Blockade of a Laminin-411-Notch Axis with CRISPR/Cas9 or a Nanobioconjugate Inhibits Glioblastoma Growth through Tumor-Microenvironment Cross-talk

There is an unmet need for the treatment of glioblastoma multiforme (GBM). The extracellular matrix, including laminins, in the tumor microenvironment is important for tumor invasion and progression. In a panel of 226 patient brain glioma samples, we found a clinical correlation between the expression of tumor vascular laminin-411 (α4β1γ1) with higher tumor grade and with expression of cancer stem cell (CSC) markers, including Notch pathway members, CD133, Nestin, and c-Myc. Laminin-411 overexpression also correlated with higher recurrence rate and shorter survival of GBM patients. We also showed that depletion of laminin-411 α4 and β1 chains with CRISPR/Cas9 in human GBM cells led to reduced growth of resultant intracranial tumors in mice and significantly increased survival of host animals compared with mice with untreated cells. Inhibition of laminin-411 suppressed Notch pathway in normal and malignant human brain cell types. A nanobioconjugate potentially suitable for clinical use and capable of crossing blood-brain barrier was designed to block laminin-411 expression. Nanobioconjugate treatment of mice carrying intracranial GBM significantly increased animal survival and inhibited multiple CSC markers, including the Notch axis. This study describes an efficient strategy for GBM treatment via targeting a critical component of the tumor microenvironment largely independent of heterogeneous genetic mutations in glioblastoma.Significance: Laminin-411 expression in the glioma microenvironment correlates with Notch and other cancer stem cell markers and can be targeted by a novel, clinically translatable nanobioconjugate to inhibit glioma growth.

Simultaneous blockade of interacting CK2 and EGFR pathways by tumor-targeting nanobioconjugates increases therapeutic efficacy against glioblastoma multiforme

Glioblastoma multiforme (GBM) remains the deadliest brain tumor in adults. GBM tumors are also notorious for drug and radiation resistance. To inhibit GBMs more effectively, polymalic acid-based blood-brain barrier crossing nanobioconjugates were synthesized that are delivered to the cytoplasm of cancer cells and specifically inhibit the master regulator serine/threonine protein kinase CK2 and the wild-type/mutated epidermal growth factor receptor (EGFR/EGFRvIII), which are overexpressed in gliomas according to The Cancer Genome Atlas (TCGA) GBM database. Two xenogeneic mouse models bearing intracranial human GBMs from cell lines LN229 and U87MG that expressed both CK2 and EGFR at different levels were used. Simultaneous knockdown of CK2α and EGFR/EGFRvIII suppressed their downstream prosurvival signaling. Treatment also markedly reduced the expression of programmed death-ligand 1 (PD-L1), a negative regulator of cytotoxic lymphocytes. Downregulation of CK2 and EGFR also caused deactivation of heat shock protein 90 (Hsp90) co-chaperone Cdc37, which may suppress the activity of key cellular kinases. Inhibition of either target was associated with downregulation of the other target as well, which may underlie the increased efficacy of the dual nanobioconjugate that is directed against both CK2 and EGFR. Importantly, the single nanodrugs, and especially the dual nanodrug, markedly suppressed the expression of the cancer stem cell markers c-Myc, CD133, and nestin, which could contribute to the efficacy of the treatments. In both tumor models, the nanobioconjugates significantly increased (up to 2-fold) animal survival compared with the PBS-treated control group. The versatile nanobioconjugates developed in this study, with the abilities of anti-cancer drug delivery across biobarriers and the inhibition of key tumor regulators, offer a promising nanotherapeutic approach to treat GBMs, and to potentially prevent drug resistance and retard the recurrence of brain tumors.

