Cerulean Pharma, a clinical-stage company developing nanoparticle-drug conjugates (NDCs), has announced top-line results from the company's phase II, randomized, multicenter clinical trial of its lead candidate, CRLX101, in combination with Avastin (bevacizumab) in the treatment of patients with advanced renal cell carcinoma (RCC).

The trial was conducted at 43 sites in the U.S. and South Korea, and enrolled 115 patients with RCC who progressed through two or three prior lines of therapy. Patients were randomized to receive CRLX101 in combination with Avastin or investigator's choice standard of care (SOC) therapy. SOC agents included axitinib, bevacizumab, everolimus, pazopanib, sorafenib, sunitinib and temsirolimus. The primary endpoint was progression free survival (PFS) in the clear cell population (n=102) assessed by independent radiological review. Secondary endpoints included overall response rate, duration of response and overall survival.

The study demonstrated no statistically significant difference in median PFS and objective response rate for the CRLX101 combination compared to SOC. Median PFS was 3.7 months for the CRLX101 combination compared with a median PFS of 3.9 months for SOC (hazard ratio: 1.25, p=0.822). The 95% confidence interval for PFS for the CRLX101 combination was 2.0 months to 4.3 months and for SOC was 2.2 months to 5.4 months. Objective response rate by independent radiological review for patients who received the CRLX101 combination was 5% (2/42) compared to 14% (6/43) for SOC (p=0.836). The CRLX101 and Avastin combination appeared to be safe and well-tolerated and the safety and tolerability profile of the combination was consistent with that observed in previous studies. The full data set from the trial are expected to be submitted for presentation at an upcoming medical conference.

"We are disappointed with this outcome and will undertake a thorough analysis of the data to understand why CRLX101 plus Avastin underperformed compared to the results we saw in an earlier investigator-sponsored trial," said Christopher D. T. Guiffre, president and chief executive officer of Cerulean. "This outcome did not support our hypothesis that targeting hypoxia inducible factor (HIF) in combination with VEGF inhibitor in RCC, a HIF-overexpressing tumor type, would be beneficial, so we will not pursue HIF as a target going forward. We will continue to focus on the potent topoisomerase 1 inhibition of CRLX101's payload, camptothecin, in topoisomerase 1-sensitive tumors. Our combinations with weekly paclitaxel and LYNPARZA™ (olaparib) are examples of ongoing trials that leverage CRLX101's topoisomerase 1 inhibition in combination with chemotherapies and DNA damage repair agents."