Drug-free macromolecular therapeutics induce apoptosis in cells isolated from patients with B cell malignancies with enhanced apoptosis induction by pretreatment with gemcitabine

Hydrophilic biomaterials: From crosslinked and self-assembled hydrogels to polymer-drug conjugates and drug-free macromolecular therapeutics

This "Magnum Opus" accentuates my lifelong belief that the future of science is in the interdisciplinary approach to hypotheses formulation and problem solving. Inspired by the invention of hydrogels and soft contact lenses by my mentors, my six decades of research have continuously proceeded from the synthesis of biocompatible hydrogels to the development of polymer-drug conjugates, then generation of drug-free macromolecular therapeutics (DFMT) and finally to multi-antigen T cell hybridizers (MATCH). This interdisciplinary journey was inspiring; the lifetime feeling that one is a beginner in some aspects of the research is a driving force that keeps the enthusiasm high. Also, I wanted to illustrate that systematic research in one wide area can be a life-time effort without the need to jump to areas that are temporarily en-vogue. In addition to generating general scientific knowledge, hydrogels from my laboratory have been transferred to the clinic, polymer-drug conjugates to clinical trials, and drug-free macromolecular systems have an excellent potential for personalizing patient therapies. There is a limit to life but no limit to imagination. I anticipate that systematic basic research will contribute to the expansion of our knowledge and create a foundation for the design of new paradigms based on the comprehension of mechanisms of physiological processes. The emerging novel platform technologies in biomaterial-based devices and implants as well as in personalized nanomedicines will ultimately impact clinical practice.

Multiantigen T-Cell Hybridizers: A Two-Component T-Cell-Activating Therapy

Multispecific T-cell-engaging scaffolds have emerged as effective anticancer therapies for the treatment of hematological malignancies. Approaches that modulate cancer cell targeting and provide personalized, multispecific immunotherapeutics are needed. Here, we report on a modular, split antibody-like approach consisting of Fab' fragments modified with complementary morpholino oligonucleotides (MORFs). We synthesized a library of B-cell-targeting Fab'-MORF1 conjugates that self-assemble, via a Watson-Crick base pairing hybridization, with a complementary T-cell-engaging Fab'-MORF2 conjugate. We aptly titled our technology multiantigen T-cell hybridizers (MATCH). Using MATCH, cancer-specific T-cell recruitment was achieved utilizing four B-cell antigen targets: CD20, CD38, BCMA, and SLAMF7. The antigen expression profiles of various malignant B-cell lines were produced, and using these distinct profiles, cell-specific T-cell activation was attained on lymphoma, leukemia, and multiple myeloma cell lines in vitro. T-cell rechallenge experiments demonstrated the modular approach of MATCH by sequentially activating the same T-cell cohort against three different cancers using cancer antigen-specific Fab'-MORF1 conjugates. Furthermore, MATCH's efficacy was demonstrated in vivo by treating xenograft mouse models of human non-Hodgkin's lymphoma with CD20-directed MATCH therapy. In the pilot study, a single dose of MATCH allowed for long-term survival of all treated mice compared to saline control. In a second in vivo model, insights regarding optimal T-cell-to-target cell ratio were gleaned when a ratio of 5:1 T-cell-to-target cell MATCH-treated mice significantly delayed the onset of disease compared to higher and lower ratios.

Human serum albumin-based drug-free macromolecular therapeutics induce apoptosis in chronic lymphocytic leukemia patient cells by crosslinking of CD20 and/or CD38 receptors

