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Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disease characterized by complement-mediated hemolysis. Pegcetacoplan is the first C3-targeted therapy approved for adults with PNH (United States), adults with PNH with inadequate response or intolerance to a C5 inhibitor (Australia), and adults with anemia despite C5-targeted therapy for ≥3 months (European Union). PRINCE was a phase 3, randomized, multicenter, open-label, controlled study to evaluate the efficacy and safety of pegcetacoplan vs control (supportive care only; eg, blood transfusions, corticosteroids, and supplements) in complement inhibitor–naive patients with PNH. Eligible adults receiving supportive care only for PNH were randomly assigned and stratified based on their number of transfusions (1-g/dL decrease in hemoglobin levels without transfusions) from baseline through week 26 and lactate dehydrogenase (LDH) change at week 26. Overall, 53 patients received pegcetacoplan (n = 35) or control (n = 18). Pegcetacoplan was superior to control for hemoglobin stabilization (pegcetacoplan, 85.7%; control, 0; difference, 73.1%; 95% confidence interval [CI], 57.2-89.0; P < .0001) and change from baseline in LDH (least square mean change: pegcetacoplan, −1870.5 U/L; control, −400.1 U/L; difference, −1470.4 U/L; 95% CI, −2113.4 to −827.3; P < .0001). Pegcetacoplan was well tolerated. No pegcetacoplan-related adverse events were serious, and no new safety signals were observed. Pegcetacoplan rapidly and significantly stabilized hemoglobin and reduced LDH in complement inhibitor–naive patients and had a favorable safety profile. This trial was registered at www.clinicaltrials.gov as NCT04085601.

Background: In the PEGASUS trial, the complement C3 inhibitor, pegcetacoplan, showed superiority to eculizumab in improving haematological outcomes in adult patients with paroxysmal nocturnal haemoglobinuria and suboptimal response to eculizumab at 16 weeks. The aim of the open-label period was to evaluate the long-term efficacy and safety of pegcetacoplan through to 48 weeks. Methods: PEGASUS was a phase 3, randomised, open-label, active-comparator controlled trial conducted in 44 centres in Australia, Belgium, Canada, France, Germany, Japan, Russia, South Korea, Spain, the UK, and the USA. Eligible participants were aged 18 years or older, had paroxysmal nocturnal haemoglobinuria, and had a haemoglobin concentration of less than 10·50 g/dL after 3 months or longer of stable eculizumab treatment. After a 4-week run-in with eculizumab plus pegcetacoplan, patients were randomly assigned (1:1) by interactive response technology to pegcetacoplan (1080 mg subcutaneously twice weekly) or eculizumab (according to their regimen at enrolment) for 16 weeks and could continue to the open-label period (32 weeks of pegcetacoplan monotherapy [pegcetacoplan-to-pegcetacoplan] or 28 weeks of pegcetacoplan monotherapy [eculizumab-to-pegcetacoplan]). Randomisation was stratified by platelet count and number of previous blood transfusions. The primary endpoint was change from baseline in haemoglobin at week 16, which has previously been reported. The outcomes of the open-label period (week 16 to week 48) are reported here. At 48 weeks, efficacy (including mean haemoglobin concentration and quality of life measured on the Functional Assessment of Chronic Illness Therapy [FACIT]-Fatigue scale) was assessed in the intention-to-treat population and safety was assessed per protocol. This trial was registered with ClinicalTrials.gov, NCT03500549, and has been completed. Findings: Between June 14, 2018, and Nov 14, 2019, 80 patients were randomly assigned to receive treatment with pegcetacoplan (41 patients) or eculizumab (39 patients). Most participants were women (49 [61%]) and 31 (39%) were men; 12 (15%) were Asian, two (3%) were Black, 49 (61%) were White, and 17 (21%) were another race or did not report their race. The open-label period had 77 participants (38 pegcetacoplan-to-pegcetacoplan, 39 eculizumab-to-pegcetacoplan). Patients in the pegcetacoplan-to-pegcetacoplan group maintained high mean haemoglobin concentrations between 16 weeks (11·54 g/dL [SD 1·96]) and 48 weeks (11·30 g/dL [1·77]; p=0·14). Patients in the eculizumab-to-pegcetacoplan group had significantly greater mean haemoglobin concentrations at 48 weeks (11·57 g/dL [2·21]) versus 16 weeks (8·58 g/dL [0·96]; p

BackgroundPost-treatment symptoms are a focal point of follow-up visits for head and neck cancer patients. While symptoms such as dysphagia and shortness-of-breath early after treatment may motivate additional work up, their precise association with disease control and survival outcomes is not well established.MethodsThis prospective data cohort study of 470 oropharyngeal cancer patients analyzed patient-reported swallowing, choking and shortness-of-breath symptoms at 3-to-6 months following radiotherapy to evaluate their association with overall survival and disease control. Associations between the presence of moderate-to-severe swallowing, choking and mild-to-severe shortness-of-breath and treatment outcomes were analyzed via Cox regression and Kaplan-Meier. The main outcome was overall survival (OS), and the secondary outcomes were local, regional, and distant disease control.ResultsThe majority of patients (91.3%) were HPV-positive. Median follow-up time was 31.7 months (IQR: 21.9-42.1). Univariable analysis showed significant associations between OS and all three symptoms of swallowing, choking, and shortness-of-breath. A composite variable integrating scores of all three symptoms was significantly associated with OS on multivariable Cox regression (p=0.0018). Additionally, this composite symptom score showed the best predictive value for OS (c-index=0.75). Multivariable analysis also revealed that the composite score was significantly associated with local recurrence/progression (p=0.025). Notably, the same significant associations with OS were seen for HPV-positive only subset analysis (pConclusionsQuantitative patient-reported measures of dysphagia and shortness-of-breath 3-to-6 months post-treatment are significant predictors of OS and disease recurrence/progression in OPC patients and in HPV-positive OPC only.

