson, M. Reza Saadatzadeh, Karen E. Pollok. Therapeutic targeting of BET bromodomain proteins increases DNA damage and potentiates salvage therapy in osteosarcoma xenografts derived from patients with replication stress signatures. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6727.

Hematopoietic and nervous systems are linked via innervation of bone marrow (BM) niche cells. Hematopoietic stem/progenitor cells (HSPCs) express neurotransmitter receptors, such as the γ-aminobutyric acid (GABA) type B receptor subunit 1 (GABBR1), suggesting that HSPCs could be directly regulated by neurotransmitters like GABA that directly bind to GABBR1. We performed imaging mass spectrometry and found that the endogenous GABA molecule is regionally localized and concentrated near the endosteum of the BM niche. To better understand the role of GABBR1 in regulating HSPCs, we generated a constitutive Gabbr1-knockout mouse model. Analysis revealed that HSPC numbers were significantly reduced in the BM compared with wild-type littermates. Moreover, Gabbr1-null hematopoietic stem cells had diminished capacity to reconstitute irradiated recipients in a competitive transplantation model. Gabbr1-null HSPCs were less proliferative under steady-state conditions and upon stress. Colony-forming unit assays demonstrated that almost all Gabbr1-null HSPCs were in a slow or noncycling state. In vitro differentiation of Gabbr1-null HSPCs in cocultures produced fewer overall cell numbers with significant defects in differentiation and expansion of the B-cell lineage. To determine whether a GABBR1 agonist could stimulate human umbilical cord blood (UCB) HSPCs, we performed brief ex vivo treatment prior to transplant into immunodeficient mice, with significant increases in long-term engraftment of HSPCs compared with GABBR1 antagonist or vehicle treatments. Our results indicate a direct role for GABBR1 in HSPC proliferation, and identify a potential target to improve HSPC engraftment in clinical transplantation.

How old is too old? In vivo engraftment of human peripheral blood stem cells cryopreserved for up to 18 years - implications for clinical transplantation and stability programs

Despite readily available graft sources for allogeneic hematopoietic cell transplantation (alloHCT), a significant unmet need remains in the timely provision of suitable unrelated donor grafts. This is due to the rarity of certain human leukocyte antigen (HLA) alleles in the donor pool, the non-clearance of donors due to infectious disease or general health status, as well as prolonged graft-procurement and processing times. An alternative hematopoietic progenitor cell (HPC) graft source obtained from the vertebral bodies (VB) of deceased organ donors could alleviate many of the obstacles associated with using grafts from healthy, living donors and umbilical cord blood (UCB). Deceased organ donor derived bone marrow (BM) can be preemptively screened, cryogenically banked for on-demand use, and made available in adequate cell dosages for HCT. We have developed a good manufacturing practice (GMP)-compliant process to recover and cryogenically bank VB-derived HPC from organ donor (OD) marrow.Herein, we present results from an analysis of HPC, Marrow obtained from 250 deceased donors, to determine if there were substantial difference in composition or quality compared to HPC, Marrow aspirated from the iliac crest of healthy living donors.BM from deceased donor VBs was processed in a central GMP facility and package for cryopreservation in 5% DMSO/2.5% human serum albumin. Living donor iliac crest aspirated BM was obtained and used for comparison. A portion of each specimen was analyzed prior to and following cryopreservation by flow cytometry and colony forming unit potential. Bone marrow chimerism potential was assessed in irradiated immunocompromised NOD.Cg-PrkdcWhen compared before and after cryopreservation, OD-derived HPC, Marrow was found to be stable, with CD34Collectively, these data demonstrate that cryopreserved HPC, Marrow from deceased organ donors is potent and functionally equivalent to living donor HPC, Marrow, and is a viable on-demand graft source for clinical HCT. Prospective clinical trials will soon commence in collaboration with the Center for International Blood and Marrow Research (CIBMTR) for feasibility, safety, and efficacy assessment of Ossium HPC, Marrow (NCT05068401).

Tumor antigen heterogeneity, a severely immunosuppressive tumor microenvironment (TME) and lymphopenia resulting in inadequate immune intratumoral trafficking, have rendered glioblastoma (GBM) highly resistant to therapy. To address these obstacles, here we describe a unique, sophisticated combinatorial platform for GBM: a cooperative multifunctional immunotherapy based on genetically engineered human natural killer (NK) cells bearing multiple antitumor functions including local tumor responsiveness that addresses key drivers of GBM resistance to therapy: antigen escape, immunometabolic reprogramming of immune responses, and poor immune cell homing. We engineered dual-specific chimeric antigen receptor (CAR) NK cells to bear a third functional moiety that is activated in the GBM TME and addresses immunometabolic suppression of NK cell function: a tumor-specific, locally released antibody fragment which can inhibit the activity of CD73 independently of CAR signaling and decrease the local concentration of adenosine. The multifunctional human NK cells targeted patient-derived GBM xenografts, demonstrated local tumor site–specific activity in the tissue, and potently suppressed adenosine production. We also unveil a complex reorganization of the immunological profile of GBM induced by inhibiting autophagy. Pharmacologic impairment of the autophagic process not only sensitized GBM to antigenic targeting by NK cells but promoted a chemotactic profile favorable to NK infiltration. Taken together, our study demonstrates a promising NK cell–based combinatorial strategy that can target multiple clinically recognized mechanisms of GBM progression simultaneously.

Establishment of clinically annotated, molecularly characterized, patient-derived xenografts (PDXs) from treatment-naïve and pretreated patients provides a platform to test precision genomics-guided therapies. An integrated multi-OMICS pipeline was developed to identify cancer-associated pathways and evaluate stability of molecular signatures in a panel of pediatric and AYA PDXs following serial passaging in mice. Original solid tumor samples and their corresponding PDXs were evaluated by whole-genome sequencing, RNA-seq, immunoblotting, pathway enrichment analyses, and the drug–gene interaction database to identify as well as cross-validate actionable targets in patients with sarcomas or Wilms tumors. While some divergence between original tumor and the respective PDX was evident, majority of alterations were not functionally impactful, and oncogenic pathway activation was maintained following serial passaging. CDK4/6 and BETs were prioritized as biomarkers of therapeutic response in osteosarcoma PDXs with pertinent molecular signatures. Inhibition of CDK4/6 or BETs decreased osteosarcoma PDX growth (two-way ANOVA, p < 0.05) confirming mechanistic involvement in growth. Linking patient treatment history with molecular and efficacy data in PDX will provide a strong rationale for targeted therapy and improve our understanding of which therapy is most beneficial in patients at diagnosis and in those already exposed to therapy.

Osteosarcoma (OS) is an aggressive pediatric cancer with ~35% of patients developing metastasis over time. The survival rate for metastatic and relapsed OS patients is Citation Format: Niknam Riyahi, Pankita H. Pandya, M. Reza Saadatzadeh, Khadijeh Bijangi-Vishehsaraei, Barbara J. Bailey, Erika A. Dobrota, Courtney Young, Melissa A. Trowbridge, Kathy Coy, Henry Mang, Reagan K. Wohlford, Anthony L. Sinn, Emily S. Sims, Matt J. Repass, Nuri Damayanti, Farinaz Barghi, Harlan E. Shannon, Michael J. Ferguson, Jamie L. Renbarger, Karen E. Pollok. Therapeutic induction of replication stress in the context of salvage therapy in osteosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2017.