MRI virtual biopsy and treatment of brain metastatic tumors with targeted nanobioconjugates: nanoclinic in the brain

Differential diagnosis of brain magnetic resonance imaging (MRI) enhancement(s) remains a significant problem, which may be difficult to resolve without biopsy, which can be often dangerous or even impossible. Such MRI enhancement(s) can result from metastasis of primary tumors such as lung or breast, radiation necrosis, infections, or a new primary brain tumor (glioma, meningioma). Neurological symptoms are often the same on initial presentation. To develop a more precise noninvasive MRI diagnostic method, we have engineered a new class of poly(β-l-malic acid) polymeric nanoimaging agents (NIAs). The NIAs carrying attached MRI tracer are able to pass through the blood-brain barrier (BBB) and specifically target cancer cells for efficient imaging. A qualitative/quantitative "MRI virtual biopsy" method is based on a nanoconjugate carrying MRI contrast agent gadolinium-DOTA and antibodies recognizing tumor-specific markers and extravasating through the BBB. In newly developed double tumor xenogeneic mouse models of brain metastasis this noninvasive method allowed differential diagnosis of HER2- and EGFR-expressing brain tumors. After MRI diagnosis, breast and lung cancer brain metastases were successfully treated with similar tumor-targeted nanoconjugates carrying molecular inhibitors of EGFR or HER2 instead of imaging contrast agent. The treatment resulted in a significant increase in animal survival and markedly reduced immunostaining for several cancer stem cell markers. Novel NIAs could be useful for brain diagnostic MRI in the clinic without currently performed brain biopsies. This technology shows promise for differential MRI diagnosis and treatment of brain metastases and other pathologies when biopsies are difficult to perform.

Near-infrared imaging of brain tumors using the Tumor Paint BLZ-100 to achieve near-complete resection of brain tumors

OBJECT

The intraoperative clear delineation between brain tumor and normal tissue in real time is required to ensure near-complete resection without damaging the nearby eloquent brain. Tumor Paint BLZ-100, a tumor ligand chlorotoxin (CTX) conjugated to indocyanine green (ICG), has shown potential to be a targeted contrast agent. There are many infrared imaging systems in use, but they are not optimized to the low concentration and amount of ICG. The authors present a novel proof-of-concept near-infrared (NIR) imaging system using a standard charge-coupled device (CCD) camera for visualizing low levels of ICG attached to the tumors. This system is small, inexpensive, and sensitive. The imaging system uses a narrow-band laser at 785 nm and a notch filter in front of the sensor at the band. The camera is a 2-CCD camera, which uses identical CCDs for both visible and NIR light.

METHODS

The NIR system is tested with serial dilution of BLZ-100 from 1 μM to 50 pM in 5% Intralipid solution while the excitation energy is varied from 5 to 40 mW/cm(2). The analog gain of the CCD was changed from 0, 6, and 12 dB to determine the signal-to-noise ratio. In addition to the Intralipid solution, BLZ-100 was injected 48 hours before euthanizing the mice that were implanted with the human glioma cell line. The brain was removed and imaged using the NIR imaging system.

RESULTS

The authors' results show that the NIR imaging system using a standard CCD is able to visualize the ICG down to 50 nM of concentration with a high signal-to-noise ratio. The preliminary experiment on human glioma implanted in mouse brains demonstrated that BLZ-100 has a high affinity for glioma compared with normal brain tissue. Additionally, the results show that NIR excitation is able to penetrate deeply and has a potential to visualize metastatic lesions that are separate from the main tumor.

CONCLUSIONS

The authors have seen that BLZ-100 has a very high affinity toward human gliomas. They also describe a small, cost-effective, and sensitive NIR system for visualizing brain tumors tagged using BLZ-100. The authors hope that the use of BLZ-100 along with NIR imaging will be useful to delineate the brain tumors in real time and assist surgeons in near-complete tumor removal to increase survival and reduce neurological deficits.

Abstract 2692: Nanoconjugates for inhibition of laminin-411-integrin β1-Dll4-Notch1 pathway to treat glioblastoma multiforme

Glioblastoma multiforme (GBM) is an aggressive tumor with 14.6 months median survival rate. We have previously shown that laminin-411, a vascular basement membrane (BM) protein is a marker of tumor blood vessels that correlates with aggressiveness of GBMs.

The laminin-411 pathway involving its β1 chain-containing integrin receptors, and ligand Dll4 for cancer stem cell (CSC) Notch1 was studied in mouse xenograft models to better understand glial tumor growth and new vasculature system development.