Heat shock protein 27 (HSP27) is a protein that works as a chaperone and an antioxidant and is activated by heat shock, environmental stress, and pathophysiological stress. However, HSP27 dysregulation is a characteristic of many human cancers. HSP27 suppresses apoptosis and cytoskeletal reorganization. As a result, it is recognized as a critical therapeutic target for effective cancer therapy. Despite the effectiveness of multiple HSP27 inhibitors in pre-clinical investigations and clinical trials, no HSP27 inhibitor has progressed to the anticancer phase of the development. These difficulties have mostly been attributable to existing anticancer therapies’ inability to target oncogenic HSP27. Highly selective HSP27 inhibitors with higher effective-ness and low toxicity led to the development of combination techniques that include computer-aided assisted therapeutic discovery and design. This study emphasizes the most recent results and roles of HSP27 in cancer and the potential for utilizing an anticancer chemical database to uncover novel compounds to inhibit HSP27.

Objective Neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is a rare, progressive, fatal neurodegenerative pediatric disorder resulting from deficiencies of the lysosomal enzyme tripeptidyl peptidase 1 that are caused by mutations in TPP1. Identifying biomarkers of CLN2 disease progression will be important in assessing the efficacy of therapeutic interventions for this disorder. Neurofilament light is an intrinsic component of healthy neurons; elevated circulating extracellular neurofilament light is a biomarker of neuropathology in several adult‐onset neurological diseases. Our objective was to assess whether circulating neurofilament light is a biomarker that is responsive to enzyme replacement therapy (ERT) in CLN2 disease. Methods Using an ultrasensitive immunoassay, we assessed plasma neurofilament light changes during disease progression in a canine model of CLN2 disease and in ERT clinical trial CLN2 disease patients. Results In tripeptidyl peptidase 1 (TPP1)‐null dogs (N = 11), but not in control dogs [N = 6 (TPP1 +/−) and N = 27 (WT)], neurofilament light levels increased more than tenfold above initial low baseline levels during disease progression. Before treatment in 21 human subjects with CLN2 disease (age range: 1.72–6.85 years), neurofilament light levels were 48‐fold higher (P

Background Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired disease characterized by chronic complement-mediated hemolysis. C5 inhibition controls intravascular hemolysis in untreated PNH but cannot address extravascular hemolysis. Pegcetacoplan, a pegylated peptide targeting proximal complement protein C3, potentially inhibits both intravascular and extravascular hemolysis. Methods We conducted a phase 3 open-label, controlled trial to assess the efficacy and safety of pegcetacoplan as compared with eculizumab in adults with PNH and hemoglobin levels lower than 10.5 g per deciliter despite eculizumab therapy. After a 4-week run-in phase in which all patients received pegcetacoplan plus eculizumab, we randomly assigned patients to subcutaneous pegcetacoplan monotherapy (41 patients) or intravenous eculizumab (39 patients). The primary end point was the mean change in hemoglobin level from baseline to week 16. Additional clinical and hematologic markers of hemolysis and safety were assessed. Results Pegcetacoplan was superior to eculizumab with respect to the change in hemoglobin level from baseline to week 16, with an adjusted (least squares) mean difference of 3.84 g per deciliter (P Conclusions Pegcetacoplan was superior to eculizumab in improving hemoglobin and clinical and hematologic outcomes in patients with PNH by providing broad hemolysis control, including control of intravascular and extravascular hemolysis. (Funded by Apellis Pharmaceuticals; PEGASUS ClinicalTrials.gov, NCT03500549. opens in new tab.)

Background The current study was performed to assess the efficacy of surveillance imaging in patients with head and neck cancer (HNC) who are treated definitively with radiotherapy. Methods Eligible patients included those with a demonstrable disease-free interval (≥1 follow-up imaging procedure without evidence of disease and a subsequent visit/imaging procedure) who underwent treatment of HNC from 2000 through 2010. Results A total of 1508 patients were included. The median overall survival was 99 months, with a median imaging follow-up period of 59 months. Of the 1508 patients, 190 patients (12.6%) experienced disease recurrence (107 patients had locoregional and 83 had distant disease recurrence). A total of 119 patients (62.6%) in the group with disease recurrence were symptomatic and/or had an adverse clinical finding associated with the recurrence. Approximately 80% of patients with locoregional disease recurrences presented with a clinical finding, whereas 60% of distant disease recurrences were detected by imaging in asymptomatic patients. Despite the earlier detection of disease recurrence via imaging, those patients in the group of patients with clinically detected disease recurrence were significantly more likely to undergo salvage therapy compared with those whose recurrence was detected on imaging (odds ratio, 0.35). There was no difference in overall survival noted between those patients with disease recurrences that were detected clinically or with imaging alone. Approximately 70% of disease recurrences occurred within the first 2 years. In those patients who developed disease recurrence after 2 years, the median time to recurrence was 51 months. After 2 years, the average number of imaging procedures per patient for the detection of a salvageable recurrence for the imaging-detected group was 1539. Conclusions Surveillance imaging in asymptomatic patients with HNC who are treated definitively with radiotherapy without clinically suspicious findings beyond 2 years has a low yield and a high cost. Physicians ordering these studies must use judicious consideration and discretion.

Treatment with intracerebroventricular (ICV)-delivered cerliponase alfa enzyme replacement therapy (ERT) in a Phase 1/2 study of 24 subjects with CLN2 disease resulted in a meaningful preservation of motor and language (ML) function and was well tolerated. Treatment was associated with anti-drug antibody (ADA) production in the cerebrospinal fluid (CSF) of 6/24 (25%) and in the serum of 19/24 (79%) of clinical trial subjects, respectively, over a mean exposure of 96.4 weeks (range 0.1–129 weeks). Neutralizing antibodies (NAb) were not detected in the CSF of any of the subjects. No events of anaphylaxis were reported. Neither the presence of serum ADA nor drug-specific immunoglobulin E was associated with the incidence or severity of hypersensitivity adverse events. Serum and CSF ADA titers did not correlate with change in ML score. Therefore, the development of an ADA response to cerliponase alfa is not predictive of an adverse safety profile or poor treatment outcome.