In children, adolescents, and young adults (AYA), osteosarcoma (OS) is the most common type of bone cancer and ~35% patients relapse following frontline cytotoxic therapy. Thus, there is a critical need to identify therapies targeting specific molecular signatures in OS. Hyperactivation of cyclin-dependent kinases 4 and 6 (CDK4/6) has been identified by us and others as a top actionable marker in OS. CDK4/6 binds to cyclin D resulting in a complex that mediates RB phosphorylation leading to cell cycle progression. While CDK4/6 inhibitors (CDK4/6i) have shown promise clinically, one drawback is that CDK4/6i induces cell cycle arrest rather than cell death. Furthermore, prolonged CDK4/6 inhibitor therapy can confer therapeutic resistance in RB1-proficient (RB+) tumors where compensatory pathways such as PI3K/mTOR are activated. To mitigate such CDK4/6i resistance in OS, we hypothesized that dual inhibition of CDK4/6 and PI3K pathways will promote cytotoxicity in hyperactivated CDK4/6 OS models. RB+ OS cell lines and a TT2-77 xenoline were evaluated in vitro. Combination index and Bliss independence analyses indicated that inhibition of OS growth by exposure to CDK4/6i (Palbociclib or Abemaciclib) and PI3K/mTOR inhibitor (PI3K/mTORi-Voxtalisib or LY3023414) was additive-to-synergistic and lead to increased apoptosis at clinically relevant concentrations. Short-term pharmacodynamic study of vehicle- versus Palbociclib-treated TT2-77 patient-derived xenograft (PDX) was analyzed by global/phospho-proteomics and kinome profiling. RB1 and MKI67 phosphopeptides as well as the total protein levels of CDK1 were reduced by Palbociclib, thus, confirming modulation of the cell cycle. Kinome profiling analysis of PDX from Palbociclib-treated mice indicated increased activity of AXL, a receptor tyrosine kinase linked to PI3K pathway activation. Increased activity of the autophagy marker PIK3C3 was also evident. OS PDX models TT2-77 and HT96 (RB+, CDKN2Anull, CCND3 amplified) were treated with Palbociclib (50 mg/kg), Voxtalisib (50 mg/kg) or Palbociclib + Voxtalisib. In TT2-77 PDXs treated for four weeks, tumor growth was significantly reduced in single-agent and combo groups compared to vehicle (p Citation Format: Farinaz Barghi, Pankita H Pandya, M. Reza Saadatzadeh, Khadijeh Bijangi-Vishehsaraei, Barbara J. Bailey, Erika A. Dobrota, Courtney Young, Melissa A. Trowbridge, Kathryn L. Coy, Henry Mang, Reagan K. Wohlford, Anthony L. Sinn, Emily C. Sims, Matt J. Repass, Nuri Damayanti, Niknam Riyahi, Harlan E. Shannon, Steve P Angus, Michael J Ferguson, Jamie L. Renbarger, Karen E. Pollok. Targeting CDK4/6 inhibitor resistance in relapsed RB-proficient osteosarcoma patient-derived xenografts via PI3 Kinase/mTOR inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2011.

The hematopoietic system is sustained by a rare population of hematopoietic stem cells (HSCs), which emerge during early embryonic development and then reside in the hypoxic niche of the adult bone marrow microenvironment. Although leptin receptor (Lepr)-expressing stromal cells are well-studied as critical regulators of murine hematopoiesis, the biological implications of Lepr expression on HSCs remain largely unexplored. We hypothesized that Lepr+HSCs are functionally different from other HSCs. Using in vitro and in vivo experimental approaches, we demonstrated that Lepr further differentiates SLAM HSCs into two distinct populations; Lepr+HSCs engrafted better than Lepr-HSCs in primary transplant. Compared to Lepr-LSK cells, Lepr+LSK cells were highly enriched for extensively repopulating and self-renewing HSCs. Molecularly, Lepr+HSCs were characterized by a pro-inflammatory transcriptomic profile enriched for Type-I Interferon and Interferon-gamma (IFN-γ) response pathways, which are known to be critical for the emergence of HSCs in the embryo. We conclude that although Lepr+HSCs represent a minor subset of HSCs, they are highly engrafting cells that possess embryonic-like transcriptomic characteristics, and that Lepr can serve as a reliable marker for functional long-term HSCs, which may have potential clinical applicability.

Background Despite aggressive treatments and care, the median survival for GBM patients is 14.6 months, which has only modestly improved over the past several decades, highlighting the need for new therapeutic approaches. NK cells, innate cytotoxic effectors, are showing potential for cancer immunotherapy for GBM.1–3 However, tumor antigen heterogeneity and a severely immunosuppressive tumor microenvironment (TME) have rendered GBM highly resistant to most single antigen-based NK monotherapies.4–6 Methods To overcome these challenges, our solution has been to develop a first multifunctional immunotherapy for GBM based on genetically-engineered NK cells bearing multiple simultaneous anti-tumor functions, including local tumor responsiveness and the ability to avoid antigen escape. The activity of these lentivirally-transduced multi-functional NK (E-pNK) cells were evaluated against patient-derived GBM cells both in vitro and in vivo. Results We have designed and synthesized a multifunctional CAR construct that expresses an anti-CD73 scFv which is cleavable by GBM-associated proteases, and a dual CAR redirected against ligands for NKG2D and GBM-associated GD2 receptors (figure 1A-B). We have isolated primary NK cells (figure 1C) and genetically manipulated them to express NKG2D, anti-GD2 scFv and anti-CD73 scFv (figure 1D-E). E-pNK cells showed a significantly higher in vitro antitumor activity towards GBM43 targets, patient-derived GBM cells, including increased percentage of tumor killing, degranulation and IFN-γ production (figure 1F-G). E-pNK cells lacking the anti-CD73 scFv following uPA treatment displayed significantly decreased killing ability of target GBM43 cells after co-culture at E/T ratios of 2.5 and 5 for 4 h (figure 1H). In addition, after treatment with cleaved anti-CD73 scFv, GBM43 cells showed a significantly reduced ability to produce adenosine due to the inhibition of CD73 enzyme activity (figure 1I). Furthermore, E-pNK cells showed potent anti-GBM activity in subcutaneously GBM43 xenografts (figure 1J-L). In vivo-adoptively transferred E-pNK cells also showed superior intratumoral infiltration into GBM43 tumors when analyzed by IHC (data not shown). Conclusions We have generated E-pNK cells showing improved antitumor activity against GBM through increased resistance to the immunosuppressive TME via adenosinergic CD73 blockade and the simultaneous ability to specifically target GBM cells via dual CARs. Based on these results, we are currently building the orthotopic GBM mouse model to further evaluate their in vivo therapeutic effects. Acknowledgements This work is supported, in part, by a Ralph W. and Grace M. Showalter Research Trust award and a Walther Cancer Foundation Embedding Grant. Ethics Approval Primary human NK (pNK) cells used in this study were obtained using Purdue University’s Institutional Review Board (IRB)-approved consent forms (IRB-approved protocol #1804020540). References Sedgwick AJ, Ghazanfari N, Constantinescu P, Mantamadiotis T, Barrow AD. The role of NK cells and innate lymphoid cells in brain cancer. Front Immunol 2020;11:01549. Burger MC, Zhang CC, Harter PN, Romanski A, Strassheimer F, Senft C, et al. CAR-engineered NK cells for the treatment of glioblastoma: turning innate effectors into precision tools for cancer immunotherapy. Front Immunol 2019;10:2683. Wang J, Lupo KB, Chambers AM, Matosevic S. Purinergic targeting enhances immunotherapy of CD73+ solid tumors with piggyBac-engineered chimeric antigen receptor natural killer cells. J Immunother Cancer 2018;6:136. Lim M, Xia YX, Bettegowda C, Weller M. Current state of immunotherapy for glioblastoma. Nat Rev Clin Oncol 2018;15:422-442. Lynes JP, Nwankwo AK, Sur HP, Sanchez VE, Sarpong KA, Ariyo OI, et al. Biomarkers for immunotherapy for treatment of glioblastoma. J Immunother Cancer 2020;8:e000348. Wang J, Matosevic S. NT5E/CD73 as Correlative factor of patient survival and natural killer cell infiltration in glioblastoma. J Clin Med 2019;8:1526.

