Dr. Bill Sheridan
Analyst · JP Morgan. Your line is open
Thanks, Jon. I’m going to focus today on our lead program, BCX7353, a plasma kallikrein inhibitor that would be the first oral targeted therapy available for both prevention of HAE attacks and treatment of acute HAE attacks. We are making excellent progress across all aspects of our program. Our timelines remain on track to the APeX-2 Phase 3 prophylaxis trial, the APeX-S open label safety study, and the ZENITH-1 exploratory Phase 2 trial for acute treatment. We have completed patient enrollment in ZENITH-1 and expect to report data for part one of this trial later this quarter. As we approach the data readout, we wanted to review for you today how we selected the dose levels to test, some relevant context from the licensing trials of currently marketed injectables, what success looks like and some unique features of ZENITH-1. The two principal goals of this exploratory trial are one, to identify activity against clinically meaningful endpoints that we could use to construct the Phase 3 registration trial; and two, to identify the doses we want to advance. The notion of using 7353 as an acute treatment was first suggested by the PK profiles of single doses in the range of 250 to 1,000 milligrams in healthy volunteers in our Phase 1 trial. These profiles are shown in the left panel on slide six. With this information, we simulated the PK profiles of additional dose levels, including 750 milligrams shown in the middle panel and then tested that dose in HAE subjects. The results were in line with the simulations and are depicted in the right hand panel. Over this dose range, drug levels that exceeded the target therapeutic range to prophylaxis of angioedema attacks in HAE are achieved with a single dose, the durations of more than 24 hours at 750 milligrams and about 6 hours at 250 milligrams. Clinical trials have of the injectable targeted treatments in the acute treatment setting shown on slide seven, all required that treatment was to be given at the clinic. These trials were done in the period when at-home, self-administered, on-demand treatment early in an attack had not yet been established as a standard of care. Other features of these trials that are worth noting include the long duration of symptoms prior to intervention. The diversity of outcome measures, and variation in both the type of rescue therapy available and when rescue treatment is used according to its protocol. The takeaway here is that because of the different endpoints and approach to rescue treatment in the prior acute treatment trials, it really is not possible to make valid comparisons between them. However, for planning our trial, it was important to look at the scientifically correct comparison of treatment effect of active drug compared to placebo in each of these trials individually, shown on slide eight. Taking each trial separately, the difference between active drug and placebo in the proportion of subjects meeting the different primary endpoints at four hours post dose varies from 16% to 43%. Similarly, the difference between active drug and placebo in proportion of subjects to receive rescue treatment varies from 19% to 38%. It is important to note that between 31% and 58% of placebo subjects met the primary endpoint at four hours and between 15% to 64% of the time, placebo subjects received no targeted treatment for their attacks. Obviously, medical care for HAE has changed dramatically over the past decade. So, we needed to craft to protocol that fitted in with modern practice. Instead of having treatment injected subcutaneously or infused in intravenously at a clinic, subjects in ZENITH-1 self administer oral BCX7353 at-home. Instead of post 12 hours of symptoms before study drug treatment, the goal in ZENITH-1 is for subject to treat within one hour of onset of symptoms. These features in ZENITH-1 are consistent with current treatment guidelines. As you can see on slide 10, once the patient in ZENITH-1 begins to have an attack, they are asked to call a physician within one hour to confirm if it’s appropriate for them to take their investigational therapy, which will be 7353 or placebo. And the course of study is blinded. So, neither the patient, nor the investigator knows, which they are receiving. Importantly, we ask patients to wait at least four hours before reaching for any risk in medication. This provides an opportunity to see a treatment effect. Of course, patients do have the option to reach for rescue medication at any time they see what is needed. We have been monitoring conducts of the study throughout on a blinded basis and these operational aspects have proceeded very smoothly. The efficacy endpoints of ZENITH-1 have been selected to maximize our ability to identify one or more clinically meaningful endpoints for a subsequent registration trial. There are multiple ways to win here. What matters to patients and physicians is clinically meaningful, when we share the data will play a big role in interpreting the results. Which of these endpoints will translate well and which won’t, cannot be determined until then. But the opportunity to assist endpoints is the beauty of an exploratory study. We can run the experiments against these endpoints and then take the most meaningful going forward to the regulators as we design the registration trial. We look forward on unblinding one of the trial and reporting results later this quarter and subsequently full study results in the first half of 2019. In a moment Lynne will discuss some of the commercial aspects of the acute market. But, I do also want to update you on our APeX program for prevention of HAE attacks. As many of you know, we completed a successful Phase 2 trial for prophylaxis of HAE attacks called APeX-1, and we were honored that just two weeks ago our peer reviewed was published in the New England Journal of Medicine. In addition, regulatory authorities have recognized the potential advance in medical care that 7353 could represent with Fast Track Designation by the U.S. FDA and Promising Innovative Medicine designation by the UK MHRA. We believe that APeX-1 provides the strong foundation for APeX-2 and highlights the value of an oral once daily therapy for prophylaxis. APeX-2 enrollment continues to proceed very well and we remain on track to report 24-week data in the second quarter of 2019. We are also pleased with the progress of the APeX-S long-term open label safety study. From a clinical standpoint, we believe that 7353 represents a highly differentiated therapy that both patients and physicians have an urgent need for. I’d now like to turn the call over to Lynne who will share some of our commercial perspectives around the acute and prophylactic markets.