49P Thromboembolic risk assessment in patients receiving combination of anti-angiogenic plus anti-PD1 or anti-PD-L1: A descriptive study

Abstract Background Patients (pts) living with cancer are exposed to higher risk for thrombotic event (TE). The thrombotic risk (TR) is related to cancer disease and could also be associated with anti-cancer drugs such as antiangiogenic (AA). AA are currently being used more and more widely, alone or in combination (combo) with anti-PD(L)1 immunotherapies. It isn’t known whether combining anti-PD1 or PD-L1 with AA drug could increase the risk of TE. This study aimed at evaluating the TR in patients receiving a combo of AA and anti-PD1 or PD-L1. Methods Observational study conducted from January 2017 to September 2019 and retrospectively investigated all consecutive adults pts with cancer treated with a combo of AA plus anti-PD(L)1. All TE (venous and arterial) occurring following investigated treatment(s) and Khorana scores (KS) were analyzed. The TR was assessed in pts receiving the combo and compared with pts treated with single anti-PD(L)1. For the single anti-PD(L)1 cohort, data were collected from the pharmacovigilance Register of Severe Adverse Effects of Immunomodulatory Monoclonal Antibody in Cancer (REISAMIC). Data were compared between the combo and REISAMIC cohort using the Fisher’s exact and CHI2 tests (α = 5%). Results Overall, 83 pts receiving a combo of anti-PD(L)1 plus AA and 484 pts treated with anti-PD(L)1 were included. Both cohorts were similar for baseline characteristics: sex ratio, age, weight. Main tumor types in single anti-PD(L)1 vs combo were (in %): renal cell carcinoma, 5 vs 37; urothelial carcinoma, 3 vs 4; thoracic (lung or mesothelioma), 45 vs 32; gynecologic, 1 vs 8. The KS score was heterogeneous. It found 334/484 (69%) pts at intermediary or high risk of TE in the REISAMIC cohort and 70/83 (84%) in combo cohort (p = 0.006). In REISAMIC cohort, TE incidence was 7% compared to 18% in the combo cohort (p value=0.0006). Conclusion These results suggest that pts treated with combo AA plus anti-PD(L)1 seem to be more at risk of developing TE compare to single therapy anti-PD(L)1, according to a KS higher in this cohort. Further prospective study're warranted to investigate the risk of TE in pts receiving AA plus anti-PD(L)1 and to investigate the benefit of preventive anticoagulants therapy. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.