IsdB antibody-mediated sepsis following S. aureus surgical site infection.

Staphylococcus aureus is prevalent in surgical site infections (SSI) and leads to death in approximately 1% of patients. Phase IIB/III clinical trial results have demonstrated that vaccination against the iron-regulated surface determinant protein B (IsdB) is associated with an increased mortality rate in patients with SSI. Thus, we hypothesized that S. aureus induces nonneutralizing anti-IsdB antibodies, which facilitate bacterial entry into leukocytes to generate "Trojan horse" leukocytes that disseminate the pathogen. Since hemoglobin (Hb) is the primary target of IsdB, and abundant Hb-haptoglobin (Hb-Hp) complexes in bleeding surgical wounds are normally cleared via CD163-mediated endocytosis by macrophages, we investigated this mechanism in vitro and in vivo. Our results demonstrate that active and passive IsdB immunization of mice renders them susceptible to sepsis following SSI. We also found that a multimolecular complex containing S. aureus protein A-anti-IsdB-IsdB-Hb-Hp mediates CD163-dependent bacterial internalization of macrophages in vitro. Moreover, IsdB-immunized CD163-/- mice are resistant to sepsis following S. aureus SSI, as are normal healthy mice given anti-CD163-neutralizing antibodies. These genetic and biologic CD163 deficiencies did not exacerbate local infection. Thus, anti-IsdB antibodies are a risk factor for S. aureus sepsis following SSI, and disruption of the multimolecular complex and/or CD163 blockade may intervene.

Pre-existing antibody-mediated adverse effects prevent the clinical development of a bacterial anti-inflammatory protein.

Bacterial pathogens have evolved to secrete strong anti-inflammatory proteins that target the immune system. It was long speculated whether these virulence factors could serve as therapeutics in diseases in which abnormal immune activation plays a role. We adopted the secreted chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS) as a model virulence factor-based therapeutic agent for diseases in which C5AR1 stimulation plays an important role. We show that the administration of CHIPS in human C5AR1 knock-in mice successfully dampens C5a-mediated neutrophil migration during immune complex-initiated inflammation. Subsequent CHIPS toxicology studies in animal models were promising. However, during a small phase I trial, healthy human volunteers showed adverse effects directly after CHIPS administration. Subjects showed clinical signs of anaphylaxis with mild leukocytopenia and increased C-reactive protein concentrations, which are possibly related to the presence of relatively high circulating anti-CHIPS antibodies and suggest an inflammatory response. Even though our data in mice show CHIPS as a potential anti-inflammatory agent, safety issues in human subjects temper the use of CHIPS in its current form as a therapeutic candidate. The use of staphylococcal proteins, or other bacterial proteins, as therapeutics or immune-modulators in humans is severely hampered by pre-existing circulating antibodies.

Phase 1 study of MEDI3902, an investigational anti-Pseudomonas aeruginosa PcrV and Psl bispecific human monoclonal antibody, in healthy adults.

OBJECTIVES: MEDI3902 is a bivalent, bispecific human immunoglobulin G1κ monoclonal antibody that binds to both the Pseudomonas aeruginosa PcrV protein involved in host cell cytotoxicity and the Psl exopolysaccharide involved in P. aeruginosa colonization and tissue adherence. MEDI3902 is being developed for the prevention of nosocomial P. aeruginosa pneumonia in high-risk patients. METHODS: This phase 1 dose-escalation study (NCT02255760) evaluated the safety, pharmacokinetics, antidrug antibody (ADA) responses and ex vivo anticytotoxicity and opsonophagocytic killing activities of MEDI3902 after a single intravenous infusion in healthy adults aged 18 to 60 years. Fifty-six subjects were randomized in a 3:1 ratio to receive 250, 750, 1500 or 3000 mg of MEDI3902 or placebo and followed for 60 days afterwards. RESULTS: Treatment-emergent adverse events (TEAEs) were mild or moderate in severity; no serious TEAEs were observed. The most common TEAEs were infusion-related reactions. MEDI3902 exhibited approximately linear pharmacokinetics across the 250, 750 and 1500 mg doses and nonlinear pharmacokinetics between the 1500 and 3000 mg doses. One subject in the 3000 mg group tested positive for ADA on day 61 and had a lower MEDI3902 serum concentration from days 43 to 61 than ADA-negative subjects. Serum anticytotoxicity antibody concentrations and opsonophagocytic killing activity were correlated with MEDI3902 serum concentrations across all doses. CONCLUSIONS: Phase 1 study results of MEDI3902 in healthy subjects support further evaluation of its safety and efficacy in subjects at risk for P. aeruginosa pneumonia.

