A cocktail of human monoclonal antibodies broadly neutralizes North American rabies virus variants as a promising candidate for rabies post-exposure prophylaxis.

Human rabies remains a globally significant public health problem. Replacement of polyclonal anti-rabies immunoglobulin (RIG), a passive component of rabies post-exposure prophylaxis (PEP), with a monoclonal antibody (MAb), would eliminate the cost and availability constraints associated with RIG. Our team has developed and licensed a human monoclonal antibody RAB1 (Rabishield©), as the replacement for RIG where canine rabies is enzootic. However, for the highly diverse rabies viruses of North America, a cocktail containing two or more MAbs targeting different antigenic sites of the rabies glycoprotein should be included to ensure neutralization of all variants of the virus. In this study, two MAb cocktails, R172 (RAB1-RAB2) and R173 (RAB1-CR57), were identified and evaluated against a broad range of rabies variants from North America. R173 was found to be the most potent cocktail, as it neutralized all the tested North American RABV isolates and demonstrated broad coverage of isolates from both terrestrial and bat species. R173 could be a promising candidate as an alternative or replacement for RIG PEP in North America.

Blocking Borrelia burgdorferi transmission from infected ticks to nonhuman primates with a human monoclonal antibody.

Disrupting transmission of Borrelia burgdorferi sensu lato complex (B. burgdorferi) from infected ticks to humans is one strategy to prevent the significant morbidity from Lyme disease. We have previously shown that an anti-OspA human mAb, 2217, prevents transmission of B. burgdorferi from infected ticks in animal models. Maintenance of a protective plasma concentration of a human mAb for tick season presents a significant challenge for a preexposure prophylaxis strategy. Here, we describe the optimization of mAb 2217 by amino acid substitutions (2217LS: M428L and N434S) in the Fc domain. The LS mutation led to a 2-fold increase in half-life in cynomolgus monkeys. In a rhesus macaque model, 2217LS protected animals from tick transmission of spirochetes at a dose of 3 mg/kg. Crystallographic analysis of Fab in complex with OspA revealed that 2217 bound an epitope that was highly conserved among the B. burgdorferi, B. garinii, and B. afzelii species. Unlike most vaccines that may require boosters to achieve protection, our work supports the development of 2217LS as an effective preexposure prophylaxis in Lyme-endemic regions, with a single dose at the beginning of tick season offering immediate protection that remains for the duration of exposure risk.

FV-100 versus valacyclovir for the prevention of post-herpetic neuralgia and the treatment of acute herpes zoster-associated pain: A randomized-controlled trial.

This prospective, parallel-group, randomized, double-blind, multicenter study compared the efficacy and safety of FV-100 with valacyclovir for reducing pain associated with acute herpes zoster (HZ). Patients, ≥50 years of age, diagnosed with HZ within 72 h of lesion appearance who had HZ-associated pain, were randomized 1:1:1 to a 7-day course of either FV-100 200 mg QD (n = 117), FV-100 400 mg QD (n = 116), or valacyclovir 1000 mg TID (n =117). Efficacy was evaluated on the basis of the burden of illness (BOI; Zoster Brief Pain Inventory scores); incidence and duration of clinically significant pain (CSP); pain scores; incidence and severity of post-herpetic neuralgia (PHN); and times to full lesion crusting and to lesion healing. Safety was evaluated on the basis of adverse event (AE)/SAE profiles, changes in laboratory and vital signs values, and results of electrocardiograms. The burden of illness scores for pain through 30 days were 114.5, 110.3, and 118.0 for FV-100 200 mg, FV-100 400 mg, and valacyclovir 3000 mg, respectively. The incidences of PHN at 90 days for FV-100 200 mg, FV-100 400 mg, and valacyclovir 3000 mg were 17.8%, 12.4%, and 20.2%, respectively. Adverse event and SAE profiles of the two FV-100 and the valacyclovir groups were similar and no untoward signals or trends were evident. These results demonstrate a potential for FV-100 as an antiviral for the treatment of shingles that could both reduce the pain burden of the acute episode and reduce the incidence of PHN compared with available treatments.