Summary Background Late-infantile neuronal ceroid lipofuscinosis type 2 (CLN2) disease, characterised by rapid psychomotor decline and epilepsy, is caused by deficiency of the lysosomal enzyme tripeptidyl peptidase 1. We aimed to analyse the characteristics and rate of progression of CLN2 disease in an international cohort of patients. Methods We did an observational cohort study using data from two independent, international datasets of patients with untreated genotypically confirmed CLN2 disease: the DEM-CHILD dataset (n=74) and the Weill Cornell Medical College (WCMC) dataset (n=66). Both datasets included quantitative rating assessments with disease-specific clinical domain scores, and disease course was measured longitudinally in 67 patients in the DEM-CHILD cohort. We analysed these data to determine age of disease onset and diagnosis, as well as disease progression—measured by the rate of decline in motor and language summary scores (on a scale of 0–6 points)—and time from first symptom to death. Findings In the combined DEM-CHILD and WCMC dataset, median age was 35·0 months (IQR 24·0–38·5) at first clinical symptom, 37·0 months (IQR 35·0 −42·0) at first seizure, and 54·0 months (IQR 47·5–60·0) at diagnosis. Of 74 patients in the DEM-CHILD dataset, the most common first symptoms of disease were seizures (52 [70%]), language difficulty (42 [57%]), motor difficulty (30 [41%]), behavioural abnormality (12 [16%]), and dementia (seven [9%]). Among the 41 patients in the DEM-CHILD dataset for whom longitudinal assessments spanning the entire disease course were available, a rapid annual decline of 1·81 score units (95% CI 1·50–2·12) was seen in motor–language summary scores from normal (score of 6) to no function (score of 0), which occurred over approximately 30 months. Among 53 patients in the DEM-CHILD cohort with available data, the median time between onset of first disease symptom and death was 7·8 years (SE 0·9) years. Interpretation In view of its natural history, late-infantile CLN2 disease should be considered in young children with delayed language acquisition and new onset of seizures. CLN2 disease has a largely predictable time course with regard to the loss of language and motor function, and these data might serve as historical controls for the assessment of current and future therapies. Funding EU Seventh Framework Program, German Ministry of Education and Research, EU Horizon2020 Program, National Institutes of Health, Nathan's Battle Foundation, Cures Within Reach Foundation, Noah's Hope Foundation, Hope4Bridget Foundation.

Recombinant human tripeptidyl peptidase 1 (cerliponase alfa) is an enzyme-replacement therapy that has been developed to treat neuronal ceroid lipofuscinosis type 2 (CLN2) disease, a rare lysosomal disorder that causes progressive dementia in children.In a multicenter, open-label study, we evaluated the effect of intraventricular infusion of cerliponase alfa every 2 weeks in children with CLN2 disease who were between the ages of 3 and 16 years. Treatment was initiated at a dose of 30 mg, 100 mg, or 300 mg; all the patients then received the 300-mg dose for at least 96 weeks. The primary outcome was the time until a 2-point decline in the score on the motor and language domains of the CLN2 Clinical Rating Scale (which ranges from 0 to 6, with 0 representing no function and 3 representing normal function in each of the two domains), which was compared with the time until a 2-point decline in 42 historical controls. We also compared the rate of decline in the motor-language score between the two groups, using data from baseline to the last assessment with a score of more than 0, divided by the length of follow-up (in units of 48 weeks).Twenty-four patients were enrolled, 23 of whom constituted the efficacy population. The median time until a 2-point decline in the motor-language score was not reached for treated patients and was 345 days for historical controls. The mean (±SD) unadjusted rate of decline in the motor-language score per 48-week period was 0.27±0.35 points in treated patients and 2.12±0.98 points in 42 historical controls (mean difference, 1.85; P0.001). Common adverse events included convulsions, pyrexia, vomiting, hypersensitivity reactions, and failure of the intraventricular device. In 2 patients, infections developed in the intraventricular device that was used to administer the infusion, which required antibiotic treatment and device replacement.Intraventricular infusion of cerliponase alfa in patients with CLN2 disease resulted in less decline in motor and language function than that in historical controls. Serious adverse events included failure of the intraventricular device and device-related infections. (Funded by BioMarin Pharmaceutical and others; CLN2 ClinicalTrials.gov numbers, NCT01907087 and NCT02485899 .).