The clearance effect of bovine anti-Helicobacter pylori antibody-containing milk in O blood group Helicobacter pylori-infected patients: a randomized double-blind clinical trial.

BACKGROUND: The failure in standard triple therapy has recently increased to high levels in China, primarily because of insufficient patient compliance, antimicrobial resistance, and high costs. Effective prevention and eradication of Helicobacter pylori (H. pylori) by artificial passive immunization with orally administered bovine antibodies in the milk has been demonstrated in many animal studies, but the clinical studies that are available have shown no H. pylori eradication. This study was to evaluate the efficacy and safety of orally administered bovine anti-H. pylori antibodies for the clearance of H. pylori infecting O blood group subpopulations. METHODS: Two local epidemic H. pylori strains that were prevalent locally were screened and then used to immunize dairy cows. After confirmation of the presence of anti-H. pylori polyclonal antibodies in the milk by enzyme-linked immunosorbent assay, the milk was subsequently defatted and processed into sterile milk by pasteurization. This study was designed as a double-blind placebo-controlled randomized clinical trial. Our 61 H. pylori-infected O blood group subjects were assigned to two groups; 31 subjects were treated with bovine milk containing antibodies and 30 subjects with the placebo. The medication-based study was continued for 28 days. Subjects were followed up for 56 days. The effect was assessed by the C-14 urea breath test (UBT). SPSS 17.0 software for Windows was used to analyze the data. RESULTS: Of the 61 subjects enrolled, 58 completed the protocol. One volunteer in the antibodies group and two volunteers in the control group dropped out. Of the 30 antibody-treated subjects, 13 became UBT negative, whereas none of the 30 of the placebo-treated subjects became UBT negative after the medication. Of 13 UBT negative patients, 3 became positive again at the end of the follow-up. Both intention to treat and per-protocol analysis indicated a significant difference in the clearance rate of infected patients between the groups treated with bovine antibody-containing milk and the placebo (P = 0.001, P < 0.05) and no significant difference in adverse effects (P > 0.05 all). CONCLUSIONS: Bovine antibody-based oral immunotherapy appears to be safe and has a significant clearance effect on intragastric H. pylori that infects O blood group adults. TRIAL REGISTRATION: ChiCTR-TRC-14005212.

A prospective treatment for sepsis.

The present paper proposes a prospective auxiliary treatment for sepsis. There exists no record in the published media on the subject. As an auxiliary therapy, efficacious extracorporeal removal of sepsis-causing bacterial antigens and their toxins (BATs) from the blood of septic patients is discussed. The principal component to this approach is a bacterial polyvalent antibody-column (BPVAC), which selectively traps wide spectrum of BATs from blood in an extracorporeal circuit, and detoxified blood returns back to the patient's body. BPVAC treatment would be a device of targeted medicine. Detoxification is performed under supervision of trained personnel using simple blood-circulating machines in which blood circulates from the patient to BPVAC and back to the patient aseptically. BPVACs' reactive sites consist of carbon nanotubes on which a vast spectra of polyvalent BATs-antibodies are bond to. The devise acts as a biological filter that selectively immobilizes harmful BATs from intoxicated blood; however, no dialysis is involved. For effective neutralization, BPVAC provides large contact surface area with blood. BPVAC approach would have advantages of: 1) urgent neutralization of notorious BATs from blood of septic patients; 2) applicability in parallel with conventional treatments; 3) potential to minimize side effects of the malady; 4) applicability for a vast range of BATs; 5) potential to eliminate contact of BATs with internal tissues and organs; 6) tolerability by patients sensitive to antiserum injections; 7) capability for universal application; 8) affectivity when antibiotic-resistant bacteria are involved and the physician has no or limited access to appropriate antibiotics; and 10) being a single-use, disposable, and stand-alone device. Before using it for clinical trials in human beings, it should pass animal evaluations accurately; however, research works should optimize its implementation in human beings. For optimization, it needs appropriate investments, collaboration of scientists in many fields of research, and development through several interdisciplinary sciences such as medical engineering, nanotechnology, immunology, biochemistry, emergency medicine, internal, and infectious diseases.

