Anti-phage serum antibody responses and the outcome of phage therapy

We examined the appearance of serum anti-phage antibodies in 25 patients with chronic sinusitis treated with phage therapy (PT). Approximately 30% of patients with weak antibody responses responded positively to PT, which was similar to the results of treatment achieved in a group of patients with high antibody production. In addition, there was no correlation between antibody level and the outcome of PT. These data, derived from a homogenous group of patients, confirm our earlier findings suggesting that the prognostic significance of serum anti-phage antibodies for the outcome of PT should be determined by relevant clinical trials.

Rapid Evaluation of Antibody Fragment Endocytosis for Antibody Fragment–Drug Conjugates

Antibody–drug conjugates (ADCs) have emerged as the most promising strategy in targeted cancer treatment. Recent strategies for the optimization ADCs include the development of antibody fragment–drug conjugates (FDCs). The critical factor in the successful development of ADCs and FDCs is the identification of tumor antigen-specific and internalizing antibodies (Abs). However, systematic comparison or correlation studies of internalization rates with different antibody formats have not been reported previously. In this study, we generated a panel of scFv-phage Abs using phage display technology and their corresponding scFv and scFv-Fc fragments and evaluated their relative internalization kinetics in relation to their antibody forms. We found that the relative rates and levels of internalization of scFv-phage antibodies positively correlate with their scFv and scFv-Fc forms. Our systematic study demonstrates that endocytosis of scFv-phage can serve as a predictive indicator for the assessment of Ab fragment internalization. Additionally, the present study demonstrates that endocytic antibodies can be rapidly screened and selected from phage antibody libraries prior to the conversion of phage antibodies for the generation of the conventional antibody format. Our strategic approach for the identification and evaluation of endocytic antibodies would expedite the selection for optimal antibodies and antibody fragments and be broadly applicable to ADC and FDC development.

Phage Display as A Bio-Technique for Cancer Immunotherapy

Background: Phage display is a biotechnological technique that presents peptides with coated proteins on the surface of phage. In the last two decades, growing applications of phage display in various fields of biotechnology have been investigated. Phage display libraries allow to present billions of peptides on phage surface for selection of a specific peptide with the desired affinity. Objective: In this regard, high-affinity phage antibodies against tumor antigens are produced and applied for diagnosis and treatment of cancer. Method: Moreover, phage display libraries are employed to select the high affinity T Cell Receptors (TCRs) for the peptide-MHC complex which is an attractive approach in cancer immunotherapy. Due to immunogenic properties of phage particles, phage-based vaccines do not require adjuvant, in addition the phage particles can effectively take up by Antigen Presenting Cells (APCs). Results: Taken together, phage-based cancer vaccines are ideal candidates that provide a key for eradication of tumor cells. Conclusion: In this review, we focus on various applications of a phage display platform in different types of cancer immunotherapy approaches.

IMMUNOLOGIC ASPECTS OF PHAGE THERAPY OF INFECTIONS RELATED TO MEDICAL CARE IN NEUROREANIMATION

Aim. Evaluate the effect of anti-phage humoral immune response on effectiveness of phage therapy of infections related to medical care (IRMC). Materials and methods. 42 patients on extended mechanical ventilation (MV) in neuroreanimation, 1 time in 2014, 4 times in 2015 and 1 time in 2016 had received bacteriophage cocktail per os - 20 ml including 6 patients - additionally 3-5 times. Effectiveness of phage therapy was evaluated by seeding of IRMC strains from samples of endotracheal aspirate, blood, urine and feces of patients before and after treatment. Results. 87.5% of samples from the patients initially had gram-negative pathogens (Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa). Effective sanation for the first episodes of phage therapy was confirmed in 54 - 62.5% of cases. Pharmacokinetic studies have indicated a systemic mechanism of action for enteral forms of bacteriophages. Repeated courses of phage therapy did not result in significant eradication of pathogens. Antiphage immunity after a single administration of the cocktail of bacteriophages with a certain strain composition was detected using ELISA by the presence of specific IgG titers in a range from 1/16 to 1/4096 (in patients not receiving the cocktail antibodies were not detected). Conclusion. Reduction of sanation effect of bacteriophage could be due to formation of anti-phage antibodies after a repeated course in the same patient. Changes of strain composition of phage cocktail of bacteriophages is necessary to preserve results of phage therapy.