Tumor antigen heterogeneity, a severely immunosuppressive tumor microenvironment (TME) and lymphopenia resulting in inadequate immune intratumoral trafficking have rendered glioblastoma (GBM) highly resistant to therapy. As a result, GBM immunotherapies have failed to demonstrate sustained clinical improvements in patient overall survival (OS). To overcome these obstacles, here we describe a novel, sophisticated combinatorial platform for GBM: the first multifunctional immunotherapy based on genetically-engineered, human NK cells bearing multiple anti-tumor functions, including local tumor responsiveness, that addresses key drivers of GBM resistance to therapy: antigen escape, poor immune cell homing, and immunometabolic reprogramming of immune responses. We engineered dual-specific CAR-NK cells to bear a third functional moiety that is activated in the GBM TME and addresses immunometabolic suppression of NK cell function: a tumor-specific, locally-released antibody fragment which can inhibit the activity of CD73 independently of CAR signaling and decrease the local concentration of adenosine. The multifunctional human NK cells targeted patient-derived GBM xenografts, demonstrated local tumor site specific activity in the tissue and potently suppressed adenosine production. We also unveil a complex reorganization of the immunological profile of GBM induced by inhibiting autophagy. Pharmacologic impairment of the autophagic process not only sensitized GBM to antigenic targeting by NK cells, but promoted a chemotactic profile favorable to NK infiltration. Taken together, our study demonstrates a promising new NK cell-based combinatorial strategy that can target multiple clinically-recognized mechanisms of GBM progression simultaneously.

Osteosarcoma (OS) patients exhibit poor overall survival, partly due to copy number variations (CNVs) resulting in dysregulated gene expression and therapeutic resistance. To identify actionable prognostic signatures of poor overall survival, we employed a systems biology approach using public databases to integrate CNVs, gene expression, and survival outcomes in pediatric, adolescent, and young adult OS patients. Chromosome 8 was a hotspot for poor prognostic signatures. The MYC-RAD21 copy number gain (8q24) correlated with increased gene expression and poor overall survival in 90% of the patients (n = 85). MYC and RAD21 play a role in replication-stress, which is a therapeutically actionable network. We prioritized replication-stress regulators, bromodomain and extra-terminal proteins (BETs), and CHK1, in order to test the hypothesis that the inhibition of BET + CHK1 in MYC-RAD21+ pediatric OS models would be efficacious and safe. We demonstrate that MYC-RAD21+ pediatric OS cell lines were sensitive to the inhibition of BET (BETi) and CHK1 (CHK1i) at clinically achievable concentrations. While the potentiation of CHK1i-mediated effects by BETi was BET-BRD4-dependent, MYC expression was BET-BRD4-independent. In MYC-RAD21+ pediatric OS xenografts, BETi + CHK1i significantly decreased tumor growth, increased survival, and was well tolerated. Therefore, targeting replication stress is a promising strategy to pursue as a therapeutic option for this devastating disease.

Osteosarcoma (OS) is the most common primary bone malignancy in children as well as in adolescents and young adults (AYA). Approximately 35% of OS patients develop metastases and relapse after first-line treatment emphasizing the need for new therapies. Our objective was to use patient -omics analyses to prioritize models of relapsed pediatric and AYA OS to investigate an unexplored combination therapy. Genomic data from pediatric and AYA patients enrolled in the Precision Genomics program at Riley Hospital for Children, Indiana University Health indicate that dysregulation of cyclin-dependent kinases 4 and 6 (CDK4/6) is one of the top actionable signatures. The cyclin D-CDK4/6 complex regulates retinoblastoma protein (RB)-E2F transcription factor interactions. Upon cyclin D-CDK4/6-mediated RB phosphorylation, the RB-E2F complex dissociates, and cell cycle progression ensues. CDK4/6 inhibitors (CDK4/6i) typically induce cell cycle arrest rather than cell death and can activate compensatory pathways such as PI3K. Moreover, aberrant PI3K activation has been reported in OS. Our hypothesis is that inhibition of CDK4/6 and PI3K pathways will be efficacious and well-tolerated in RB1-proficient (RB+) OS models exhibiting hyperactivation of the cyclin D-CDK4/6 complex. Cell growth response to CDK4/6i (Palbociclib or Abemaciclib) and a PI3K/mTOR inhibitor (PI3K/mTORi, Voxtalisib) was evaluated in RB+ OS cell lines and an RB+ patient-derived xenograft (PDX)-derived xenoline (TT2-77). Combination index and Bliss independence analyses indicated that CDK4/6i+PI3K/mTORi resulted in additive to synergistic inhibition of growth in RB+ OS cell lines at clinically relevant concentrations. In the TT2-77 PDX, whole genome sequencing indicated that the original OS biopsy and the TT2-77 PDX generated from a resection sample harbor signatures associated with CDK4/6 pathway up-regulation. Global and phosphoproteome analysis were conducted on TT2 PDX tumors from NOD/SCIDγnull mice treated with vehicle vs. Palbociclib for 5 days. Modulation of 6226 phosphopeptides and 3870 total proteins were observed and included downregulation of phosphopeptides and total protein levels of CDK1 as well as DNA replication proteins in Palbociclib-treated TT2-77 PDX mice. Furthermore, TT2-77 PDX mice were treated with Palbociclib daily (10-120 mg/kg) for 3 weeks. TT2-77 PDX growth was completely blocked by high dose Palbociclib. While all mice survived, clinical observation criteria indicated that this dose was not optimal. In TT2-77 PDX mice treated with 50 mg/kg Palbociclib, tumor growth significantly decreased compared to vehicle (p Citation Format: Farinaz Barghi, Pankita H. Pandya, M. Reza Saadatzadeh, Khadijeh Bijangi-Vishehsaraei, Barbara J. Bailey, Erika A. Dobrota, Courtney Young, Melissa A. Trowbridge, Kathy Coy, Anthony L. Sinn, Harlan E. Shannon, Jamie L. Renbarger, Karen E. Pollok. Targeting CDK4/6 inhibitor resistance in relapsed osteosarcoma via PI3 Kinase inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3043.

