CROCuS, a Phase II Study Evaluating the Antiviral Activity, Clinical Outcomes, and Safety of Rilematovir in Children Aged ≥ 28 Days and ≤ 3 Years with Acute Respiratory Tract Infection Due to Respiratory Syncytial Virus

BACKGROUND

Respiratory syncytial virus (RSV) causes significant morbidity and mortality in children aged ≤ 5 years and adults aged ≥ 60 years worldwide. Despite this, RSV-specific therapeutic options are limited. Rilematovir is an investigational, orally administered inhibitor of RSV fusion protein-mediated viral entry.

OBJECTIVE

To establish the antiviral activity, clinical outcomes, safety, and tolerability of rilematovir (low or high dose) in children aged ≥ 28 days and ≤ 3 years with RSV disease.

METHODS

CROCuS was a multicenter, international, double-blind, placebo-controlled, randomized, adaptive phase II study, wherein children aged ≥ 28 days and ≤ 3 years with confirmed RSV infection who were either hospitalized (Cohort 1) or treated as outpatients (Cohort 2) were randomized (1:1:1) to receive rilematovir (low or high dose) or placebo. Study treatment was administered daily as an oral suspension from days 1 to 7, with dosing based on weight and age groups. The primary objective was to establish antiviral activity of rilematovir by evaluating the area under the plasma concentration-time curve of RSV viral load in nasal secretions from baseline through day 5. Severity and duration of RSV signs and symptoms and the safety and tolerability of rilematovir were also assessed through day 28 (± 3).

RESULTS

In total, 246 patients were randomized, treated, and included in the safety analysis population (Cohort 1: 147; Cohort 2: 99). Of these, 231 were included in the intent-to-treat-infected analysis population (Cohort 1: 138; Cohort 2: 93). In both cohorts, demographics were generally similar across treatment groups. In both cohorts combined, the difference (95% confidence interval) in the mean area under the plasma concentration-time curve of RSV RNA viral load through day 5 was - 1.25 (- 2.672, 0.164) and - 1.23 (- 2.679, 0.227) log10 copies∙days/mL for the rilematovir low-dose group and the rilematovir high-dose group, respectively, when compared with placebo. The estimated Kaplan-Meier median (95% confidence interval) time to resolution of key RSV symptoms in the rilematovir low-dose, rilematovir high-dose, and placebo groups of Cohort 1 was 6.01 (4.24, 7.25), 5.82 (4.03, 8.18), and 7.05 (5.34, 8.97) days, respectively; in Cohort 2, estimates were 6.45 (4.81, 9.70), 6.26 (5.41, 7.84), and 5.85 (3.90, 8.27) days, respectively. A similar incidence of adverse events was reported in patients treated with rilematovir and placebo in Cohort 1 (rilematovir: 61.9%; placebo: 58.0%) and Cohort 2 (rilematovir: 50.8%; placebo: 47.1%), with most reported as grade 1 or 2 and none leading to study discontinuation. The study was terminated prematurely, as the sponsor made a non-safety-related strategic decision to discontinue rilematovir development prior to full recruitment of Cohort 2.

CONCLUSIONS

Data from the combined cohort suggest that rilematovir has a small but favorable antiviral effect of indeterminate clinical relevance compared with placebo, as well as a favorable safety profile. Safe and effective therapeutic options for RSV in infants and young children remain an unmet need.

CLINICAL TRIAL REGISTRATION

EudraCT Number: 2016-003642-93; ClinicalTrials.gov Identifier: NCT03656510. First posted date: 4 September, 2018.

A pilot phase 2a, randomized, double-blind, placebo-controlled study to explore the antiviral activity, clinical outcomes, safety, and tolerability of rilematovir at two dose levels in non-hospitalized adults with respiratory syncytial virus infection

OBJECTIVES

To assess the antiviral effect, clinical outcomes, and safety of the respiratory syncytial virus (RSV) fusion inhibitor rilematovir in non-hospitalized RSV-infected adults.

METHODS

This phase 2a, double-blind, multicentre study randomly assigned RSV-positive adult outpatients ≤5 days from symptom onset 1:1:1 to receive rilematovir 500 mg, 80 mg, or placebo once-daily for 7 days. Antiviral effect was assessed by RSV RNA viral load (VL), measured by quantitative RT-PCR, and Kaplan-Meier (KM) estimates of time to undetectable VL. Clinical course was assessed by KM estimates of median time to resolution of key RSV symptoms assessed through patient-reported outcomes.