Background: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, potentially life-threatening hematologic disease characterized by various degrees of hemolysis, bone marrow failure, and thrombophilia. Pegcetacoplan (PEG), a C3 complement-inhibitor approved by the FDA for treatment of adults with PNH, has demonstrated improved hemoglobin (Hb) levels for PNH patients with screening Hb levels Aims: This post hoc analysis evaluated the safety and efficacy of 16 weeks of PEG therapy for PNH treatment in a subgroup of patients with baseline Hb levels ≥10.0 g/dL from the PADDOCK (NCT02588833) Phase 1b, PEGASUS (NCT03500549) Phase 3, and PRINCE (NCT04085601) Phase 3 studies. Methods: Adult PNH patients from the PADDOCK, PEGASUS, and PRINCE studies with baseline Hb levels ≥10.0 g/dL and no transfusions within 14 days of baseline were included in this analysis. PADDOCK evaluated PEG therapy at 270-360 mg/day subcutaneously (SC) in complement-inhibitor naïve PNH patients. PEGASUS enrolled PNH patients that remained anemic despite stable ECU treatment (≥3 months) with Hb levels Post hoc analyses were performed at Week 16 for PADDOCK and PRINCE, Week 16 for PEGASUS patients treated with PEG during the RCP, and Week 36 for PEGASUS patients who switched from ECU to PEG during the OLP (16 weeks of PEG monotherapy). Endpoints included change from baseline (CFB) in Hb, percentage of patients with Hb response (≥1 g/dL Hb increase without transfusion), percentage of patients with Hb ≥12 g/dL without transfusion, and CFB in absolute reticulocyte count (ARC), lactate dehydrogenase level (LDH), and Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) after 16 weeks of PEG monotherapy. Transfusion recipients (PADDOCK, n=0; PEGASUS, n=2, [1 RCP, 1 OLP]; PRINCE=0) were defined as Hb non-responders and censored for all analyses. Results: In total, 24 patients had baseline Hb levels ≥10.0 g/dL at the baseline visit: six from PADDOCK, nine from PEGASUS (6 RCP, 3 OLP), and nine from PRINCE (1 SOC escape [began PEG at Week 6], 8 PEG). Overall, patients from all three studies achieved improved Hb levels (Table) with the majority demonstrating a Hb response and Hb ≥12 g/dL (Table). Mean decreases in ARC and LDH (Table) were observed with mean LDH less than the upper limit of normal at 16 weeks in all studies (Table). Clinically significant increases in mean FACIT-Fatigue scores were observed in all three groups (Table). No thrombotic incidents were noted in this patient population. Two PEGASUS patients had transfusions of 5 units over 2 days and of 6 units over 16 weeks due to breakthrough hemolysis. Conclusions: These results demonstrate that PEG can further improve hematological outcomes in PNH patients with baseline Hb levels ≥10.0 g/dL who are complement-inhibitor naïve or remained anemic after ECU therapy. While these patients had near normal Hb at baseline, they also had elevated ARC prior to PEG therapy, suggesting ongoing hemolysis. Improvements in mean Hb level, Hb response, ARC, LDH level, and FACIT-Fatigue score suggest that PEG is effective in this subgroup resulting in a decline in overall hemolytic activity and a clinically significant improvement in fatigue. Overall, these results suggest that the utility of PEG is not restricted to naïve and complement-inhibitor experienced PNH patients with low baseline Hb but can be efficacious in those with near-normal baseline Hb, resulting in further clinical improvements in relevant PNH parameters. Figure 1 Figure 1. Disclosures Panse: Apellis Pharmaceuticals: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Grunenthal: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; MSD: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Boehringer Ingelheim: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Speakers Bureau; Chugai: Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Blueprint Medicines: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Peffault De Latour: Apellis Pharmaceuticals Inc: Consultancy, Honoraria; Alexion: Consultancy, Honoraria, Research Funding; Amgen: Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Swedish Orphan Biovitrum AB: Consultancy, Honoraria. Schafhausen: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Swedish Orphan Biovitrum AB: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Blueprint Medicines: Membership on an entity's Board of Directors or advisory committees. Straetmans: Alexion: Membership on an entity's Board of Directors or advisory committees. Al-Adhami: Apellis Pharmaceuticals: Current Employment. Ajayi: Apellis Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Chen: Apellis Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Yeh: Apellis Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Wong: Alexion: Consultancy, Honoraria, Research Funding, Speakers Bureau; Apellis Pharmaceuticals: Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau.

Background: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare and life-threatening disease characterized by hemolysis and thrombosis. Many patients with PNH use C5-inhibitors (i.e., eculizumab/ravulizumab) to control their symptoms. Although C5-inhibition prevents intravascular hemolysis (IVH), it fails to prevent extravascular hemolysis (EVH). Because of persistent EVH, up to 72% of eculizumab-treated patients remain anemic, and up to 36% require at least one transfusion per year. Pegcetacoplan (PEG), a C3-inhibitor recently approved by the US FDA to treat adults with PNH, controls IVH and prevents EVH. Studies of PEG treatment in patients with PNH that remained anemic despite eculizumab treatment demonstrated that PEG was superior to eculizumab in achieving improvements in hemoglobin (Hb) levels (Hillmen P, et al., N Engl J Med, 2021 384 (11):1028-1037). Additionally, two early phase open-label trials demonstrated the efficacy of PEG in complement-inhibitor naïve patients with PNH (Wong RS, et al., Blood, 2020 136 [Supplement 1]). Aims: To present results from the Phase 3 PRINCE study (NCT04085601), a multicenter, randomized, open-label, controlled study evaluating the efficacy and safety of PEG compared to standard of care (SOC; excluding complement-inhibitors) in complement-inhibitor naïve patients with PNH. Methods: Fifty-three adult (≥18 years old), complement-inhibitor naïve (no complement-inhibitor treatment [i.e., eculizumab/ravulizumab] within 3 months prior to screening) patients with PNH and Hb levels below the lower limits of normal (males: ≤13.6 g/dL; females: ≤12.0 g/dL), and lactate dehydrogenase (LDH) levels ≥1.5 times the upper limit of normal (1.5x ULN; ≥339 U/L) were enrolled. Patients were randomized 2:1 to receive PEG (1080 mg subcutaneously twice weekly [n=35]) or SOC (excluding complement-inhibitors eculizumab/ravulizumab [n=18]) through Week 26. Patients on SOC had the option to switch to the PEG group if their Hb decreased by ≥2 g/dL from baseline. Co-primary endpoints were Hb stabilization (avoidance of a >1 g/dL decrease in Hb levels in the absence of transfusions) and change from baseline (CFB) in LDH level from baseline to Week 26. Secondary endpoints included CFB in Hb levels, transfusion avoidance (defined as the proportion of subjects who did not require a transfusion through Week 26), and the incidence of adverse events (AEs). Statistical analyses were performed using the Cochran-Mantel-Haenszel test and ANCOVA model. Results: PEG was superior to SOC in both co-primary endpoints. Hb stabilization was achieved by 85.7% (n=30) of PEG-treated patients and 0.0% of SOC patients through Week 26 (p Conclusions: Patients with PNH that were naïve to complement-inhibitor treatment demonstrated meaningful hematological and clinical improvements following 26 weeks of PEG treatment. The safety profile of PEG was similar to previous study results and represent a favorable risk-benefit profile. These results provide evidence for the safety and efficacy of PEG treatment in complement-inhibitor naïve patients with PNH. Figure 1 Figure 1. Disclosures Wong: Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Apellis Pharmaceuticals: Research Funding, Speakers Bureau; Alexion: Consultancy, Honoraria, Research Funding, Speakers Bureau. Al-Adhami: Apellis Pharmaceuticals: Current Employment. Ajayi: Apellis Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Alvarenga: Apellis Pharmaceuticals: Consultancy. Deschatelets: Apellis Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Francois: Apellis Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Grossi: Apellis Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company.