Assessment of panobacumab as adjunctive immunotherapy for the treatment of nosocomial Pseudomonas aeruginosa pneumonia.

The fully human anti-lipopolysaccharide (LPS) immunoglobulin M (IgM) monoclonal antibody panobacumab was developed as an adjunctive immunotherapy for the treatment of O11 serotype Pseudomonas aeruginosa infections. We evaluated the potential clinical efficacy of panobacumab in the treatment of nosocomial pneumonia. We performed a post-hoc analysis of a multicenter phase IIa trial (NCT00851435) designed to prospectively evaluate the safety and pharmacokinetics of panobacumab. Patients treated with panobacumab (n = 17), including 13 patients receiving the full treatment (three doses of 1.2 mg/kg), were compared to 14 patients who did not receive the antibody. Overall, the 17 patients receiving panobacumab were more ill. They were an average of 72 years old [interquartile range (IQR): 64-79] versus an average of 50 years old (IQR: 30-73) (p = 0.024) and had Acute Physiology and Chronic Health Evaluation II (APACHE II) scores of 17 (IQR: 16-22) versus 15 (IQR: 10-19) (p = 0.043). Adjunctive immunotherapy resulted in an improved clinical outcome in the group receiving the full three-course panobacumab treatment, with a resolution rate of 85 % (11/13) versus 64 % (9/14) (p = 0.048). The Kaplan-Meier survival curve showed a statistically significantly shorter time to clinical resolution in this group of patients (8.0 [IQR: 7.0-11.5] versus 18.5 [IQR: 8-30] days in those who did not receive the antibody; p = 0.004). Panobacumab adjunctive immunotherapy may improve clinical outcome in a shorter time if patients receive the full treatment (three doses). These preliminary results suggest that passive immunotherapy targeting LPS may be a complementary strategy for the treatment of nosocomial O11 P. aeruginosa pneumonia.

Phase I study evaluating the safety and pharmacokinetics of MDX-1303, a fully human monoclonal antibody against Bacillus anthracis protective antigen, in healthy volunteers.

MDX-1303 (Valortim) is a fully human monoclonal antibody (hMAb) with a high affinity for Bacillus anthracis protective antigen (PA). MDX-1303 binds to PA and interferes with the activity of the anthrax toxin; it was selected based on its superior functional activity in the toxin neutralization activity (TNA) assay. MDX-1303 has demonstrated efficacy in the postexposure and therapeutic settings in New Zealand White rabbits, cynomolgus monkeys, and African green monkeys. This phase I study sought to characterize the safety, tolerability, immunogenicity, and pharmacokinetics (PK)/pharmacodynamics (PD) of MDX-1303 in healthy human subjects. Cohorts of 3 to 10 subjects were administered MDX-1303 as either a single intravenous (i.v.) dose at dose levels of 0.3, 1, 3, 10, and 20 mg/kg of body weight or as a single intramuscular (i.m.) dose at 100 mg. Forty-six subjects were enrolled, and 16 (35%) of these subjects experienced one or more grade 1 adverse events considered to be related to treatment with MDX-1303. There were no grade 2 to 4 adverse events or serious adverse events (SAEs) considered to be related to treatment. The mean half-life of MDX-1303 ranged from 22 to 33 days across the i.v. administration cohorts and was approximately 32 days following i.m. administration. Systemic exposure following 100-mg i.m. administration was within the range of exposure following 1-mg/kg i.v. administration with a relative bioavailability of approximately 65%. MDX-1303 was generally well tolerated, and no anti-MDX-1303 antibodies were detected following a single dose.

