Luc Truyen
Analyst · Truist Securities. Joon, please go ahead
Thank you, Tim, and good morning, everyone. I'm very excited as we have a positive data readout for my first conference call as Chief Medical Officer of argenx, a role which I assumed on April 1st. Let's start with the trial design on Slide 6. We included patients both on concomitant therapy or a watch-and-wait approach of therapy. 131 patients were randomized 2:1 treatment versus placebo after a two-week screening period. All patients received a fixed weekly infusions for the first four weeks. Between weeks five and 16, if patients have platelet counts of 100,000 or more for three out of four visits, they could transition to every other week dosing. The primary endpoint was measured starting at week 19 and patients were classified as sustained responders if they achieve a platelet counts of 50,000 in four out of the last six visits. This primary endpoint was selected to fulfill regulatory requirements, but we also look at metrics throughout the study that align with real-world treatment objectives. One of these is the International Working Group assessment. Patients who completed ADVANCE could roll over in ADVANCE-Plus to open-label extension. We had 101 patients total rollover, which is 95% of those who completed the trial. On Slide 7 are the patient baseline characteristics. We enrolled primarily chronic ITT patients into ADVANCE, but also had a small number of persistent patients in each arm. We stratified for history of splenectomy and a concomitant therapy. Approximately half of the patient had platelet counts below 15,000 at baseline. The mean time since diagnosis was approximately 10 years and over 50% of patients had received three or more prior ITP therapies. This could be classified as a refractory heavily pretreated patient group. Turning to Slide 8. On the left is the clear correlation of VYVGART infusions and platelet count improvement. The separation of the treated group from placebo is evidenced throughout the trial period. On the right is a primary endpoint analysis. In a treated arm, we had a response rate of 21.8%, or 17 out of 78, compared to 5% in placebo. This was encouraging in such a heavily pretreated population. And even with a tough primary endpoint measure, we met a high regulatory hurdle. On Slide 9, we can see that we also looked at the responders based on criteria from the international working group for ITP. These endpoints were developed by leading ITP physicians as a way to incorporate real-world treatment implications into clinical trial assessments. We include this as a secondary endpoint because these are incorporated in the ENA guidelines for drug development of novel ITP drugs, and we also wanted to capture our response rate along the same access as how physicians think about treatment goals. A response on IWG scale is defined as having platelet counts of at least 30,000 and a two-fold increase from baseline in the absence of bleeding events for at least two separate consecutive visits. A complete response has a higher threshold for platelet counts and is defined as having at least 100,000 platelet counts and absence of bleeding for at least two separate consecutive analysis visits. You can see how this aligns with the treatment goals of physicians the platelets to a safe level in the absence of bleeding events. 51.2% of treated patients achieved an IWG response and 27.9% a complete response, compared to placebo where 20% achieved an IWG response and 4.4% the complete response. On Slide 10, we highlight additional context around the platelet response in VYVGART-treated patients throughout the trial. The fast onset of action is evident, and you can see a clear separation between the VYVGART and placebo arms as early as week one. The durable platelet count increase is observed over the duration of the study with a clear separation between VYVGART and placebo arms at each week. We have 10 VYVGART patients switched to every other week dosing. Patients are eligible to make this switch if they surpass the 100,000 platelet counts at three out of four consecutive visits. Importantly, nine of the 10 patients who switched remained responders. Only one placebo patient was able to switch to every other week dosing and this patient was not a responder. Moving to Slide 11. We look at sustained platelet counts response across many different subtypes. And as you can see on the slide that regardless of the category, there's a high response rate in VYVGART-treated patients. We observed responders in each patient type regardless of age, disease severity, time since diagnosis, prior ITP treatment, use of background medication or history of splenectomy. Next slide, please. You can see on the chart here that we showed statistical significance in our key platelet-derived secondary endpoints, including cumulative number of weeks where platelet counts were at least 50,000 in the chronic ITP population and sustained platelet response in the overall population, including both chronic and persistent ITP patients. The response rate in the overall population was slightly higher than the chronic population alone, which indicates that a small number of persistent patients performed well in the trial. We did not show statistical significance in the number of WHO classified bleeding events. This was not surprising because bleeding events below that baseline, making a delta difficult to achieve. We did see numerically fewer bleeding events categorized as adverse events in treated patients compared to placebo. And we also saw fewer platelet transfusions as a rescue therapy in treated patients compared to placebo. This would indicate that placebo patients required more immediate rescue therapy than VYVGART patients. And finally, with our last key secondary endpoint, we showed a significant difference between VYVGART and placebo patients in durable sustained platelet count response [indiscernible] testing, we could not classify it as having met the endpoint. This is an important data point, though, because the response rate holds up whether you look at four of the last six visits, six of the last eight visits, or even eight of the last 12. This means if you're a responder, you're a durable responder. On Slide 13, we cover safety and tolerability. ADVANCE is our first registrational trial with chronic administration. We are very pleased to confirm the safety and tolerability profile of VYVGART as we move from a cyclical treatment scheduling in ADAPT, with chronic 24-week scheduled in ADVANCE. There were no new meaningful safety findings. To conclude, we are very excited with the totality of the data we're showing today. First, we met the primary endpoint, which was a high bar, especially for a difficult-to-treat patient group. We also gathered important data for physicians that aligns with how they make treatment decisions. We showed a fast onset of action and a durable platelet count with clear separation from placebo throughout the trial. We saw a significant proportion of responder switch to every other week dosing and maintain their response. And we are particularly pleased with the safety profile as we move from cyclical to chronic dosing. With that, I will turn the call over to Karl for the financial update. Karl?