William Sheridan
Analyst · Jessica Fye with JPMorgan
Thanks very much, Megan. We are very excited to share early data from the lowest dose cohort of treatment-naïve patients in our ongoing PNH proof-of-concept study with our oral Factor D inhibitor BCX9930. You will see from the 50 and 100 milligrams twice a day data that we are well on our way to a goal of achieving monotherapy.We have seen dose related effects on control of hemolysis and clinical benefit. And in the healthy subjects multiple ascending dose study, the effect of 9930 on alternative pathway activity was superior at 200 milligrams and 400 milligrams twice a day compared to the lower doses. We’ve seen no safety signals. As you move next to the 200 and 400 milligram twice a day cohort in treatment-naïve PNH patients. These data tell us we should see complete control of hemolysis.As a reminder, the design of the PNH study is shown on Slide 20. Cohort 1 is testing 50 and 100 milligrams twice a day, cohort 2 will test 200 and 400 milligrams twice a day. So where are we today? So far, we have enrolled treatment-naïve PNH patients that means they have not had C5 inhibitor drugs. 9930 is administered orally twice a day as monotherapy. 3 PNH patients have completed 14 days of dosing and 50 milligrams twice a day, followed by 14 days of dosing at 100 milligrams twice a day. At the day 28 visit, all 3 had clinical benefit assessed by the investigators from that drug, so all 3 continued on 100 milligrams twice a day in the long-term extension.On Slide 21, you can see that these patients were seriously ill with PNH. One, had – previously had a cerebral vein thrombosis from the disease, the second required red cell transfusions, and the third had aplastic anemia and PNH.In PNH patients show quite variable degrees of hemolysis and anemia, before treatment among our 3 patients, the LDH or lactate dehydrogenase level a sensitive marker of hemolysis range from over 800 to over 2,400 units per liter, or 3.7 to 11 times the upper limit of normal. And the degree of anemia was severe with hemoglobin of 6.0 to 8.2 grams per deciliter. All 3 patients had elevated reticulocytes counts, reflecting the bone marrow working overtime to try to get the hemoglobin up.We are very encouraged by the laboratory and clinical responses that we’re seeing with the lowest doses of 9930, but 50 milligrams twice a day and 100 milligrams twice a day, the key biomarkers of hemolysis all improved. You can see the individual data on Slide 22. All 3 had clinically meaningful and dose dependent drops in LDH. The magnitude of effect is impressive, given that these sources are low and not optimized. Reticulocytes counts fill in all 3 patients. Total Bilirubin, another marker of hemolysis in PNH was elevated in 2 patients at baseline and normalized on 9930.Previous studies of complement inhibitors have shown it takes about 8 weeks to see stabilization in hemoglobin with optimized doses. Hemoglobin is already increasing in our 4 week study window at our lowest doses, subject 2, for example, and at the study dependent on transfusions with a day 1 hemoglobin of 7.0 following a 2 unit red cell transfusion on day 15. This patient has now been transfusion free for 6 weeks, and the hemoglobin has risen from 8.9 post transfusion to 11.1 at week eight of study, while on 9930 at 100 milligrams twice a day.The safety and tolerability profile of 9930 during the 28 day evaluation period is shown on Slide 23. Unlike our earlier Phase 1 experience in healthy volunteers, no patients developed a drug rash. There were no drug related serious adverse events. Most common observation was transient headache early in dosing, which is a well-recognized class effect of complement inhibitor treatment in PNH.One unrelated serious adverse event occurred in the extension period, disseminated varicella infection that led to a patient death. This patient has PNH was treated with chronic corticosteroids and azathioprine, was a frontline healthcare worker, who is exposed to a subsequently contracted varicella. Varicella is known to be especially dangerous in patients taking steroids and other drugs that suppress lymphocytes. Based on this clinical history, we investigator determined the event was unrelated to 9930.Our fourth treatment-naïve patient in cohort 1 was recently enrolled in South Africa, following completion of cohort 1, we expect to begin enrollment of C5 inhibitor naïve patients in cohort 2, testing 200 and 400 milligrams twice a day. And despite the COVID challenges, we continue to receive strong interest from investigators and patient efficacy to enroll PNH patients, who are poor responders to C5 inhibitors. We expect to beginning rolling for responding patients in the third quarter and report data from these patients by the end of the year. We’re very excited about this early data at 50 and 100 milligrams twice a day in PNH patients.Also, we have completed the MAD cohorts for 200 and 400 milligrams twice a day in healthy subjects. The pharmacodynamic profile of these doses is clearly superior to the PD profile of 50 and 100 milligrams twice a day and there were no safety signals. The steady state results for individual healthy subjects in the MAD are shown on Slide 26 for both the AP Hemolysis and AP Weislab assays. Note that the assays were continued for 24 hours after the last dose, importantly for PNH treatment, the higher doses provide more consistent coverage, especially in the period beyond 12 hours after the dose.The main values as shown on Slide 27, at both 200 and 400 milligrams twice a day, AP activity was blocked by more than 98% in both assays throughout the dosing interval of steady state. When you see the level of complement suppression, we have at 200 and 400 milligrams, you may ask if this could be the profile of once-a-day drug, it might be. And we do plan to explore once daily dosing in the healthy subject MAD study, as well as wrapping up the study by characterization of clinical pharmacology of 9930 with additional cohorts of testing super therapeutic doses.So what have we learned about dose? First, there is a clear dose response at 50 and 100 milligrams twice a day in treatment-naïve PNH patients with clinical benefits. Second, PD results of 200 and 400 milligram twice a day doses in healthy subjects were superior to the lower doses. Therefore, we plan to begin the C5 poor responder cohort at that dose level i.e., 200 milligram, 400 milligram.Our goal is to develop BCX9930 as an all monotherapy for PNH and other complement mediated disease. The PNH patient and MAD healthy subject data we share today strongly support that goal. We’re excited to complete a proof-of-concept study and to speak with regulators about our next steps in PNH and other diseases caused by dis-regulation of complement.