RESULTS

RSV-positive patients (n = 72) were randomly assigned; 66 had confirmed RSV infection and received rilematovir 500 mg (n = 23), 80 mg (n = 21) or placebo (n = 22). Differences versus placebo in mean RSV RNA VL area under the curve (90% CI) through days 3, 5 and 8, respectively, were 0.09 (-0.837; 1.011), -0.10 (-2.171; 1.963), and -1.03 (-4.746; 2.682) log10 copies.day/mL for rilematovir 500 mg, and 1.25 (0.291; 2.204), 2.53 (0.430; 4.634), and 3.85 (0.097; 7.599) log10 copies.day/mL for rilematovir 80 mg. KM estimates of median (90% CI) time-to-first confirmed undetectable VL were 5.9 (3.85; 6.90), 8.0 (6.86; 12.80) and 7.0 (6.62; 10.88) days and 5.7 (2.93; 7.01), 8.1 (6.74; 12.80) and 7.9 (6.62; 11.74) days in patients with symptom onset ≤3 days, for rilematovir 500 mg, 80 mg, and placebo, respectively. KM estimates of median (90% CI) time to resolution of key RSV symptoms were 7.1 (5.03; 11.43), 7.6 (5.93; 8.32), and 9.6 (5.95; 14.00) days for rilematovir 500 mg, 80 mg, and placebo, respectively; and in patients with symptom onset ≤3 days, median 8.0, 7.6, and 11.8 days, respectively.

DISCUSSION

Rilematovir use, initiated early, suggests a potential clinical benefit in RSV-infected adults, with data supporting development of RSV therapeutic options.

TRIAL REGISTRATION

This study is registered with clinicaltrials.gov (NCT03379675).

Lumicitabine, an orally administered nucleoside analog, in infants hospitalized with respiratory syncytial virus (RSV) infection: Safety, efficacy, and pharmacokinetic results

Respiratory syncytial virus (RSV) infection is the leading cause of infant hospitalizations and mortality. Lumicitabine, an oral nucleoside analog was studied for the treatment of RSV. The phase 1b and phase 2b studies reported here assessed the safety, pharmacokinetics, and pharmacodynamics of lumicitabine in infants/neonates hospitalized with RSV. In the phase 1b study, infants (≥1 to ≤12 months) and neonates (<28 days) received a single-ascending or multiple-ascending doses (single loading dose [LD] then 9 maintenance doses [MD] of lumicitabine, or placebo [3:1]). In the phase 2b study, infants/children (28 days to ≤36 months old) received lumicitabine 40/20 mg/kg, 60/40 mg/kg LD/MD twice-daily or placebo (1:1:1) for 5 days. Safety, pharmacokinetics, and efficacy parameters were assessed over 28 days. Lumicitabine was associated with a dose-related increase in the incidence and severity of reversible neutropenia. Plasma levels of ALS-008112, the active nucleoside analog, were dose-proportional with comparable mean exposure levels at the highest doses in both studies. There were no significant differences between the lumicitabine groups and placebo in reducing viral load, time to viral non-detectability, and symptom resolution. No emergent resistance-associated substitutions were observed at the RSV L-gene positions of interest. In summary, lumicitabine was associated with a dose-related increase in the incidence and severity of reversible neutropenia and failed to demonstrate antiviral activity in RSV-infected hospitalized infants. This contrasts with the findings of the previous RSV-A adult challenge study where significant antiviral activity was noted, without incidence of neutropenia. Trial registration ClinicalTrials.gov Identifier: NCT02202356 (phase 1b); NCT03333317 (phase 2b).

Pharmacokinetics, Safety, and Antiviral Effects of Multiple Doses of the Respiratory Syncytial Virus (RSV) Fusion Protein Inhibitor, JNJ-53718678, in Infants Hospitalized With RSV Infection: A Randomized Phase 1b Study

Background

This phase 1b study evaluated the pharmacokinetics, safety, and antiviral effects of the respiratory syncytial virus (RSV)–specific fusion inhibitor JNJ-53718678 (JNJ-8678) in hospitalized RSV-infected patients aged > 1 to ≤24 months.

