Phase 1 Study of IMP321 (Eftilagimod Alpha) Adjuvant to Anti-PD-1 Therapy in Unresectable or Metastatic Melanoma

Main Inclusion Criteria * Histologically confirmed diagnosis of locally advanced (unresectable Stage III) or metastatic (Stage IV) melanoma * Currently receiving anti-PD-1 therapy with pembrolizumab and after 3 cycles achieved asymptomatic irPD (slowly progressive, not requiring urgent intervention, and stable performance status) or sub-optimal response (irSD, irPR) as demonstrated in imaging assessments performed within 6 weeks prior to study start * Female or male 18 years of age or above * ECOG performance status 0-1 * Evidence of measurable disease as defined by Response Evaluation Criteria in Solid Tumours (RECIST) version 1.1 10. Adequate Laboratory criteria Main Exclusion Criteria * More than four prior lines of therapies for advanced or metastatic disease. * Prior PD-1/PDL-1 targeted therapy * Currently receiving treatment with another investigational drug, or less than 4 weeks since ending treatment on another investigational drug * Currently receiving systemic chemotherapy, targeted small molecule therapy, radiotherapy, or biological cancer therapy (other than pembrolizumab) or less than 4 weeks since completion of these therapies and first dose of study treatment * History of irAEs from ipilimumab of CTCAE Grade 4 requiring steroid treatment * Known cerebral or leptomeningeal metastases * Serious intercurrent infection within 4 weeks prior to first dose of study treatment * Active acute or chronic infection * History or evidence of interstitial lung disease or active non-infectious pneumonitis * Active auto-immune disease requiring immunosuppressive therapy * HIV positivity, active hepatitis B or hepatitis C * Continuous systemic treatment with either corticosteroids or other immunosuppressive medications within 4 weeks prior to first dose of study treatment