Elevated baseline serum PD-1 or PD-L1 predicts poor outcome of PD-1 inhibition therapy in metastatic melanoma

Selma Ugurel, Dirk Schadendorf, Kai Horny, Antje Sucker, Sabine Schramm, Jochen Utikal, Claudia Pföhler, Rudolf Herbst, Bastian Schilling, Christian U. Blank, Jürgen C. Becker, Annette Paschen, Lisa Zimmer, Elisabeth Livingstone, Peter A. Horn, Vera Rebmann