Changes in immunocompetent blood cells in patients with recurrent ovarian cancer depending on platinum sensitivity.

e17550 Background: Despite surgery and adjuvant chemotherapy, up to 80% of patients with ovarian cancer (OC) experience recurrence. Treatment choice depends on the platinum-free interval. Assessment of the immune system may identify novel markers of treatment response for therapy personalization and outcome improvement. This study aimed to evaluate blood immune cell subpopulations according to platinum sensitivity in recurrent OC patients. Methods: The study included patients with serous adenocarcinoma (mean age 57.53 ± 2 years). The main group (n=30) comprised patients with recurrent OC, subdivided into platinum-sensitive (n=15) and platinum-resistant relapse (n=15). A control group (n=30) was presented with patients in remission. Peripheral blood samples were collected before treatment and analyzed by flow cytometry for major and minor lymphocyte populations. Statistical analysis was performed using STATISTICA 13.3 software. Results: In the platinum-sensitive subgroup total lymphocyte count increased by 43%, accompanied by a 142% increase in NKT cells and a 34% decrease in NK cells comparing to control group (p<0.05). A 20% increase in CD4⁺CD8⁺ cells was noted. Myeloid populations also increased: CD33⁺ (33%), CD14⁺CD15⁺CD11b⁺ (86%), CD14⁺CD11b⁺CD33⁺ (200%), and CD14⁺CD15⁺CD33⁺ (233%) (p<0.05). In the platinum-resistant subgroup, total lymphocytes increased by 33%, NKT cells by 89% (p<0.05), and CD4⁺CD8⁺ cells by 50%. Myeloid markers CD14⁺CD11b⁺CD33⁺ and CD14⁺CD15⁺CD33⁺ increased by 100% and 200%, respectively (p<0.05). Conclusions: There are significant differences in peripheral blood immune cell profiles between platinum-sensitive and platinum-resistant recurrent ovarian cancer. These distinct immune signatures may serve as potential markers for disease stratification and treatment personalization.