INTRODUCTION Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, clonal, nonmalignant hematologic disease characterized by complement-mediated red blood cell hemolysis. The current standard of care for patients with PNH is C5 inhibition. Anemia persists in up to ~70% of patients receiving eculizumab and is attributed to persistent intravascular hemolysis (IVH) and mostly to C3-mediated extravascular hemolysis (EVH). Pegcetacoplan is a pegylated pentadecapeptide C3 inhibitor targeting proximal complement to control both IVH and EVH. PEGASUS is a phase 3, open-label, active-comparator controlled study of efficacy and safety of pegcetacoplan versus eculizumab. This post hoc analysis of data from PEGASUS categorized the clinical response to pegcetacoplan or ECU in patients with PNH and hemoglobin METHODS Hematologic response to treatment was categorized (per Risitano AM, et al. Front Immunol. 2019;10:1157) as complete, major, good, partial, minor, or no response, using number of packed red blood cell transfusions required, hemoglobin level, lactate dehydrogenase (LDH) level, and absolute reticulocyte count (ARC). Complete response: no transfusions required, stable hemoglobin in the normal range, and no evidence of hemolysis (ie, LDH ≤1.5× upper limit of normal, ARC ≤150,000/µL). Major response: no transfusion, normal hemoglobin, but with evidence of hemolysis (LDH >1.5× upper limit of normal and/or ARC >150,000/µL). Good response: no transfusion, but with chronic mild anemia or evidence of hemolysis. Partial response: chronic moderate anemia and/or occasional transfusions (6 units/6 months). Nine patients (6 from the pegcetacoplan arm and 3 from the eculizumab arm) did not readily fit within the existing criteria due to the availability of data at week 16. Although these 9 patients were manually categorized identically by the lead and senior author in a blinded, independent manner, they were not included among these data. RESULTS The intention-to-treat population was comprised of 41 patients randomized to pegcetacoplan and 39 patients randomized to eculizumab. Four patients in the pegcetacoplan arm and 1 patient in the eculizumab arm were not evaluable for analysis due to incomplete data at week 16. Altogether, 61.0% of patients (25/41) in the pegcetacoplan arm have achieved at least a good hematological response, in contrast to 5.1% (2/39) of the eculizumab arm. At week 16, the distribution of response categories was as follows (Figure): in the pegcetacoplan arm and eculizumab arm, respectively, complete responses were 36.6% and 0%, good responses were 24.4% and 5.1%, partial responses were 12.2% and 33.3%, minor responses were 2.4% and 23.1%, and no responses were 0% and 28.2%. The addition of the 9 manually categorized patients did not significantly alter the proportions reported here. Among the factors that may contribute to heterogeneity of hematologic response to treatment are impaired bone marrow function, residual IVH, and residual C3-mediated EVH. Bone marrow failure was ruled out, and no difference in LDH was observed, suggesting that the major factor accounting for the difference between the 2 arms was the prevention of C3-mediated EVH (as confirmed by reduction of C3-opsonization of PNH red blood cells). CONCLUSION In PEGASUS, treatment with pegcetacoplan resulted in a greater proportion of patients with better hematological responses compared to eculizumab. These results further support the concept that proximal complement inhibition, by preventing EVH in addition to controlling IVH, leads to clinical and hematological improvement in the treatment of PNH. Disclosures Risitano: Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Alnylam: Research Funding; Alexion: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Samsung: Membership on an entity's Board of Directors or advisory committees; Amyndas: Consultancy; RA pharma: Research Funding; Biocryst: Membership on an entity's Board of Directors or advisory committees; Achillion: Membership on an entity's Board of Directors or advisory committees; Jazz: Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Pfizer: Speakers Bureau; Apellis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Weitz:Alexion: Consultancy, Honoraria, Speakers Bureau; Apellis: Consultancy, Honoraria. de Castro:Novartis: Honoraria, Other: Steering committee; Alexion: Honoraria, Research Funding; Biocryst: Honoraria, Other: Data monitoring committee; Apellis: Consultancy, Honoraria, Research Funding. Kiladjian:AbbVie: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees. Griffin:Biocryst: Membership on an entity's Board of Directors or advisory committees; Alexion Pharmaceuticals: Honoraria, Other: Conference Support. Hamdani:Apellis: Current Employment, Current equity holder in publicly-traded company. Ajayi:Apellis Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Baver:Apellis: Current Employment, Current equity holder in publicly-traded company. Peffault De Latour:Novartis: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Amgen: Research Funding; Alexion Pharmaceuticals Inc.: Consultancy, Honoraria, Research Funding. OffLabel Disclosure: Pegcetacoplan is an investigational drug for the treatment of paroxysmal nocturnal hemoglobinuria.

