The disclosure features, inter alia, immunogenic XBP1-, CD138-, and CS1-derived peptides (and pharmaceutical compositions thereof). The peptides can be used in a variety of methods such as methods for inducing an immune response, methods for producing an antibody, and methods for treating a cancer (e.g., a plasma cell disorder such as multiple myeloma or Waldenstrom's macroglobulinemia). The peptides can also be included in MHC molecule multimer compositions and used in, e.g., methods for detecting a T cell in a population of cells.
