Background Many subjects with asthma exhibit sputum eosinophilia associated with exacerbations. Benralizumab targets eosinophils by binding interleukin-5 receptor alpha, inducing apoptosis via antibody-dependent cell-mediated cytotoxicity. Objectives To evaluate the safety of benralizumab in adults with eosinophilic asthma, and its effects on eosinophil counts in airway mucosal/submucosal biopsies, sputum, bone marrow, and peripheral blood. Methods In this multicenter, double-blind, placebo-controlled Phase I study, 13 subjects were randomized to single intravenous placebo or benralizumab 1 mg/kg (day 0) [Cohort 1], and 14 subjects were randomized to three monthly subcutaneous doses of placebo or benralizumab 100 or 200 mg (days 0, 28, and 56) [Cohort 2]. Cohorts 1 and 2 were consecutive. Results The incidence of adverse events was similar between groups. No serious adverse events related to benralizumab occurred. Cohort 1: intravenous benralizumab produced a median decrease from baseline of 61.9% in airway mucosal eosinophils (day 28; placebo: +19.6%; P = .28), 18.7% (day 21) in sputum and 100% (day 28) in blood. Eosinophils were not detectable in bone marrow of benralizumab-treated subjects (day 28, n=4). Cohort 2: subcutaneous benralizumab demonstrated a combined (100 + 200 mg) median reduction of 95.8% in airway eosinophils (day 84; placebo −46.7%; P = .06), 89.9% (day 28) in sputum and 100% (day 84) in blood. Conclusion Single-dose intravenous and multiple-dose subcutaneous benralizumab reduced eosinophil counts in airway mucosa/submucosa and sputum, and suppressed eosinophils in bone marrow and peripheral blood. The safety profile supports further development. Additional studies are needed to assess clinical benefit in asthma.

Group A streptococcus (GAS) is an important human pathogen that causes pharyngitis and invasive infections, including necrotizing fasciitis. Streptolysin S (SLS) is the cytolytic factor that creates the zone of betahemolysis surrounding GAS colonies grown on blood agar. We recently reported the discovery of a potential genetic determinant involved in SLS production, sagA, encoding a small peptide of 53 amino acids (S. D. Betschel, S. M. Borgia, N. L. Barg, D. E. Low, and J. C. De Azavedo, Infect. Immun. 66:1671-1679, 1998). Using transposon mutagenesis, chromosomal walking steps, and data from the GAS genome sequencing project (www .genome.ou.edu/strep.html), we have now identified a contiguous nine-gene locus (sagA to sagI) involved in SLS production. The sag locus is conserved among GAS strains regardless of M protein type. Targeted plasmid integrational mutagenesis of each gene in the sag operon resulted in an SLS-negative phenotype. Targeted integrations (i) upstream of the sagA promoter and (ii) downstream of a terminator sequence after sagI did not affect SLS production, establishing the functional boundaries of the operon. A rho-independent terminator sequence between sagA and sagB appears to regulate the amount of sagA transcript produced versus transcript for the entire operon. Reintroduction of the nine-gene sag locus on a plasmid vector restored SLS activity to the nonhemolytic sagA knockout mutant. Finally, heterologous expression of the intact sag operon conferred the SLS beta-hemolytic phenotype to the nonhemolytic Lactococcus lactis. We conclude that gene products of the GAS sag operon are both necessary and sufficient for SLS production. Sequence homologies of sag operon gene products suggest that SLS is related to the bacteriocin family of microbial toxins.Group A streptococcus (GAS), specifically Streptococcus pyogenes, is a common cause of pharyngitis, impetigo, and many other human respiratory tract and soft tissue infections. Recently, there has been a dramatic increase in reports of severe invasive GAS infections, including necrotizing fasciitis and toxic shock syndrome (44). Although GAS produces a wide array of virulence factors, those responsible for the rapid bacterial spread and tissue injury seen with invasive GAS infections are unknown.A hallmark feature of GAS in the clinical laboratory is the zone of beta-hemolysis observed surrounding colonies grown on the surface of blood agar media. The factor responsible for the beta-hemolytic phenotype is streptolysin S (SLS), the oxygen-stable cytolytic toxin of GAS. Despite detailed investigations over several decades, the exact chemical nature of SLS has remained a great mystery of GAS biology. SLS can exist in intracellular, cell-surface-bound, and extracellular forms (16), but attempts at purification are complicated by instability of the cytolytic activity in the absence of high-molecular-weight carriers, such as yeast RNA core or albumin (47).We have adopted a molecular genetic approach towards the identification of SLS and the study of...

