Arsanis, Inc. (NASDAQ:ASNS) announced on 6/28/2018 the discontinuation of its Phase 2 clinical trial of ASN100 for the prevention of S. aureuspneumonia in high-risk, mechanically ventilated patients following the completion of a planned interim analysis of unblinded trial data by an independent data review committee (DRC). Based on the results of this analysis, the DRC determined that the trial was futile, meaning that it was not likely to meet its primary end-point upon completion and recommended that trial enrollment be discontinued. Arsanis intends to conduct follow-up visits on all patients dosed with ASN100 per the study protocol.
“We are disappointed that this clinical study was futile despite the survival benefit of ASN100 as compared to placebo observed in preclinical models of pneumonia, however Arsanis remains confident in the potential of monoclonal antibodies to prevent and treat serious infections, while also reducing the threat of antibiotic resistance,” said René Russo, President and Chief Executive Officer of Arsanis. “We intend to evaluate the complete dataset from the patients that were enrolled in the ASN100 study to better understand the basis for this result and expect to provide an update on the program following this review. We thank the patients and their caregivers who participated in the ASN100 Phase 2 study.”
The ASN100 Phase 2 clinical trial was a double-blind, placebo-controlled superiority trial evaluating the efficacy and safety of ASN100 for the prevention of S. aureus pneumonia in high-risk, mechanically ventilated patients, an indication for which there are no approved therapies. The primary efficacy endpoint of the trial was the proportion of patients who develop S. aureuspneumonia through 21 days after dosing. The trial was designed to detect a 50% reduction in the occurrence of S. aureuspneumonia in the ASN100 arm when compared to placebo.
ASN100 is a combination of two co-administered fully human monoclonal antibodies (mAbs), ASN-1 and ASN-2, that together neutralize the six cytotoxins critical to S. aureus pneumonia pathogenesis. ASN-1 neutralizes alpha-hemolysin (Hla), a cytotoxin that damages lung epithelial cells, and four leukocidins, cytotoxins that destroy human immune cells: gamma-hemolysin AB (HlgAB), gamma-hemolysin CB (HlgCB), Panton-Valentine leukocidin (PVL), and leukocidin ED (LukED). ASN-2 neutralizes the fifth leukocidin, LukGH, a particularly potent human cytotoxin also responsible for the destruction of human immune cells.
Arsanis has three additional monoclonal antibody based therapies in preclinical development.