Pharmacokinetics and safety of panobacumab: specific adjunctive immunotherapy in critical patients with nosocomial Pseudomonas aeruginosa O11 pneumonia.

OBJECTIVES: Nosocomial Pseudomonas aeruginosa pneumonia remains a major concern in critically ill patients. We explored the potential impact of microorganism-targeted adjunctive immunotherapy in such patients. PATIENTS AND METHODS: This multicentre, open pilot Phase 2a clinical trial (NCT00851435) prospectively evaluated the safety, pharmacokinetics and potential efficacy of three doses of 1.2 mg/kg panobacumab, a fully human monoclonal anti-lipopolysaccharide IgM, given every 72 h in 18 patients developing nosocomial P. aeruginosa (serotype O11) pneumonia. RESULTS: Seventeen out of 18 patients were included in the pharmacokinetic analysis. In 13 patients receiving three doses, the maximal concentration after the third infusion was 33.9 ±â€Š8.0 µg/mL, total area under the serum concentration-time curve was 5397 ±â€Š1993 µg h/mL and elimination half-life was 102.3 ±â€Š47.8 h. Panobacumab was well tolerated, induced no immunogenicity and was detected in respiratory samples. In contrast to Acute Physiology and Chronic Health Evaluation II (APACHE II) prediction, all 13 patients receiving three doses survived, with a mean clinical resolution in 9.0 ±â€Š2.7 days. Two patients suffered a recurrence at days 17 and 20. CONCLUSIONS: These data suggest that panobacumab is safe, with a pharmacokinetic profile similar to that in healthy volunteers. It was associated with high clinical cure and survival rates in patients developing nosocomial P. aeruginosa O11 pneumonia. We concluded that these promising results warrant further trials.

Open-label, dose escalation phase I study in healthy volunteers to evaluate the safety and pharmacokinetics of a human monoclonal antibody to Clostridium difficile toxin A.

BACKGROUND: Recent data suggest that Clostridium difficile-associated diarrhea is becoming more severe and difficult to treat. Antibody responses to C. difficile toxin A are protective against symptomatic disease and recurrence. We examined the safety and pharmacokinetics (pk) of a novel neutralizing human monoclonal antibody against C. difficile toxin A (CDA1) in healthy adults. METHODS: Five cohorts with 6 subjects each received a single intravenous infusion of CDA1 at escalating doses of 0.3, 1, 5, 10, and 20 mg/kg. Safety evaluations took place on days 1, 2, 3, 7, 14, 28, and 56 post-infusion. Samples for pk analysis were obtained before and after infusion, and at each safety evaluation. Serum CDA1 antibody concentrations and human anti-human antibody (HAHA) titers were measured with enzyme-linked immunosorbent assays. A noncompartmental model was used for pk analysis. RESULTS: Thirty subjects were enrolled. The median age was 27.5 yrs. There were no serious adverse events (AE) related to CDA1. Twenty-one of the 48 reported non-serious adverse events were possibly related to CDA1, and included transient blood pressure changes requiring no treatment, nasal congestion, headache, abdominal cramps, nausea, and self-limited diarrhea. Serum CDA1 concentrations increased with escalating doses: mean C(max) ranged from 6.82 microg/ml for the 0.3 mg/kg cohort to 511 microg/ml for the 20 mg/kg cohort. The geometric mean values of the half-life of CDA1 ranged between 25.3 and 31.8 days, and the volume of distribution approximated serum. No subject formed detectable HAHA titers. CONCLUSION: Administration of CDA1 as a single intravenous infusion was safe and well tolerated. C(max) increased proportionally with increasing doses. A randomized study of CDA1 in patients with C. difficile associated diarrhea is underway.

Neither antibody to a group B streptococcal conjugate vaccine nor the vaccine itself is teratogenic in rabbits.

