Activity of cediranib in alveolar soft part sarcoma (ASPS) confirmed by CASPS (cediranib in ASPS), an international, randomised phase II trial (C2130/A12118).

11004 Background: ASPS is a rare disease (0.5-1% of soft tissue sarcomas) mainly affecting young people. It is unresponsive to conventional chemotherapy. Cediranib (C), an inhibitor of vascular endothelial growth factor receptors and other receptor tyrosine kinases, has shown significant activity in ASPS in single arm phase II trials. CASPS (NCT01337401) was designed to permit discrimination between the impact of cediranib and the often intrinsically indolent nature of the disease. Methods: CASPS compared C (30mg od) with placebo (P) in a 2:1 double blind randomisation in patients (pts) age ≥16 years with metastatic ASPS progressive in the previous 6 months. Pts were unblinded at week 24, or at progression if sooner, when those on P started C. The primary endpoint of percentage change in the sum of target marker lesions (TMLsum) between baseline and week 24 (or progression if sooner) was compared between groups by Mann-Whitney test. Secondary endpoints were progression-free survival (PFS), week 24 response rate and best response (RECIST v1.1), safety/tolerability and overall survival (OS). One-sided p-values and two-sided 90% confidence intervals are reported. Results: 48 pts were recruited between 07/2011 and 07/2016 from 12 centres (UK, Australia & Spain). 52% of pts were female, median age was 31. Most common grade ≥3 adverse events on C were hypertension (23%), diarrhoea (14%) and fatigue (9%). In the evaluable population (N = 44) median change in TMLsum on C was minus 8.3% (IQR minus 26.2% to +5.9%); versus P: +13.4% (IQR minus 0.6% to +21.3%), p = 0.0013. Best response by week 24 was partial response for 6/28 (21%) C pts compared with 0/16 on P (p = 0.053) and stable disease for an additional 19/28 (68%) on C and 12/16 (75%) on P. The PFS HR (C versus P) was 0.54 (90% CI 0.30-0.97, p = 0.041), median PFS: 10.8 mths on C versus 3.7 mths on P, OS at 12 mths was C: 96%; P: 64.3%. Conclusions: CASPS, the largest randomised trial to date in this disease, confirms the activity of C in ASPS, showing a significant reduction in tumour burden and improvement in PFS. Tumour tissue and serial blood samples will subsequently be investigated to identify potential predictive and prognostic biomarkers. Clinical trial information: NCT01337401.