Bispecific antibodies, nanoparticles and cells: bringing the right cells to get the job done

Liposomal-Based Nanoarchitectonics as Bispecific T Cell Engagers in Neuroblastoma Therapy

Neuroblastoma (NB) is an aggressive pediatric solid tumor that lacks efficient treatment. In the past few years, the use of engineered lymphocytes endowed with chimeric antigen receptors (CAR T), which improve their natural search and destroy skills against tumoral cells, has provided a highly valuable strategy to eradicate tumors in a specific and safe manner. Unfortunately, despite the excellent results achieved by these cell-based therapies in liquid tumors, their efficacy in the treatment of solid malignancies is usually modest due to the existence of several biological barriers which compromise their efficacy. Herein, a strategy to guide CAR T toward NB cells based on the use of nanometric bispecific T engagers (NBTEs) is presented. These novel bispecific nanoplatforms are based on liposomes and protocells doubly functionalized with synthetic targeting moieties (para-aminobenzylguanidine and fluorescein) able to selectively bind to membrane cell receptors of NB and anti-FITC CAR T, respectively. The binding process of NBTEs to NB cells was monitored by confocal fluorescence microscopy showing the excellent capacity of these nanodevices to place fluorescence labels on the surface of the malignant cells. Then, NB cells previously incubated in the presence of NBTEs were rapidly detected and destroyed by anti-FITC CAR T, which confirmed the excellent capacity of these nanoplatforms to improve the natural capacity of CAR T to eradicate malignant cells. Finally, the high versatility of the NBTE design and its easy-to-tune nature would allow their rapid application to different types of solid tumors.

Targeted Radium Alpha Therapy in the Era of Nanomedicine: In Vivo Results

Targeted alpha-particle therapy using radionuclides with alpha emission is a rapidly developing area in modern cancer treatment. To selectively deliver alpha-emitting isotopes to tumors, targeting vectors, including monoclonal antibodies, peptides, small molecule inhibitors, or other biomolecules, are attached to them, which ensures specific binding to tumor-related antigens and cell surface receptors. Although earlier studies have already demonstrated the anti-tumor potential of alpha-emitting radium (Ra) isotopes-Radium-223 and Radium-224 (223/224Ra)-in the treatment of skeletal metastases, their inability to complex with target-specific moieties hindered application beyond bone targeting. To exploit the therapeutic gains of Ra across a wider spectrum of cancers, nanoparticles have recently been embraced as carriers to ensure the linkage of 223/224Ra to target-affine vectors. Exemplified by prior findings, Ra was successfully bound to several nano/microparticles, including lanthanum phosphate, nanozeolites, barium sulfate, hydroxyapatite, calcium carbonate, gypsum, celestine, or liposomes. Despite the lengthened tumor retention and the related improvement in the radiotherapeutic effect of 223/224Ra coupled to nanoparticles, the in vivo assessment of the radiolabeled nanoprobes is a prerequisite prior to clinical usage. For this purpose, experimental xenotransplant models of different cancers provide a well-suited scenario. Herein, we summarize the latest achievements with 223/224Ra-doped nanoparticles and related advances in targeted alpha radiotherapy.

Functional bionanomaterials for cell surface engineering in cancer immunotherapy

The cell surface is the forward position in cancer immunotherapy, with surface ligand and receptor interactions between various cells for determining immune privilege or recognition. Therefore, cell surface engineering (CSE) that manipulates the surface interactions between the immune effector cells (IECs) and tumor cells represents a promising means for eliciting effective anticancer immunity. Specifically, taking advantage of the development in biomaterials and nanotechnology, the use of functional bionanomaterials for CSE is attracting more and more attention in recent years. Rationally designed functional biomaterials have been applied to construct artificial functional modules on the surface of cells through genetic engineering, metabolic labeling, chemical conjugation, hydrophobic insertion, and many other means, and the CSE process can be performed both ex vivo and in vivo, on either IECs or tumor cells, and results in enhanced anticancer immunity and various new cancer immunity paradigms. In this review, we will summarize the recent exciting progresses made in the application of functional bionanomaterials for CSE especially in establishing effective recognition and interaction between IECs and tumor cells.

