Understanding nanomedicine treatment in an aggressive spontaneous brain cancer model at the stage of early blood brain barrier disruption

Targeted Hyperbranched Nanoparticles for Delivery of Doxorubicin in Breast Cancer Brain Metastasis

Breast cancer brain metastases (BM) are associated with a dismal prognosis and very limited treatment options. Standard chemotherapy is challenging in BM patients because the high dosage required for an effective outcome causes unacceptable systemic toxicities, a consequence of poor brain penetration, and a short physiological half-life. Nanomedicines have the potential to circumvent off-target toxicities and factors limiting the efficacy of conventional chemotherapy. The HER3 receptor is commonly expressed in breast cancer BM. Here, we investigate the use of hyperbranched polymers (HBP) functionalized with a HER3 bispecific-antibody fragment for cancer cell-specific targeting and pH-responsive release of doxorubicin (DOX) to selectively deliver and treat BM. We demonstrated that DOX-release from the HBP carrier was controlled, gradual, and greater in endosomal acidic conditions (pH 5.5) relative to physiologic pH (pH 7.4). We showed that the HER3-targeted HBP with DOX payload was HER3-specific and induced cytotoxicity in BT474 breast cancer cells (IC50: 17.6 μg/mL). Therapeutic testing in a BM mouse model showed that HER3-targeted HBP with DOX payload impacted tumor proliferation, reduced tumor size, and prolonged overall survival. HER3-targeted HBP level detected in ex vivo brain samples was 14-fold more than untargeted-HBP. The HBP treatments were well tolerated, with less cardiac and oocyte toxicity compared to free DOX. Taken together, our HER3-targeted HBP nanomedicine has the potential to deliver chemotherapy to BM while reducing chemotherapy-associated toxicities.

Overcoming brain barriers through surface-functionalized liposomes for glioblastoma therapy; current status, challenges and future perspective

Glioblastoma (GB) originating from astrocytes is considered a grade IV astrocytoma tumor with severe consequences. The blood-brain barrier (BBB) offers a major obstacle in drug delivery to the brain to overcome GB. The current treatment options possess limited efficacy and maximal systemic toxic effects in GB therapy. Emerging techniques such as targeted drug delivery offer significant advantages, including enhanced drug delivery to the tumor site by overcoming the BBB. This review article focuses on the status of surface-modified lipid nanocarriers with functional ligands to efficiently traverse the BBB and improve brain targeting for successful GB treatment. The difficulties with surface-functionalized liposomes and potential future directions for opening up novel treatment options for GB are highlighted.

Development of an Anti-EphB4 Monoclonal Antibody for Multiple Applications Against Breast Cancers

The erythropoietin-producing hepatocellular carcinoma (Eph) receptors are the largest receptor tyrosine kinase family. EphB4 is essential for cell adhesion and motility during embryogenesis. Pathologically, EphB4 is overexpressed and contributes to poor prognosis in various tumors. Therefore, specific monoclonal antibodies (mAbs) should be developed to predict the prognosis for multiple tumors with high EphB4 expression, including breast and gastric cancers. This study aimed to develop specific anti-EphB4 mAbs for multiple applications using the Cell-Based Immunization and Screening method. EphB4-overexpressed Chinese hamster ovary (CHO)-K1 (CHO/EphB4) cells were immunized into mice, and we established an anti-EphB4 mAb (clone B4Mab-7), which is applicable for flow cytometry, Western blot, and immunohistochemistry (IHC). B4Mab-7 reacted with endogenous EphB4-positive breast cancer cell line, MCF-7, but did not react with EphB4-knockout MCF-7 (BINDS-52) in flow cytometry. Dissociation constant (KD) values were determined to be 2.9 × 10-9 M and 1.3 × 10-9 M by flow cytometric analysis for CHO/EphB4 and MCF-7 cells, respectively. B4Mab-7 detected the EphB4 protein bands from breast cancer cells in Western blot, and stained breast cancer tissues in IHC. Altogether, B4Mab-7 is very useful for detecting EphB4 in various applications.

Nanomedicine strategies for central nervous system (CNS) diseases

The blood-brain barrier (BBB) is a crucial part of brain anatomy as it is a specialized, protective barrier that ensures proper nutrient transport to the brain, ultimately leading to regulating proper brain function. However, it presents a major challenge in delivering pharmaceuticals to treat central nervous system (CNS) diseases due to this selectivity. A variety of different vehicles have been designed to deliver drugs across this barrier to treat neurodegenerative diseases, greatly impacting the patient's quality of life. The two main types of vehicles used to cross the BBB are polymers and liposomes, which both encapsulate pharmaceuticals to allow them to transcytose the cells of the BBB. For Alzheimer's disease, Parkinson's disease, multiple sclerosis, and glioblastoma brain cancer, there are a variety of different nanoparticle treatments in development that increase the bioavailability and targeting ability of existing drugs or new drug targets to decrease symptoms of these diseases. Through these systems, nanomedicine offers a new way to target specific tissues, especially for the CNS, and treat diseases without the systemic toxicity that often comes with medications used currently.

