A Safety and Efficacy Study of Intetumumab, Alone and in Combination With Dacarbazine, in Participants With Stage 4 Melanoma

This is a Phase 1/2, multi-center, randomized (the study medication is assigned by chance) study. This study will be conducted in 2 Phases (Phase 1 and Phase 2). Phase 1 of this study will be non-randomized, open-label (all people know the identity of the intervention) and dose-escalation phase. It includes screening period and treatment period, which consists of 2 parts (Part 1 and Part 2). In Part 1, participants will receive 1 of 3 single dose levels of intetumumab \[3 milligram per kilogram (mg/kg), 5 mg/kg or 10 mg/kg\]. Part 2 will include 2 dose cohorts: dacarbazine plus intetumumab (5 mg/kg) or dacarbazine plus intetumumab (10 mg/kg). Phase 2 of this study will be randomized, blinded (neither physician nor participant knows the intervention which the participant will receive) and controlled (an inactive substance and other medication is compared with a study medication to test whether the medication has a real effect in this clinical study). This phase of the study will include screening period, treatment period (8 cycles of treatment with every cycle once in 3 weeks) and follow-up period (24 weeks). During the treatment period, participants will be randomly assigned to 1 of 4 treatment groups, Group 1: dacarbazine plus placebo, Group 2: intetumumab (5 mg/kg), Group 3: intetumumab (10 mg/kg) and Group 4: dacarbazine plus intetumumab. Randomization will be further based on the site of metastases and Eastern Cooperative Oncology Group performance status at Baseline. Single-medication intetumumab treatment groups will be open-label, while the dacarbazine plus intetumumab or placebo groups will be blinded. The total duration of the Phase 2 of this study will be up to 52 weeks or up to 76 weeks in case of extended dosing (extended administrations \[up to 8 additional cycles\] of the same assigned treatment will be allowed for participants that are responding to therapy with stable disease or better). Participants will be assessed for incidence of dose limiting toxicities, pharmacokinetics and tumor responses. Participants' safety will be monitored throughout the study.