#$%^&*AU2013227994A120130926.pdf#####H: fm Intrwovn NRPortbl DCC FMT 5446060_I.doc-5/09/2013 ABSTRACT Methods of treating cancer and infectious diseases utilizing a treatment regimen comprising administering a compound that reduces inhibitory signal transduction in T cells, in combination with a potentiating agent, such as cyclophosphamide, to product potent T cell mediated responses, as described. Compositions comprising the PD-1 antagonists and potentiating agents useful in the methods of the invention are also disclosed.