SOCS1 and melanoma: Of the 12 melanoma tumors with primary resistance to ipilimumab, 75% (9/12) harbored circulating nucleic acids (CNAs) related to INF-γ pathway genes (IFNGR1, IFNGR2, IRF1, JAK2, suppressor of cytokine signaling 1 [SOCS1], and STAT4), while tumors from responders did not harbor CNAs related to INF-γ signaling (0/4, 0%).