Pazopanib in metastatic soft tissue sarcomas: Testing the waters in developing world

In metastatic soft tissue sarcoma (M-STS), pazopanib has demonstrated promising activity; however, there is dearth of data from lower and middle income countries. It is important to explore the feasibility (toxicity, acceptance), efficacy (response rates, survival), and optimal dose requirement of pazopanib in M-STS in India.

All patients who received pazopanib for M-STS in 2013-2018 in Tata Memorial Centre were included. Institutional ethics committee approval was obtained. Assessment for response with contrast computed tomography scans was done as per the response evaluation criteria in solid tumors (RECIST) 1.1 criteria. Pazopanib was continued until progression or unacceptable toxicity. Clinical benefit rates and survival were evaluated by Kaplan-Meier method. All statistical calculations were done using SPSS version 21.0.

Seventy-two consecutive patients with a median follow-up of 17 (4-40) months were included in this study. Median lines of prior therapy were 2 (0-2). Among 50 evaluable patients, there were 12/50 (24%) partial responses, 25/50 (50%) stable disease, and 15/50 (30%) progressive disease. Median progression-free survival was 5 (95% confidence interval (CI) 3-6.9) months and median overall survival was 11 (95% CI 6.8-15.2) months. Adverse effects (G2/G3) in patients: hand foot syndrome-28%, hyperbilirubinemia/transaminitis-10%, diarrhea-20%, hypertension-17%, hypothyroidism-15%, anemia-6%, and fatigue-17%. Notably, 40% patient required dose reduction and median dose was 600 (200-800) mg daily.

Pazopanib was found a feasible treatment option for M-STS in India with internationally comparable outcomes. However, significant patients required dose modifications, and median tolerated dose was lower than the standard 800 mg dose. This novel finding merits confirmation in larger cohorts for reproducibility.