To confirm the importance of laminin-411 expression for GBM progression and outcome prediction, sections from formalin-fixed paraffin embedded human brain tumors were studied. Immunohistochemical analysis of 107 GBM samples has revealed 87% cases with overexpression of laminin-411, whereas it was only 34% for high-grade (III) and 10.6% for low-grade (I/II) gliomas. The median survival for patients with GBM overexpressing laminin-411 was 10 months, compared to 20.2 months for those expressing “normal” laminin-421. The median recurrence rate was 5.6 and 9.3 months respectively. Morphometric analysis of CSC Notch1, nestin, CD133, and c-myc was correlated with laminin-411 overexpression in patients with high-grade gliomas.

Nanobioconjugate PolycefinTM was synthesized to block BM laminin-411 in mice bearing intracranial human U87MG-derived GBM. Two antisense oligonucleotides against laminin-411 α4 and β1 chains were covalently attached on polymalic acid nanoplatform. The nanodrug, PolycefinTM, was able to cross blood brain tumor barrier and delivered drugs into cancer cells (Ding et al. 2010, 2013) using pH-dependent endosome releasing unit Leu-Leu-Leu. Evidence of cross talk was observed between BM, CSCs and tumor proliferation when mice were treated with PolycefinTM. It is shown that blocking synthesis of laminin-411 leads to significally lower tumor expression of integrin β1 chain, Notch ligand Dll4, and Notch1. The CSC markers nestin, CD133, and c-myc that are known indicators of glial tumor progression also showed quantitative reduction by morphometric analysis in tumors of mice treated with anti-laminin-411 Polycefin compared to PBS-treated animals. The data point to the importance of laminin-411-integrin β1-Dll4-Notch1 pathway in GBM development and to the ability of Polycefin to negatively impact CSC as a possible mechamism of GBM inhibition. The results provide new insights in glioma microenvironment and tumor endothelial and parenchymal cell signaling suggesting a novel approach for future therapeutics to target CSCs in vivo through inhibition of laminin-411 to treat highly infiltrating GBMs.

Citation Format: Pallavi R. Gangalum, Alexander V. Ljubimov, Alexandra Chesnokova, Bindu Konda, Hui Ding, Jose Portilla-Arias, Adam Mamelak, Serguei Bannykh, Surasak Phuphanich, Jeremy Rudnick, Jethro Hu, Keith L. Black, Julia Y. Ljubimova. Nanoconjugates for inhibition of laminin-411-integrin β1-Dll4-Notch1 pathway to treat glioblastoma multiforme. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2692. doi:10.1158/1538-7445.AM2014-2692

Polymalic acid-based nano biopolymers for targeting of multiple tumor markers: an opportunity for personalized medicine?

Tumors with similar grade and morphology often respond differently to the same treatment because of variations in molecular profiling. To account for this diversity, personalized medicine is developed for silencing malignancy associated genes. Nano drugs fit these needs by targeting tumor and delivering antisense oligonucleotides for silencing of genes. As drugs for the treatment are often administered repeatedly, absence of toxicity and negligible immune response are desirable. In the example presented here, a nano medicine is synthesized from the biodegradable, non-toxic and non-immunogenic platform polymalic acid by controlled chemical ligation of antisense oligonucleotides and tumor targeting molecules. The synthesis and treatment is exemplified for human Her2-positive breast cancer using an experimental mouse model. The case can be translated towards synthesis and treatment of other tumors.

Toxicity and efficacy evaluation of multiple targeted polymalic acid conjugates for triple-negative breast cancer treatment

Engineered nanoparticles are widely used for delivery of drugs but frequently lack proof of safety for cancer patient's treatment. All-in-one covalent nanodrugs of the third generation have been synthesized based on a poly(β-L-malic acid) (PMLA) platform, targeting human triple-negative breast cancer (TNBC). They significantly inhibited tumor growth in nude mice by blocking synthesis of epidermal growth factor receptor, and α4 and β1 chains of laminin-411, the tumor vascular wall protein and angiogenesis marker. PMLA and nanodrug biocompatibility and toxicity at low and high dosages were evaluated in vitro and in vivo. The dual-action nanodrug and single-action precursor nanoconjugates were assessed under in vitro conditions and in vivo with multiple treatment regimens (6 and 12 treatments). The monitoring of TNBC treatment in vivo with different drugs included blood hematologic and immunologic analysis after multiple intravenous administrations. The present study demonstrates that the dual-action nanoconjugate is highly effective in preclinical TNBC treatment without side effects, supported by hematologic and immunologic assays data. PMLA-based nanodrugs of the Polycefin™ family passed multiple toxicity and efficacy tests in vitro and in vivo on preclinical level and may prove to be optimized and efficacious for the treatment of cancer patients in the future.