The hematopoietic system is maintained by the hematopoetic stem and progenitor cells (HSCs/HPCs), a group of rare cells that reside in a hypoxic bone marrow (BM) microenvironment. Leptin (Lep) is well-known for its neuroendocrine and immunological functions, and its receptor (Lepr) has been studied extensively in the BM niche cells. Yet, its biological implications in HSC/HPC biology remained largely unknown. In this study, we hypothesized that Lepr-expressing HSCs/HPCs are functionally and transcriptomically distinct from their negative counterparts. To test our hypothesis, we utilized both in vitro and in vivo approaches. We first employed Fluorescence-activated cell sorting (FACS) analysis to confirm expression of Lepr on HSCs/HPCs in adult mouse BM. We then isolated equal numbers of Lepr+Lineage-Sca1+cKit+ (LSK cells - a heterogenous population of long-term, short-term HSCs and multipotent HPCs) and Lepr-LSK cells from C57BL/6 (CD45.2+) mouse BM to perform colony-forming unit (CFU) assay and competitive transplantation assay, which also included using competitor cells from BoyJ (CD45.1+) unseparated BM and lethally-irradiated F1 (CD45.1+CD45.2+) as hosts. To determine whether Lepr can further hierarchize HSCs into two distinct populations, we repeated the competitive transplants using freshly isolated C57BL/6 Lepr+HSCs or Lepr-HSCs cells instead. At the end of primary transplants, whole BM were analyzed for donor chimerisms in the peripheral blood (PB) and BM as well as transplanted in a non-competitive fashion into lethally-irradiated secondary recipients. To gain mechanistic insights, we assessed homing potential as homing plays a role in increased engraftment. We also performed bulk RNA-seq using freshly sorted BM Lepr+HSCs or Lepr-HSCs to elucidate potential molecular pathways that are responsible for the differences in their functional capacity. By phenotypic studies, our FACS analyses showed that Lepr+ cells represented a smaller population within the hematopoietic compartment in the BM. However, HSCs contained a higher percentage of Lepr+ cells than other HPC populations. By functional assessments, Lepr+LSK cells were more highly enriched for colony-forming progenitor cells in CFU assay as compared to Lepr-LSK cells. Interestingly, Lepr+LSK cells exhibited more robust engraftment capability in primary transplants and substantial self-renewal capacity in secondary transplants throughout different time points in both PB and BM. In addition, Lepr+HSCs showed significantly higher donor chimerisms in PB month 1, 2, 4 and BM month 4 with similar lineage output compared to Lepr-HSCs. Higher engraftment could be due to increased homing of HSCs to the BM; however, Lepr+HSCs and Lepr-HSCs showed similar homing capacity as well as levels of surface CXCR4 expression. Molecularly, Fast Preranked Gene Set Enrichment Analysis (FGSEA) showed that Lepr+HSCs were enriched for Type-I Interferon and Interferon-gamma response pathways with Normalized Enrichment Scores of 2 or higher. Lepr+HSC transcriptomic study also revealed that these cells as compared to Lepr-HSCs expressed significantly higher levels of genes involved in megakaryopoiesis and proinflammatory immune responses including the NF-κB subunits (Rel and Relb). Interestingly, both IFN-γ and NF-κB signalings have been demonstrated to be critical for the emergence of HSCs from the hemogentic endothelium during embryonic development. In summary, although Lepr+LSK cells occupied a minor fraction compared to their negative counterparts in the BM, they possessed higher colony-forming capacity and were more highly enriched for long-term functional HSCs. In line with this, Lepr+HSCs engrafted significantly higher and self-renewed more extensively than Lepr-HSCs, suggesting that Lepr not only can be used as a marker for functional HSCs but also further differentiate HSCs into two functionally distinguishable populations. Intriguingly, Lepr+HSCs were characterized with a proinflammatory transcriptomic profile that was previously suggested to be critical for the development of HSCs in the embryo. All together, our work demonstrated that Lepr+HSCs represent a subset of highly engrafting adult BM HSCs with an embryonic-like transcriptomic signature. This can have potential therapeutic implications in the field of hematopoietic transplantation as Lepr is highly conserved between mice and human. Disclosures No relevant conflicts of interest to declare.

Patients with aggressive osteosarcoma (OS) have poor prognosis due in part to copy number variations (CNVs) that contribute to dysregulation of gene expression (GE) and therapeutic resistance. The objective of the present study was to utilize the TARGET database to integrate CNV and corresponding GE with poor prognosis in pediatric OS (n=85) followed by functional validation of prioritized targets. Cox regression analysis indicated that CNVs in 2642 genes correlated with relapse risk in pediatric OS. Furthermore, the top 10 genes with CNVs significantly associated with increased risk for relapse were present on chromosome 8. The MYC and RAD21 copy number gain (MYC-RAD21 CNV+) located on chromosome 8q correlated with increased GE and poor survival in >90% of the relapsed patients. Based on network analysis, the MYC-RAD21 CNV+ was prioritized for development of targeted therapy. MYC, an oncogenic driver of OS growth, can be indirectly inhibited by bromodomain and extra-terminal domain inhibitors (BETi). RAD21 expression has been associated with increased sensitivity to cell cycle checkpoint kinase 1 inhibitors (CHK1i) in melanoma. Additionally, mechanistic links exist between MYC and CHK1, especially during replication stress. Our hypothesis was that the MYC-RAD21 CNV+ serves as a biomarker of poor prognosis and therapeutic response to BETi+CHK1i therapy. Cell growth response to BETi and CHK1i was evaluated in MYC-RAD21 CNV+ pediatric OS cell lines and a patient-derived xenograft (PDX)-derived xenoline (TT2-77). OS lines (G292, MG63, U2OS, and TT2-77) were highly sensitive to single agent BETi/OTX-015, CHK1i/ SRA737 or CHK1i/LY2606368 at clinically relevant concentrations. Combination index and Bliss independence analysis indicated that BETi+CHK1i did not result in synergistic or additive inhibition of growth at clinically relevant concentrations. However, in OS lines Saos2 and Saos2-LM7 BETi+CHK1i resulted in additive to synergistic inhibition of growth at multiple dose-ratios and at clinically relevant concentrations. In the TT2-77 PDX, whole genome sequencing indicated that the original OS biopsy and the TT2-77 PDX generated from a resection sample harbor the MYC-RAD21 CNV+ (4 copies/amplicon). PDX tumor fragments were implanted into the flank of immunodeficient NOD/SCID/IL2Rγ mice. Once tumor volumes reached 100-150 mm3, mice were randomized and treated with four 5-day cycles of BETi/OTX-015 and/or CHK1i/SRA737. BETi+CHK1i significantly decreased TT2-77 growth, increased probability of survival, and was well tolerated. BETi+CHK1i is a promising therapeutic approach for treatment of relapsed pediatric MYC-RAD21 CNV+ OS. It is possible that MYC, BETs, RAD21 and CHK1 protein levels could dictate sensitivity to combination BETi+CHK1i independent of MYC-RAD2 CNV+ status. Studies are in progress to identify responder versus non-responder signatures in OS. Citation Format: Khadijeh Bijangi-Vishehsaraei, Pankita Pandya, Cheng Lijun, Tang Shan, Anthony Sinn, Melissa Trowbridge, Kathy Coy, Courtney Hemenway, Barbara Bailey, Harlan Shannon, Jixin Ding, Erika Dobrota, M. Reza Saadatzadeh, Adily Elmi, Jeremiah Shultz, Mary Murray, Mark Marshall, Michael Ferguson, Todd Bertrand, L. Daniel Wurtz, Sandeep Batra, Lang Li, Jamie Renbarger, Karen Pollok. Systems biology approach provides rationale for dual-targeted inhibition of BET and CHK1 in aggressive pediatric osteosarcoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 450.

