- Hepatitis B, hepatitis C, and HIV serology-positive (or known history of HIV seropositive status) participants are ineligible because these underlying diseases will confound interpretation of important safety assessments, e.g. liver function tests, increased potential for reactivation or exacerbation of viral infections. Such individuals may be taking or require other drugs, and may be at higher risk of opportunistic infections and adverse effects. Hepatitis B, hepatitis C, and HIV serology-positive individuals were excluded from the pivotal pembrolizumab clinical trial in melanoma, so safety of this drug in this setting is unknown.