Comprehensive assessments of pharmacokinetics and immunogenicity of farletuzumab ecteribulin, a novel antibody-drug conjugate against tumors expressing folate receptor α, in monkeys

Farletuzumab ecteribulin (MORAb-202) is a novel antibody-drug conjugate (ADC) comprising farletuzumab and eribulin with a cathepsin-B cleavable linker, currently under development for tumors expressing folate receptor α. It is crucial to comprehend the pharmacokinetics (PK) of MORAb-202 in monkeys to enhance the accuracy of PK prediction in humans. To this end, a series of assays were devised for the total antibody (Tab) as the sum of conjugated and unconjugated antibodies, the conjugated antibody as the ADC, and the unconjugated eribulin (payload) by a ligand binding assay (LBA) and liquid chromatography with tandem mass spectrometry. The LBA by Gyrolab was employed for the quantification of Tab and ADC. Additionally, a semi-quantitative assay for anti-drug antibody (ADA) was developed using the LBA for the immunogenicity assessment. The quantifiable range for ADC and Tab in monkey serum was from 0.4 and 4 µg/mL, respectively, while eribulin was quantified from 0.2 ng/mL. The aforementioned methodologies were subsequently validated and employed in a PK study in monkeys. The accuracy and precision of the assay were within the criteria. Following intravenous administration, the PK profiles of Tab and ADC were similar, while minimal levels of eribulin. No ADA against MORAb-202 was detected in postdose samples.