IL2 and Merkel cell skin cancer: [12], [13], [14] M_ENREF_10oreover, in several case reports, MCC patients experienced tumor regression in response to withdrawal of T cell suppressive therapeutics such as azathioprine [15] or cyclosporine. [16] One HIV+ patient with metastatic MCC experienced a complete and sustained regression of this cancer after initiating highly active antiretroviral therapy together with interleukin-2 administration. [17]