This study explores the efficacy of human serum albumin (HSA)-based Drug-Free Macromolecular Therapeutics (DFMT) in treating Chronic Lymphocytic Leukemia (CLL), a prevalent adult leukemia subtype. DFMT, a novel strategy, employs biomimetic crosslinking of CD20 and CD38 receptors on malignant B cells without the need for low molecular weight drugs. Apoptosis is initiated via a two-step process: i) Recognition of a bispecific engager, Fab' fragment conjugated with morpholino oligonucleotide (Fab'-MORF1), by a cell surface antigen; followed by ii) crosslinking of the MORF1-decorated cells with a multivalent effector, HSA holding multiple copies of complementary MORF2, HSA-(MORF2)x. Herein we evaluated the efficacy of HSA-based DFMT in the treatment of 56 samples isolated from patients diagnosed with CLL. Fab' fragments from Obinutuzumab (OBN) and Isatuximab (ISA) were employed in the synthesis of anti-CD20 (Fab'OBN-MORF1) and anti-CD38 (Fab'ISA-MORF1) bispecific engagers. The efficacy of DFMT was significantly influenced by the expression levels of CD20 and CD38 receptors. Dual-targeting DFMT strategies (CD20 + CD38) were more effective than single-target approaches, particularly in samples with elevated receptor expression. Pretreatment of patient cells with gemcitabine or ricolinostat markedly increased cell surface CD20 and CD38 expression, respectively. Apoptosis was effectively initiated in 62.5% of CD20-targeted samples and in 42.9% of CD38-targeted samples. Our findings demonstrate DFMT's potential in personalized CLL therapy. Further research is needed to validate these outcomes in a larger number of patient samples and to explore DFMT's applicability to other malignancies.

Obinutuzumab-Based Drug-Free Macromolecular Therapeutics Synergizes with Topoisomerase Inhibitors

Drug-free macromolecular therapeutics (DFMT) utilizes modified monoclonal antibodies (or antibody fragments) to generate antigen-crosslinking-induced apoptosis in target cells. DFMT is a two-component system containing a morpholino oligonucleotide (MORF1) modified antibody (Ab-MORF1) and human serum albumin conjugated with multiple copies of complementary morpholino oligonucleotide (MORF2), (HSA-(MORF2)x ). The two components recognize each other via the Watson-Crick base pairing complementation of their respective MORFs. One HSA-(MORF2)x molecule can hybridize with multiple Ab-MORF1 molecules on the cell surface, thus serving as the therapeutic crosslink-inducing mechanism of action. Herein, various anti-neoplastic agents in combination with the anti-CD20 Obinutuzumab (OBN)-based DFMT system are examined. Three different classes of chemotherapies are examined: DNA alkylating agents; proliferation pathway inhibitors; and DNA replication inhibitors. Chou-Talalay combination index mathematics is utilized to determine which drugs engaged synergistically with OBN-based DFMT. It is determined that OBN-based DFMT synergizes with topoisomerase inhibitors and DNA nucleotide analogs but is antagonistic with proliferation pathway inhibitors. Cell mechanism experiments are performed to analyze points of synergism or antagonism by investigating Ca2+ influx, mitochondrial health, lysosomal stability, and cell cycle arrest. Finally, the synergistic drug combinatorial effects of OBN-based DFMT with etoposide in vivo are demonstrated using a human xenograft non-Hodgkin's lymphoma mouse model.

Multi-targeted immunotherapeutics to treat B cell malignancies

The concept of multi-targeted immunotherapeutic systems has propelled the field of cancer immunotherapy into an exciting new era. Multi-effector molecules can be designed to engage with, and alter, the patient's immune system in a plethora of ways. The outcomes can vary from effector cell recruitment and activation upon recognition of a cancer cell, to a multipronged immune checkpoint blockade strategy disallowing evasion of the cancer cells by immune cells, or to direct cancer cell death upon engaging multiple cell surface receptors simultaneously. Here, we review the field of multi-specific immunotherapeutics implemented to treat B cell malignancies. The mechanistically diverse strategies are outlined and discussed; common B cell receptor antigen targeting strategies are outlined and summarized; and the challenges of the field are presented along with optimistic insights for the future.

