Predictors of the immunochemotherapy effectiveness of atezolizumab in combination with etoposide and carboplatin in patients with advanced small cell lung cancer

Introduction. Lung cancer remains the leading cause of cancer-related deaths worldwide. For the first time in 30 years, the randomized clinical studies employing immunochemotherapy showed a significant increase in median overall survival for patients with advanced small cell lung cancer. However, no significant predictors of the immunochemotherapy effectiveness were identified.Aim. To improve long-term outcomes of treatment of patients with advanced small cell lung cancer through search for predictors of the immunochemotherapy effectiveness.Materials and methods. A total of 35 patients (11 women and 24 men) with advanced small cell lung cancer who received immunochemotherapy with atezolizumab combined with etoposide and carboplatin as first-line treatment were included in the analysis. The average age for patients was 61 years. At the immunochemotherapy baseline, 10 patients had stage IVA disease, 24 patients had stage IVB disease, and one patient had stage IIIB disease. We retrospectively assessed the prognostic impact on the median progression-free survival and overall survival of such factors as leukocytosis, thrombocytosis, lactate dehydrogenase level, neutrophil to lymphocyte ratio, fibrinogen level, blood type.Results. Median progression-free survival was 6.2 (95% CI 4.6–7.8) months, median overall survival was 16.0 (95% CI 9.4– 22.6) months. There was an increasing trend in median progression-free survival, but without statistically significant differences in leukocytosis, thrombocytosis, elevated fibrinogen levels and normal lactate dehydrogenase levels at the beginning of therapy. The neutrophil to lymphocyte ratio at the beginning of therapy had a significant impact on median progression-free survival. There was a statistically significant increase in median progression-free survival from 4.5 (95% CI 3.9–5.1) to 6.9 (95% CI 5.6–8.2) months when the neutrophil to lymphocyte ratio was < 3. A significant decrease in median progression-free survival – 5.0 (95% CI 3.5–6.5) months was also observed in patients with blood group B (III) vs 6.2 (95% CI 4.7–7.7) months for patients with a different blood group (p = 0.047). Factors such as leukocytosis, thrombocytosis, fibrinogen level, lactate dehydrogenase level and neutrophil to lymphocyte ratio did not have a significant impact on overall survival. Patients with blood type B (III) showed significantly worse survival: median overall survival was 12.1 (95% CI 9.3–14.9) months in blood group B (III) and was not achieved in patients with other blood groups (p = 0.017).Conclusion. The significance of the identified predictors of the immunochemotherapy effectiveness in patients with advanced small cell lung cancer should be confirmed with the larger sampling size using a multivariate analysis. The study continues a recruitment of patients.