Aridis Pharmaceuticals’ monoclonal antibody has flunked a phase 3 clinical trial of patients with bacterial infections. After stopping enrollment early because of COVID-19 and the war in Ukraine, the biotech failed to show AR-301 improves the rate of clinical cure but is nonetheless planning a second phase 3.
The study, AR-301-002, assessed the effect of a single intravenous dose of AR-301 in combination with standard-of-care antibiotics on mechanically ventilated patients who were likely to have pneumonia caused by Staphylococcus aureus. Aridis designed the placebo-controlled study to show if AR-301 increased the clinical cure rate at day 21. It didn’t.
Aridis linked AR-301 plus standard care to a 68.9% clinical cure rate, compared to 57.6% in the control arm. The biotech said many key opinion leaders view a 10% improvement in the cure rate as clinically meaningful. But the numerical improvement over placebo fell short of statistical significance and the study, therefore, missed its primary endpoint.
To explain the failure, Aridis noted that the sample size was “limited.” The biotech planned to enroll 240 patients so the study would “be overpowered versus n=138 patients to achieve superiority in primary endpoint.” However, the trial ultimately enrolled 174 patients, 120 of whom met the criteria for inclusion in the primary efficacy analysis.
Aridis presented subgroup analyses to make the case for AR-301, pointing to the cure rate in adults aged 65 years and older and patients with methicillin-resistant S. aureus as evidence that the drug candidate has a future.
“This study highlights the efficacy limitations of standard of care antibiotics and therefore the unmet medical needs in high-risk, vulnerable patient populations such as older adults and those infected with antibiotic-resistant MRSA; populations where AR-301 has the potential to fulfill an unmet need,” Hasan Jafri, M.D., Aridis’ chief medical officer, said in a statement.
Aridis plans to discuss the data with regulators before starting a second phase 3 trial. Investors were unconvinced and sent shares in the biotech down around 25% to under $1 in trading before the Nasdaq opened on Thursday. Aridis ended September with $3.1 million, although it subsequently raised money.
https://www.fiercebiotech.com/biotech/miss-aridis-antibody-flunks-undersized-phase-3-pneumonia-trial
