A Comparative Study of Pharmacokinetics, Safety, and Immunogenicity of RPH-030 and Vectibix® in Patients With Metastatic Colorectal Cancer With Wild-type RAS as First-line Therapy in Combination With FOLFIRI

This study is a multicenter, double-blind, randomized, comparative, phase I study Treatment with panitumumab in combination with FOLFIRI (de Gramont) within of this study will continue for up to 2 years or disease progression/unacceptable toxicity/patient refusal to continue therapy (in whichever comes first) The study will include the following periods: 1. Screening period: days -27 to 0 (up to 1 administration of the study therapy) If a tumor biopsy is required for histological diagnosis verification and testing of KRAS/NRAS, BRAF mutation status, Her2/neu status, and MSI status, the screening period may be extended up to 42 days 2. Main period: days 1 to 182 Eligible patients will be randomized at the ratio of 1:1 to one of the two study arms: RPH-030 and Vectibix®. During the Main Period of the study, patients will receive panitumumab (RPH-030 or Vectibix®) at a dose of 6 mg/kg intravenously (IV) once every 2 weeks (2 weeks = 1 cycle) in combination with FOLFIRI (after 8 cycles, patients will be switched to the de Gramont regimen) Therapy during the Main Study Period will continue until the earliest of the following: * Completion of 6 months (up to 13 cycles inclusive) * Disease progression (according to RECIST 1.1 criteria or clinical progression) * Development of unacceptable toxicity * Patient's withdrawal of consent to continue treatment Tumor response assessment during the Main Study Period will be performed approximately every 6 weeks Patients will be hospitalized at least twice: at Visit 1 (Day 1) and Visit 3 (Day 29) either before drug administration or on the eve of it; the duration of hospitalization will be at least 24 hours from the start of panitumumab infusion 3. Period of continued therapy: days 183 to 365 During the period of continued therapy, all patients will receive RPH-030 therapy, including those patients who received Vectibix® therapy during the Main Period Therapy during this period will continue until the earliest of the following: * Up to 1 year of therapy * Disease progression (according to RECIST 1.1 criteria or clinical progression) * Development of unacceptable toxicity * Patient's withdrawal of consent to continue treatment Assessment of the tumor response to therapy during the period of continued therapy will be performed approximately once every 8 weeks 4. Treatment Extension Period: days 366 to 729 Participants in the Treatment Extension Period will be patients who demonstrate stable disease (SD) or tumor response after 1 year of therapy. The decision to enter this period will be made by the investigator Therapy during the Treatment Extension Period will continue until the earliest of the following: * For a total duration of up to 2 years * Disease progression (according to RECIST 1.1 criteria or clinical progression) * Development of unacceptable toxicity * Patient's withdrawal of consent to continue treatment 5. Follow-up period (follow-up/FU) For patients who complete the Treatment Extension Period (either as scheduled or prematurely), a Follow-up visit will be scheduled 28 ± 3 days after the last dose of panitumumab. Following this visit, the patient's participation in the study will be considered complete Follow-up (FU) visits will be conducted every 8 weeks (±7 days) until Day 365, death, or withdrawal of consent (whichever occurs first): * For patients who discontinue study therapy due to disease progression or start a new line of treatment (including surgery), FU will be conducted via telephone contact with the patient or relatives to collect overall survival data * For patients who discontinue study therapy for reasons other than progression and have not started new treatment, FU will include CT/MRI assessments until disease progression, initiation of new therapy, or Day 365. Once progression occurs or new therapy starts, these patients will switch to telephone survival follow-up