Group B Streptococcus (GBS) is a leading cause of human neonatal bacterial disease, resulting in pneumonia, sepsis, meningitis and sometimes, death. Supportive preclinical studies of GBS capsular polysaccharide (CPS)-protein conjugate vaccines have led to several phase 1 and phase 2 trials in healthy, non-pregnant adults, which demonstrated that the vaccines, produced at the Channing Laboratory, were safe and immunogenic. However, evaluation of the safety and immunogenicity of a GBS conjugate vaccine administered to pregnant women demanded that it be manufactured under current good manufacturing practices (cGMP) and that it undergo developmental toxicity evaluation. In this report, we describe a GBS type III CPS-tetanus toxoid (III-TT) vaccine lot 3-1-96 manufactured and vialed under cGMP and our evaluation of the effect of this vaccine and of GBS type III CPS-specific antibody on conception and early- and late-stage fetal development in rabbits. III-TT lot 3-1-96 was compositionally similar to prototype III-TT lot 91-1, produced under non-GMP, and was potent in a mouse maternal vaccination-neonatal pup challenge model of GBS disease. Four groups of 30 female rabbits each were randomized to receive III-TT lot 3-1-96 vaccine, saline-alum, or combinations of these treatments before and after insemination. The dose of conjugated CPS on a weight basis was 1 microg/kg, mimicking the anticipated actual human dose. Based on the weight of the rabbits, this was 20- to 100-fold greater than the expected human dose. Does were pre-assigned to deliver litters naturally or have their kits delivered by Caesarean-section at gestation day 29, to assess late fetal development. Sera from does and kits were collected, and the presence of type III CPS-specific IgG was confirmed by quantitative ELISA. Based on all assessments, GBS type III-TT lot 3-1-96, nor antibody to it did not affect embryo fetal viability, sex ratio, growth or cause malformations (i.e., it was non-teratogenic). In addition, that III-TT lot 3-1-96 was found to be safe and immunogenic in two clinical studies involving healthy non-pregnant adults supports a clinical evaluation of this vaccine in pregnant women.

Phase I study of single, escalating doses of a superantigen-antibody fusion protein (PNU-214565) in patients with advanced colorectal or pancreatic carcinoma.

To develop a T-cell-based therapy for carcinomas, the superantigen staphylococcal enterotoxin A (SEA) was supplied with tumor specificity by means of a recombinant fusion of the Fab fragment of the monoclonal antibody C242 recognizing human colorectal (CRC) and pancreatic carcinomas (PC). Using this Fab-SEA fusion protein (PNU-214565), potent cytotoxicity by activation of T cells can be obtained in the targeted area. Twenty-one patients with CRC and 3 with PC were treated with single, escalating doses of PNU-214565 to establish the maximum tolerated dose (MTD) and to define toxicities. The doses ranged from 0.01 ng/kg to 4.0 ng/kg with three patients at each dose level, except for the dose of 1.5 ng/kg with which six patients were treated because of dose-limiting toxicity. Adverse events (AE) were transient: 13 patients experienced mild to moderate fever. In one patient, a grade 3 fever was followed by a grade 2 hypotension. Other mild or moderate AEs were fatigue, nausea, vomiting, diarrhea, and abdominal pain. No significant hematological toxicity occurred. Immune activation was highly variable with strong activity in peripheral blood seen only in two patients at the dosage level 1.5 ng/kg. They showed pronounced elevations of interleukin-2 (IL-2), IL-6, tumor necrosis factor-alpha, and interferon-gamma, 3-5 hours after the start of infusion. In one patient, IL-2 and IL-6 increased substantially (2,925 U/mL and 32,000 U/mL) concomitantly with grade 3 fever and transient grade 2 neutropenia, grade 2 lymphopenia, and grade 2 monocytopenia. In conclusion, a single 3-hour infusion of PNU-214565 could be safely administered up to 4 ng/kg. MTD was not determined. Instead, a repeat-dose trial was initiated starting at 0.5 ng/kg, considered safe in this trial, with the objective of defining the MTD.