Pharmacokinetics and Biodistribution of 89Zr-Miltuximab and Its Antibody Fragments as Glypican-1 Targeting Immuno-PET Agents in Glioblastoma

Glioblastoma (GBM) is the most aggressive form of primary brain cancer, accounting for about 85% of all primary central nervous system (CNS) tumors. With standard treatment strategies like surgery, radiation, and chemotherapy, the median survival time of patients with GBM is only 12-15 months from diagnosis. The poor prognosis of GBM is due to a very high tumor recurrence rate following initial treatment, indicating a dire need for improved diagnostic and therapeutic alternatives for this disease. Antibody-based immunotheranostics holds great promise in treating GBM, combining the theranostic applications of radioisotopes and target-specificity of antibodies. In this study, we developed and validated antibody-based positron emission tomography (PET) tracers targeting the heparan sulfate proteoglycan, glypican-1 (GPC-1), for noninvasive detection of disease using diagnostic molecular imaging. GPC-1 is overexpressed in multiple solid tumor types, including GBM, and is a promising biomarker for novel immunotheranostics. Here, we investigate zirconium-89 (⁸⁹Zr)-conjugated Miltuximab (a clinical stage anti-GPC-1 monoclonal antibody developed by GlyTherix, Ltd.) and engineered fragments for their potential as immuno-PET tracers to detect GPC-1^positive GBM tumors in preclinical models. We explore the effects of molecular size, avidity, and Fc-domain on the pharmacokinetics and biodistribution in vivo, by comparing in parallel the full-length antibody (Miltuximab), Fab'2, Fab, and single-chain variable fragment (scFv) formats. High radiolabeling efficiency (>95%) was demonstrated by all the formats and the stability post-radiolabeling was higher for larger constructs of Miltuximab and the Fab. Receptor-mediated internalization of all ⁸⁹Zr-labeled formats was observed in a human GBM cell line in vitro, while full-length Miltuximab demonstrated the highest tumor retention (5.7 ± 0.94% ID/g, day-9 postinjection (p.i.)) and overall better tumor-to-background ratios than the smaller Fc-less formats. Results from in vivo PET image quantification and ex vivo scintillation counting were highly correlated. Altogether, ⁸⁹Zr-DFO-Miltuximab appears to be an effective immuno-PET imaging agent for detecting GPC-1^positive tumors such as GBM and the current results support utility of the Fc containing whole mAb format over smaller antibody fragments for this target.

Probing the Biocompatibility and Immune Cell Association of Chiral, Water-Soluble, Bottlebrush Poly(2-oxazoline)s

Poly(2-oxazoline)s (POx) have received substantial attention as poly(ethylene glycol) (PEG) alternatives in the biomedical field due to their biocompatibility, high functionality, and ease of synthesis. While POx have demonstrated strong potential as biomaterial constituents, the larger family of poly(cyclic imino ether)s (PCIE) to which POx belongs remains widely underexplored. One highly interesting sub-class of PCIE is poly(2,4-disubstituted-2-oxazoline)s (PdOx), which bear an additional substituent on the backbone of the polymers' repeating units. This allows fine-tuning of the hydrophilic/hydrophobic balance and renders the PdOx chiral when enantiopure 2-oxazoline monomers are used. Herein, we synthesize new water-soluble (R-/S-/RS-) poly(oligo(2-ethyl-4-methyl-2-oxazoline) methacrylate) (P(OEtMeOxMA)) bottlebrushes and compare them to well-established PEtOx- and PEG-based bottlebrush controls in terms of their physical properties, hydrophilicity, and biological behavior. We reveal that the P(OEtMeOxMA) bottlebrushes show a lower critical solution temperature behavior at a physiologically relevant temperature (∼44 °C) and that the enantiopure (R-/S-) variants display a chiral secondary structure. Importantly, we demonstrate the biocompatibility of the chiral P(OEtMeOxMA) bottlebrushes through cellular association and mouse biodistribution studies and show that these systems display higher immune cell association and organ accumulation than the two control polymers. These novel materials possess properties that hold promise for applications in the field of nanomedicine and may be beneficial carriers for therapeutics that require enhanced cellular association and immune cell interaction.

Antibody-Based Formats to Target Glioblastoma: Overcoming Barriers to Protein Drug Delivery

Glioblastoma (GB) is recognized as the most aggressive form of primary brain cancer. Despite advances in treatment strategies that include surgery, radiation, and chemotherapy, the median survival time (∼15 months) of patients with GB has not significantly improved. The poor prognosis of GB is also associated with a very high chance of tumor recurrence (∼90%), and current treatment measures have failed to address the complications associated with this disease. However, targeted therapies enabled through antibody engineering have shown promise in countering GB when used in combination with conventional approaches. Here, we discuss the challenges in conventional as well as future GB therapeutics and highlight some of the known advantages of using targeted biologics to overcome these impediments. We also review a broad range of potential alternative routes that could be used clinically to administer anti-GB biologics to the brain through evasion of its natural barriers.