The orally bioavailable mesylate salt of an amino boronic dipeptide with antineoplastic and hematopoiesis- stimulating activities. By cleaving N-terminal Xaa-Pro or Xaa-Ala residues, talabostat inhibits dipeptidyl peptidases, such as fibroblast activation protein (FAP), resulting in the stimulation of cytokine and chemokine production and specific T-cell immunity and T-cell- dependent activity. This agent may also stimulate the production of colony stimulating factors, such as granulocyte colony stimulating factor (G-CSF), resulting in the stimulation of hematopoiesis. Dipeptidyl peptidases are involved in the activation of polypeptide hormones and chemokines. or A substance being studied in the treatment of cancer, including certain types of lung, pancreas, and brain cancer. Talabostat mesylate may help the immune system block the growth of cancer cells. It may also increase the growth of new blood cells. It is a type of enzyme inhibitor. Also called PT-100 and talabostat.