INTRODUCTION Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired hematologic disease characterized by chronic complement-mediated intravascular and extravascular hemolysis. In the phase 3 PEGASUS study (NCT03500549), pegcetacoplan, a C3 inhibitor targeting the proximal complement pathway, was superior to eculizumab (ECU) on the primary endpoint of hemoglobin (Hb) change from baseline at week 16, and improved clinical and hematologic parameters. Additional analyses assessed if any groups of patients might experience further benefit from pegcetacoplan. METHODS Patients ≥18 years old with a diagnosis of PNH and persistent anemia (Hb RESULTS Pegcetacoplan treatment was associated with significantly greater increases in Hb levels than ECU at week 16, regardless of baseline age group, sex, race, prior transfusions, or platelet count (Tables 1-2). At week 16, regardless of baseline platelet count strata, mean Hb significantly increased from baseline in the pegcetacoplan group and decreased in the ECU group. The proportion of transfusion-free patients was similar in the pegcetacoplan group, regardless of age (≤65 years, 87.1%; >65 years, 80%), sex (female, 81.5%; male, 92.9%), race (Asian, 100%; black, 100%; white, 75.0%), transfusion strata (65 years, 0%), sex (female, 18.2%; male, 11.8%), race (Asian, 28.6%; black, 0%; white, 16.0%), transfusion strata ( CONCLUSIONS In this prespecified stratified analysis of the phase 3 PEGASUS study of patients with PNH and persistent anemia, mean Hb levels increased significantly more, the proportion of transfusion-free patients was significantly higher, ARC change from baseline at week 16 was significantly lower, and LDH decreases were larger with pegcetacoplan versus ECU, regardless of baseline age group, sex, race, prior transfusion numbers, and platelet count. Disclosures Peffault De Latour: Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Alexion Pharmaceuticals Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Research Funding; Apellis: Membership on an entity's Board of Directors or advisory committees. de Castro:Alexion: Honoraria, Research Funding; Apellis: Consultancy, Honoraria, Research Funding; Novartis: Honoraria, Other: Steering committee; Biocryst: Honoraria, Other: Data monitoring committee. Szer:Apellis: Consultancy; Pfizer: Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Alexion Pharmaceuticals Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Prevail Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees. Usuki:Alexion: Research Funding, Speakers Bureau; Apellis: Research Funding; Chugai: Research Funding; Novartis: Research Funding, Speakers Bureau. Hillmen:Alexion: Consultancy, Research Funding, Speakers Bureau; Apellis: Consultancy, Research Funding, Speakers Bureau; Gilead: Other: Financial or material support, Research Funding; AstraZeneca: Consultancy, Speakers Bureau; Roche: Consultancy, Other: Financial or material support, Research Funding, Speakers Bureau; AbbVie: Consultancy, Other: Financial or material support, Research Funding, Speakers Bureau; Pharmacyclics: Other: Financial or material support, Research Funding; Janssen: Consultancy, Other: Financial or material support, Research Funding, Speakers Bureau; Acerta: Other: Financial or material support. Griffin:Alexion Pharmaceuticals: Honoraria, Other: Conference Support; Biocryst: Membership on an entity's Board of Directors or advisory committees. Hamdani:Apellis Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Ajayi:Apellis Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Weitz:Alexion: Consultancy, Honoraria, Speakers Bureau; Apellis: Consultancy, Honoraria. OffLabel Disclosure: Pegcetacoplan is an investigational drug for the treatment of paroxysmal nocturnal hemoglobinuria.

BACKGROUND A possible surveillance model for patients with head and neck cancer (HNC) who received definitive radiotherapy was created using a partially observed Markov decision process. The goal of this model is to guide surveillance imaging policies after definitive radiotherapy. METHODS The partially observed Markov decision process model was formulated to determine the optimal times to scan patients. Transition probabilities were computed using a data set of 1508 patients with HNC who received definitive radiotherapy between the years 2000 and 2010. Kernel density estimation was used to smooth the sample distributions. The reward function was derived using cost estimates from the literature. Additional model parameters were estimated using either data from the literature or clinical expertise. RESULTS When considering all forms of relapse, the model showed that the optimal time between scans was longer than the time intervals used in the institutional guidelines. The optimal policy dictates that there should be less time between surveillance scans immediately after treatment compared with years after treatment. Comparable results also held when only locoregional relapses were considered as relapse events in the model. Simulation results for the inclusive relapse cases showed that

Farkas’ Lemma is a foundational result in linear programming, with implications in duality, optimality conditions, and stochastic and bilevel programming. Its generalizations are known as theorems of the alternative. There exist theorems of the alternative for integer programming and conic programming. We present theorems of the alternative for conic integer programming. We provide a nested procedure to construct a function that characterizes feasibility over right-hand sides and can determine which statement in a theorem of the alternative holds.

BackgroundAlthough cough is a commonly reported symptom, objective quantitation of cough during normal activity has not been performed in patients with CF.MethodsAn ambulatory device was used to characterize cough over 24hours. Pulmonary function and subject-reported coughing were also assessed.ResultsPatients included 19 clinically stable adults with CF (males:females=10:9; median age [range]=26 [19-57] years; median %-predicted FEV1 [range]=65 [44-106]%). Median [range] cough rate was 27 [13-66] coughs/hour, with values while awake of 41 [20-102] and while asleep of 2 [0.1-7] (p

Background: Higher plasma and pulmonary edema fluid levels of plasminogen activator inhibitor-1 (PAI-1) are associated with increased mortality in patients with pneumonia and acute lung injury. The 4G allele of the 4G/5G polymorphism of the PAI-1 gene is associated with higher PAI-1 levels and an increased incidence of hospitalizations for pneumonia. The authors hypothesized that the 4G allele would be associated with worse clinical outcomes (mortality and ventilator-free days) in patients with severe pneumonia. Methods: The authors enrolled patients admitted with severe pneumonia in a prospective cohort. Patients were followed until hospital discharge. DNA was isolated from blood samples, and genotyping detection for the PAI-1 4G/5G polymorphism was carried out using Taqman-based allelic discrimination. Results: A total of 111 patients were available for analysis. Distribution of genotypes was 4G/4G 26 of 111 (23%), 4G/5G 59 of 111 (53%), and 5G/5G 26 of 111 (23%). Of 111 patients, 32 (29%) died before hospital discharge and 105 patients (94%) received mechanical ventilation. Patients with the 4G/4G and the 4G/5G genotypes had higher mortality (35% vs. 8%, P 0.007) and fewer ventilator-free days (median 4 vs. 13, P 0.04) compared to patients with the 5G/5G genotype. Conclusions: The 4G allele of the 4G/5G polymorphism in the PAI-1 gene is associated with fewer ventilator-free days and increased mortality in hospitalized patients with severe pneumonia. These findings suggest that PAI-1 may have a role in pathogenesis and that the 4G/5G polymorphism may be an important biomarker of risk in patients with severe pneumonia. PROCOAGULANT activity is increased and anticoagulant and fibrinolytic activities are decreased in the alveoli of patients with pneumonia. Intraalveolar fibrin deposition, which is the hallmark of many acute inflammatory lung diseases, including pneumonia, exerts beneficial effects by sealing leakage sites when the capillary endothelium and alveolar epithelial barrier are compromised. However, when this process of fibrin deposition is severe and persistent, it can have deleterious effects. Excessive fibrin deposition enhances inflammatory responses by activating endothelial cells to produce proinflammatory mediators and an increase in vascular permeability. Fibrin is degraded by plasmin, a proteolytic enzyme that is present in the tissues in the form of an inactive precursor, plasminogen. The decreased fibrinolysis in patients with pneumonia is mainly attributed to elevation in plasminogen activator inhibitor–1 (PAI-1) activity. 1– 8 PAI-1 is activated during infection and has been shown to be elevated in the air spaces of patients with ventilator-associated pneumonia, aspiration pneumonia, and acute lung injury. 2–5,8 –11 Higher plasma and bronchoalveolar lavage (BAL) fluid levels of PAI-1 levels are associated with severe disease and adverse clinical outcomes both in patients with pneumonia and in patients with the acute respiratory distress syndrome. In patients with pneumonia, PAI-1 concentration in BAL fluid is higher in patients requiring mechanical ventilation than in those who do not require

