Liquid chromatography-high resolution mass spectrometric method for the quantification of monomethyl auristatin E (MMAE) and its preclinical pharmacokinetics.

MMAE is a potent antimitotic drug used as payload of an antibody-drug conjugate which shows potent activity in preclinical and clinical studies against a range of lymphomas, leukemia and solid tumors. Liquid chromatography-high resolution mass spectrometric method was developed for the quantification of MMAE and its preclinical pharmacokinetics. The method consisted of protein precipitation using acetonitrile (ACN) for sample preparation and liquid chromatography - quadrupole - time-of-flight - tandem mass spectrometry (LC-qTOF-MS/MS) analysis in the positive ion mode. A quadratic regression (weighted 1/concentration2 ), with an equation y = ax2  + bx + c, was used to fit calibration curves over the concentration range of 1.01-2,200 ng/mL for MMAE. The qualification run met the acceptance criteria of ±25% accuracy and precision values for QC samples. Recovery was 42.84%. The dilution integrity was determined for 5-fold dilution and the accuracy and precision ranged within ±25%. The stability results indicated that MMAE was stable for the following conditions: short-term (4 h), long-term (4 weeks), freeze/thaw (3 cycles) and post-preparative stability (12 h). This qualified method was successfully applied to a pharmacokinetic study of MMAE in rat as a preclinical animal model. The PK results suggest that MMAE has moderate CL and low BA.Also, these results would be helpful in having a comprehensive understanding of the PK characteristics of MMAE and developing ADC in future.