The KIF14 locus is gained and overexpressed in various malignancies, with prognostic relevance. Its protein product, a mitotic kinesin, accelerates growth of normal mammary epithelial cells in vitro and retinoblastoma tumours in a mouse model, while KIF14 knockdown blocks growth of brain, liver, ovarian, breast, prostate, and other tumour cells and xenografts. However, the tumour-initiating effects of Kif14 overexpression have not been studied. We aged a cohort of Kif14-overexpressing transgenic mice and wild-type littermates and documented survival, cause of death, and tumour burden. The Kif14 transgene was expressed in all tissues examined, and was associated with increased proliferation marker expression. Neither mouse weights nor overall survival differed between genotypes. However, Kif14 transgenic mice showed a higher incidence of fatal lymphomas (73 vs. 50%, p = 0.03, Fisher’s exact test), primarily follicular and diffuse B-cell lymphomas. Non-tumour findings included a bilateral ballooning degeneration of lens in 12% of Kif14 transgenic mice but no wild-type mice (p = 0.02). Overall, this work reveals a novel association of Kif14 overexpression with lymphoma but suggests that Kif14 does not have as prominent a role in initiating cancer in other cell types as it does in accelerating tumour development in response to other oncogenic insults.

Triple-negative breast cancers (TNBC) are typically resistant to treatment, and strategies that build upon frontline therapy are needed. Targeting the murine double minute 2 (Mdm2) protein is an attractive approach, as Mdm2 levels are elevated in many therapy-refractive breast cancers. The Mdm2 protein–protein interaction inhibitor Nutlin-3a blocks the binding of Mdm2 to key signaling molecules such as p53 and p73α and can result in activation of cell death signaling pathways. In the present study, the therapeutic potential of carboplatin and Nutlin-3a to treat TNBC was investigated, as carboplatin is under evaluation in clinical trials for TNBC. In mutant p53 TMD231 TNBC cells, carboplatin and Nutlin-3a led to increased Mdm2 and was strongly synergistic in promoting cell death in vitro. Furthermore, sensitivity of TNBC cells to combination treatment was dependent on p73α. Following combination treatment, γH2AX increased and Mdm2 localized to a larger degree to chromatin compared with single-agent treatment, consistent with previous observations that Mdm2 binds to the Mre11/Rad50/Nbs1 complex associated with DNA and inhibits the DNA damage response. In vivo efficacy studies were conducted in the TMD231 orthotopic mammary fat pad model in NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice. Using an intermittent dosing schedule of combined carboplatin and Nutlin-3a, there was a significant reduction in primary tumor growth and lung metastases compared with vehicle and single-agent treatments. In addition, there was minimal toxicity to the bone marrow and normal tissues. These studies demonstrate that Mdm2 holds promise as a therapeutic target in combination with conventional therapy and may lead to new clinical therapies for TNBC. Mol Cancer Ther; 14(12); 2850–63. ©2015 AACR.

Triple negative breast cancer accounts for 15–20% of all breast cancer cases, but despite its lower incidence, contributes to a disproportionately higher rate of mortality. As there are currently no Food and Drug Administration-approved targeted agents for triple negative breast cancer, we embarked on a genomic-guided effort to identify novel targeted modalities. Analyses by our group and The Cancer Genome Atlas have identified activation of the PI3K-pathway in the majority of triple negative breast cancers. As single agent therapy is commonly subject to resistance, we investigated the use of combination therapy against compensatory pathways. Herein, we demonstrate that pan-PI3K inhibition in triple negative breast cancers results in marked activation of the Wnt-pathway. Using the combination of two inhibitors currently in clinical trial as single agents, buparlisib(pan-PI3K) and WNT974(WNT-pathway), we demonstrate significant in vitro and in vivo synergy against triple negative breast cancer cell lines and xenografts. Taken together, these observations provide a strong rationale for testing dual targeting of the PI3K and WNT-pathways in clinical trials., Therapeutics: Dual therapy shrinks triple negative breast tumors Two experimental drugs currently in clinical trials as single agents might work better together against triple negative breast cancer. Jeffrey Solzak and Milan Radovich, and colleagues from the Indiana University School of Medicine in Indianapolis, USA, analyzed gene expression data from cancerous and healthy breast tissues and from published genomic datasets. They found the PI3K pathway consistently activated in the majority of breast cancers that test negative for the three most common receptors known to fuel breast tumor growth. Inhibiting PI3K in these cells led to a marked increase in the activity of another critical pathway called Wnt, an observation that prompted the researchers to test a combination of a PI3K inhibitor, buparlisib, and a Wnt inhibitor, WNT974, in cell lines and xenograft models. Tumor cells shrunk more and mice lived longer than treatment with either agent alone.

Current treatments for allergies include epinephrine and antihistamines, which treat the symptoms after an allergic response has taken place; steroids, which result in local and systemic immune suppression; and IgE-depleting therapies, which can be used only for a narrow range of clinical IgE titers. The limitations of current treatments motivated the design of a heterobivalent inhibitor (HBI) of IgE-mediated allergic responses that selectively inhibits allergen–IgE interactions, thereby preventing IgE clustering and mast cell degranulation. The HBI was designed to simultaneously target the allergen binding site and the adjacent conserved nucleotide binding site (NBS) found on the Fab of IgE Abs. The bivalent targeting was accomplished by linking a hapten to an NBS ligand with an ethylene glycol linker. The hapten moiety of HBI enables selective targeting of a specific IgE, whereas the NBS ligand enhances avidity for the IgE. Simultaneous bivalent binding to both sites provided HBI with 120-fold enhancement in avidity for the target IgE compared with the monovalent hapten. The increased avidity for IgE made HBI a potent inhibitor of mast cell degranulation in the rat basophilic leukemia mast cell model, in the passive cutaneous anaphylaxis mouse model of allergy, and in mice sensitized to the model allergen. In addition, HBI did not have any observable systemic toxic effects even at elevated doses. Taken together, these results establish the HBI design as a broadly applicable platform with therapeutic potential for the targeted and selective inhibition of IgE-mediated allergic responses, including food, environmental, and drug allergies.

We previously identified a distinct population of human circulating hematopoietic stem and progenitor cells (CHSPCs; CD14(-)glyA(-)CD34(+)AC133(+/-)CD45(dim)CD31(+) cells) in the peripheral blood (PB) and bone marrow, and their frequency in the PB can correlate with disease state. The proangiogenic subset (pCHSPC) play a role in regulating tumor progression, for we previously demonstrated a statistically significant increase in C32 melanoma growth in NOD.Cg-Prkdc (scid) (NOD/SCID) injected with human pCHSPCs (p < 0.001). We now provide further evidence that pCHSPCs possess proangiogenic properties. In vitro bio-plex cytokine analyses and tube forming assays indicate that pCHSPCs secrete a proangiogenic profile and promote vessel formation respectively. We also developed a humanized bone marrow-melanoma orthotopic model to explore in vivo the biological significance of the pCHSPC population. Growth of melanoma xenografts increased more rapidly at 3-4 weeks post-tumor implantation in mice previously transplanted with human CD34(+) cells compared to control mice. Increases in pCHSPCs in PB correlated with increases in tumor growth. Additionally, to determine if we could prevent the appearance of pCHSPCs in the PB, mice with humanized bone marrow-melanoma xenografts were administered Interferon α-2b, which is used clinically for treatment of melanoma. The mobilization of the pCHSPCs was decreased in the mice with the humanized bone marrow-melanoma xenografts. Taken together, these data indicate that pCHSPCs play a functional role in tumor growth. The novel in vivo model described here can be utilized to further validate pCHSPCs as a biomarker of tumor progression. The model can also be used to screen and optimize anticancer/anti-angiogenic therapies in a humanized system.

