Quetmolimab

E6011 is a monoclonal antibody that is currently under development for the treatment of rheumatoid arthritis. While ligand binding assays (LBAs) are typically employed for the determination of therapeutic antibodies, ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) represents an alternative platform. E6011 in monkey serum was treated with ammonium sulfate to obtain pellets for subsequent processing. The pellets were subjected to denaturalization reduction, alkylation, and tryptic digestion. The resulting signature peptide of E6011, TLADGVPSR, was assayed. The pellet digestion assay was validated in accordance with the established bioanalytical guidelines. E6011 in monkey serum was quantifiable from 3 to 729 µg/mL, with a sample volume of 0.02 mL. The selectivity was confirmed in 12 individual monkey sera. The accuracy and precision were within ± 11.2 % and 15.0 %, respectively. The validated UPLC-MS/MS assay was employed in a pharmacokinetic study in monkeys. After the intravenous dose at 1 mg/kg, E6011 reached the maximum of 27.4 μg/mL, then declined with the half-life of 169 h. The serum E6011 concentrations determined by the UPLC-MS/MS were comparable to those obtained by the LBA with electrochemiluminescence detection. These findings suggest that the established simple UPLC-MS/MS assay is reproducible and can serve as an alternative assay platform.

To evaluate the long-term safety and efficacy of E6011, a humanized anti-fractalkine monoclonal antibody, in patients with rheumatoid arthritis (RA) with an inadequate response to methotrexate (MTX).

Active RA patients with an inadequate response to MTX were randomly assigned to the E6011 or placebo group and received the study drug subcutaneously every 2 weeks during a 24-week double-blind study period. Subjects who completed evaluations at Week 24 were rolled over into the extension phase and received open-label E6011 (200 or 400 mg) every 2 weeks until Week 102. The safety analysis was conducted up to Week 104, and the efficacy analysis was conducted up to Week 84.

A total of 169 subjects completed the double-blind treatment phase and were rolled over into the extension phase. In total, 167 (98.8%) subjects experienced any adverse events, and the incidence of treatment-related adverse events was 56.2%. The American College of Rheumatology 20 response rates were observed between 40 and 70% during the extension phase.

E6011 was safe and well tolerated with no notable safety concerns up to 102 weeks in RA patients with an inadequate response to MTX.