Recommendation of a milder cleaning-in-place method for Cytiva's second-generation protein L resin MabSelect VL

Protein L-based media are a type of affinity resin whose application in antibody purification is only secondary to Protein A resins. As Protein L resins exhibit stronger byproduct separation capabilities than Protein A resins, they are particularly preferred when purifying complex molecules such as bispecific antibodies (bsAbs). Despite the growing use of Protein L resins, comprehensive evaluations of their lifetime and cleaning-in-place (CIP) methods are generally lacking. In the current study, we examined MabSelect VL, Cytiva's second-generation Protein L resin, for its alkaline stability. In specific, the resin's performance was evaluated after 80 cycles of sanitization with 0.1 M sodium hydroxide (NaOH). In addition, the binding behavior of monomer and aggregates to aged resin was studied to understand the change in resin ligands during use. According to the data, 0.1 M NaOH is not well tolerated by MabSelect VL, and its repeated treatment causes performance degradation. Therefore, we recommend a milder sanitization method, 0.05 M NaOH, which can be combined with 1 % benzyl alcohol to improve microbial control.