Safety and Efficacy of Alfimeprase in Subjects with Occluded Central Venous Access Devices: The SONOMA-2 Study.

Introduction: The infusion of chemotherapy and blood products is facilitated by central venous access devices (CVAD), and the occurrence of thrombotic CVAD occlusion results in delays in these crucial therapies. Alfimeprase is a direct-acting thrombolytic agent with the potential to rapidly re-establish catheter function.

Methods: SONOMA-2 was a multicenter, multinational, randomized, double blind, placebo-controlled phase 3 study evaluating the efficacy and safety of alfimeprase in subjects with occluded CVADs. Subjects were randomized in a 2:1 ratio to receive either intra-luminal alfimeprase (A) at a dose of 3.0 mg or placebo (P). Study drug was delivered in a total volume of 2 mL. If re-establishment of catheter function was not established within 30 minutes, a second dose of the same study drug was instilled and allowed to dwell for an additional 30 minutes. Re-establishment of catheter function was assessed by an attempt to withdraw 3 mL of blood and infuse 5 mL of saline. The primary efficacy endpoint was re-establishment of a functional CVAD at 15 minutes post first infusion. The primary efficacy analysis prespecified a significance level of ≤ 0.00125.

Results: A total of 303 patients (201 (A), 102 (P)) were randomized into the study. Treatment groups were well balanced at baseline with respect to overall demographics, catheter insertion site, and median days since last failed infusion or blood draw. The primary efficacy endpoint, re-establishment of a functional CVAD at 15 minutes post first infusion, was achieved in 34.3% (A) versus 21.6% (P) of subjects (p = 0.022). The cumulative proportion of subjects with re-establishment of a functional CVAD at 30 minutes post first or second infusions was 52.7% (A) versus 30.4% (P) (p = 0.0002). Rates of adverse events (65.8% (A), 59.4% (P)), serious adverse events (15.5% (A), 16.8% (P)), and hemorrhagic adverse events (3.6% (A), 10.9% (P)) were comparable between treatment groups. No intracranial hemorrhages were observed.

Conclusions: Alfimeprase restored CVAD function in a numerically greater fraction of subjects than did placebo; however, the study did not achieve statistical significance for the primary endpoint at the prespecified p-value of ≤ 0.00125 necessary for demonstrating efficacy with a single pivotal study. Alfimeprase was well tolerated. Further clinical studies are underway that evaluate a higher and more concentrated alfimeprase dose which preclinical studies predict will result in greater efficacy. Alfimeprase remains a promising potential candidate for use in patients with CVAD occlusion.