Esther H. Chang

Purpose: This study explores a nanoparticle-based delivery system for alisertib, a selective aurora kinase A (AURKA) inhibitor. This nanocomplex is designed to enhance tumor-specific delivery. AURKA is overexpressed in various cancers, including atypical teratoid/rhabdoid tumors (ATRTs) and is associated with poor clinical outcomes. Alisertib has demonstrated promising efficacy in multiple preclinical studies, which supported its advancement into clinical trials across various cancer types. However, alisertib has not met key efficacy endpoints primarily due to its poor biodistribution to tumors and inadequate penetration of biological barriers, including the blood-brain barrier (BBB). Our study aims to address these issues. Methods: To address the limitations of alisertib, we developed scL-ALI, a nanocomplex formulation designed to improve BBB penetration and to enhance tumor uptake of alisertib, to achieve higher effective intratumoral doses. Our new formulation of alisertib comprises a cationic liposome encapsulating the kinase inhibitor. This formulation incorporates an anti-transferrin receptor antibody fragment to enable efficient delivery into the central nervous system and facilitate tumor targeting. Here, we assessed the therapeutic efficacy of nano-formulated scL-ALI versus conventional alisertib utilizing patient-derived tumor cells and xenograft tumor models of various cancer types, including ATRT. Additionally, we investigated the potential synergistic effects of combining scL-ALI with radiation therapy, a standard treatment modality for brain tumors. Results: Compared to conventional alisertib, scL-ALI more effectively inhibited AURKA activity and enhanced tumor cell killing of multiple cancer cell lines. In mouse models of ATRT, glioblastoma, and lung cancer, scL-ALI significantly improved tumor growth inhibition relative to conventional unencapsulared alisertib. Furthermore, when combined with radiation therapy, scL-ALI produced further improved antitumor effects, leading to extended survival in ATRT-bearing mice. Conclusion: These findings highlight the superiority of scL-ALI in overcoming delivery barriers and enhancing therapeutic efficacy of alisertib, while possibly minimizing undesirable side effects in normal tissues. The scL-ALI nanocomplex shows enhanced therapeutic potential for treating AURKA-driven malignancies, particularly in combination with radiation therapy.

The blood-brain barrier (BBB) blocks ~98% of drugs, so brain tumors tend to be refractory to chemotherapy. Transferrin receptors (TfRs) are expressed on the endothelial cell that comprise the BBB and mediate the movement of transferrin into the brain via transcytosis. Tumor cells overexpress TfRs, so encapsulating drugs within nanocomplexes that bind to TfRs has the potential to enhance both entry into the brain and delivery to tumor cells. Here, we present data on the use of TfR-targeted platform nanotechnology termed scL (for single-chain Liposome) to encapsulate five different chemotherapeutic agents. Data are provided showing that scL nanoformulations of these drugs were more effective in killing cancer cells than their unencapsulated counterparts. It is not our intention to study any one of these nanoformulations in detail but rather to highlight the general versatility of this drug delivery system. The scL formulation of TMZ (scL-TMZ) was more effective than unencapsulated TMZ against TMZ-resistant glioblastoma (GBM) and displayed improved efficacy in impeding tumor growth and extending lifespan in mice bearing intracranial GBM tumors. The scL formulation of irinotecan displayed both enhanced potency in killing lung cancer cells in culture and improved in vivo efficacy in a murine lung cancer xenograft model.

Due to their inhibition of acetylcholinesterase, organophosphates are among the most toxic of chemicals. Pralidoxime (a.k.a 2-PAM) is the only acetylcholinesterase reactivator approved in the U.S., but 2-PAM only poorly traverses the blood–brain barrier. Previously, we have demonstrated that scL-2PAM, a nanoformulation designed to enter the brain via receptor-mediated transcytosis, is superior to unencapsulated 2-PAM for reactivating brain acetylcholinesterase, ameliorating cholinergic crisis, and improving survival rates for paraoxon-exposed mice. Here, we employ histology and transcriptome analyses to assess the ability of scL-2PAM to prevent neurological sequelae including microglial activation, expression of inflammatory cytokines, and ultimately loss of neurons in mice surviving paraoxon exposures. Levels of the mRNA encoding chemokine ligand 2 (CCL2) were significantly upregulated after paraoxon exposures, with CCL2 mRNA levels in the brain correlating well with the intensity and duration of cholinergic symptoms. Our nanoformulation of 2-PAM was found to be superior to unencapsulated 2-PAM in reducing the levels of the CCL2 transcript. Moreover, brain histology revealed that scL-2PAM was more effective than unencapsulated 2-PAM in preventing microglial activation and the subsequent loss of neurons. Thus, scL-2PAM appears to be a new and improved countermeasure for reducing neuroinflammation and mitigating brain damage in survivors of organophosphate exposures.

