A randomized controlled trial of presatovir for respiratory syncytial virus after lung transplant.

BACKGROUND: Respiratory syncytial virus (RSV) infection in lung transplant recipients is associated with high morbidity. This study evaluated the RSV fusion inhibitor presatovir in RSV-infected lung transplant recipients. METHODS: In this international Phase 2b, randomized, double-blind, placebo-controlled trial (NCT02534350), adult lung transplant recipients with symptomatic confirmed RSV infection for ≤7 days received oral presatovir 200 mg on day 1 and 100 mg daily on days 2 to 14, or placebo (2:1), with follow-up through day 28. There were 2 coprimary endpoints: time-weighted average change in nasal RSV load from day 1 to 7, calculated from nasal swabs, in the full analysis set ([FAS]; all patients who received study drug and had quantifiable baseline nasal RSV load) and time-weighted average change in nasal RSV load from day 1 to 7 in the subset of patients with pretreatment symptom duration at the median or shorter of the FAS. Secondary endpoints were changes in respiratory infection symptoms assessed using the Influenza Patient-Reported Outcomes questionnaire and lung function measured by spirometry. RESULTS: Sixty-one patients were randomized, 40 received presatovir, 20 placebo, and 54 were included in efficacy analyses. Presatovir did not significantly improve the primary endpoint in the FAS (treatment difference [95% CI], 0.10 [-0.43, 0.63] log10 copies/ml; p = 0.72) or the shorter symptom-duration subgroup (-0.12 [-0.94, 0.69] log10 copies/ml; p = 0.76). Secondary endpoints were not different between presatovir and placebo groups. Presatovir was generally well tolerated. CONCLUSIONS: Presatovir treatment did not significantly improve change in nasal RSV load, symptoms, or lung function in lung transplant recipients.

Assessment of Drug Resistance during Phase 2b Clinical Trials of Presatovir in Adults Naturally Infected with Respiratory Syncytial Virus.

This study summarizes drug resistance analyses in 4 recent phase 2b trials of the respiratory syncytial virus (RSV) fusion inhibitor presatovir in naturally infected adults. Adult hematopoietic cell transplant (HCT) recipients, lung transplant recipients, or hospitalized patients with naturally acquired, laboratory-confirmed RSV infection were enrolled in 4 randomized, double-blind, placebo-controlled studies with study-specific presatovir dosing. Full-length RSV F sequences amplified from nasal swabs obtained at baseline and postbaseline were analyzed by population sequencing. Substitutions at RSV fusion inhibitor resistance-associated positions are reported. Genotypic analyses were performed on 233 presatovir-treated and 149 placebo-treated subjects. RSV F variant V127A was present in 8 subjects at baseline. Population sequencing detected treatment-emergent substitutions in 10/89 (11.2%) HCT recipients with upper and 6/29 (20.7%) with lower respiratory tract infection, 1/35 (2.9%) lung transplant recipients, and 1/80 (1.3%) hospitalized patients treated with presatovir; placebo-treated subjects had no emergent resistance-associated substitutions. Subjects with substitutions at resistance-associated positions had smaller decreases in viral load during treatment relative to those without, but they had similar clinical outcomes. Subject population type and dosing regimen may have influenced RSV resistance development during presatovir treatment. Subjects with genotypic resistance development had decreased virologic responses compared to those without genotypic resistance but had comparable clinical outcomes.

Drug Resistance Assessment Following Administration of Respiratory Syncytial Virus (RSV) Fusion Inhibitor Presatovir to Participants Experimentally Infected With RSV.

