Pembrolizumab in Subjects With Incurable Platinum-Refractory Germ Cell Tumors

Inclusion Criteria: * Written informed consent and HIPAA authorization for release of personal health information. NOTE: HIPAA authorization may be included in the informed consent or obtained separately. * Age ≥ 18 years at the time of consent. * ECOG Performance Status of 0 or 1 within 14 days prior to registration for protocol therapy. * Subjects must have histological or serological proof of metastatic germ cell neoplasm (gonadal or extragonadal primary) with disease not amenable to cure with either surgery or chemotherapy. Subjects with seminoma and non-seminoma are eligible, as are women with ovarian GCTs. * Subjects must have evidence of recurrent or metastatic carcinoma by one or more of the following: the appearance of metastatic disease on chest x-ray or CT scan, or the appearance of rising tumor marker: AFP or beta-HCG. NOTE: If a rising tumor marker is the only evidence of progressive disease, at least 2 consecutive rising values at least one week apart are needed. Subjects with only evidence of disease as rising tumor marker AFP and beta-HCG will be provided alternate causes of increased serum levels of these markers are not present, such as cross reaction with luteinizing hormone (LH) (that can be tested if needed by testosterone suppression of LH), hepatitis, use of marijuana, or second primary tumor, etc. * Subjects must have received initial cisplatin based combination therapy, such as bleomycin-etoposide-cisplatin (BEP), cisplatin-etoposide (EP), etoposide-…