Abstract 3911: Imaging and treatment of brain metastatic tumors using nanopolymers

A significant clinical problem with brain metastatic (BM) tumors is drug delivery and diagnostic imaging to verify MRI enhancement(s) for planning treatment. MRI enhancement in cancer patient's brain may result from infection after chemotherapy that impairs immune system; metastasis from primary lung/breast cancer; or a new primary brain tumor. Unlike lung/breast, brain biopsies are often technically impossible. Most drugs or monoclonal antibodies (mAb) are effective for primary tumors but cannot penetrate blood brain barrier (BBB) failing to treat brain metastasis.

We used a natural nanobiopolymer, polymalic acid (PMLA), as a platform for the tumor-targeted PolycefinTM drugs for differential brain tumor imaging and treatment.

Three xenogeneic orthotropic human brain metastatic tumors, MDA-MB-474, HER2+ breast cancer; A549 lung cancer, and MDA-MB-468, triple negative breast cancer (TNBC), both EGFR+, were injected into the brain of mice.

For imaging, PolycefinTM had a covalently attached MRI tracer Gadolinium (Gd-DOTA). Antisense oligonucleotides (AON) were conjugated to PolycefinTM to inhibit gene/protein expression to block tumor growth. The combination of cell surface targeting mAbs, including anti-transferrin receptor (TfR) mAb for drug BBB transcytosis, and AONs to multiple tumor markers on the same delivery polymer was used for tumor treatment.

MRI 1H imaging was performed on a 9.4-Tesla MRI system. Treatment groups of animals included (1) HER2+ MDA-MB-474 breast cancer metastases targeted with PMLA-Gd-DOTA/Trastuzumab/TfR mAb; (2) EGFR+ MDA-MB-468 TNBC metastases targeted with PMLA-Gd-DOTA/Cetuximab/TfR mAb; and (3) Controls inoculated with PMLA-IgG mAb and clinical Gd.

Imaging: Specific tumor imaging was shown for brain-implanted lung and breast tumors: the inverse of T1-1 relaxation time proportional to Gd concentration was measured in healthy brain and in the tumor. T1-1 time dependence for Gd-DOTA-Polycefin (T1-1 ratio tumor/normal brain) was compared with clinical Gd, MultiHance®. After reaching a maximum, high T1-1 relative values prevailed for several hours for Gd-DOTA-mAb-Polycefin, but declined rapidly for Gd. High contrast for Gd was seen in 20 min, whereas that for Gd-DOTA-Polycefin peaked in 45-60 min, and remained for up to 3 hrs. By differential MRI with anti-HER2 (Trastuzumab) or anti-EFGR (Cetuximab) mAb attached to the nanoplatform, we were able to differentiate HER2+ from EGFR+ metastatic brain tumors.

Treatment: Animal survival after Polycefin treatment was significantly higher than in untreated or mAb (Herceptin or Cetuximab) treated animals. Survival increases were as follows: 66% for lung cancer, 47% for HER2+ breast cancer, and 81% for TNBC.

We developed a system for differential imaging and successful systemic treatment of various metastatic brain tumors based on specific metastasis targeting, and inhibition of expression of tumor-specific genes/proteins.

