Comparison of two biosimilarity studies of FKB327 with the adalimumab reference product: randomized phase 1 studies of single-blind, single-dose subcutaneous injection in healthy Japanese male participants.

BACKGROUND: FKB327 has been developed as a biosimilar of the adalimumab reference product (RP). We compared the pharmacokinetics (PK), safety, and immunogenicity of FKB327 with those of the adalimumab RP after a single dose by subcutaneous (SC) injection in Japanese male participants. METHODS: Two randomized, single-blind, single-dose studies were conducted in healthy Japanese male participants to compare PK characteristics between FKB327 and the RP. Study 1 included 130 participants who were randomized in a 1:1 ratio to receive a subcutaneous injection of 40 mg of either FKB327 or the RP into the abdomen. In Study 2, another 130 subjects were randomized in a 1:1 ratio to receive either drug as in Study 1, but the drug administration site was changed to the thigh. The primary PK endpoints of both studies were area under the concentration-time curve from time zero to the last measurable concentration (AUC0-t) and maximum serum concentration; area under the concentration-time curve from time zero to 360 h was also evaluated as one of the primary endpoints in Study 1. Biosimilarity in terms of pharmacokinetics was determined if the 90% confidence interval of the mean difference in geometric mean ratio of all primary PK parameters was within the prespecified equivalence criteria (0.80-1.25). Immunogenicity and safety were also evaluated as secondary endpoints. RESULTS: The serum concentration-time profiles were comparable between the FKB327 and the RP treatment groups in both studies. Primary PK parameters were within the prespecified bioequivalence range in Study 2, although AUC0-t was slightly outside the upper side of the range in Study 1. No differences in safety profile were observed in these studies. The incidence of anti-drug antibodies (ADAs) and impact of ADAs on PK profile were similar among the treatment groups in both studies. CONCLUSION: Biosimilarity between FKB327 and the RP after a single 40-mg SC injection was confirmed in healthy Japanese male participants by modifying the study design. TRIAL REGISTRATION: jRCT2071200058 (https://jrct.niph.go.jp/en-latest-detail/jRCT2071200058, https://rctportal.niph.go.jp/en/detail?trial_id=jRCT2071200058) and jRCT2071200057 (https://jrct.niph.go.jp/en-latest-detail/jRCT2071200057, https://rctportal.niph.go.jp/en/detail?trial_id=jRCT2071200057). Retrospectively registered 25/11/2020.

SARS-CoV-2 Seroprevalence among Healthcare Workers in General Hospitals and Clinics in Japan.

Coronavirus disease 2019 (COVID-19) has become a serious public health problem worldwide. In general, healthcare workers are considered to be at higher risk of COVID-19 infection. However, the prevalence of COVID-19 among healthcare workers in Japan is not well characterized. In this study, we aimed to examine the seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies among 2160 healthcare workers in hospitals and clinics that are not designated to treat COVID-19 patients in Japan. The prevalence of SARS-CoV-2 immunoglobulin G was 1.2% in August and October 2020 (during and after the second wave of the pandemic in Japan), which is relatively higher than that in the general population in Japan (0.03-0.91%). Because of the higher risk of COVID-19 infection, healthcare workers should be the top priority for further social support and vaccination against SARS-CoV-2.

A phase 1 randomized study assessing safety and immunogenicity of two 3-dose regimens of a Clostridium difficile vaccine in healthy older Japanese adults.

BACKGROUND: Clostridium difficile infection (CDI) is a major global cause of nosocomial and community-acquired infections. Despite potentially severe or fatal complications and frequent recurrence, no preventive vaccine is currently available. This randomized, observer-blinded, placebo-controlled phase 1 study in older Japanese adults evaluated safety and immunogenicity of an investigational C difficile vaccine containing a mixture of genetically detoxified and chemically inactivated toxoids, A and B. METHODS: Healthy Japanese adults aged 65 to 85 years were randomized in a 3:3:2 ratio to receive 100 or 200 µg of C difficile vaccine or placebo, respectively, at 0, 1, and 6 months (month regimen) or 1, 8, and 30 days (day regimen). The primary objective was safety evaluation. Vaccine immunogenicity, the secondary objective, was determined by assessing toxin A- and toxin B-specific neutralizing antibody levels in human sera. RESULTS: Local reactions were reported by up to 33.3% of subjects per dose in the month regimen; percentages were generally higher in the 200-µg group. Such reactions were all mild or moderate in severity and generally transient. No adverse events in the month regimen led to subject withdrawal, and no serious adverse events were considered vaccine related. Further enrollment and dosing in the day regimen were discontinued after 3 subjects in the 100-µg group reported severe redness after dose 2. In the month regimen study arm, immune responses as measured by toxin-neutralizing antibody geometric mean concentrations, geometric mean fold rises, and proportions of subjects achieving prespecified fold rises were generally higher in the 200-µg group, peaked at month 7, and remained elevated at month 12. CONCLUSIONS: The C difficile vaccine candidate was safe, well tolerated, and immunogenic when administered to healthy older Japanese adults at 0, 1, and 6 months. Results support continued development of the vaccine for the prevention of CDI. ClinicalTrials.gov identifier: NCT02725437.

