Characterization of the pharmacokinetics of ofatumumab administered via the PFS used inclinical trials and the to-be-marketed autoinjector at the clinical dose of 20 mg will be conducted after an initial depletion of CD20 positive B-cells. Comparing the ofatumumab pharmacokinetics between the two drug-device combinations only after the induction period is expected to reduce initial high variability due to target-mediated clearance. This ensures a more stable baseline for PK comparison in a parallel group study design and reflects the clinical situation where systemic concentrations are at steady-state. In order to justify the resulting longterm B-cell depletion, a PK comparability study between the PFS and the AI can only be conducted in MS patients rather than in healthy subjects to balance the risk/benefit and to obtain PK data from the relevant patient population. In order for patients to obtain a clinical benefit from participation in the study, continued treatment with ofatumumab will be offered to all eligible patients through enrollment into the open-label Phase 3 extension study (separate protocol, COMB157G2399).
A secondary objective of the study is to characterize the pharmacokinetics following subcutaneous administration of ofatumumab to either the abdominal region or the thigh which are two injections sites allowed in the Phase 3 study and planned for inclusion in the label. Another secondary objective is assessment of immunogenicity during the 12 weeks duration of the study addressing potential differences in ofatumumab anti-drug antibody formation between the PFS and AI devices as well as between abdomen and thigh injection sites.
This was a randomized, open-label, multi-center, parallel group 12-week study to evaluate the pharmacokinetic bioequivalence of ofatumumab injected by pre-filled syringe (PFS) or autoinjector (AI) devices. The study design included four parallel groups of relapsing multiple sclerosis (RMS) patients. Assessment of the primary and secondary endpoints was based on data collected through the dosing interval between Week 8 and Week 12 where approximate steady-state pharmacokinetics was anticipated.
All patients received open-label ofatumumab 20 mg sc every 4 weeks (after an initial loading regimen of three weekly 20 mg doses in the first 14 days) and were randomized (5:5:1:1) into 4 groups dependent on device and location of injection. Randomization was not blinded. Groups: 1: PFS, abdomen, 2: AI, abdomen 3: PFS, thigh 4: AI, thigh.
The study had 3 Parts. Part 1 was a 30 day screening period. Part 2 was a treatment period which had an induction period of 4 weeks, followed by 4 weeks to ensure steady state was reached and a 4 week pharmacokinetics phase for a total of 12 weeks.
Part 3 was a safety follow-up period for patients who completed the study but did not enter the extension study and patients who prematurely discontinued the study. This period was 9 months for patients who had repleted their B-cells (back to baseline value). For patients who had not repleted their B-cells, 3 month assessments were done until their B-cells were repleted or patients had initiated other disease modifying/immunosuppressive thereapy.
