For target-engagement applications, a comparative analysis was performed to assess the suitability, ease of implementation and cost-effectiveness between Cellular Thermal Shift Assay (CETSA) and Proteome Integral Solubility Alteration (PISA). Human multiple myeloma cells U266B1 cell lysate was treated with either 1 μM BCL-XL inhibitor or DMSO as a vehicle to perform i) label-free PISA approach to analyse each PISA pool by data-independent acquisition (DIA) approach (PISA-DIA-MS) and ii) traditional TMT labelled proteome-wide CETSA approach (CETSA-TMT-MS).