Citation Format: Julia Y. Ljubimova, Rameshwar Patil, Pallavi Gangalum, Shawn Wagner, Satoshi Inoue, Hui Ding, Jose Portilla-Arias, Arthur Rekechenetskiy, Bindu Konda, Janet Markman, Alexandra Chesnokova, Keith L. Black, Eggehard Holler. Imaging and treatment of brain metastatic tumors using nanopolymers. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3911. doi:10.1158/1538-7445.AM2013-3911

Abstract A50: Nanobiocojugates of differential imaging and treatment of brain metastatic tumors

Introduction: A significant clinical problem with brain metastatic (BM) tumors is drug delivery and diagnostic imaging to verify MRI enhancement(s) for planning treatment. MRI enhancement in cancer patient's brain might result from infection after chemotherapy that impairs immune system; metastasis from primary lung/breast cancer; or a new primary brain tumor. Unlike lung/breast, brain biopsies are often technically impossible. Therefore, there is urgent need for the development of effective theranostic (dual therapy and diagnostic) systems against brain metastatic cancer.

Most chemotherapeutic drugs or therapeutic monoclonal antibodies (mAb), Trastuzumab, Cetuximab, and Rituximab, are effective for primary tumor treatment but cannot penetrate blood brain barrier (BBB) failing to treat brain metastasis.

We used a natural nanobiopolymer, polymalic acid (PMLA), as a nanoplatform for the family of tumor-targeted PolycefinTM drugs to provide differential brain tumor imaging and treatment.

Methods: Three xenogeneic orthotropic human brain metastatic tumors, MDA-MB-474, HER2+ breast cancer; A549 lung cancer, and MDA-MB-468, triple negative breast cancer (TNBC), both EGFR+, were inoculated stereotactically into the brain of mice.

For diagnostic imaging, PolycefinTM was used with covalently attached MRI tracer Gadolinium (Gd-DOTA). Morpholino antisense oligonucleotides (AON) were conjugated to PolycefinTM to specifically inhibit gene/protein expression to block tumor growth. The combination of cell surface targeting mAbs, including anti-transferrin receptor (TfR) mAb for drug BBB transcytosis, and AONs to multiple tumor markers on the same delivery polymer was used for anti-tumor treatment.

MRI 1H imaging was performed on a 9.4-Tesla small animal MRI system. Treatment groups of animals included (1) HER2+ MDA-MB-474 breast cancer metastases targeted with PMLA-Gd-DOTA/HER2 mAb/TfR mAb; (2) EGFR+ MDA-MB-468 TNBC metastases targeted with PMLA-Gd-DOTA/EGFR mAb/TfR mAb; and (3) Controls for all treatments inoculated with PMLA-IgG mAb and clinical Gd.

Unpublished Results. Imaging: Dynamic T1 analysis. Similar data for specific tumor imaging were obtained for brain-implanted lung and breast tumors: the inverse of T1-1 relaxation time (proportional to Gd concentration) was measured in healthy brain part and in the tumor. T1-1 time dependence for Gd-DOTA-Polycefin (T1-1 ratio tumor/normal brain) was compared with clinically used Gd MRI agent, MultiHance®. After reaching a maximum, high T1-1 relative values prevailed for several hours for Gd-DOTA-mAb-Polycefin, but declined rapidly for Gd. High contrast for Gd was seen in 20 min, whereas that for Gd-DOTA-Polycefin peaked in 45-60 min, and remained for up to 3 hrs. By differential MRI with anti-HER2 (Trastuzumab) or anti-EFGR (Cetuximab) mAb attached covalently to the nanoplatform, we were able to differentiate HER2+ from EGFR+ metastatic brain tumors with corresponding imaging controls.

Treatment: Animal survival after Polycefin treatment of various brain metastases was significantly higher than in untreated (PBS) or therapeutic mAb (Herceptin or Cetuximab) treated animals. These survival increases were as follows: 66% for lung cancer metastasis, 47% for HER2+ breast cancer metastasis, and 81% for TNBC metastasis.

Conclusions. We have developed a system for differential imaging and treatment of various metastatic brain tumors based on specific metastasis targeting, and inhibition of expression of tumor-specific genes/proteins. Systemic treatment with this system resulted in significantly increased survival of brain metastatic tumor-bearing animals.

Citation Format: Julia Y. Ljubimova, R. Patil, P. Gangalum, S. Wagner, S. Inoue, H. Ding, J. Portilla, K. Rekechenetskiy, K. Bindu, J. Markman, A. Chesnokova, K. L. Black, E. Holler. Nanobiocojugates of differential imaging and treatment of brain metastatic tumors. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr A50.