Purpose: Atypical teratoid rhabdoid tumor (ATRT) is a deadly, fast-growing form of pediatric brain cancer with poor prognosis. Most ATRTs are associated with inactivation of SMARCB1, a subunit of the chromatin remodeling complex, which is involved in developmental processes. The recent identification of SMARCB1 as a tumor suppressor gene suggests that restoration of SMARCB1 could be an effective therapeutic approach. Methods: We tested SMARCB1 gene therapy in SMARCB1-deficient rhabdoid tumor cells using a novel tumor-targeted nanomedicine (termed scL-SMARCB1) to deliver wild-type SMARCB1. Our nanomedicine is a systemically administered immuno-lipid nanoparticle that can actively cross the blood-brain barrier via transferrin receptor-mediated transcytosis and selectively target tumor cells via transferrin receptor-mediated endocytosis. We studied the antitumor activity of the scL-SMARCB1 nanocomplex either as a single agent or in combination with traditional treatment modalities in preclinical models of SMARCB1-deficient ATRT. Results: Restoration of SMARCB1 expression by the scL-SMARCB1 nanocomplex blocked proliferation, and induced senescence and apoptosis in ATRT cells. Systemic administration of the scL-SMARCB1 nanocomplex demonstrated antitumor efficacy as monotherapy in mice bearing ATRT xenografts, where the expression of exogenous SMARCB1 modulates MYC-target genes. scL-SMARCB1 demonstrated even greater antitumor efficacy when combined with either cisplatin-based chemotherapy or radiation therapy, resulting in significantly improved survival of ATRT-bearing mice. Conclusion: Collectively, our data suggest that restoring SMARCB1 function via the scL-SMARCB1 nanocomplex may lead to therapeutic benefits in ATRT patients when combined with traditional chemoradiation therapies.

Introduction: Organophosphates are among the deadliest of known chemicals based on their ability to inactivate acetylcholinesterase in neuromuscular junctions and synapses of the central and peripheral nervous systems. The consequent accumulation of acetylcholine can produce severe acute toxicities and death. Oxime antidotes act by reactivating acetylcholinesterase with the only such reactivator approved for use in the United States being 2-pyridine aldoxime methyl chloride (a.k.a., pralidoxime or 2-PAM). However, this compound does not cross the blood–brain barrier readily and so is limited in its ability to reactivate acetylcholinesterase in the brain. Methods: We have developed a novel formulation of 2-PAM by encapsulating it within a nanocomplex designed to cross the blood–brain barrier via transferrin receptor-mediated transcytosis. This nanocomplex (termed scL-2PAM) has been subjected to head-to-head comparisons with unencapsulated 2-PAM in mice exposed to paraoxon, an organophosphate with anticholinesterase activity. Results and Discussion: In mice exposed to a sublethal dose of paraoxon, scL-2PAM reduced the extent and duration of cholinergic symptoms more effectively than did unencapsulated 2-PAM. The scL-2PAM formulation was also more effective than unencapsulated 2-PAM in rescuing mice from death after exposure to otherwise-lethal levels of paraoxon. Improved survival rates in paraoxon-exposed mice were accompanied by a higher degree of reactivation of brain acetylcholinesterase. Conclusion: Our data indicate that scL-2PAM is superior to the currently used form of 2-PAM in terms of both mitigating paraoxon toxicity in mice and reactivating acetylcholinesterase in their brains.

Lung cancer is among the most common and lethal cancers and warrants novel therapeutic approaches to improving patient outcomes. Although immune checkpoint inhibitors (ICIs) have demonstrated substantial clinical benefits, most patients remain unresponsive to currently approved ICIs or develop resistance after initial response. Many ongoing clinical studies are investigating combination therapies to address the limited efficacy of ICIs. Here, we have assessed whether p53 gene therapy via a tumor-targeting nanomedicine (termed SGT-53) can augment anti-programmed cell death-1 (PD-1) immunotherapy to expand its use in non-responding patients. Using syngeneic mouse models of lung cancers that are resistant to anti-PD-1, we demonstrate that restoration of normal p53 function potentiates anti-PD-1 to inhibit tumor growth and prolong survival of tumor-bearing animals. Our data indicate that SGT-53 can restore effective immune responses against lung cancer cells by reducing immuno-suppressive cells (M2 macrophages and regulatory T cells) and by downregulating immunosuppressive molecules (e.g., galectin-1, a negative regulator of T cell activation and survival) while increasing activity of cytotoxic T cells. These results suggest that combining SGT-53 with anti-PD-1 immunotherapy could increase the fraction of lung cancer patients that responds to anti-PD-1 therapy and support evaluation of this combination particularly in patients with ICI-resistant lung cancers.