Inhibition of vascular endothelial growth factor increases response rates to chemotherapy and progression-free survival in glioblastoma. However, resistance invariably occurs, prompting the urgent need for identification of synergizing agents. One possible strategy is to understand tumor adaptation to microenvironmental changes induced by antiangiogenic drugs and test agents that exploit this process. We used an in vivo glioblastoma-derived xenograft model of tumor escape in presence of continuous treatment with bevacizumab. U87-MG or U118-MG cells were subcutaneously implanted into either BALB/c SCID or athymic nude mice. Bevacizumab was given by intraperitoneal injection every 3 days (2.5 mg/kg/dose) and/or dichloroacetate (DCA) was administered by oral gavage twice daily (50 mg/kg/dose) when tumor volumes reached 0.3 cm3 and continued until tumors reached approximately 1.5-2.0 cm3. Microarray analysis of resistant U87 tumors revealed coordinated changes at the level of metabolic genes, in particular, a widening gap between glycolysis and mitochondrial respiration. There was a highly significant difference between U87-MG-implanted athymic nude mice 1 week after drug treatment. By 2 weeks of treatment, bevacizumab and DCA together dramatically blocked tumor growth compared to either drug alone. Similar results were seen in athymic nude mice implanted with U118-MG cells. We demonstrate for the first time that reversal of the bevacizumab-induced shift in metabolism using DCA is detrimental to neoplastic growth in vivo. As DCA is viewed as a promising agent targeting tumor metabolism, our data establish the timely proof of concept that combining it with antiangiogenic therapy represents a potent antineoplastic strategy. © 2013 Springer-Verlag Berlin Heidelberg.

Pancreatic cancer is especially a deadly form of cancer with a survival rate less than 2%. Pancreatic cancers respond poorly to existing chemotherapeutic agents and radiation, and progress for the treatment of pancreatic cancer remains elusive. To address this unmet medical need, a better understanding of critical pathways and molecular mechanisms involved in pancreatic tumor development, progression, and resistance to traditional therapy is therefore critical. Reduction–oxidation (redox) signaling systems are emerging as important targets in pancreatic cancer. AP endonuclease1/Redox effector factor 1 (APE1/Ref-1) is upregulated in human pancreatic cancer cells and modulation of its redox activity blocks the proliferation and migration of pancreatic cancer cells and pancreatic cancer-associated endothelial cells in vitro. Modulation of APE1/Ref-1 using a specific inhibitor of APE1/Ref-1′s redox function, E3330, leads to a decrease in transcription factor activity for NFκB, AP-1, and HIF1α in vitro. This study aims to further establish the redox signaling protein APE1/Ref-1 as a molecular target in pancreatic cancer. Here, we show that inhibition of APE1/Ref-1 via E3330 results in tumor growth inhibition in cell lines and pancreatic cancer xenograft models in mice. Pharmacokinetic studies also show that E3330 attains more than10 μmol/L blood concentrations and is detectable in tumor xenografts. Through inhibition of APE1/Ref-1, the activity of NFκB, AP-1, and HIF1α that are key transcriptional regulators involved in survival, invasion, and metastasis is blocked. These data indicate that E3330, inhibitor of APE1/Ref-1, has potential in pancreatic cancer and clinical investigation of APE1/Ref-1 molecular target is warranted. Mol Cancer Ther; 10(9); 1698–708. ©2011 AACR.

Disease-free survival in relapsed Ewing's Sarcoma Family of Tumors (ESFT) has not improved over the past 25 years. Current standard-of-care (SOC) agents result in 70% survival in patients with localized ESFT; however, for relapsed patients the survival rates remain between 15-20%. Approximately 85% of ESFTs have the chromosomal translocation t(11;22)(q24;q12) which encodes for the oncogenic EWS/FL1 fusion protein. The EWS/FL1 functions as a potent transcription factor leading to the dysregulated expression of genes that promote and maintain tumorigenesis. A major epigenetic regulator that is a downstream target of EWS/FL1 is the enhancer of Zeste Homolog 2 (EZH2). EZH2 is the catalytic component of the polycomb repressor complex 2 (PRC2). Notably, it is overexpressed in ESFT and maintains tumor oncogenicity by tri-methylating histone 3 lysine 27 (H3K27me3) to modulate gene expression. Genome and transcriptome data obtained by the Pediatric Precision Genomics Program at Riley Hospital for Children at Indiana University Health (IUH) indicate that EZH2 is expressed at high levels in ESFT biopsies. Additionally, other groups have reported that high levels of EZH2 protein in ESFT and other cancers correlate with increased chemoresistance to SOC therapy. We are testing tested the hypothesis that EZH2 contributes to chemoresistance in ESFT by regulating critical growth and survival genes. In addition, we are investigating if pharmacological inhibition of EZH2 will enhance sensitivity to the cytotoxic effects of SOC agents. Pediatric primary and relapsed ESFT cell lines and ESFT xenografts were validated for the EWS/FLI, EZH2, and H3K27me3 signatures. In vitro- and in vivo-pharmacodynamic studies of EZH2 inhibition via tazemetostat were conducted to optimize dosing effect. In ESFT cell lines (TC71, A673, CHLA-9, and CHLA-10), tazemetostat dose-response experiments indicated a significant reduction of H3K27me3 by one day post-treatment which was either sustained or completely blocked by 7-days post-treatment compared to vehicle treated (p Citation Format: Pankita H. Pandya, Barbara Bailey, Adily E. Elmi, Heather R. Bates, Courtney N. Hemenway, Anthony L. Sinn, Khadijeh Bijangi-Vishehsaraei, M. Reza Saadatzadeh, Harlan E. Shannon, Jixin Ding, Mark S. Marshall, Michael J. Ferguson, Lijun Cheng, Lang Li, Mary E. Murray, Jamie L. Renbarger, Karen E. Pollok. Preclinical validation of EZH2 as a therapeutic target in pediatric Ewing's sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3180.

ENMD-2076 is a novel, orally-active molecule that has been shown to have significant activity against aurora and multiple receptor tyrosine kinases. We investigated the activity of ENMD-2076 against multiple myeloma (MM) cells in vitro and in vivo. ENMD-2076 showed significant cytotoxicity against MM cell lines and primary cells, with minimal cytotoxicity to haematopoietic progenitors. ENMD-2076 inhibited the phosphoinositide 3-kinase/AKT pathway and downregulated survivin and X-linked inhibitor of apoptosis as early as 6 h after treatment. With longer treatment (24-48 h), ENMD-2076 also inhibited aurora A and B kinases, and induced G(2)/M cell cycle arrest. In non-obese diabetic/severe combined immunodeficient mice implanted with H929 human plasmacytoma xenografts, oral treatment with ENMD-2076 (50, 100, 200 mg/kg per day) resulted in a dose-dependent inhibition of tumour growth. Immunohistochemical staining of excised tumours showed significant reduction in phospho-Histone 3 (pH3), Ki-67, and angiogenesis, and also a significant increase in cleaved caspase-3 at all dose levels compared to tumours from vehicle-treated mice. In addition, a significant reduction in p-FGFR3 was observed on Western blot. ENMD-2076 shows significant activity against MM cells in vitro and in vivo, and acts on several pathways important for myeloma cell growth and survival. These results provide preclinical rationale for clinical investigation of ENMD-2076 in MM.