A randomized, double-blind, multiple-dose study of the pan-genotypic NS5A inhibitor samatasvir in patients infected with hepatitis C virus genotype 1, 2, 3 or 4.

BACKGROUND & AIMS: Samatasvir is a pan-genotypic inhibitor of the hepatitis C (HCV) non-structural protein 5A (NS5A). This study evaluated the antiviral activity, pharmacokinetics and safety of samatasvir monotherapy in treatment-naïve subjects infected with HCV genotype 1-4. METHODS: Thirty-four genotype 1 and thirty genotype 2, 3 or 4 subjects were randomized to receive for 3days placebo or samatasvir 25-100mg per day. Plasma samples for HCV RNA, pharmacokinetics and sequencing were collected up to day 10. RESULTS: Samatasvir achieved potent antiviral activity across genotypes: mean maximum reductions from baseline were 3.2-3.6 (genotype 1a), 3.0-4.3 (genotype 1b), 3.2-3.4 (genotype 3), and 3.6-3.9 (genotype 4) log10/ml respectively; no viral rebound was observed during the 3-day treatment period. For genotype 2 HCV, samatasvir was active in subjects with NS5A L31 polymorphism at baseline (individual range 2.5-4.1 log10/ml), but showed minimal activity in those with baseline M31 polymorphism. Samatasvir exhibited a long plasma half-life of approximately 20h which supports once daily dosing. Samatasvir was well tolerated in all subjects with no safety-related discontinuations or serious adverse events. The most common adverse events included constipation, nausea and headache and occurred at similar frequency in active and placebo subjects. All events were mild or moderate in intensity. There were no patterns or dose dependence of adverse events, vital signs, laboratory parameters or electrocardiograms. CONCLUSIONS: Samatasvir 25-100mg monotherapy for 3days was well tolerated and induced a rapid and profound reduction in plasma HCV RNA in subjects infected with HCV genotype 1-4. Samatasvir is being evaluated in combination with other direct-acting antiviral agents in subjects with HCV infection.

IDX184 in combination with pegylated interferon-α2a and ribavirin for 2 weeks in treatment-naive patients with chronic hepatitis C.

BACKGROUND: IDX184 is a liver-targeted nucleotide prodrug that selectively inhibits HCV NS5B polymerase. METHODS: This randomized, double-blind, placebo-controlled, ascending-dose study investigated the antiviral activity, safety and pharmacokinetics of IDX184 plus pegylated interferon-α2a and ribavirin (P/R) in treatment-naive patients with genotype-1 HCV. A total of 81 patients with baseline HCV RNA≥5 log10 IU/ml, alanine aminotransferase ≤3× upper limit of normal and compensated liver disease were dosed. Sequential cohorts of 20 patients, randomized 16:4 (active:placebo), received IDX184 for 14 days at rising daily doses of 50, 100, 150 or 200 mg in combination with P/R for 14 days. RESULTS: At the end of triple dosing, HCV RNA changes from baseline (mean ±sd log10) and proportion of patients achieving undetectable viral load (<15 IU/ml) based on the efficacy-evaluable population were -2.7 ±1.3 (13%), -4.0 ±1.7 (50%), -4.2 ±1.9 (50%), -4.1 ±1.2 (40%), -4.3 ±1.5 (29%) and -3.7 ±1.2 (25%) for the 50 mg once daily, 50 mg twice daily, 100 mg once daily, 150 mg once daily, 100 mg twice daily and 200 mg once daily IDX184 doses, respectively. P/R alone resulted in a reduction of -1.5 ±1.3 log10 with only 6% of patients with undetectable viral load. Patients with genotypes-1a or -1b responded similarly. No viral breakthrough or resistance associated with IDX184 was observed. Anti-HCV activity of IDX184 correlated with plasma exposure of its nucleoside metabolite 2'-methylguanosine. Most adverse events were mild or moderate in severity and were consistent with those associated with P/R. The most common adverse events were fatigue and headache. CONCLUSIONS: IDX184 in combination with P/R for 14 days was well tolerated and demonstrated greater antiviral activity with more patients achieving undetectable viral load than P/R.