Targeted and modular architectural polymers employing bioorthogonal chemistry for quantitative therapeutic delivery

There remain several key challenges to existing therapeutic systems for cancer therapy, such as quantitatively determining the true, tissue-specific drug release profile in vivo, as well as reducing side-effects for an increased standard of care. Hence, it is crucial to engineer new materials that allow for a better understanding of the in vivo pharmacokinetic/pharmacodynamic behaviours of therapeutics. We have expanded on recent “click-to-release” bioorthogonal pro-drug activation of antibody-drug conjugates (ADCs) to develop a modular and controlled theranostic system for quantitatively assessing site-specific drug activation and deposition from a nanocarrier molecule, by employing defined chemistries. The exploitation of quantitative imaging using positron emission tomography (PET) together with pre-targeted bioorthogonal chemistries in our system provided an effective means to assess in real-time the exact amount of active drug administered at precise sites in the animal; our methodology introduces flexibility in both the targeting and therapeutic components that is specific to nanomedicines and offers unique advantages over other technologies. In this approach, the in vivo click reaction facilitates pro-drug activation as well as provides a quantitative means to investigate the dynamic behaviour of the therapeutic agent.

There remain several key challenges to existing therapeutic systems for cancer therapy, such as quantitatively determining the true, tissue-specific drug release profile in vivo, as well as reducing side-effects for an increased standard of care.

A New Era of Cardiac Cell Therapy: Opportunities and Challenges

Myocardial infarction (MI), caused by coronary heart disease (CHD), remains one of the most common causes of death in the United States. Over the last few decades, scientists have invested considerable resources on the study and development of cell therapies for myocardial regeneration after MI. However, due to a number of limitations, they are not yet readily available for clinical applications. Mounting evidence supports the theory that paracrine products are the main contributors to the regenerative effects attributed to these cell therapies. The next generation of cell-based MI therapies will identify and isolate cell products and derivatives, integrate them with biocompatible materials and technologies, and use them for the regeneration of damaged myocardial tissue. This review discusses the progress made thus far in pursuit of this new generation of cell therapies. Their fundamental regenerative mechanisms, their potential to combine with other therapeutic products, and their role in shaping new clinical approaches for heart tissue engineering, are addressed.

Recent Advances in the Generation of Antibody-Nanomaterial Conjugates

Targeted nanomedicines have significantly changed the way new therapeutics are designed to treat disease. Central to successful therapeutics is the ability to control the dynamics of protein-nanomaterial interactions to enhance the therapeutic effect of the nanomedicine. The aim of this review is to illustrate the diversity and versatility of the conjugation approaches involved in the synthesis of antibody-nanoparticle conjugates, and highlight significant new advances in the field of bioconjugation. Such nanomedicines have found utility as both advanced therapeutic agents, as well as more complex imaging contrast agents that can provide both anatomical and functional information of diseased tissue. While such conjugates show significant promise as next generation targeted nanomedicines, it is recognized that there are in fact no clinically approved targeted therapeutics on the market. This fact is reflected upon within this review, and attempts are made to draw some reasoning from the complexities associated with the bioconjugation chemistry approaches that are typically utilized. Present trends, as well as future directions of next generation targeted nanomedicines are also discussed.

Bispecific antibodies and their applications

Bispecific antibodies (BsAbs) recognize two different epitopes. This dual specificity opens up a wide range of applications, including redirecting T cells to tumor cells, blocking two different signaling pathways simultaneously, dual targeting of different disease mediators, and delivering payloads to targeted sites. The approval of catumaxomab (anti-EpCAM and anti-CD3) and blinatumomab (anti-CD19 and anti-CD3) has become a major milestone in the development of bsAbs. Currently, more than 60 different bsAb formats exist, some of them making their way into the clinical pipeline. This review summarizes diverse formats of bsAbs and their clinical applications and sheds light on strategies to optimize the design of bsAbs.

Magnetically Targeted Stem Cell Delivery for Regenerative Medicine

Stem cells play a special role in the body as agents of self-renewal and auto-reparation for tissues and organs. Stem cell therapies represent a promising alternative strategy to regenerate damaged tissue when natural repairing and conventional pharmacological intervention fail to do so. A fundamental impediment for the evolution of stem cell therapies has been the difficulty of effectively targeting administered stem cells to the disease foci. Biocompatible magnetically responsive nanoparticles are being utilized for the targeted delivery of stem cells in order to enhance their retention in the desired treatment site. This noninvasive treatment-localization strategy has shown promising results and has the potential to mitigate the problem of poor long-term stem cell engraftment in a number of organ systems post-delivery. In addition, these same nanoparticles can be used to track and monitor the cells in vivo, using magnetic resonance imaging. In the present review we underline the principles of magnetic targeting for stem cell delivery, with a look at the logic behind magnetic nanoparticle systems, their manufacturing and design variants, and their applications in various pathological models.