Targeted immunotherapy of cancer: development of antibody-induced cellular immunity

Safety and Tolerability of Antimicrobial Agents in the Older Patient

Older patients are at high risk of infections, which often present atypically and are associated with high morbidity and mortality. Antimicrobial treatment in older individuals with infectious diseases represents a clinical challenge, causing an increasing burden on worldwide healthcare systems; immunosenescence and the coexistence of multiple comorbidities determine complex polypharmacy regimens with an increase in drug-drug interactions and spread of multidrug-resistance infections. Aging-induced pharmacokinetic and pharmacodynamic changes can additionally increase the risk of inappropriate drug dosing, with underexposure that is associated with antimicrobial resistance and overexposure that may lead to adverse effects and poor adherence because of low tolerability. These issues need to be considered when starting antimicrobial prescriptions. National and international efforts have been made towards the implementation of antimicrobial stewardship (AMS) interventions to help clinicians improve the appropriateness and safety of antimicrobial prescriptions in both acute and long-term care settings. AMS programs were shown to decrease consumption of antimicrobials and to improve safety in hospitalized patients and older nursing home residents. With the abundance of antimicrobial prescriptions and the recent emergence of multidrug resistant pathogens, an in-depth review of antimicrobial prescriptions in geriatric clinical practice is needed. This review will discuss the special considerations for older individuals needing antimicrobials, including risk factors that shape risk profiles in geriatric populations as well as an evidence-based description of antimicrobial-induced adverse events in this patient population. It will highlight agents of concern for this age group and discuss interventions to mitigate the effects of inappropriate antimicrobial prescribing.

Immunotargeting of Gram-Positive Pathogens via a Cell Wall Binding Tick Antifreeze Protein

Immunological agents that supplement or modulate the host immune response have proven to have powerful therapeutic potential, although this modality is less explored against bacterial pathogens. We describe the application of a bacterial binding protein to re-engage the immune system toward pathogenic bacteria. More specifically, a hapten was conjugated to a protein expressed by Ixodes scapularis ticks, called I. scapularis antifreeze glycoprotein (IAFGP), that has high affinity for the d-alanine residue on the bacterial peptidoglycan. We showed that a fragment of this protein retained high surface binding affinity. Moreover, conjugation of a hapten to this peptide led to the display of haptens on the cell surface of vancomycin-resistant Enterococcus faecalis. Hapten display then induced the recruitment of antibodies and promoted uptake of bacterial pathogens by immune cells. These results demonstrate the feasibility in using cell wall binding agents as the basis of a class of bacterial immunotherapies.

Induction of Endogenous Antibody Recruitment to the Surface of the Pathogen Enterococcus faecium

For the foreseeable future, conventional small molecule antibiotics will continue to be the predominant treatment option due to wide patient coverage and low costs. Today, however, there is already a significant portion of patients that fail to respond to small molecule antibiotics and, according to the Centers for Disease Control and Prevention, this number is poised to increase in the coming years. Therefore, this rise in drug resistant bacteria must be countered with the development of nontraditional therapies. We propose a measure based on the re-engagement of the immune system toward pathogenic bacteria by grafting bacterial cell surfaces with immunogenic agents. Herein, we describe a class of cell wall analogues that selectively graft bacterial cell surfaces with epitopes that promote their opsonization. More specifically, synthetic analogues of peptidoglycan conjugated to haptens were designed to be incorporated by the cell wall biosynthetic machinery into live Enterococcus faecium. E. faecium is a formidable human pathogen that poses a considerable burden to healthcare and often results in fatalities. We showed that treatment of E. faecium and vancomycin-resistant strains with the cell wall analogues led to the display of haptens on the cell surface, which induced the recruitment of antibodies existing in the serum of humans. These results demonstrate the feasibility in using cell wall analogues as the basis of a class of bacterial immunotherapies against dangerous pathogens.