Simultaneous crosslinking of CD20 and CD38 receptors by drug-free macromolecular therapeutics enhances B cell apoptosis in vitro and in vivo

Drug-Free Macromolecular Therapeutics (DFMT) is a new paradigm in macromolecular therapeutics that induces apoptosis in target cells by crosslinking receptors without the need of low molecular weight drugs. Programmed cell death is initiated via a biomimetic receptor crosslinking strategy using a two-step approach: i) recognition of cell surface antigen by a morpholino oligonucleotide-modified antibody Fab' fragment (Fab'-MORF1), ii) followed by crosslinking with a multivalent effector motif - human serum albumin (HSA) grafted with multiple complementary morpholino oligonucleotides (HSA-(MORF2)x). This approach is effective in vitro, in vivo, and ex vivo on cells from patients diagnosed with various B cell malignancies. We have previously demonstrated DFMT can be applied to crosslink CD20 and CD38 receptors to successfully initiate apoptosis. Herein, we show simultaneous engagement, and subsequent crosslinking of both targets ("heteroreceptor crosslinking"), can further enhance the apoptosis induction capacity of this system. To accomplish this, we incubated Raji (CD20+; CD38+) cells simultaneously with anti-CD20 and anti-CD38 Fab'-MORF1 conjugates, followed by addition of the macromolecular crosslinker, HSA-(MORF2)x to co-cluster the bound receptors. Fab' fragments from Rituximab and Obinutuzumab were employed in the synthesis of anti-CD20 bispecific engagers (Fab'RTX-MORF1 and Fab'OBN-MORF1), whereas Fab' fragments from Daratumumab and Isatuximab (Fab'DARA-MORF1 and Fab'ISA-MORF1) targeted CD38. All heteroreceptor crosslinking DFMT combinations demonstrated potent apoptosis induction and exhibited synergistic effects as determined by Chou-Talalay combination index studies (CI < 1). In vitro fluorescence resonance energy transfer (FRET) experiments confirmed the co-clustering of the two receptors on the cell surface in response to the combination treatment. The source of this synergistic therapeutic effect was further explored by evaluating the effect of combination DFMT on key apoptosis signaling events such as mitochondrial depolarization, caspase activation, lysosomal enlargement, and homotypic cell adhesion. Finally, a xenograft mouse model of CD20+/CD38+ Non Hodgkin lymphoma was employed to demonstrate in vivo the enhanced efficacy of the heteroreceptor-crosslinking DFMT design versus single-target systems.

Development of Highly Sensitive Molecular Blocks at Cancer Microenvironment for Rapid Cancer Cell Death

Improving the efficiency and selectivity of drug delivery systems (DDS) is still a major challenge in cancer therapy. Recently, the low transport efficiency of anticancer drugs using a nanocarrier due to the elimination of the carriers from the blood circulation and the blocking by tumor stromal tissues surrounding cancer cells has been reported. Furthermore, multiple steps are required for their intracellular delivery. We recently reported a cancer microenvironment-targeting therapy termed molecular block (MB) which induced cancer cell death by a pH-driven self-aggregation and cell membrane disruption at tumor microenvironment. The MB were designed to disperse as nanoscale assemblies in the bloodstream for efficient circulation and penetration through the stromal tissues. When the MBs reach the tumor site, they self-assembled in microscale aggregates on the cancer cell surfaces in response to the cancer microenvironment and induced cancer cell death. However, in vivo study in mice showed that the MB could not efficiently accumulate at the tumor site because slight hydrophobic aggregations in the bloodstream might potentially be the reason for the off-target accumulation. In this study, we optimize the hydrophilic-hydrophobic balance of MB for avoiding the off-target accumulation and for gaining higher sensitivity to the cancer microenvironment at weak acid condition. Copper-free click reaction with propiolic acid was used to reduce the hydrophobicity of the main chain and obtain higher responsive MB at cancer microenvironment for rapid cell killing. The optimized MB can be considered as a promising approach for an improved cancer cell targeting.

