OC06 | PRIMARY THROMBOPROPHYLAXIS IN ADVANCED PANCREATIC DUCTAL ADENOCARCINOMA UNDERGOING SYSTEMIC ANTICANCER TREATMENT: A CANCER-CENTER COHORT STUDY ON CLINICAL PRACTICE AND OUTCOMES

F. Haque^1|2, A. Adekeye^1|2, Z. Mohtashim², K. Page¹, M. Goodman¹, A. Maraveyas ^1|2 | ¹Hull University Teaching Hospital NHS Trust, UK; ²Hull York Medical School, UK

Introduction. The lifetime incidence of venous thromboembolism (VTE) in patients with aPDAC ranges from 25% to 35%. Only increased-dose primary thromboprophylaxis (IDPTP) with low-molecular-weight heparin (LMWH) has demonstrated significant efficacy. Thromboprophylaxis (TP) with 10 mg of rivaroxaban did not achieve the endpoint significance threshold in the CASSINI study. Effective TP with an oral agent, often preferred by patients, may also depend on dose. We present our real-world experience with direct oral anticoagulants (DOACs) for PTP.

Aim. We aimed to evaluate the efficacy and safety of PTP with DOAC for reducing the incidence of VTE in ambulatory patients with aPDAC receiving SACT.
Methods. 186 ambulatory patients from 2018 to 2023 were included. Outcomes assessed were breakthrough VTE and major bleeding (MB). Statistical analysis was performed using SPSS v29 and StataNow 18 BE.

Results. The median follow-up period was 8.2 months (range, 0.4–52), with a median age of 66 years. 87.6% received SACT with palliative intent. 143 patients were included in the comparative analysis; 55 (38.5%) received no TP, 63 (44.1%) received IDPTP (Rivaroxaban 15 mg OD), and 25 (17.5%) received conventional TP (Apixaban 2.5 mg BD/Rivaroxaban 10 mg OD), indicating individual clinician bias in interpreting evidence. The cumulative incidence rate (CIR) of breakthrough VTE events (death as a competing risk) was 6.3% (4/63) in the ‘IDPTP’ group. The CIR was 34% in the ‘No TP’ and 17% in the ‘conventional TP’ group. VTE risk decreased without a significant rise in MB, with rates of 5.4% in the ‘No TP’ group and 7.9% in the ‘IDPTP’ group. Competing-risk regression showed a significant reduction in VTE risk with IDPTP (SHR = 0.17, 95% CI: 0.06, 0.50; p = 0.001), but not with conventional TP (SHR = 0.4473, 95% CI: 0.15, 1.31; p = 0.141). Patients without TP had a higher risk of VTE (SHR = 5.77; 95% CI: 1.98, 16.82; p = 0.001).

Conclusions. At an increased prophylactic dose of 15 mg once daily, rivaroxaban demonstrated favorable efficacy in reducing VTEs with an acceptable safety profile. This supports the conclusion that an increased dose of DOAC for TP is a superior intervention in patients with aPDAC receiving SACT. A large-scale randomized study testing this approach is warranted to validate these outcomes.