Solution stability of the monoclonal antibody-vinca alkaloid conjugate, KS1/4-DAVLB.

A 3-month solution stability study at 5 degrees C of the monoclonal antibody-vinca alkaloid conjugate KS1/4-DAVLB indicated that phosphate-buffered saline solutions at pH 4.5-5.5 had little tendency to lose vinca by hydrolysis, improved vinca stability, showed acceptable physical stability, and formed minimal amounts of soluble aggregates compared to solutions at pH 6.5-7.4. Hydrolysis and aggregation with concomitant loss of stability were accelerated at 30 degrees C throughout the pH range investigated. As determined by ELISA, the binding properties of KS1/4-DAVLB to tumor antigens were not affected by pH or temperature. A formulation suitable for initial clinical trials in cancer patients is described.