A Trial of LNS8801 With or Without Pembrolizumab in Patients With Refractory Melanoma

Inclusion Criteria: * Confirmed unresectable and/or metastatic cutaneous melanoma. * 2 copies of the fully functional form of GPER protein-coding sequence. * Eligible for and willing to receive 1 or more of the physician's choice (PC) therapies. * Able to swallow tablets. * Progressed on treatment with an anti-PD-1 monoclonal antibody (mAb) administered either as monotherapy or in combination with other therapies. * Received an anti-CTLA-4 and/or BRAF containing regimen or is not eligible for or has declined anti-CTLA-4 and/or BRAF therapy prior to and for this study. * Measurable disease. * Eastern Cooperative Oncology Group Performance Status of 0 to 1.Performance status Exclusion Criteria: * Blue nevus subtype, mucosal, acral lentiginous, or uveal/ocular/choroidal Melanoma. * Previous anti-cancer or investigational drug/device treatment within 4 weeks of the first dose of study drug. * Radiotherapy within 2 weeks of starting study drug. * Allogeneic tissue/solid organ transplant. * Unstable autoimmune or immunodeficiency disease. * Other concurrent health issues that would make participation or completion of the study difficult. * Prior reaction to anti PD-1 therapy that would make treatment with pembrolizumab unadvisable. * Other protocol-defined inclusion/exclusion criteria may apply.