Objective: Acute lung injury in Pseudomonas aeruginosa pneumonia depends primarily on ExoU toxin being delivered directly into the eukaryotic cell cytosol through the type III secretion system. The amino-acid sequence of ExoU has a potato patatin-like phospholipase domain, similar to the sequence of mammalian Ca2+-independent phospholipase A2. We examined whether the acute lung injury caused by cytotoxic P. aeruginosa was dependent on the patatin-like phospholipase domain of ExoU. Design: Laboratory investigation using an established mouse model for P. aeruginosa pneumonia with quantitative measurements of acute lung injury and mortality. Setting: University experimental research laboratory. Subjects: Balb/c mice. Interventions: First, a site-directional mutation was introduced in the predicted catalytically active site of the patatin-like phospholipase domain of recombinant ExoU protein. The effect of the mutation on the catalytic activity of ExoU was tested by the in vitro lysophospholipase A assay. Second, the same site-directional mutation was introduced into the exoU gene of P. aeruginosa PA103. Mice were intratracheally infected with either a wild-type P. aeruginosa strain PA103 or an isogenic mutant containing the mutation in exoU. Acute epithelial lung injury, lung edema, bacteremia, and mortality were evaluated quantitatively. Measurements and Main Results: Recombinant ExoU had lysophospholipase A activity. Site-directional mutations in the predicted catalytic site of ExoU caused a loss of the lysophospholipase A activity. Whereas the airspace instillation of PA103 caused acute lung injury and death of the infected mice, the airspace instillation of isogenic mutants secreting catalytically inactive ExoU were noncytotoxic and did not cause acute lung injury or death of the infected mice. Conclusion: Virulent P. aeruginosa causes acute lung injury and death by the cytotoxic activity derived from the patatin-like phospholipase domain of ExoU.

Acute lung injury in Pseudomonas aeruginosa pneumonia depends primarily on ExoU that is delivered directly into the eukaryotic cell via the type III secretion system. Recent studies demonstrated that ExoU has lipase activity, and that the cytotoxicity of ExoU is dependent on its patatin-like phospholipase domain. We investigated the phospholipase A (PLA) activity of ExoU. ExoU, but not non-catalytic ExoU- S142A , preincubated with the BEAS-2B cell lysate showed a weak increase of Ca 2+ -independent PLA 2 activity. When activated ExoU was mixed with secretory type PLA 2 , more phospholipase activity was observed, suggesting that ExoU has lysophospholipase A (lysoPLA) activity. A significant increase in lysoPLA activity was also observed. Glycerol enhanced this activity and inhibitors of iPLA 2 suppressed ExoU’s lysoPLA activity. Our results suggest that ExoU has a potent lysoPLA activity that requires the presence of the catalytically active site Ser 142 with an unknown eukaryotic cell factor(s) for its activation.

Ataluren was developed to restore functional protein production in genetic disorders caused by nonsense mutations, which are the cause of cystic fibrosis in 10% of patients. This trial was designed to assess the efficacy and safety of ataluren in patients with nonsense-mutation cystic fibrosis.This randomised, double-blind, placebo-controlled, phase 3 study enrolled patients from 36 sites in 11 countries in North America and Europe. Eligible patients with nonsense-mutation cystic fibrosis (aged ≥ 6 years; abnormal nasal potential difference; sweat chloride40 mmol/L; forced expiratory volume in 1 s [FEV1] ≥ 40% and ≤ 90%) were randomly assigned by interactive response technology to receive oral ataluren (10 mg/kg in morning, 10 mg/kg midday, and 20 mg/kg in evening) or matching placebo for 48 weeks. Randomisation used a block size of four, stratified by age, chronic inhaled antibiotic use, and percent-predicted FEV1. The primary endpoint was relative change in percent-predicted FEV1 from baseline to week 48, analysed in all patients with a post-baseline spirometry measurement. This study is registered with ClinicalTrials.gov, number NCT00803205.Between Sept 8, 2009, and Nov 30, 2010, 238 patients were randomly assigned, of whom 116 in each treatment group had a valid post-baseline spirometry measurement. Relative change from baseline in percent-predicted FEV1 did not differ significantly between ataluren and placebo at week 48 (-2.5% vs -5.5%; difference 3.0% [95% CI -0.8 to 6.3]; p=0.12). The number of pulmonary exacerbations did not differ significantly between treatment groups (rate ratio 0.77 [95% CI 0.57-1.05]; p=0.0992). However, post-hoc analysis of the subgroup of patients not using chronic inhaled tobramycin showed a 5.7% difference (95% CI 1.5-10.1) in relative change from baseline in percent-predicted FEV1 between the ataluren and placebo groups at week 48 (-0.7% [-4.0 to 2.1] vs -6.4% [-9.8 to -3.7]; nominal p=0.0082), and fewer pulmonary exacerbations in the ataluern group (1.42 events [0.9-1.9] vs 2.18 events [1.6-2.7]; rate ratio 0.60 [0.42-0.86]; nominal p=0.0061). Safety profiles were generally similar for ataluren and placebo, except for the occurrence of increased creatinine concentrations (ie, acute kidney injury), which occurred in 18 (15%) of 118 patients in the ataluren group compared with one (1%) of 120 patients in the placebo group. No life-threatening adverse events or deaths were reported in either group.Although ataluren did not improve lung function in the overall population of nonsense-mutation cystic fibrosis patients who received this treatment, it might be beneficial for patients not taking chronic inhaled tobramycin.PTC Therapeutics, Cystic Fibrosis Foundation, US Food and Drug Administration's Office of Orphan Products Development, and the National Institutes of Health.