Methods

Patients categorized by age (cohort 1: ≥6 to ≤24 months; cohort 2: ≥3 to < 6 months; cohort 3: > 1 to < 3 months) were randomized to oral JNJ-8678 or placebo once daily for 7 days. Dose increases followed data review committee recommendations (cohort 1: 2/6/8/9 mg/kg; cohort 2: 1.5/4.5/6 mg/kg; cohort 3: 1/3/5 mg/kg). Cohort 1 included a 9 mg/kg dose, as target exposures were not reached at lower doses. Sparse pharmacokinetic samples were assessed using population pharmacokinetics modeling. Safety was assessed by adverse events (AEs), laboratory tests, and electrocardiograms. To assess antiviral effects, RSV RNA viral load from nasal swabs was quantified over time using reverse-transcription quantitative polymerase chain reaction.

Results

Patients received JNJ-8678 (n = 37) or placebo (n = 7). Pharmacokinetic parameters were similar at the highest doses for cohorts 1–3 (area under the plasma concentration–time curve from time of administration up to 24 hours postdosing at day 7: 35 840, 34 980, and 39 627 ng × hour/mL, respectively). Two grade 3 AEs were reported (both bronchiolitis; 1 JNJ-8678, 1 placebo), reported as serious AEs; all other AEs were grade 1 or 2. Two additional serious AEs were reported (rhinitis [JNJ-8678]; pneumonia [placebo]). No deaths, grade 4 AEs, or AEs leading to discontinuation were reported. Median RSV viral load change from baseline in JNJ-8678 vs placebo by day 3 was −1.98 vs −0.32 log₁₀ copies/mL.

Conclusions

In RSV-infected infants, JNJ-8678 was well tolerated. Target exposures were reached and antiviral activity was observed.

Clinical Trials Registration

NCT02593851.

1958. Antiviral Effects, Pharmacokinetics (PK), and Safety of the Respiratory Syncytial Virus (RSV) Fusion Protein Inhibitor, JNJ-53718678 (JNJ-8678), in RSV-infected Infants With Bronchiolitis, in the Phase 1b Study 53718678RSV1005

Background

JNJ-8678 is a RSV-specific fusion inhibitor and a potential new treatment for respiratory infections caused by RSV. Data from a Phase 1b study of PK, safety and antiviral effects in hospitalized RSV-infected infants are presented.

Methods

37 and 7 patients, respectively, were randomized to JNJ-8678 (ascending doses, Table) or placebo (PBO) treatment once daily for 7 days. PK assessments were based on sparse sampling using a population PK model in adults scaled for pediatrics, accounting for allometric principles and maturation of drug clearance pathways. Safety was evaluated by AE reporting, lab and ECG assessments. Antiviral activity was assessed by measuring viral load (VL) using a quantitative RT-PCR assay for RSV RNA from nasal swabs.

Results

Sparse PK data are described by an integrated PK model (table) and indicated PK parameters for different dose levels were similar across age groups. Treatment with JNJ-8678 appeared to reduce VL more rapidly than PBO (figure). Median change in VL from baseline (BL) in JNJ-8678-treated patients (combined dose groups) vs. PBO was −1.98 vs. −0.32 log₁₀ copies/mL at Day 3. Mean differences in change from BL (90% CI) of JNJ-8678 (combined dose groups) vs. PBO on Days 2 and 3 were estimated −1.33 (−2.26; −0.39) and −1.62 (−2.55; −0.69) log₁₀ copies/mL, respectively (general linear model, adjusted for BL VL; P ≤ 0.05). There was a clear separation between JNJ-8678 and PBO, but no evident exposure–response relationship. JNJ-8678 was generally well tolerated with no new safety signals compared with adults and no dose relationship with AEs or lab abnormalities were observed.

Conclusion

This dataset in RSV-infected infants showed a clear trend for an early antiviral effect of JNJ-8678, which was similar across dose groups. JNJ-8678 treatment was generally well tolerated.

Disclosures

F. Martinon-Torres, Pfizer: Consultant, Consulting fee. SPMSD: Consultant, Consulting fee. GSK: Consultant, Consulting fee. S. Rusch, Janssen: Employee and Shareholder, Salary. D. Huntjens, Janssen: Employee and Shareholder, Salary. B. Remmerie, Janssen: Employee and Shareholder, Salary. J. Vingerhoets, Janssen: Employee and Shareholder, Salary. K. McFadyen, Janssen: Employee and Shareholder, Salary. E. Baraldi, Abbvie: Lectures, Speaker honorarium. Chiesi Farmaceutici: Consultant, Consulting fee. Novartis: Consultant, Consulting fee. Janssen: Consultant, Consulting fee. M. Stevens, Janssen: Employee and Shareholder, Salary.