Widespread drug resistance due to empiric use of broad-spectrum antibiotics has stimulated development of bacteria-specific strategies for prophylaxis and therapy based on modern monoclonal antibody (mAb) technologies. However, single-mechanism mAb approaches have not provided adequate protective activity in the clinic. We constructed multifunctional bispecific antibodies, each conferring three mechanisms of action against the bacterial pathogen Pseudomonas aeruginosa by targeting the serotype-independent type III secretion system (injectisome) virulence factor PcrV and persistence factor Psl exopolysaccharide. A new bispecific antibody platform, BiS4, exhibited superior synergistic protection against P. aeruginosa-induced murine pneumonia compared to parent mAb combinations or other available bispecific antibody structures. BiS4αPa was protective in several mouse infection models against disparate P. aeruginosa strains and unexpectedly further synergized with multiple antibiotic classes even against drug-resistant clinical isolates. In addition to resulting in a multimechanistic clinical candidate (MEDI3902) for the prevention or treatment of P. aeruginosa infections, these antibody studies suggest that multifunctional antibody approaches may be a promising platform for targeting other antibiotic-resistant bacterial pathogens.

PURPOSE To assess the efficacy of pembrolizumab in patients with advanced relapsed or refractory mycosis fungoides (MF) or Sézary syndrome (SS). PATIENTS AND METHODS CITN-10 is a single-arm, multicenter phase II trial of 24 patients with advanced MF or SS. Patients were treated with pembrolizumab 2 mg/kg every 3 weeks for up to 24 months. The primary end point was overall response rate by consensus global response criteria. RESULTS Patients had advanced-stage disease (23 of 24 with stage IIB to IV MF/SS) and were heavily pretreated with a median of four prior systemic therapies. The overall response rate was 38% with two complete responses and seven partial responses. Of the nine responding patients, six had 90% or more improvement in skin disease by modified Severity Weighted Assessment Tool, and eight had ongoing responses at last follow-up. The median duration of response was not reached, with a median response follow-up time of 58 weeks. Immune-related adverse events led to treatment discontinuation in four patients. A transient worsening of erythroderma and pruritus occurred in 53% of patients with SS. This cutaneous flare reaction did not result in treatment discontinuation for any patient. The flare reaction correlated with high PD-1 expression on Sézary cells but did not associate with subsequent clinical responses or lack of response. Treatment responses did not correlate with expression of PD-L1, total mutation burden, or an interferon-γ gene expression signature. CONCLUSION Pembrolizumab demonstrated significant antitumor activity with durable responses and a favorable safety profile in patients with advanced MF/SS.

Alpha-toxin (AT) is a major virulence factor in the disease pathogenesis of Staphylococcus aureus. We previously identified a monoclonal antibody (MAb) against AT that reduced disease severity in a mouse dermonecrosis model. Here, we evaluate the activity of an affinity-optimized variant, LC10, in a mouse model of S. aureus pneumonia. Passive immunization with LC10 increased survival and reduced bacterial numbers in the lungs and kidneys of infected mice and showed protection against diverse S. aureus clinical isolates. The lungs of S. aureus-infected mice exhibited bacterial pneumonia, including widespread inflammation, whereas the lungs of mice that received LC10 exhibited minimal inflammation and retained healthy architecture. Consistent with reduced immune cell infiltration, LC10-treated animals had significantly lower (P < 0.05) proinflammatory cytokine and chemokine levels in the bronchoalveolar lavage fluid than did those of the control animals. This reduction in inflammation and damage to the LC10-treated animals resulted in reduced vascular protein leakage and CO 2 levels in the blood. LC10 was also assessed for its therapeutic activity in combination with vancomycin or linezolid. Treatment with a combination of LC10 and vancomycin or linezolid resulted in a significant increase (P < 0.05) in survival relative to the monotherapies and was deemed additive to synergistic by isobologram analysis. Consistent with improved survival, the lungs of animals treated with antibiotic plus LC10 exhibited less inflammatory tissue damage than those that received monotherapy. These data provide insight into the mechanisms of protection provided by AT inhibition and support AT as a promising target for immunoprophylaxis or adjunctive therapy against S. aureus pneumonia.