This clinical study is designed as a randomized, double-blind trial. Subjects with unresectable, metastatic, or recurrent skin melanoma will be randomized to one of the two study groups (BCD-201 group and Keytruda group) at a 1:1 ratio.

The goal of this study is to compare the efficacy and safety of BCD-201 and Keytruda as first-line therapy in subjects with unresectable, metastatic, or recurrent skin melanoma.

Inclusion Criteria:

• Signed informed consent;
• Histologically confirmed melanoma;
• Tumor first detected at the stage of advanced unresectable or metastatic disease, or disease progressing during or recurring after previous radical therapy;
• ECOG score 0-1;
• At least one measurable lesion according to RECIST 1.1;
• Laboratory test results consistent with adequate functioning of systems and organs;
• Willingness of men and women of childbearing potential to use highly effective contraceptive methods from the signing of the informed consent form, throughout the study and for 6 months after the administration of the last product dose.

Exclusion Criteria:

• Indications for radical therapy (surgery, radiation therapy);
• Uveal, ocular or mucosal melanoma;
• Active CNS metastases and/or carcinomatous meningitis;
• Subjects with severe concomitant disorders, life-threatening acute complications of the primary disease;
• Concomitant diseases and/or conditions that significantly increase the risk of AEs during the study;
• Active, known or suspected autoimmune disorders (subjects with type 1 diabetes mellitus or hypothyroidism requiring only hormone-replacement therapy and those with skin disorders [vitiligo, alopecia, or psoriasis] not requiring systemic therapy are eligible to participate);
• The need for therapy with glucocorticoids or any other drugs with immunosuppressive effects within 14 days prior to randomization;
• History of (non-infectious) pneumonitis requiring glucocorticoid therapy or pneumonitis at the time of screening;
• Hypersensitivity or allergy to any of the pembrolizumab product components;
• Pregnancy or breastfeeding, as well as intention to become pregnant or father a child during the study period.