Background. The results of several multicenter studies indicate a high risk of severe COVID-19 and fatal outcomes in immunocompromised patients, including those with cancer. Effective prevention is critical to saving cancer patients' lives during the pandemic. Additional passive immunization with a combination of monoclonal antibodies to the SARS-CoV-2 S protein in clinical studies showed a significant reduction in the risk of severe disease and death and a decrease in the frequency of hospitalizations. Real clinical practice shows the high efficiency of this approach in patients with oncological diseases receiving immunosuppressive therapy.
 Aim. To perform a comparative analysis of prevention effectiveness and COVID-19 severity in patients with solid malignant tumors receiving antitumor drug therapy.
 Materials and methods. The analysis included 100 vaccinated patients aged 22 to 84 with metastatic or inoperable solid tumors who received cytostatic therapy with or without a targeted agent. The median age was 56.5 years in Group 1 and 57.7 years in Group 2. In both groups, 32 (64%) patients had breast cancer, 10 (20%) had gastric, colon, and rectal cancers, 2 (4%) had lung cancer, 4 (8%), and 6 (12%) had reproductive cancers. In addition, Group 1 included 1 patient each with bladder and brain cancer. All were treated with antitumor drug therapy following clinical guidelines according to tumor localization.
 Results. The median number of received treatment lines of patients in Group 1 was 2.2, and 2.38 in Group 2. In Group 1, 42% of patients got infected, and 64% in Group 2. The combination of tixagevimab 150 mg + cilgavimab 150 mg monoclonal antibodies reduced the incidence of COVID-19 infection in any clinical form by 1.5-fold and hospitalizations by 1.3-fold. In Group 1, the rate of mild COVID-19 was higher; in Group 2, a higher risk of severe course was observed. In Group 1, viral pneumonia was 1.6-fold less common than in Group 2. Overall mortality in Group 1 was 6.5-fold lower than in Group 2. In Group 1, no COVID-19-related deaths were registered; in Group 2, the mortality rate was 8% (n=4). Mortality related to underlying disease in Group 2 was 3.5 times higher, and the risk of dying from the malignant tumor progression was 50% higher. In addition, in Group 2, 15% of deaths were related to cardiovascular diseases.
 Conclusion. Adding Evusheld to vaccinated patients significantly reduces the burden of COVID-19 infection in individuals with solid neoplasms who are receiving antitumor drug therapy. Patients receiving Evusheld at any stage of the underlying disease are less likely to have COVID-19, including severe infection, which requires hospitalization in an infectious hospital. The reduction in overall mortality in the Evusheld group suggests that COVID-19 affects overall survival in cancer patients. Evusheld reduced the risk of death in cancer patients from any causes: the progression of malignant tumors, COVID-19 infection, and other comorbidities.