Subjects
Study 1 (protocol number FKB327–004, jRCT2071200058; 25/11/2020) was conducted at Souseikai Sumida Hospital in Japan from December 2015 to June 2016; Study 2 (protocol number FKB327–006, jRCT2071200057; 25/11/2020), with almost the same study design as Study 1, was conducted at Souseikai Hakata Clinic and Souseikai Sumida Hospital in Japan from July 2017 to November 2017. Both FKB327–004 and − 006 studies were approved by the Hakata Clinic Institutional Review Board, Fukuoka, Japan, under the committee’s reference numbers: 1570BS (18/12/2015) and 1570BS-2 (16/06/2017), respectively, and the studies were conducted in compliance with the International Ethical Guidelines for Biomedical Research Involving Human Subjects, International Conference on Harmonisation Good Clinical Practice (ICH-GCP) guidelines, the Declaration of Helsinki, and local laws. All participants provided written informed consent prior to initiation of the study, in accordance with ICH-GCP.
A total of 130 healthy male participants, aged 20 to 44 years, with a body mass index ≥18.5 kg/m2 and < 25.0 kg/m2 at screening were enrolled in each study. Participants were excluded from these studies if they had an infection (bacterial, viral, fungal, or parasitic) ≤28 days prior to administration of the study drugs; tested positive for an infectious disease, including hepatitis B surface antigen/antibody, hepatitis C virus antigen/antibody, HIV antigen/antibody, or tuberculosis; had a history of cancer; participated in another clinical study within the past 4 months; or were previously treated with the RP.
Study design
Studies 1 and 2 were Phase 1 randomized, active-controlled, single-blinded, single-dose, parallel-group studies designed to compare the PK similarity of FKB327 and the RP in a Japanese population. Eligible participants were admitted to the investigational site 1 day before dosing (Day − 1) and underwent predose examinations. The eligible participants were randomized in a 1:1 ratio to either of the treatment groups (65 participants each planned in the FKB327 and RP groups) by weight (< 65 kg and ≥ 65 kg) according to the computer-generated randomization list. Trial site was included as a stratification factor in Study 2 because the study was conducted at 2 sites. Randomisation was stratified with with each cohort using a block size of four. Participants received a 40-mg single dose of either FKB327 or the RP in accordance with the study drug allocation by SC injection in the abdomen (Study 1) or in the thigh (Study 2) in a blinded manner by masking the injection during the studies. After completing specified examinations and assessments on Day 9, participants were discharged if no clinical abnormalities requiring hospitalization for follow-up were observed. Thereafter, the participants revisited the trial site on specified days between Days 16 and 65 for PK and safety assessments.
Assessments
Blood samples for PK analysis were taken prior to dosing and at 4, 12, 24, 36, and 48 h, and on Days 4, 5, 6, 7, 8, 9, 16, 23, 30, 37, 44, 51, and 65 after dosing. Serum concentrations of FKB327 and the RP were determined using a validated immunoassay on an electrochemiluminescence (ECL) platform using 96-well Meso Scale Discovery (MSD) high-bind plates coated with TNF-α [12]. The lower limit of reliable quantification was 100 ng/mL. ADA activity as an immunogenicity assessment for FKB327 and the RP were analyzed at pre-dose and at Days 1, 16, 30, and 65 after a single dose of the study drug in both studies. A highly sensitive ECL bridging format (MSD) with acid dissociation to increase drug tolerance was used for ADA assessments and ADA titer [13, 16]. ADA titer was defined as low (≤25th percentile), moderate (between the lower and upper percentile), or high (≥75th percentile). The percentage of patients with neutralizing ADAs (NAbs) was determined by sensitive competitive ligand binding [17]. Mean serum drug concentration-time profiles by ADA categorical titers at the last sampling time point were analyzed to evaluate the impact of ADA on the PK of FKB327 and the RP.
The safety of FKB327 compared with the RP was assessed through the reporting of adverse events (AEs), physical examinations, vital sign measurements, electrocardiograms (ECGs), and clinical laboratory safety tests of blood and urine, which were measured at trial sites. Treatment-emergent AEs (TEAEs) were summarized by system organ class and preferred term using the Medical Dictionary for Regulatory Activities in both studies (version 19.0 in Study 1, version 20.1 in Study 2). In Study 1, as local tolerability checks, injection-site reaction and injection-site pain were also evaluated immediately after dosing and at 0.5, 1, 12, and 24 h after SC dosing, using a visual analog scale (VAS) for pain (0 = no pain; 100 = intolerable pain) [18].
Investigational product
In both studies, participants were randomized 1:1 (each treatment group, n = 65) to receive 40 mg of either FKB327 (supplied by Fujifilm Kyowa Kirin Co., Ltd., Tokyo, Japan) or US-approved RP, (citrate-containing [2]) administered via prefilled syringe (both at 40 mg/0.8 mL). In Study 1, participants received a single SC injection of 40 mg of FKB327 or the RP into the abdomen. In Study 2, participants received the same SC dose of FKB327 or the RP, with the injection site changed to the thigh, with the expectation of less PK variability [19]. All participants in both studies received the study drug under single-blinded conditions to evaluate safety without bias.
Statistical analysis
All participants who received the study drug were included in the safety analysis set. The sample sizes for these studies were estimated based on previous bioavailability or bioequivalence studies with the RP and/or FKB327 [5, 12, 20], in which the coefficient of variation (CV) of maximum concentration (Cmax) and area under the concentration-time curve from time zero to the last measurable concentration (AUC0-t) of FKB327 and the RP were reported to be approximately 40%. A total of 130 participants (65 in each treatment group) were enrolled so that the 90% confidence interval (CI) for the mean difference of primary PK values would be within the bioequivalence criteria with a power of 80%. PK parameters were calculated using noncompartmental analyses (WinNonlin, Pharsight; St. Louis, Missouri, USA) for all participants with an evaluable FKB327 or RP serum concentration-time profile, and this population was used for the primary analysis of biosimilarity. If data were missing in the analyses shown in this section, the data were treated as missing without imputation. Concentration below the lower limit of quantification was treated as 0 ng/mL in the PK analyses.
PK similarity was evaluated by comparing the 90% CIs for the geometric mean ratios for the primary PK endpoint of Cmax and AUC0-t between treatments using bioequivalence criteria of 0.80 to 1.25 in both studies; area under the concentration-time curve from time 0 to 360 h was also evaluated as one of the primary endpoints in Study 1. Area under the concentration-time curve from time 0 to infinity (AUC0-∞) and half-life were evaluated as secondary PK parameters.
In Study 1, the primary hypothesis was evaluated using analysis of variance (ANOVA) as a prespecified analysis method without adjustment by protein content of drugs used in the study. In addition, an analysis of covariance (ANCOVA) was used, including ADA categorical titers at the last sampling time point in the model. By contrast, in Study 2, primary PK analyses were performed using a protein content–corrected serum drug concentration (RP/FKB327 = 0.98), and primary PK similarity analysis was performed by an ANCOVA that included trial site, body weight, and age in the model due to the potential impact of one of the primary PK parameters that was slightly outside the bioequivalence criteria in Study 1 [12]. In addition, the ANOVA was performed as post hoc analysis, using measured serum concentration (no correction by protein content of drugs) in Study 2 to compare the PK similarity results from Study 1. The safety of FKB327 compared with that of the RP was evaluated through descriptive summaries of AEs, clinical laboratory tests, physical examinations, vital signs, ECGs, and incidence of ADAs and NAbs. Datasets and outputs were produced using SAS® version 9.1 (Cary, NC, USA) or higher.