Prolgolimab 250 mg Q3W in Patients With Unresectable or Metastatic Melanoma

Inclusion Criteria:

* Signed informed consent and the subject's ability to comply with the protocol requirements.
* Age ≥18 years at the time of informed consent.
* Histologically confirmed unresectable or metastatic melanoma (with available documented evidence of relevant examinations).
* Primarily detected advanced or metastatic melanoma, or the disease progression on or after previous systemic therapy.
* Measurable target tumor lesions (at least 1 lesion) according to RECIST 1.1 criteria, confirmed by an independent reviewer.
* ECOG score 0-1.
* Absence of severe organ and system disorders.
* Life expectancy of at least 12 weeks at screening.
* For patients of childbearing potential: willingness to use reliable methods of contraception throughout the study, from the time of informed consent and for up to 6 weeks after the last dose of the study drug.
* Available blocks for a histological examination and/or the patient's consent for collection of biopsy43 samples to obtain histological material to assess the PD-L1 status.

Exclusion Criteria:

* Patients with severe concomitant disorders, life-threatening acute complications of the primary disease (including massive pleural, pericardial, or peritoneal effusions requiring intervention, pulmonary lymphangitis) at the time of informed consent.
* CNS metastases that are progressing or associated with clinical symptoms (e.g., cerebral edema, spinal compression) or requiring the use of glucocorticosteroids and/or anticonvulsants;
* Ongoing concomitant diseases at the time of screening increasing the risk of severe adverse events during the study treatment.
* The need for glucocorticoids or any other drugs with immunosuppressive effects.
* Hematologic abnormalities.
* Renal impairment.
* Hepatic impairment.
* Increased LDH \>2 ULN.
* Prior treatment with anti-CTLA4 and/or anti-PD-1/PD-L1/PDL-2 drugs.
* Prior targeted therapy.
* A history of malignancies, except for radically treated diseases in remission for over 5 years prior to starting the study.
* Conditions limiting the patient's ability to comply with the protocol requirements (dementia, neurologic or mental disorders, drug or alcohol addiction, etc).
* Simultaneous participation in other clinical studies55 or participation in other clinical studies within 30 days prior to starting the study treatmen.
* Acute infections or activation of chronic infectious diseases within 28 days prior to the beginning of the study treatment.
* Active hepatitis B, active hepatitis C, HIV-infection, syphilis.
* Impossibility to administer the study drug intravenously.
* Impossibility to perform imaging examinations requiring administration of intravenous contrast media.
* Hypersensitivity to any of the components of BCD-100.
* A history of hypersensitivity to monoclonal antibody products.
* Pregnancy or breastfeeding.