BACKGROUND: Presatovir is an oral respiratory syncytial virus (RSV) fusion inhibitor targeting RSV F protein. In a double-blind, placebo-controlled study in healthy adults experimentally infected with RSV (Memphis-37b), presatovir significantly reduced viral load and clinical disease severity in a dose-dependent manner. METHODS: Viral RNA from nasal wash samples was amplified and the F gene sequenced to monitor presatovir resistance. Effects of identified amino acid substitutions on in vitro susceptibility to presatovir, viral fitness, and clinical outcome were assessed. RESULTS: Twenty-eight treatment-emergent F substitutions were identified. Of these, 26 were tested in vitro; 2 were not due to lack of recombinant virus recovery. Ten substitutions did not affect presatovir susceptibility, and 16 substitutions reduced RSV susceptibility to presatovir (2.9- to 410-fold). No substitutions altered RSV susceptibility to palivizumab or ribavirin. Frequency of phenotypically resistant substitutions was higher with regimens containing lower presatovir dose and shorter treatment duration. Participants with phenotypic presatovir resistance had significantly higher nasal viral load area under the curve relative to those without, but substitutions did not significantly affect peak viral load or clinical manifestations of RSV disease. CONCLUSIONS: Emergence of presatovir-resistant RSV occurred during therapy but did not significantly affect clinical efficacy in participants with experimental RSV infection.

A Phase 2b, Randomized, Double-blind, Placebo-Controlled Multicenter Study Evaluating Antiviral Effects, Pharmacokinetics, Safety, and Tolerability of Presatovir in Hematopoietic Cell Transplant Recipients with Respiratory Syncytial Virus Infection of the Lower Respiratory Tract.

BACKGROUND: Presatovir significantly reduced nasal viral load, signs, and symptoms of respiratory syncytial virus (RSV) infection in a human challenge study. We evaluated presatovir in hematopoietic-cell transplant (HCT) recipients with RSV lower respiratory tract infection (LRTI). METHODS: Patients with confirmed RSV in upper and lower respiratory tract and new chest X-ray abnormalities were randomized (1:1), stratified by supplemental oxygen and ribavirin use, to receive oral presatovir 200 mg or placebo every 4 days for 5 doses. The primary endpoint was time-weighted average change in nasal RSV viral load through day 9. Secondary endpoints included supplemental oxygen-free days, incident respiratory failure requiring mechanical ventilation, and all-cause mortality. RESULTS: From January 31, 2015, to March 20, 2017, 60 patients from 17 centers were randomized (31 presatovir, 29 placebo); 59 received study treatment (50 allogeneic, 9 autologous HCT). In the efficacy population (29 presatovir, 28 placebo), presatovir treatment did not significantly reduce time-weighted average change in viral load (-1.12 vs -1.09 log10 copies/mL; treatment difference -0.02 log10 copies/mL, 95% confidence interval: -.62, .57; P = .94), median supplemental oxygen-free days (26 vs 28 days, P = .84), incident respiratory failure (10.3 vs 10.7%, P = .98), or all-cause mortality (0 vs 7.1%, P = .19) versus placebo. Adverse events were similar between arms (presatovir 80%, placebo 79%). Resistance-associated substitutions in RSV fusion protein emerged in 6/29 presatovir-treated patients. CONCLUSIONS: Presatovir treatment was well tolerated in HCT patients with RSV LRTI but did not improve virologic or clinical outcomes versus placebo. CLINICAL TRIALS REGISTRATION: www.clinicaltrials.gov, NCT02254421; EudraCT, #2014-002475-29.

A Phase 2, Randomized, Double-blind, Placebo-Controlled Trial of Presatovir for the Treatment of Respiratory Syncytial Virus Upper Respiratory Tract Infection in Hematopoietic-Cell Transplant Recipients.