Short-term monotherapy with IDX184, a liver-targeted nucleotide polymerase inhibitor, in patients with chronic hepatitis C virus infection.

IDX184 is a liver-targeted prodrug of 2'-methylguanosine (2'-MeG) monophosphate. This study investigated the safety, tolerability, antiviral activity, and pharmacokinetics of IDX184 as a single agent in treatment-naïve patients with genotype-1 chronic hepatitis C virus (HCV) infection. Forty-one patients with baseline HCV RNA ≥ 5 log(10) IU/ml, alanine aminotransferase (ALT) ≤ 2.5× the upper limit of normal, and compensated liver disease were dosed. Sequential cohorts of 10 patients, randomized 8:2 (active:placebo), received 25, 50, 75, and 100 mg of IDX184 once daily for 3 days, with a 14-day follow-up. There were no safety-related treatment discontinuations or serious adverse events. The adverse events and laboratory abnormalities observed for IDX184- and placebo-treated patients were similar. At the end of the 3-day treatment period, changes from baseline in HCV RNA levels (means ± standard deviations) were -0.5 ± 0.6, -0.7 ± 0.2, -0.6 ± 0.3, and -0.7 ± 0.5 log(10) for the 25-, 50-, 75-, and 100-mg doses, respectively, while viral load remained unchanged for the pooled placebo patients (-0.05 ± 0.3 log(10)). Patients with genotype-1a and patients with genotype-1b responded similarly. Serum ALT levels decreased, especially at daily doses ≥ 75 mg. During the posttreatment period, plasma viremia and serum aminotransferase levels returned to near pretreatment levels. No resistance mutations associated with IDX184 were detected. Plasma exposure of IDX184 and its nucleoside metabolite 2'-MeG was dose related and low. Changes in plasma viral load correlated with plasma exposure of 2'-MeG. In conclusion, the results from this proof-of-concept study show that small doses of the liver-targeted prodrug IDX184 were able to deliver significant antiviral activity and support further clinical evaluation of the drug candidate.

Rapid decline of viral RNA in chronic hepatitis C patients treated once daily with IDX320: a novel macrocyclic HCV protease inhibitor.

BACKGROUND: The addition of direct-acting antivirals to pegylated interferon-α plus ribavirin for the treatment of chronic HCV infection can result in an increased sustained viral response rate and may permit reduction in treatment duration. IDX320 is a potent non-covalent macrocyclic inhibitor of the HCV NS3/4A protease. METHODS: This was a randomized double-blind placebo-controlled single- and multiple-dose study to assess the safety, tolerability, antiviral activity and pharmacokinetics of IDX320 in healthy volunteers (HV) and patients with chronic HCV genotype 1 infection. HV (n=48) received single or multiple ascending doses of IDX320. Two HCV-infected patients received a single dose of 200 mg IDX320. Dosages for other HCV-infected patients were as follows: placebo, 50, 100, 200 or 400 mg of IDX320 orally once daily for 3 days (n=30) or placebo/200 mg of IDX320 twice-daily for 3 days (n=8). RESULTS: In total, 48 HV and 40 HCV-infected patients were enrolled and all completed the study. There were no serious adverse events. The majority of adverse events were of mild or moderate intensity. Pharmacokinetics supported a once-daily dosing regimen. A rapid decline in plasma HCV RNA was observed in all patients. In the multiple-dose study, mean HCV RNA reductions were 2.6, 3.1, 3.1, 3.3 and 3.8 log(10) IU/ml after 3 days in the IDX320 50, 100, 200, 400 mg once-daily and 200 mg twice-daily treatment groups, respectively. This compared to a mean HCV RNA reduction of 0.04 log(10) in the placebo group. CONCLUSIONS: Once-daily IDX320 dosing demonstrated potent dose-dependent antiviral activity in treatment-naive HCV genotype-1-infected patients.

Safety and pharmacokinetics of IDX184, a liver-targeted nucleotide polymerase inhibitor of hepatitis C virus, in healthy subjects.

