Clinical Trial to Evaluate the PK and Safety of BCD-201 and Keytruda® in Patients With Advanced Malignancies

Inclusion Criteria: * Signed informed consent; * Body weight 60 to 90 kg; * Histologically confirmed melanoma or NSCLC (patients with NSCLC are eligible to participate if high tumor PD-L1 expression \[≥50%\] is confirmed by local or central laboratory results); * ECOG score 0-1; * Laboratory test results consistent with adequate functioning of systems and organs; * Willingness of males and females of childbearing potential to use highly effective contraceptive methods from the signing of the informed consent form, throughout the study and within 6 months after the administration of the last product dose Exclusion Criteria: * Indications for radical therapy (surgery, radiation therapy); * Previous systemic anti-tumor therapy for advanced unresectable, recurrent or metastatic melanoma or NSCLC (history of neoadjuvant or adjuvant therapy is acceptable provided that the treatment was completed at least 6 weeks prior to randomization); * Active metastases in the central nervous system and/or carcinomatous meningitis; * Patients with severe concomitant disorders, life-threatening acute complications of the primary disease (including massive pleural, pericardial, or peritoneal effusions requiring intervention, pulmonary lymphangitis, bleeding or organ perforation) at the time of signing the informed consent and during the screening period; * For patients with NSCLC: presence of activating EGFR mutations/ALK translocations; * 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.