Sarah Gheuens
Analyst · RBC Capital Markets. Your line is now open
Thanks, Brian. As we approach top line data readout for the Phase 3 ENERGIZE-T study of mitapivat in transfusion-dependent thalassemia, I would like to highlight a few key elements of the mitapivat development program in thalassemia. As a reminder, the Phase 3 program of mitapivat with thalassemia, namely ENERGIZE and ENERGIZE-T, was designed to deliver data across all subpopulations of thalassemia, including alpha and beta thalassemia and populations with different transfusion needs. As Brian mentioned, only patients with transfusion-dependent beta thalassemia, which represents one-third of U.S. patients, have an FDA-approved treatment option. The other two-third of patients in the U.S., including all patients with alpha thalassemia and those patients with beta thalassemia who are non-transfusion dependent, have no approved treatment. It is a common misperception that non-transfusion dependent or NTD thalassemia patients are less sick. When the reality is that these patients suffer from a poor quality of life and a higher rate of serious morbidities, including thrombosis and premature death, this population, which represents approximately two-thirds of total thalassemia patients in the U.S., has a high unmet need for any treatment. This unmet need was strongly reinforced through our Phase 3 ENERGIZE study by the speed of enrollment, the total number of patients enrolled and the high completion and rollover rates we observe. We were very pleased to announce positive results from this study in January and are eagerly awaiting the opportunity to present more complete results at an upcoming medical meeting. Turning to those results. Our goal is to build from our Phase 2 findings with a more rigorous way to measure hemoglobin response in the Phase 3 ENERGIZE trial, which we defined in the primary endpoint as an increase of equal or more than 1 gram per deciliter in average hemoglobin concentrations from week 12 through week 24 compared to baseline, but in a much larger trial. We were excited to be able to announce success in this trial as treatment with 100 milligrams mitapivat BID demonstrated a highly statistically significant result on the primary endpoint of hemoglobin response rate, with 42.3% of patients in the treatment arm achieving a hemoglobin response versus 1.6% of patients in the placebo arm. In addition, treatment with mitapivat also resulted in statistically significant improvements in both key secondary end points, including a change from baseline in average FACIT-Fatigue score, an important patient-reported measure of how patients feel. In line with its novel mechanism of action that improves overall red blood cell health, mitapivat is the first molecule that has shown in a randomized controlled trial that it does not only improve hemoglobin, but actually makes people with thalassemia feel less fatigue. In addition, across the primary and secondary endpoints, all prespecified subgroup analyses favored mitapivat compared to placebo, suggesting that no single subgroup was responsible for driving the results, which supports our aim to file for a broad label covering all thalassemia subtypes. Turning to ENERGIZE-T. Let me highlight 3 key reasons why we are excited about the upcoming readout in transfusion-dependent thalassemia. First, it is important to recall that regardless of a patient’s transfusion needs, thalassemia is a hemolytic anemia. By [indiscernible] PK activity and improving overall red blood cell health, mitapivat’s novel mechanism of action directly addresses the underlying pathophysiology of hemolysis in all thalassemia subtypes. Second, this is a similar approach to the one we took for our PK deficiency program. In that case, in the Phase 3 ACTIVATE-T study of mitapivat in regularly transfused adults with pyruvate [indiscernible] deficiency, mitapivat demonstrated a statistically significant and clinically meaningful reduction in transfusion burden. These data, together with positive data from the Phase 3 ACTIVATE study in patients with PK deficiency who are not regularly transfused, led to FDA approval of mitapivat for adults with PK deficiency regardless of transfusion status, and we look forward to the potential to achieve the same in thalassemia. And third, in line with mitapivat’s mechanism of action, we have seen consistency in the data with improvements in hemolysis and ineffective erythropoiesis in clinical studies across three hemolytic anemias, namely PK deficiency, sickle cell disease and non-transfusion-dependent thalassemia. As a reminder, the primary endpoint of ENERGIZE-T is a transfusion reduction response, defined as a 50% or greater reduction in transfused red blood cell units, with a reduction of equal or more than 2 units of transfused red blood cells in any consecutive 12-week period through week 48 compared with baseline. This definition allows two ways for patients to achieve a reduction in transfusion burden. First, we have an increased time interval between transfusions, or second, through the use of fewer units or both. In order to standardize as much as possible the standard of care in this large global trial, each patient had a specific hemoglobin threshold value that was calculated based on their individual transfusion history prior to enrolling in the trial. Each patient’s individual hemoglobin threshold value that derms the hemoglobin value by which they will receive a transfusion in the trial. As the mechanism of action of mitapivat focuses on increasing red blood cell health and decreasing hemolysis, we are hoping to maintain hemoglobin levels above this threshold and reduce the need for transfusions. We designed this study by incorporating learnings from prior studies as well as agency feedback, and believe the primary endpoint dynamic assessment period reflects what matters to patients and physicians as well as regulators. We now look forward to the readout of this study in the second quarter, and are planning to submit a single regulatory filing to the FDA encompassing data from both ENERGIZE and ENERGIZE-T by the end of this year, seeking a label that covers people living with all subtypes of thalassemia. Turning to sickle cell disease. Enrollment in the Phase 3 portion of the RISE UP study of mitapivat continues to progress, and we are on track to complete enrollment by the end of the year. We have increasing conviction about the role of mitapivat in sickle cell disease, where we believe we have the potential to be both best-in-class and first-in-class. We look forward to reporting top line data from this 52-week study next year and believe firmly in mitapivat’s potential to address the high unmet need in this disease by improving anemia, making patients feel better and reducing sickle cell [indiscernible]. We also remain on track to deliver on all milestones across the rest of our advancing pipeline. This quarter, we commenced dosing in the Phase 1 study of AG-181, an oral phenylalanine hydroxylase or PAH stabilizer for phenylketonuria, abbreviated as PKU, a patient population with limited treatment options. We are excited about the potential to introduce a novel mechanism of action for PKU treatment and look forward to providing an update on next steps as enrollment progresses. Based on the data generated in the Phase 2a study of our novel PK activator AG-946 in lower-risk MDS, we plan to increase the doses evaluated in the upcoming Phase 2b study, which we expect to initiate in mid-2024. And in pediatric PK deficiency, we expect to complete enrollment of the Phase 3 ACTIVATE-kids study in the middle of this year, and we also now expect to report top line data from the Phase 3 ACTIVATE-kids-T study in mid-2024, sooner than our original projection of year end. This is a very exciting time at Agios, and we look forward to providing additional readouts and progress as we proceed through the year. In particular, we are looking forward to sharing with you the set of submissions for eHow and they are made public in a couple of weeks. With that, I will now turn the call over to Tsveta.