IDX184 is a nucleotide prodrug designed to enhance formation in the liver of the active triphosphate of 2'-methylguanosine (2'-MeG), a potent and specific polymerase inhibitor of the hepatitis C virus (HCV). In the present study, single ascending oral doses of 5, 10, 25, 50, 75, and 100 mg IDX184 were administered sequentially to cohorts of 8 healthy subjects, randomized 6:2, active/placebo. Plasma and urine pharmacokinetic sampling was performed over a period of 120 h after dosing. Upon absorption, IDX184 rapidly disappeared from plasma, with a mean half-life (t(1/2)) of approximately 1 h, while plasma concentrations of 2'-MeG gradually increased. Consistent with a liver-targeting approach, plasma exposure of IDX184 and 2'-MeG was low and was also dose related: the mean maximum concentrations ranged from 1.1 to 17 ng/ml for IDX184 and 1.7 to 19 ng/ml for 2'-MeG, and the respective mean total area under the curve ranged from 1.2 to 22.7 and 17.3 to 334 ng·h/ml. Mean 2'-MeG plasma concentrations 24 h after dosing were 0.6 to 3 ng/ml for the 25- to 100-mg doses. Mean 2'-MeG t(1/2) values ranged from 18 to 43 h for doses of 25 mg and above. Mean cumulative urine excretion was 0.2% and 12 to 20% of administered doses for the unchanged IDX184 and 2'-MeG, respectively. IDX184 was safe and well tolerated; no serious adverse events (SAEs), dose-dependent adverse events (AEs), or dose-limiting toxicities were observed. The incidence of AEs and laboratory abnormalities was low and was similar among subjects receiving IDX184 or a placebo. All AEs were mild to moderate and resolved at the end of study. The favorable safety and pharmacokinetic profiles support further clinical evaluation of IDX184 in HCV-infected patients.

Single-dose escalation and multiple-dose safety, tolerability, and pharmacokinetics of IDX899, a candidate human immunodeficiency virus type 1 nonnucleoside reverse transcriptase inhibitor, in healthy subjects.

IDX899 is a novel nonnucleoside reverse transcriptase inhibitor (NNRTI) with potent in vitro activity against wild-type and NNRTI-resistant strains of human immunodeficiency virus type 1 (HIV-1) and with a high genetic barrier to resistance. Single rising doses of 50 and 100 (given by use of a 50-mg capsule) and 200, 400, 800, and 1,200 mg (given by use of a 200-mg capsule) of IDX899 or matching placebo were administered sequentially to cohorts of healthy male subjects, followed by the administration of multiple doses of 800 mg once daily (QD) or 400 mg twice daily (BID) for 7 days. A single dose of 400 mg was also administered to a cohort of females. IDX899 was administered orally under fasted (50- to 400-mg doses) and then fed (> or = 200-mg doses) conditions. Exposure to IDX899 was dose proportional and comparable in males and females. With a different drug-to-excipient ratio, the 50-mg capsule led to a higher exposure but a shorter mean terminal half-life (t(1/2)) of 6.2 to 6.8 h. The 200-mg capsule resulted in a more sustained exposure with a longer mean t(1/2) of 7.9 to 14.6 h. Food enhanced absorption by approximately twofold, while it delayed the time to the maximum concentration. The mean concentration at 24 h following the administration of a single 200-mg dose under fed conditions exceeded the in vitro protein binding-adjusted 90% inhibitory concentration by fourfold. The levels of plasma exposure were similar between the single dosing and the repeat dosing with 800 mg QD and was approximately twofold higher with 400 mg BID. Mean steady-state trough levels were 0.9 microg/ml (range, 0.2 to 2.5 microg/ml) and 2.1 microg/ml (range, 0.5 to 4.5 microg/ml) for the 800-mg QD and 400-mg BID regimens, respectively. The level of excretion of unchanged drug in urine was negligible. IDX899 was well tolerated; and no serious adverse events, dose-dependent adverse events, or laboratory abnormalities were detected. These favorable safety and pharmacokinetic results support further clinical studies with patients with HIV-1 infection by the use of a QD regimen.