Because lung cancer remains the most common and lethal of cancers, novel therapeutic approaches are urgently needed. RB94 is a truncated form of retinoblastoma tumor suppressor protein with elevated anti-tumor efficacy. Our investigational nanomedicine (termed scL-RB94) is a tumor-targeted liposomal formulation of a plasmid containing the gene encoding RB94. In this research, we studied anti-tumor and immune modulation activities of scL-RB94 nanocomplex in preclinical models of human non-small cell lung cancer (NSCLC). Systemic treatment with scL-RB94 of mice bearing human NSCLC tumors significantly inhibited tumor growth by lowering proliferation and increasing apoptosis of tumor cells in vivo. scL-RB94 treatment also boosted anti-tumor immune responses by upregulating immune recognition molecules and recruiting innate immune cells such as natural killer (NK) cells. Antibody-mediated depletion of NK cells blunted the anti-tumor activity of scL-RB94, suggesting that NK cells were crucial for the observed anti-tumor activity in these xenograft models. Treatment with scL-RB94 also altered the polarization of tumor-associated macrophages by reducing immune-suppressive M2 macrophages to lower immune suppression in the tumor microenvironment. Collectively, our data suggest that the efficacy of scL-RB94 against NSCLC is due to an induction of tumor cell death as well as enhancement of innate anti-tumor immunity.

SGT-53 is a novel investigational agent that comprises an immunoliposome carrying a plasmid vector driving expression of the human TP53 gene that encodes wild-type human p53. SGT-53 is currently in phase II human trials for advanced pancreatic cancer. Although p53 is best known as a tumor suppressor, its participation in both innate and adaptive immune responses is well documented. It is now clear that p53 is an important component of the host response to various viral infections. To facilitate their viral life cycles, viruses have developed a diverse repertoire of strategies for counteracting the antiviral activities of host immune system by manipulating p53-dependent pathways in host cells. Coronaviruses reduce endogenous p53 levels in the cells they infect by enhancing the degradation of p53 in proteasomes. Thus, interference with p53 function is an important component in viral pathogenesis. Transfection of cells by SGT-53 has been shown to transiently produce exogenous p53 that is active as a pleiotropic transcription factor. We herein summarize the rationale for repurposing SGT-53 as a therapy for infection by SARS-CoV-2, the pathogen responsible for the COVID-19 pandemic. Because p53 regulation was found to play a crucial role in different infection stages of a wide variety of viruses, it is rational to believe that restoring p53 function based on SGT-53 treatment may lead to beneficial therapeutic outcomes for infectious disease at large including heretofore unknown viral pathogens that may emerge in the future.

2Hippocrates of Kos (Greek: Ἱπποκράτης ὁ ΚCpος, translit. Hippokrátēs ho Kṓos), also known as Hippocrates II, was a Greek physician of the Age of Pericles, who is considered one of the most outstanding ϐigures in the history of medicine. Hippocrates (460–370 BC) is traditionally referred to as the “Father of Medicine” in recognition of his lasting contributions to the ϐield, such as the use of prognosis and clinical observation and the systematic categorization of diseases. He was born in Kos—but apart from that, little is known of his life. Hippocrates is credited with being the ϐirst person to believe that diseases were caused naturally, not because of superstition and gods: “Science is the father of knowledge, but opinion breeds ignorance.” He was the ϐirst to describe many diseases and also to set out standards of ethical behavior to which physicians were expected to adhere: “Cure sometimes, treat often, comfort always.” He realized the vast amount of learning required to practice medicine—impossible for a person to learn even in a lifetime: “The life so short, the craft so long to learn.” He emphasized that the purpose of medicine was to help nature apply its natural healing powers and to avoid doing harm: “Natural forces within us are the true healers of disease.” He was the ϐirst to describe many signs and diseases—from clubbing to empyema. He classiϐied diseases as acute or chronic and described the natural history of many diseases—from onset to convalescence. Some of his ideas and theories were proven to be incorrect.

Despite its anticipated clinical potential, anti‐PD‐1 immunotherapy has only yielded poor outcomes in recent clinical trials for glioblastoma patients. Strategies combining anti‐PD‐1 antibody with other treatment modalities are being explored to alter the immunosuppressive microenvironment that appears to characterize these anti‐PD‐1‐insensitive tumors. Here, we evaluated whether introducing wild‐type p53 gene via a tumor‐targeting nanomedicine (termed SGT‐53) could provide immune stimulation and augment anti‐PD‐1 therapy in mouse syngeneic GL261 tumor models (either subcutaneous or intracranial). In both models, anti‐PD‐1 monotherapy had no demonstrable therapeutic effect. However, combining anti‐PD‐1 with our investigational nanomedicine SGT‐53 was very effective in inhibiting tumor growth, inducing tumor cell apoptosis and increasing intratumoral T‐cell infiltration. A significant survival benefit was observed in mice bearing intracranial glioblastoma receiving combination treatment. Importantly, SGT‐53 upregulated PD‐L1 expression both in vitro and in vivo. Transcriptome analysis revealed modulation of genes linked to either cancer progression or immune activation after combination treatment. Our data suggest that SGT‐53 can boost antitumor immunity and sensitize glioblastoma to anti‐PD‐1 therapy by converting immunologically “cold” tumors into “hot” tumors. Combining SGT‐53 with anti‐PD‐1 might benefit more patients from anti‐PD‐1 immunotherapy and our data support evaluation of this combination in patients with glioblastoma.