Pharmacokinetics of Tenofovir Alafenamide, Tenofovir, and Emtricitabine Following Administration of Coformulated Emtricitabine/Tenofovir Alafenamide in Healthy Japanese Subjects.

A fixed-dose combination of tenofovir alafenamide (TAF) and emtricitabine (FTC) is available in 2 tablet strengths in Japan (FTC/TAF 200/10 mg and FTC/TAF 200/25 mg). These are used once daily in combination with other antiretroviral agents for the treatment of human immunodeficiency virus type 1 infection. The primary objective of this study was to investigate if there is any clinically relevant pharmacokinetic difference for TAF, tenofovir (TFV), and FTC between Japanese and non-Japanese with historical data. Three treatment groups were set in the study; FTC/TAF 200/10 mg in combination with darunavir (DRV) 800 mg + ritonavir (RTV) 100 mg (treatment A) or DRV/cobicistat (COBI) 800/150 mg (treatment B) and FTC/TAF 200/25 mg alone (treatment C). Especially for treatment C, it was designated for another purpose to evaluate the pharmacokinetic boosting effects of RTV and COBI on TAF bioavailability. As a result, the mean exposure of TAF among treatment groups was 125 to 154 ng/mL for Cmax and 119 to 179 ng·h/mL for AUCinf , which were comparable with the historical data in non-Japanese. The exposures of TFV and FTC were also consistent with the historical data. Therefore, no clinically relevant pharmacokinetic differences for TAF, TFV, and FTC were observed between Japanese and non-Japanese. Boosting effects of RTV and COBI on TAF bioavailability were slightly lower than we expected, less than a 2.5-fold increase, but it was within the range of exposures associated with efficacy and safety in phase 3 studies. Therefore, it was not considered clinically relevant.

Safety, tolerability, and immunogenicity of a novel 4-antigen Staphylococcus aureus vaccine (SA4Ag) in healthy Japanese adults.

A novel Staphylococcus aureus 4-antigen vaccine (SA4Ag) is under development, comprising capsular polysaccharide serotypes 5 and 8 (CP5 and CP8) conjugated to CRM197, recombinant protein clumping factor A (rmClfA), and recombinant manganese transporter protein C (MntC). We evaluated SA4Ag safety, tolerability, and immunogenicity in Japanese adults aged 20 to 64 and 65 to 85 years. A total of 136 healthy Japanese adults (68 per age group) were randomized 1:1 to receive single-dose SA4Ag or placebo intramuscularly (Day 1). Safety assessments included reactogenicity and adverse events. The ability of the vaccine to induce immune responses that are considered functional due to their ability to facilitate the killing of S. aureus or neutralize S. aureus virulence mechanisms was assessed using 5 different antigen-specific assays. SA4Ag was well tolerated in both age groups, with no safety concerns. At Day 29, > 85% of SA4Ag recipients in each age group achieved predefined thresholds for each antigen. Antibody geometric mean-fold rises from baseline to Day 29 in SA4Ag groups were: > 80 and > 30 for CP5 and CP8 (opsonophagocytic activity assay), > 10 for ClfA (fibrinogen-binding inhibition assay), and > 15 and > 7 for ClfA and MntC (competitive Luminex® immunoassay), respectively. Antibody titers decreased through Month 12 but remained well above baseline and placebo levels. SA4Ag had an acceptable safety profile and induced rapid and robust functional immune responses in both age groups. These results support ongoing development of SA4Ag for the prevention of invasive S. aureus disease in elective-surgery patients in Japan, North America, and Europe.

Effects of Milk or Apple Juice Ingestion on the Pharmacokinetics of Elvitegravir and Cobicistat in Healthy Japanese Male Volunteers: A Randomized, Single-Dose, Three-Way Crossover Study.

Elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide (EVG/COBI/FTC/TAF) is specified in its package insert to be taken with food to obtain sufficient exposure of EVG. It has been reported that a nutritional protein-rich drink shows comparable pharmacokinetics (PK) of EVG to those with a standard breakfast. In this study, the PK profiles of EVG and COBI were evaluated by administration of a single dose of EVG/COBI/FTC/TAF, after ingestion of either a nutritional protein-rich drink, milk, or apple juice. The geometric means for Cmax and AUCinf of EVG following milk ingestion slightly decreased by 21% and 14%, respectively, and those following apple juice ingestion decreased by 67% and 61%, respectively, compared with a nutritional protein-rich drink. There were no differences in any PK parameters of COBI. Therefore, taking EVG/COBI/FTC/TAF after milk or apple juice ingestion appeared to be not appropriate. However, for plasma trough concentrations (Ctau ), it is known that Ctau is best correlated with the efficacy of EVG. The mean C24 of EVG after milk ingestion was 620.6 ng/mL, which was more than 10-fold the protein binding-adjusted 95% inhibitory concentration. With all the above considerations, it was concluded that taking EVG/COBI/FTC/TAF with milk could be an option to maintain sufficient plasma concentrations of EVG.