Exploratory Study of Molecular Characterization in Patients With Metastatic Germ Cell Tumours Refractory/Resistant to Platinum Treatment

1. To establish whether circulating tumour DNA is detectable in the plasma of patients with platinum refractory/resistant Germ Cell Tumours 2. If ctDNA is detectable, perform exploratory analyses to: 1. Describe the molecular aberrations in plasma from metastatic GCTs with platinum refractory/resistant disease 2. Describe aberrations detected in sequential detected in sequential samples form the same individual patient and evaluate whether there are hyposthesis-generating changes that temporarily associate with clinical resistance.