Ipilimumab With or Without Talimogene Laherparepvec in Unresected Melanoma

The phase 1b part is an open-label, multicenter, single-arm study where all participants will receive talimogene laherparepvec in combination with ipilimumab. The phase 2 part of the study is an open-label, multicenter, randomized study to further assess the safety and to evaluate the efficacy of talimogene laherparepvec in combination with ipilimumab. Participants will be randomized 1:1 to receive talimogene laherparepvec plus ipilimumab or ipilimumab alone. Participants randomized before amendment 2 will be stratified by stage of disease (stage IIIB/C, IVM1a, and stage IVM1b vs IVM1c) and v-raf murine sarcoma viral oncogene homolog B1 (BRAF) V600E (a mutation resulting in a substitution of glutamic acid for valine at codon 600) (mutation vs mutation not present). Participants randomized after amendment 2 will be stratified by stage of disease (stage IIIB/C and IVM1a vs stage IVM1b and IVM1c) and prior therapy (treatment naïve vs previously treated with systemic anticancer immunotherapy vs previously treated with systemic anticancer treatment other than immunotherapy).