Nanomedicines in B cell-targeting therapies

B cells play multiple roles in immune responses related to autoimmune diseases as well as different types of cancers. As such, strategies focused on B cell targeting attracted wide interest and developed intensively. There are several common mechanisms various B cell targeting therapies have relied on, including direct B cell depletion, modulation of B cell antigen receptor (BCR) signaling, targeting B cell survival factors, targeting the B cell and T cell costimulation, and immune checkpoint blockade. Nanocarriers, used as drug delivery vehicles, possess numerous advantages to low molecular weight drugs, reducing drug toxicity, enhancing blood circulation time, as well as augmenting targeting efficacy and improving therapeutic effect. Herein, we review the commonly used targets involved in B cell targeting approaches and the utilization of various nanocarriers as B cell-targeted delivery vehicles. STATEMENT OF SIGNIFICANCE: As B cells are engaged significantly in the development of many kinds of diseases, utilization of nanomedicines in B cell depletion therapies have been rapidly developed. Although numerous studies focused on B cell targeting have already been done, there are still various potential receptors awaiting further investigation. This review summarizes the most relevant studies that utilized nanotechnologies associated with different B cell depletion approaches, providing a useful tool for selection of receptors, agents and/or nanocarriers matching specific diseases. Along with uncovering new targets in the function map of B cells, there will be a growing number of candidates that can benefit from nanoscale drug delivery.

Crosslinking of CD38 Receptors Triggers Apoptosis of Malignant B Cells

Recently, we designed an inventive paradigm in nanomedicine—drug-free macromolecular therapeutics (DFMT). The ability of DFMT to induce apoptosis is based on biorecognition at cell surface, and crosslinking of receptors without the participation of low molecular weight drugs. The system is composed of two nanoconjugates: a bispecific engager, antibody or Fab’ fragment—morpholino oligonucleotide (MORF1) conjugate; the second nanoconjugate is a multivalent effector, human serum albumin (HSA) decorated with multiple copies of complementary MORF2. Here, we intend to demonstrate that DFMT is a platform that will be effective on other receptors than previously validated CD20. We appraised the impact of daratumumab (DARA)- and isatuximab (ISA)-based DFMT to crosslink CD38 receptors on CD38+ lymphoma (Raji, Daudi) and multiple myeloma cells (RPMI 8226, ANBL-6). The biological properties of DFMTs were determined by flow cytometry, confocal fluorescence microscopy, reactive oxygen species determination, lysosomal enlargement, homotypic cell adhesion, and the hybridization of nanoconjugates. The data revealed that the level of apoptosis induction correlated with CD38 expression, the nanoconjugates meet at the cell surface, mitochondrial signaling pathway is strongly involved, insertion of a flexible spacer in the structure of the macromolecular effector enhances apoptosis, and simultaneous crosslinking of CD38 and CD20 receptors increases apoptosis.

When liposomes met antibodies: Drug delivery and beyond

Drug encapsulated liposomes and monoclonal antibodies (Mabs) are two distinctively different classes of therapeutics, but both aim to become the ultimate "magic bullet". While PEGylated liposomes rely on the enhanced permeability and retention (EPR) effect for accumulation in solid tumor tissues, Mabs are designed to bind tightly to specific surface antigens on target cells to exert effector functions. Immunoliposome (IL) refers to the structural combination of liposomes and antibodies, whereas the antibodies are usually decorated on the liposome surface. ILs can therefore take advantage of interactions between antibodies and cancer cells for more efficient endocytosis and intracellular drug delivery. The antibody structure, affinity, density, as well as the liposome surface properties and drug to lipid ratios all contribute to the IL pharmacokinetic(PK) and pharmacodynamic(PD) behaviors. The optimal formulation parameters may vary for different target cells and tissues. Furthermore, besides the delivery of cytotoxic drugs to cancer cells, new ILs are being developed to interact with multiple target receptors, multiple target cells and trigger multiple therapeutic effects. We envision that the IL format can be a great platform for the molecular engineering of multi-valent, multi-specific interactions to achieve complex biological functions for therapeutic benefits, especially in the area of cancer immunotherapy.