Objective We recently reported that murine marrow cultured ex vivo for γ-retrovirus transduction engrafts approximately 10-fold less well than fresh marrow upon transplantation into submyeloablated hosts. Here, we evaluated homing efficiency as a potential mechanism for this engraftment disparity, and whether CD26 inhibition with the tripeptide Diprotin A (DipA) would enhance engraftment of ex vivo cultured cells in submyeloablated hosts. Materials and Methods Homing and engraftment of fresh and ex vivo cultured lineage-negative (lin − ) marrow cells in submyeloablated congenic hosts with and without DipA treatment was evaluated. Expression of CXCR4 and CD26 on fresh and cultured lin − marrow cells was compared. Results Homing of lin − cells cultured for γ-retrovirus transduction was at least threefold less than that of fresh lin − cells 20 hours after transplantation into submyeloablated hosts. DipA treatment of fresh lin − cells resulted in at least twofold increased homing and engraftment in submyeloablated hosts. DipA treatment, however, did not significantly improve homing or engraftment of cells undergoing a 3-day culture protocol for γ-retrovirus transduction in submyeloablated hosts. CXCR4 expression on lin − cells was significantly decreased following 3 days of culture; CXCR4 expression was not significantly altered following overnight culture. Conclusions Ex vivo culture of lin − cells for γ-retroviral transduction downregulates CXCR4 expression and markedly impairs homing and engraftment of murine lin − marrow in submyeloablated hosts. While inhibition of CD26 activity with DipA increases homing and engraftment of fresh lin − cells, DipA treatment does not improve homing and engraftment of cultured lin − marrow cells in submyeloablated congenic hosts.

The use of nonmyeloablative conditioning prior to bone marrow transplantation is an important component of transplantation-based therapies for nonmalignant blood diseases. In this study, treatment of recipient mice with granulocyte colony-stimulating factor (G-CSF) prior to low-dose total body irradiation (LD-TBI) enhanced long-term engraftment of freshly isolated congenic marrow 1.5- to 2-fold more than treatment with LD-TBI alone. This combined regimen was also evaluated in a mouse model of X-linked chronic granulomatous disease (X-CGD), where neutrophils have a defective NADPH oxidase due to genetic deletion of the gp91phox subunit. Long-term engraftment of male X-CGD bone marrow cells cultured ex vivo for retroviral transduction of gp91phox was enhanced by ∼40% when female X-CGD recipients were pretreated with G-CSF prior to 300 cGy. These data confirm that sequential treatment with G-CSF and LD-TBI prior to transplantation increases long-term engraftment of donor marrow, and they extend this approach to transplantation of murine donor marrow cultured ex vivo for gene transfer. Additional studies showed that the administration of G-CSF prior to LD-TBI did not alter early homing of donor marrow cells. However, the combined regimen significantly decreased the content of long-term repopulating cells in recipient marrow compared with LD-TBI alone, as assessed in competitive assays, which may contribute to the enhanced engraftment of donor marrow cells. Disclosure of potential conflicts of interest is found at the end of this article.

KIF14 is a mitotic kinesin and microtubule-associated molecular motor that plays an essential role in the last stages of cytokinesis. In multiple cancer types, KIF14, overexpression in tumors correlates with stage, aggressiveness, and poor patient outcomes. There is considerable interest in KIF14 as a possible oncogene, since the KIF14 locus is in a common region of genomic gain in multiple cancers. In this study, wild type BDF-1 mice and a strain constitutively overexpressing Kif14, known as Kif14-Tg mice, were evaluated at the end of their natural lifespan, specifically for the occurrence of tumors. There were approximately fifty mice per genotype, and eighty of these mice have died. These mice were necropsied and the following tissues were collected: kidney, liver, lung, spleen, seminal vesicles, ovary, mammary gland, bone marrow, pituitary gland, eye, and brain. Any gross nodules were also collected. These tissues were then fixed in 10% neutral buffered formalin, processed, sectioned, and stained with hematoxylin and eosin. Although there was no significant difference in mouse weights through the lifespan or in the survival curve between the Kif14-Tg and their wild type littermates, a significant increase in follicular lymphoma and diffuse large B cell lymphoma was seen in Kif14-Tg mice compared to the wild type mice. Thirty-three mice developed either a follicular lymphoma or a diffuse large B cell lymphoma, and twenty-four of those mice were Kif14-Tg mice. These were the two most common tumors in Kif14-Tg mice. Other lesions and tumors that were seen in both strains included thymic lymphoma, sarcomas, myeloid dysplasia, and other carcinomas. Nontumorous lesions were seen in both strains of mice including hydronephrosis and telangiectasia in multiple organs. Ballooning degeneration of the lens of the eyes was observed in five mice from the strain Kif14-Tg. Our finding of increased follicular lymphoma and diffuse large B cell lymphoma proves the first evidence that Kif14 can promote tumor formation in a wild-type background. This is the first evidence that Kif14 may have a role in lymphoma, but complements our earlier finding that Kif14 overexpression can accelerate tumor formation in a mouse model of retinoblastoma. Together, these outcomes further support Kif14’s potential as an oncogene. Citation Format: Natalie Pitt, Kamakshi Sishtla, Mehdi Shadmand, Rania Sulaiman, Anthony L. Sinn, Keith Condon, George E. Sandusky, Timothy W. Corson. Effect of kif14 overexpression on tumor formation in mice in a lifespan study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2814. doi:10.1158/1538-7445.AM2017-2814

The purpose of the present study was to develop and validate noninvasive bioluminescence imaging methods for differentially monitoring primary and abdominal metastatic tumor growth in mouse orthotopic models of pancreatic cancer.A semiautomated maximum entropy segmentation method was implemented for the primary tumor region of interest, and a rule-based method for manually drawing a region of interest for the abdominal metastatic region was developed for monitoring tumor growth in orthotopic models of pancreatic cancer. The 2 region-of-interest methods were validated by having 2 observers independently segment Panc-1 tumors, and the results were compared with the number of mesenteric lymph node nodules and histopathologic assessment of liver metastases. The findings were extended to orthotopic tumors of the more metastatic MIA PaCa-2 and AsPC-1 cells where separate groups of animals were implanted with different numbers of cells.The results demonstrated that the segmentation methods were highly reliable, reproducible, and robust and allowed statistically significant discrimination in the growth rates of primary and abdominal metastatic tumors of different cell lines implanted with different numbers of cells.The present results demonstrate that primary tumors and abdominal metastatic foci in orthotopic pancreatic cancer models can be reliably quantified separately and noninvasively over time with bioluminescence imaging.

