Nivolumab as second-line treatment of patients with metastatic renal cell carcinoma with high or normal fibrinogen levels: A prospective, cohort study

e16510 Background: In a number of coagulation-related studies, elevated fibrinogen levels were found in patients with renal cell carcinoma (RCC) and correlated with more advanced disease. The impact of hyperfibrinogenemia on the clinical outcomes of immunotherapy remains uncertain. Methods: In this prospective cohort study, fibrinogen levels were measured one week prior to the second-line nivolumab therapy (240 mg or 480 mg every 2 or 4 weeks) and then monthly until disease progression or unacceptable toxicity. High fibrinogen level was defined as ≤5 g/L. Key eligibility criteria included metastatic clear cell RCC resistant to the first-line targeted therapy, ≤3 MSKCC risk factors, ECOG PS 0-2, platelet count <400×10(9)/L, no heart diseases, no anticoagulation therapy, and age 40-65 years. The primary endpoint was overall survival (OS) in cohorts with high (H) and normal (N) fibrinogen levels. Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and fibrinogen levels during therapy. Results: Between November 2018 and January 2021, 82 patients were enrolled, of whom 41 and 41, respectively, were recruited in H and N cohorts. The groups were well balanced at baseline. The median follow-up time was 32.4 months. Compared to patients in N cohort, patients in H cohort had shorter OS (P=0.001), shorter PFS (P<0.01), and lower ORR (P=0.012). In H cohort, a below-median fibrinogen level was associated with longer observed OS (median, 23.7 vs. 19.4 months; P=0.03). In N cohort, 6 (15%) patients with stable disease had an increase in fibrinogen levels during nivolumab therapy. Patient characteristics and clinical outcomes are summarized. Conclusions: High fibrinogen levels affect the clinical outcomes in patients with metastatic renal cell carcinoma treated with second-line nivolumab. These findings require large-scale prospective validation. Clinical trial information: KCRB0181209 . [Table: see text]