Biomarker analysis and final results of INT70/09 phase II proof-of-concept study of pazopanib (PZP) in refractory urothelial cancer (UC).

Abstract

4507 Background: Discouraging results have been achieved with standard and novel compounds in refractory UC. The final results with biomarker analysis of INT70/09 trial with pazopanib are presented. Methods: Pts failing ≥ 1 chemotherapy regimen for metastatic disease underwent PZP 800 mg once daily until PD or unacceptable toxicity. CT scan and PET scan were planned at baseline and q4weeks thereafter. Independent review of all CT scans was made and ≥ 5 RECIST CR+PR were required to conclude for activity according to Simon’s 2-stage design. 50 mL of EDTA blood samples were collected at baseline and q4wks in all pts to analyze plasma VEGF, sVEGFR-1,-2 and -3, c-Kit, IL-6, 8 and 12 by multiplex ELISA plates. Results: 41 pts were enrolled from 02/2010 to 07/2011. 15 pts (37%) had UC of the upper urinary tract. 20/41 pts were treated in 3rd line or beyond. 19 pts (46%) were CDDP-refractory and 22 (54%) had hepatic metastases. 27 (66%) had ECOG PS 1-2. 7 pts (17%) had a confirmed PR, 24 had a SD (76% clinical benefit). 20 pts (49%) had a confirmed necrotic evolution of metastases and/or a decreased SUV at PET consistent with PR. Median PFS and OS (95% CL) were 2.6 (1.7-3.7) and 4.7 mos (4.2-7.3), respectively but 7 pts (17%) had long-term cure for >10mos (4/7 beyond 2nd line). G3 hypertension occurred in 2 pts, diarrhoea in 5, anemia and hand-foot syndrome in 3 pts each. Significant increase from T0 (baseline) to T1 (+4wks) level was observed for VEGF (p<0.0001), IL6 (p<0.0129) and IL8 (p<0.0013) and decrease for VEGFR2 and c-Kit (p<0.0001 each). Rising IL8T1 levels significantly associated with RECIST progression at covariance analysis (p=0.0104). Elevated IL8T1 levels (IQ range, HR=2.11), liver mets (HR=2.33), PS (HR=3.73) and upper tract UC (HR=0.33) were significant variables for OS at multivariate Cox analysis. Conclusions: This is the 1st trial ever presented to meet the primary endpoint with a targeted drug in UC. A role for antiangiogenesis in UC has been set. Increasing levels of IL8 were associated with PD and worse outcome and may be included in a new prognostic model. Future investigation should aim at targeting IL8 to improve efficacy results by prolonging responses.