In vitro and in silico analysis of the effects of D2 receptor antagonist target binding kinetics on the cellular response to fluctuating dopamine concentrations

Background and Purpose

Target binding kinetics influence the time course of the drug effect (pharmacodynamics) both (i) directly, by affecting the time course of target occupancy, driven by the pharmacokinetics of the drug, competition with endogenous ligands and target turnover, and (ii) indirectly, by affecting signal transduction and homeostatic feedback. For dopamine D₂ receptor antagonists, it has been hypothesized that fast receptor binding kinetics cause fewer side effects, because part of the dynamics of the dopaminergic system is preserved by displacement of these antagonists.

Experimental Approach

Target binding kinetics of D₂ receptor antagonists and signal transduction after dopamine and D₂ receptor antagonist exposure were measured in vitro. These data were integrated by mechanistic modelling, taking into account competitive binding of endogenous dopamine and the antagonist, the turnover of the second messenger cAMP and negative feedback by PDE turnover.

Key Results

The proposed signal transduction model successfully described the cellular cAMP response for 17 D₂ receptor antagonists with widely different binding kinetics. Simulation of the response to fluctuating dopamine concentrations revealed that a significant effect of the target binding kinetics on the dynamics of the signalling only occurs at endogenous dopamine concentration fluctuations with frequencies below 1 min⁻¹.

Conclusions and Implications

Signal transduction and feedback are important determinants of the time course of drug effects. The effect of the D₂ receptor antagonist dissociation rate constant (k_off) is limited to the maximal rate of fluctuations in dopamine signalling as determined by the dopamine k_off and the cAMP turnover.

A comparison of RSV and influenza in vitro kinetic parameters reveals differences in infecting time

Influenza and respiratory syncytial virus (RSV) cause acute infections of the respiratory tract. Since the viruses both cause illnesses with similar symptoms, researchers often try to apply knowledge gleaned from study of one virus to the other virus. This can be an effective and efficient strategy for understanding viral dynamics or developing treatment strategies, but only if we have a full understanding of the similarities and differences between the two viruses. This study used mathematical modeling to quantitatively compare the viral kinetics of in vitro RSV and influenza virus infections. Specifically, we determined the viral kinetics parameters for RSV A2 and three strains of influenza virus, A/WSN/33 (H1N1), A/Puerto Rico/8/1934 (H1N1), and pandemic H1N1 influenza virus. We found that RSV viral titer increases at a slower rate and reaches its peak value later than influenza virus. Our analysis indicated that the slower increase of RSV viral titer is caused by slower spreading of the virus from one cell to another. These results provide estimates of dynamical differences between influenza virus and RSV and help provide insight into the virus-host interactions that cause observed differences in the time courses of the two illnesses in patients.

Therapeutic efficacy of a respiratory syncytial virus fusion inhibitor

Respiratory syncytial virus is a major cause of acute lower respiratory tract infection in young children, immunocompromised adults, and the elderly. Intervention with small-molecule antivirals specific for respiratory syncytial virus presents an important therapeutic opportunity, but no such compounds are approved today. Here we report the structure of JNJ-53718678 bound to respiratory syncytial virus fusion (F) protein in its prefusion conformation, and we show that the potent nanomolar activity of JNJ-53718678, as well as the preliminary structure–activity relationship and the pharmaceutical optimization strategy of the series, are consistent with the binding mode of JNJ-53718678 and other respiratory syncytial virus fusion inhibitors. Oral treatment of neonatal lambs with JNJ-53718678, or with an equally active close analog, efficiently inhibits established acute lower respiratory tract infection in the animals, even when treatment is delayed until external signs of respiratory syncytial virus illness have become visible. Together, these data suggest that JNJ-53718678 is a promising candidate for further development as a potential therapeutic in patients at risk to develop respiratory syncytial virus acute lower respiratory tract infection.

Respiratory syncytial virus causes lung infections in children, immunocompromised adults, and in the elderly. Here the authors show that a chemical inhibitor to a viral fusion protein is effective in reducing viral titre and ameliorating infection in rodents and neonatal lambs.