The uPAR·uPA protein-protein interaction (PPI) is involved in signaling and proteolytic events that promote tumor invasion and metastasis. A previous study had identified 4 (IPR-803) from computational screening of a commercial chemical library and shown that the compound inhibited uPAR·uPA PPI in competition biochemical assays and invasion cellular studies. Here, we synthesize 4 to evaluate in vivo pharmacokinetic (PK) and efficacy studies in a murine breast cancer metastasis model. First, we show, using fluorescence polarization and saturation transfer difference (STD) NMR, that 4 binds directly to uPAR with sub-micromolar affinity of 0.2 μM. We show that 4 blocks invasion of breast MDA-MB-231, and inhibits matrix metalloproteinase (MMP) breakdown of the extracellular matrix (ECM). Derivatives of 4 also inhibited MMP activity and blocked invasion in a concentration-dependent manner. 4 also impaired MDA-MB-231 cell adhesion and migration. Extensive in vivo PK studies in NOD-SCID mice revealed a half-life of nearly 5 hours and peak concentration of 5 μM. Similar levels of the inhibitor were detected in tumor tissue up to 10 hours. Female NSG mice inoculated with highly malignant TMD-MDA-MB-231 in their mammary fat pads showed that 4 impaired metastasis to the lungs with only four of the treated mice showing severe or marked metastasis compared to ten for the untreated mice. Compound 4 is a promising template for the development of compounds with enhanced PK parameters and greater efficacy.

Virtual screening targeting the urokinase receptor (uPAR) led to (3R)-4-cyclohexyl-3-(hexahydrobenzo[d][1,3]dioxol-5-yl)-N-((hexahydrobenzo[d][1,3]dioxol-5-yl)methyl)butan-1-aminium 1 (IPR-1) and 4-(4-((3,5-dimethylcyclohexyl)carbamoyl)-2-(4-isopropylcyclohexyl)pyrazolidin-3-yl)piperidin-1-ium 3 (IPR-69). Synthesis of an analog of 1, namely 2 (IPR-9), and 3 led to breast MDA-MB-231 invasion, migration and adhesion assays with IC50 near 30 μM. Both compounds blocked angiogenesis with IC50 of 3 μM. Compounds 2 and 3 inhibited cell growth with IC50 of 6 and 18 μM and induced apoptosis. Biochemical assays revealed lead-like properties for 3, but not 2. Compound 3 administered orally reached peak concentration of nearly 40 μM with a half-life of about 2 hours. In NOD-SCID mice inoculated with breast TMD-231 cells in their mammary fat pads, compound 3 showed a 20% reduction in tumor volumes and less extensive metastasis was observed for the treated mice. The suitable pharmacokinetic properties of 3 and the encouraging preliminary results in metastasis make it an ideal starting point for next generation compounds.

Purpose: Preclinical in vivo studies can help guide the selection of agents and regimens for clinical testing. However, one of the challenges in screening anticancer therapies is the assessment of off-target human toxicity. There is a need for in vivo models that can simulate efficacy and toxicities of promising therapeutic regimens. For example, hematopoietic cells of human origin are particularly sensitive to a variety of chemotherapeutic regimens, but in vivo models to assess potential toxicities have not been developed. In this study, a xenograft model containing humanized bone marrow is utilized as an in vivo assay to monitor hematotoxicity. Experimental Design: A proof-of-concept, temozolomide-based regimen was developed that inhibits tumor xenograft growth. This regimen was selected for testing because it has been previously shown to cause myelosuppression in mice and humans. The dose-intensive regimen was administered to NOD.Cg-PrkdcscidIL2rgtm1Wjl/Sz (NOD/SCID/γchainnull), reconstituted with human hematopoietic cells, and the impact of treatment on human hematopoiesis was evaluated. Results: The dose-intensive regimen resulted in significant decreases in growth of human glioblastoma xenografts. When this regimen was administered to mice containing humanized bone marrow, flow cytometric analyses indicated that the human bone marrow cells were significantly more sensitive to treatment than the murine bone marrow cells and that the regimen was highly toxic to human-derived hematopoietic cells of all lineages (progenitor, lymphoid, and myeloid). Conclusions: The humanized bone marrow xenograft model described has the potential to be used as a platform for monitoring the impact of anticancer therapies on human hematopoiesis and could lead to subsequent refinement of therapies prior to clinical evaluation. Clin Cancer Res; 17(8); 2195–206. ©2011 AACR.

Humanized bone-marrow xenograft models that can monitor the long-term impact of gene-therapy strategies will help facilitate evaluation of clinical utility. The ability of the murine bone-marrow microenvironment in NOD/SCID versus NOD/SCID/γ chainnull mice to support long-term engraftment of MGMTP140K-transduced human-hematopoietic cells following alkylator-mediated in vivo selection was investigated. Mice were transplanted with MGMTP140K-transduced CD34+ cells and transduced cells selected in vivo. At 4 months after transplantation, levels of human-cell engraftment, and MGMTP140K-transduced cells in the bone marrow of NOD/SCID versus NSG mice varied slightly in vehicle- and drug-treated mice. In secondary transplants, although equal numbers of MGMTP140K-transduced human cells were transplanted, engraftment was significantly higher in NOD/SCID/γ chainnull mice compared to NOD/SCID mice at 2 months after transplantation. These data indicate that reconstitution of NOD/SCID/γ chainnull mice with human-hematopoietic cells represents a more promising model in which to test for genotoxicity and efficacy of strategies that focus on manipulation of long-term repopulating cells of human origin.

ENMD-2076 is a novel, orally-active molecule that has been shown to have significant activity against aurora and multiple receptor tyrosine kinases. We investigated the activity of ENMD-2076 against multiple myeloma (MM) cells in vitro and in vivo. ENMD-2076 showed significant cytotoxicity against MM cell lines and primary cells, with minimal cytotoxicity to haematopoietic progenitors. ENMD-2076 inhibited the phosphoinositide 3-kinase/AKT pathway and downregulated survivin and X-linked inhibitor of apoptosis as early as 6 h after treatment. With longer treatment (24-48 h), ENMD-2076 also inhibited aurora A and B kinases, and induced G(2)/M cell cycle arrest. In non-obese diabetic/severe combined immunodeficient mice implanted with H929 human plasmacytoma xenografts, oral treatment with ENMD-2076 (50, 100, 200 mg/kg per day) resulted in a dose-dependent inhibition of tumour growth. Immunohistochemical staining of excised tumours showed significant reduction in phospho-Histone 3 (pH3), Ki-67, and angiogenesis, and also a significant increase in cleaved caspase-3 at all dose levels compared to tumours from vehicle-treated mice. In addition, a significant reduction in p-FGFR3 was observed on Western blot. ENMD-2076 shows significant activity against MM cells in vitro and in vivo, and acts on several pathways important for myeloma cell growth and survival. These results provide preclinical rationale for clinical investigation of ENMD-2076 in MM.

Cellular FLICE-like inhibitory protein (c-FLIP) is an inhibitor of death receptor-mediated apoptosis and exerts its anti-apoptotic function by blocking the activation of caspase-8. We recently showed that the siRNA-mediated knockdown of c-FLIP in MCF-7 breast cancer cells growing in vitro triggered apoptosis. The aim of this study was to determine if the in vivo knockdown of c-FLIP in MCF-7 breast cancer xenografts affected tumor viability. Immunohistochemical detection of c-FLIP in the tumor sections revealed that the knockdown of c-FLIP eliminated the neoplastic cells within the breast cancer xenografts without affecting the normal stromal and fibroblastic cells. These results indicate that c-FLIP is required for breast cancer growth and is a relevant therapeutic target for the treatment of breast cancer.