In December 2019, we initiated the Phase 3 DISRUPT (Direct Lysis of
Resistant Pathogen Trial) study of exebacase. The DISRUPT study is a randomized, double-blind, placebo-controlled Phase 3 clinical trial conducted in the U.S. alone to assess the efficacy and safety of exebacase in approximately 350 patients with
bacteremia, including right-sided endocarditis. Patients entering the study will be randomized 2:1 to either exebacase or placebo, with all patients receiving
(“SOC”) antibiotics. The primary efficacy endpoint of the study is clinical response at Day 14 in patients with MRSA bacteremia, including right-sided endocarditis. Secondary endpoints will include clinical response at Day 14 in the All
patient group (MRSA and methicillin-sensitive
(“MSSA”)),
30-day
all-cause
mortality in MRSA patients, and clinical response at later timepoints. We will also evaluate the impact of treatment with exebacase on health resource utilization, including hospital length of stay, ICU length of stay and
30-day
readmission rates. We plan to conduct an interim futility analysis following the enrollment of approximately 60% of the study population. We obtained concurrence with the U.S. Food and Drug Administration (“FDA”) on the Phase 3 study protocol at an
2 meeting with the FDA in September 2019, including the key design features of the study population, the endpoints and the size of the safety database that would be needed to support a Biologics License Application (“BLA”) for approval of exebacase, under the FDA’s “streamlined development” paradigm for agents to treat bacterial infections associated with high unmet medical need.
We completed a Phase 2 superiority study of exebacase that evaluated its safety, tolerability, efficacy and pharmacokinetics (“PK”) when used in addition to background SOC antibiotics compared to SOC antibiotics alone for the treatment of
bacteremia, including endocarditis in adult patients. The results from this study showed clinically meaningful improvement in clinical responder rates among patients treated with exebacase in addition to SOC antibiotics compared to SOC antibiotics alone. In the primary efficacy analysis population of 116 patients with documented
bacteremia, including endocarditis, who received a single intravenous (“IV”) infusion of blinded study drug, the clinical responder rate at Day 14 was 70.4% for patients treated with exebacase and 60.0% for patients dosed with SOC antibiotics alone (p=0.314). The clinical responder rate at Day 14 in the subset of patients with bacteremia including right-sided endocarditis was 80.0% for patients treated with exebacase compared to 59.5% for patients treated with SOC antibiotics alone, an increase of 20.5% (p=0.028). In the subset of patients with bacteremia alone, the clinical responder rate at Day 14 was 81.8% for patients treated with exebacase compared to 61.5% for patients treated with SOC antibiotics alone, an increase of 20.3% (p=0.035).
In a
pre-specified
analysis of MRSA-infected patients, the clinical responder rate at Day 14 in patients treated with exebacase was nearly
43-percentage
points higher than in patients treated with SOC antibiotics alone (74.1% for patients treated with exebacase compared to 31.3% for patients treated with SOC antibiotics alone (p=0.010)). In addition to the higher rate of clinical response, MRSA-infected patients treated with exebacase showed a
21-percentage
point reduction in
30-day
all-cause
mortality (p=0.056), a four day lower median length of hospital stay and meaningful reductions in hospital readmission rates. Exebacase was well-tolerated and treatment emergent adverse events, including serious treatment-emergent serious adverse events (“SAEs”) were balanced between the treatment groups. There were no SAEs that we determined to be related to exebacase, there were no reports of hypersensitivity related to exebacase and no patients discontinued treatment with study drug in either treatment group.
We also performed a
post-hoc
Phase 3 simulation analysis using the Phase 2 data to evaluate the clinical outcomes for the Phase 2 patient population that would meet the Phase 3 inclusion criteria. In this simulated Phase 3 analysis population of 84 U.S. patients with documented
bacteremia, including right-sided endocarditis, who received a single IV infusion of blinded study drug, the clinical responder rate at Day 14 was 83.7% for patients treated with exebacase and 54.3% for patients dosed with SOC antibiotics alone, an improvement in the responder rate of over
29-percentage
points. The clinical responder rate at Day 14 in the subset of patients with MRSA bacteremia including right-sided endocarditis was 82.6% for patients treated with exebacase compared to 33.3% for patients treated with SOC antibiotics alone, an improvement in the responder rate of over
49-percentage
points. In the subset of patients with MSSA bacteremia including right-sided, the clinical responder rate at Day 14 was 84.6% for patients treated with exebacase compared to 66.7% for patients treated with SOC antibiotics alone, an increase of nearly
18-percentage
points.
We believe these data established proof of concept for exebacase and for DLAs as therapeutic agents. In particular, the data for MRSA-infected patients treated with exebacase, which, in the Phase 2 superiority study, demonstrated superior outcomes in clinical response at Day 14 and in
30-day
all-cause
mortality as well as health economics benefits, provided the basis for the FDA to grant Breakthrough Therapy designation to exebacase for the treatment of MRSA bloodstream infections (bacteremia), including right-sided endocarditis, when used in addition to SOC anti-staphylococcal antibiotics in adult patients. Breakthrough Therapy designation is a program designed by the FDA to expedite the development and review of medicines for serious or life-threatening diseases where preliminary clinical evidence suggests that the investigational therapy may demonstrate substantial improvement on at least one clinically significant endpoint over available therapies. The Breakthrough Therapy designation provides additional benefits, such as expedited meetings and interactions with the FDA and the potential for priority review, over the Fast Track designation granted to exebacase in August 2015.
On March 10, 2021, we entered into a cost-share contract (the “BARDA Contract”) with BARDA, a division of the U.S. Department of Health and Human Services’ Office of the Assistant Secretary for Preparedness and Response. Under the BARDA Contract, we will receive funding of up to an estimated $86.8 million to advance the development of exebacase. The base period for the BARDA Contract includes government funding of up to $9.8 million to reimburse expenses for approximately one year to support the conduct of the ongoing Phase 3 clinical trial and futility analysis. Following successful completion of the base period, the BARDA