(P 349) LONG-TERM SURVIVAL OF PARTICIPANTS IN THE PASART-1 AND PASART-2 TRIALS OF NEO-ADJUVANT PAZOPANIB AND RADIOTHERAPY IN SOFT TISSUE SARCOMA

Objective: This study aims to assess the long-term safety and efficacy of adding pazopanib to neo-adjuvant radiotherapy followed by surgery in patients with high-risk non-metastatic soft tissue sarcoma treated in the PASART-1 and PASART-2 trials, as well as to compare the PASART cohorts to a historical control cohort from the Netherlands Cancer Registry (IKNL) to test if adding pazopanib improves Overall Survival (OS).

Methods: Updated follow-up data on disease control, survival and long-term toxicities of the PASART-trials were extracted from electronic patient records. The effect of adding pazopanib to neo-adjuvant radiotherapy on OS was then explored by directly comparing the combined PASART cohorts to the IKNL cohort and with an exact matching analysis.

Results: PASART-trials included 34 patients, IKNL cohort included 487 patients (4,957 before excluding patients with systemic treatment and adjuvant radiotherapy). After a median follow-up of 75.4 months (range: 30–131 months) the 1-year, 2-year and 5-year OS in the PASART-trials were 97% (95% Confidence Interval (CI): 91.5%-100%), 85.3% (95%CI: 74.2%-98.1%), 79.3% (95%CI: 66.8%-94.2%) respectively. Exact matching resulted in 24 PASART and 93 IKNL patients. The addition of pazopanib to neo-adjuvant radiotherapy did not significantly improve OS when compared to the IKNL cohort in a direct comparison (Hazard Ratio, 0.58; 95%CI, 0.3-1.13) or matched analysis (Hazard Ratio, 0.77; 95%CI, 0.35-1.68). Long-term toxicities were observed in eleven PASART patients and comparable to historical controls.

Conclusion: The addition of pazopanib was generally well tolerated, however failed to significantly improve OS when compared to historical controls.