Covalent Immune Recruiters: Tools to Gain Chemical Control Over Immune Recognition

Unprecedented progress made in the treatment of cancer using the body's own immune system has encouraged the development of synthetic molecule based immunotherapeutics. An emerging class of these compounds, called Antibody Recruiting Molecules (ARMs) or Antibody Engagers (AEs), functions by reversibly binding antibodies naturally present in human serum and recruiting these to cancer cells. The recruited antibodies then engage immune cells to form quaternary complexes that drive cancer erradication. Despite their promise, the requirement to form quaternary complexes governed by multiple equilibria complicates an understanding of their in vivo efficacy. Particularly problematic are low endogenous serum antibody concentrations and rapid clearance of AEs from circulation. Here we describe a new class of trifunctional chemical tools we call covalent immune recruiters (CIRs). CIRs covalently label specific serum antibodies in a selective manner with a target protein binding ligand. CIRs thereby exert well-defined control over antibody recruitment and simplify quaternary complex equilibium, enabling probing of the resultant effects on immune recognition. We demonstrate CIRs can selectively covalently label anti-DNP IgG, a natural human antibody, directly in human serum to drive efficient immune cell recognition of targets. We expect CIRs will be useful tools to probe how quaternary complex stability impacts the immune recognition of cancer in vivo, revealing new design principles to guide the development of future AEs.

Nanocarrier-based systems for targeted and site specific therapeutic delivery

Systemic drug delivery methods such as oral or parenteral administration of free drugs possess relatively low treatment efficiency and marked adverse side effects. The use of nanoparticles for drug delivery in most cases substantially enhances drug efficacy, improves pharmacokinetics and drug release and limits their side effects. However, further enhancement in drug efficacy and significant limitation of adverse side effects can be achieved by specific targeting of nanocarrier-based delivery systems especially in combination with local administration. The present review describes major advantages and limitations of organic and inorganic nanocarriers or living cell-based drug and nucleic acid delivery systems. Among these, different nanoparticles, supramolecular gels, therapeutic cells as living drug carriers etc. have emerged as a new frontier in modern medicine.

Re-engineering the Immune Response to Metastatic Cancer: Antibody-Recruiting Small Molecules Targeting the Urokinase Receptor

Developing selective strategies to treat metastatic cancers remains a significant challenge. Herein, we report the first antibody-recruiting small molecule (ARM) that is capable of recognizing the urokinase-type plasminogen activator receptor (uPAR), a uniquely overexpressed cancer cell-surface marker, and facilitating the immune-mediated destruction of cancer cells. A co-crystal structure of the ARM-U2/uPAR complex was obtained, representing the first crystal structure of uPAR complexed with a non-peptide ligand. Finally, we demonstrated that ARM-U2 substantially suppresses tumor growth in vivo with no evidence of weight loss, unlike the standard-of-care agent doxorubicin. This work underscores the promise of antibody-recruiting molecules as immunotherapeutics for treating cancer.

A potential carrier for targeted therapy of DNFB hapten-induced immune

AIM: To investigate the influence of dinitroflourobenzene (DNFB) on the antibody titer of hepatitis B immunoglobulin (HBIG).

METHODS: Three different doses (2, 4, 8 mg) of DNFB were mixed with phosphate buffer solution (PBS) of HBIG respectively, 13 mg in a volume of 500 µL PBS, while same solutions of HBIG were used as controls. The 2, 4 mg tubes and the control tubes were not precipitated except for the 8 mg tube with 10 000 r/min configuration. The 3 transparent tubes were desalted with column of Sephadex G-25 Superfine HiTrap respectively. All of the eluents of the 3 tubes were half-diluted consecutively with phosphate buffer saline (PBS) respectively to change totally into 36 samples of 2 mg group, 4 mg group and control group, with 12 in each group. The above samples were all tested for the antibody titer of HBIG using ELISA. The 2 mg tube, 4 mg tube and the control tube were all precipitated in solution of saturated (NH₄)₂SO₄. Compared with standard curves of both quantity of DNFB and gauges of A340 in supernants made of same controlled tubes, the remaining DNFB in supernants in different tubes were all obtained respectively.

RESULTS: Except for the 8 mg group, there were no difference in the 3 groups in terms of the absorbance values (A₄₅₀-A₆₃₀) of HBIG in same dilution grade of any group with two-way anova (analysis of variance)(P > 0.05). However there was great difference between different dilution grades in any group with two-way anova (P < 0.01). The 6.5 mg of HBIG in the 2 mg tube and 4 mg tube were respectively combined with 0.67 mg and 0.86 mg of DNFB, meaning that each molecule of HBIG with 88.72 and 103.48 molecules of DNFB, namely 6.12% and 7.86% in residual amino acid of each molecule of HBIG combined with DNFB.

CONCLUSION: The immune globulin (antibody) might be used as a carrier for DNFB target therapy.