The association of O-antigen serotypes with type III secretory toxins was analyzed in 99 clinical isolates of Pseudomonas aeruginosa . Isolates secreting ExoU were frequently serotyped as O11, but none were serotype O1. Most of the isolates that were nontypeable for O antigen did not secrete type III secretory toxins.

Nonsense (premature stop codon) mutations in mRNA for the cystic fibrosis transmembrane conductance regulator (CFTR) cause cystic fibrosis (CF) in approximately 10% of patients. Ataluren (PTC124) is an oral drug that permits ribosomes to readthrough premature stop codons in mRNA to produce functional protein.To evaluate ataluren activity, safety, and pharmacokinetics in children with nonsense mutation CF.Patients were assessed in two 28-day cycles, comprising 14 days on and 14 days off ataluren. Patients took ataluren three times per day (morning, midday, and evening) with randomization to the order of receiving a lower dose (4, 4, and 8 mg/kg) and a higher dose (10, 10, and 20 mg/kg) in the two cycles.The study enrolled 30 patients (16 male and 14 female, ages 6 through 18 yr) with a nonsense mutation in at least one allele of the CFTR gene, a classical CF phenotype, and abnormal baseline nasal epithelial chloride transport. Ataluren induced a nasal chloride transport response (at least a -5-mV improvement) or hyperpolarization (value more electrically negative than -5 mV) in 50% and 47% of patients, respectively, with more hyperpolarizations at the higher dose. Improvements were seen in seven of nine nonsense mutation genotypes represented. Ataluren significantly increased the proportion of nasal epithelial cells expressing apical full-length CFTR protein. Adverse events and laboratory abnormalities were infrequent and usually mild. Ataluren pharmacokinetics were similar to those in adults.In children with nonsense mutation CF, ataluren can induce functional CFTR production and is well tolerated.

The type III secretion system of Pseudomonas aeruginosa, responsible for acute infection, is composed of over twenty proteins that facilitate cytotoxin injection directly into host cells. Integral to this process is production and secretion of PcrV. Administration of a recently developed, anti-PcrV immunoglobulin, either as a therapeutic or prophylactic has previously demonstrated efficacy against laboratory strains of P. aeruginosa in a murine model. To determine if this therapy is universally applicable to a variety of P. aeruginosa clinical isolates, genetic heterogeneity of pcrV was analyzed among strains collected from three geographically distinct regions; United States, France and Japan. Sequence analysis of PcrV demonstrated limited variation among the clinical isolates examined. Strains were grouped according to the presence of non-synonymous single nucleotide polymorphisms. Representative isolates from each mutant group were examined for the ability of anti-PcrV to bind the protein secreted by these strains. The protective effect of anti-PcrV IgG against each strain was determined using an epithelial cell line cytotoxicity assay. The majority of strains tested demonstrated reduced cytotoxicity in the presence of anti-PcrV IgG. This study provides insights into the natural sequence variability of PcrV and an initial indication of the amino acid residues that appear to be conserved across strains. It also demonstrates the protective effect of anti-PcrV immunotherapy against a multitude of P. aeruginosa strains from diverse global regions with a variety of mutations in PcrV.

The pcrV genotype was analyzed in clinical isolates of Pseudomonas aeruginosa which showed a negative phenotype for secretion of V-antigen PcrV. The suppression of PcrV secretion in these isolates was due not to a lack of the pcrV gene but rather to suppression of PcrV expression.

We mapped the coding single nucleotide polymorphisms in four toxin genes— exoS , exoT , exoU , and exoY —of the Pseudomonas aeruginosa type III secretion system among several clinical isolates. We then used this information to design a multiplex PCR assay based on the simultaneous amplification of fragments of these genes. Eight strains of known genotype were used to test our multiplex PCR method, which showed 100% sensitivity and specificity in this small sample size. This assay appears to be promising for the rapid and accurate genotyping of the presence of these genes in clinical strains of P. aeruginosa .

Background The relative contributions of the cytotoxic phenotype of P. aeruginosa expressing type III secretory toxins and an immunocompromised condition lacking normal Toll-like receptor 4 (TLR4) signaling in the pathogenesis of acute lung injury and sepsis were evaluated in a mouse model for Pseudomonas aeruginosa pneumonia. By using lipopolysaccharide-resistant C3H/HeJ mice missing normal TLR4 signaling due to a mutation on the tlr4 gene, we evaluated how TLR4 signaling modulates the pneumonia caused by cytotoxic P. aeruginosa expressing type III secretory toxins. Methods We infected C3H/HeJ or C3H/FeJ mice with three different doses of either a cytotoxic P. aeruginosa strain (wild type PA103) or its non-cytotoxic isogenic mutant missing the type III secretory toxins (PA103ΔUT). Survival of the infected mice was evaluated, and the severity of acute lung injury quantified by measuring alveolar epithelial permeability as an index of acute epithelial injury and the water to dry weight ratios of lung homogenates as an index of lung edema. Bacteriological analysis and cytokine assays were performed in the infected mice. Results Development of acute lung injury and sepsis was observed in all mouse strains when the cytotoxic P. aeruginosa strain but not the non-cytotoxic strain was instilled in the airspaces of the mice. Only C3H/HeJ mice had severe bacteremia and high mortality when a low dose of the cytotoxic P. aeruginosa strain was instilled in their lungs. Conclusion The cytotoxic phenotype of P. aeruginosa is the critical factor causing acute lung injury and sepsis in infected hosts. When the P. aeruginosa is a cytotoxic strain, the TLR4 signaling system is essential to clear the batcteria to prevent lethal lung injury and bacteremia.