BACKGROUND: Hematopoietic-cell transplant (HCT) recipients are at risk for severe respiratory syncytial virus (RSV) infection. We evaluated the RSV fusion inhibitor presatovir in a randomized, double-blind, Phase II trial in HCT recipients with RSV upper respiratory tract infections. METHODS: Patients were stratified by lymphopenia (<200/µL) and ribavirin use; were randomized, stratified by lymphopenia (<200/µL) and ribavirin use, to receive oral presatovir at 200 mg or a placebo on Days 1, 5, 9, 13, and 17, and were followed through Day 28. The coprimary efficacy endpoints were the time-weighted average change in the nasal RSV viral load between Days 1 and 9 and the proportion of patients developing lower respiratory tract complications (LRTCs) through Day 28. RESULTS: From 23 January 2015 to 16 June 2017, 189 patients were randomly assigned to treatment (96 to presatovir and 93 to the placebo). Presatovir treatment, compared with the placebo treatment, did not significantly affect (prespecified α = 0.01) a time-weighted average decline in the RSV viral load from Day 1 to 9 (treatment difference, -0.33 log10 copies/mL; 95% confidence interval [CI] -.64 to -.02 log10 copies/mL; P = .040) or the progression to LRTC (11.2% vs 19.5%, respectively; odds ratio, 0.50; 95% CI, .22-1.18; P = .11). In a post hoc analysis among patients with lymphopenia, presatovir decreased LRTC development by Day 28 (2/15 [13.3%] vs 9/14 [64.3%], respectively; P = .008), compared with the placebo. Adverse events were similar for patients receiving presatovir and the placebo. CONCLUSIONS: Presatovir had a favorable safety profile in adult HCT recipients with RSV but did not achieve the coprimary endpoints. Exploratory analyses suggest an antiviral effect among patients with lymphopenia. CLINICAL TRIALS REGISTRATION: NCT02254408; EUDRA-CT#2014-002474-36.

Phase 1 First-in-Human, Single- and Multiple-Ascending Dose, and Food Effect Studies to Assess the Safety, Tolerability, and Pharmacokinetics of Presatovir for the Treatment of Respiratory Syncytial Virus Infection.

Respiratory syncytial virus (RSV)-associated respiratory tract infection is a leading cause of hospitalizations in infants for which no effective treatment exists. RSV infection is also an important cause of respiratory disease in adults and immunocompromised patients. Presatovir (GS-5806) is an orally bioavailable antiviral agent that inhibits fusion of RSV with host cell membranes. Here, results from 2 phase 1 studies that evaluated safety, tolerability, and pharmacokinetics of presatovir in healthy adults following administration of single and multiple (7 days) once- or twice-daily ascending doses (first-in-human study) and in the presence or absence of food (food effect study) are described. Presatovir exhibited favorable safety and pharmacokinetic profiles that supported once-daily dosing. Presatovir exposure increased in an approximately dose-proportional manner across the evaluated dose range (single doses 25-300 mg; multiple doses 10-75 mg once daily for 7 days). Administration of presatovir with a high-fat meal did not alter exposure, supporting administration without regard to a meal in further clinical studies. These data were subsequently used to inform presatovir dosing regimens in a phase 2a challenge study of adults experimentally infected with RSV. Collectively, results from phase 1 evaluations and a phase 2a challenge study support further clinical investigation of presatovir for the treatment of RSV infection.

The Drug-Drug Interaction Profile of Presatovir.

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in young children. Presatovir (previously GS-5806) is a novel, orally administered RSV fusion inhibitor with a favorable safety profile and proven antiviral efficacy in preclinical and clinical studies. In vitro, presatovir is a substrate of the efflux transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) and hepatic uptake transporters organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 and is slowly metabolized by cytochrome P450 (CYP) 3A4 and CYP3A5. This study enrolled 64 healthy subjects to evaluate the effect of cyclosporine, a P-gp, BCRP, and OATP1B1/1B3 inhibitor; rifampin, a strong CYP3A4 and P-gp inducer; efavirenz, a moderate CYP3A4 inducer; and cobicistat, a potent CYP3A inhibitor, on presatovir pharmacokinetics. Presatovir plasma exposures (maximum observed plasma concentration [Cmax ] and area under the plasma concentration-time curve from time 0 extrapolated to infinity [AUCinf ]) were not affected by coadministration of cyclosporine, suggesting presatovir is not a sensitive substrate of P-gp, BCRP, or OATP1B1/1B3. As expected, based on the role of CYP3A in presatovir metabolism, presatovir exposure was increased by cobicistat (122% in AUCinf ), and decreased by rifampin (40.3% in Cmax and 82.5% in AUCinf ) and efavirenz (55.7% in AUCinf ). These data support coadministration of presatovir with inhibitors of P-gp, BCRP, OATP1B1/1B3, or CYP3A, but not with moderate or strong CYP3A4 inducers. Presatovir was well-tolerated with the most common drug-related adverse events of dizziness (n = 12) and somnolence (n = 4) reported during efavirenz treatment.