Polymer nanomedicines

Polymer nanomedicines (macromolecular therapeutics, polymer-drug conjugates, drug-free macromolecular therapeutics) are a group of biologically active compounds that are characterized by their large molecular weight. This review focuses on bioconjugates of water-soluble macromolecules with low molecular weight drugs and selected proteins. After analyzing the design principles, different structures of polymer carriers are discussed followed by the examination of the efficacy of the conjugates in animal models and challenges for their translation into the clinic. Two innovative directions in macromolecular therapeutics that depend on receptor crosslinking are highlighted: a) Combination chemotherapy of backbone degradable polymer-drug conjugates with immune checkpoint blockade by multivalent polymer peptide antagonists; and b) Drug-free macromolecular therapeutics, a new paradigm in drug delivery.

Advanced nanomedicines for the treatment of inflammatory diseases

Inflammation, a common feature of many diseases, is an essential immune response that enables survival and maintains tissue homeostasis. However, in some conditions, the inflammatory process becomes detrimental, contributing to the pathogenesis of a disease. Targeting inflammation by using nanomedicines (i.e. nanoparticles loaded with a therapeutic active principle), either through the recognition of molecules overexpressed onto the surface of activated macrophages or endothelial cells, or through enhanced vasculature permeability, or even through biomimicry, offers a promising solution for the treatment of inflammatory diseases. After providing a brief insight on the pathophysiology of inflammation and current therapeutic strategies, the review will discuss, at a pre-clinical stage, the main innovative nanomedicine approaches that have been proposed in the past five years for the resolution of inflammatory disorders, finally focusing on those currently in clinical trials.

Exploration and Evaluation of Therapeutic Efficacy of Drug-Free Macromolecular Therapeutics in Collagen-Induced Rheumatoid Arthritis Mouse Model

Monoclonal antibodies (mAbs) against B cell antigens are extensively used in the treatment of rheumatoid arthritis (RA). The B cell depletion therapy prevents RA symptoms and/or alleviates existing inflammation. The previously established two-step drug-free macromolecular therapeutics (DFMT) is applied in the treatment of collagen-induced rheumatoid arthritis in a collagen-induced rheumatoid arthritis mouse model. DFMT is a B cell depletion strategy utilizing Fab' fragment of anti-CD20 mAb for biorecognition and receptor crosslinking to induce B cell apoptosis. DFMT is composed from two nanoconjugates: 1) bispecific engager, Fab'-MORF1 (anti-CD20 Fab' fragment conjugated with morpholino oligonucleotide MORF1), and 2) a crosslinking (effector) component P-(MORF2)X (N-(2-hydroxypropyl)methacrylamide copolymer grafted with multiple copies of complementary morpholino oligonucleotide MORF2). The absence of Fc fragment has the potential to avoid development of resistance and infusion-related reactions. DFMT produces B cell depletion, keeps the RA score low for more than 100 days, and shows minimal cartilage and bone erosion and inflammatory cell infiltration. Further improvements will be explored to optimize DFMT strategy in autoimmune disease treatment.

Next-generation paclitaxel-nanoparticle formulation for pancreatic cancer treatment

Pancreatic cancer (PanCa) is a major cause of cancer-related death due to limited therapeutic options. As pancreatic tumors are highly desmoplastic, they prevent appropriate uptake of therapeutic payloads. Thus, our objective is to develop a next-generation nanoparticle system for treating PanCa. We generated a multi-layered Pluronic F127 and polyvinyl alcohol stabilized and poly-L-lysine coated paclitaxel loaded poly(lactic-co-glycolic acid) nanoparticle formulation (PPNPs). This formulation exhibited optimal size (~160 nm) and negative Zeta potential (-6.02 mV), efficient lipid raft mediated internalization, pronounced inhibition in growth and metastasis in vitro, and in chemo-naïve and chemo-exposed orthotopic xenograft mouse models. Additionally, PPNPs altered nanomechanical properties of PanCa cells as suggested by the increased elastic modulus in nanoindentation analyses. Immunohistochemistry of orthotopic tumors demonstrated decreased expression of tumorigenic and metastasis associated proteins (ki67, vimentin and slug) in PPNPs treated mice. These results suggest that PPNPs represent a viable and robust platform for (PanCa).