ENERGIZE-T: Positive results for mitapivat in thalassemia

These findings were shared in an oral presentation (abstract #409) at the 66^th American Society of Hematology (ASH) Annual Meeting and Exposition in San Diego, California.

Thalassemia is a rare inherited blood disorder caused by genetic mutations that lead to a reduced production of healthy hemoglobin, compromising red blood cell development, health and survival, and resulting in chronic anemia. Patients with thalassemia often experience a range of debilitating complications, both from the disease itself and as secondary effects of common management strategies such as blood transfusions and iron chelation therapy, including organ damage, stroke, and other serious health issues.

In the ENERGIZE-T trial, mitapivat demonstrated a statistically significant reduction in transfusion burden compared to placebo in patients with transfusion-dependent alpha- or beta-thalassemia, achieving its primary endpoint. Additionally, the ENERGIZE-T study met all the key secondary endpoints, with mitapivat demonstrating a statistically significant reduction in additional measures of transfusion reduction response compared to placebo. In June 2024, Agios also presented positive results from the Phase III ENERGIZE study, which evaluated mitapivat in adults with non-transfusion-dependent alpha- or beta-thalassemia.

“Treatment options for patients with transfusion-dependent thalassemia are extremely limited, and transfusions carry serious risks, such as iron overload, infections and immune reactions. There is a significant need for alternative treatments to manage this debilitating disease,” said Maria Domenica Cappellini, M.D., professor, Internal Medicine, University of Milan, Italy. “The strong Phase III ENERGIZE-T results build on the positive findings from the Phase III ENERGIZE study in patients with non-transfusion-dependent alpha- or beta-thalassemia presented earlier this year, pointing to mitapivat as a potential transformative advancement in thalassemia care.”

Phase III ENERGIZE-T Study Results ENERGIZE-T is a Phase III, double-blind, randomized, placebo-controlled and multicenter 48-week study. A total of 258 patients were enrolled in the study worldwide, with 171 patients randomized to mitapivat 100 mg twice-daily (BID) and 87 patients randomized to matched placebo.

The study’s primary endpoint of transfusion reduction response (TRR) was defined as a ≥50% reduction in transfused red blood cell (RBC) units with a reduction of ≥2 units of transfused RBCs in any consecutive 12-week period through Week 48 compared with baseline. A TRR was achieved by 30.4% (n=52/171) of patients in the mitapivat arm compared to 12.6% (n=11/87) of patients in the placebo arm (2-sided p=0.0003).

Additionally, mitapivat demonstrated statistically significant reductions in transfusion burden compared with placebo as measured by the three key secondary endpoints of transfusion reduction response reflective of durability of response up to 36 weeks during the 48-week double-blind period. The key secondary endpoint TRR2, defined as a ≥50% reduction in transfused RBC units in any consecutive 24-week period through Week 48 compared with baseline, was achieved in 13.5% (n=23/171) versus 2.3% (n=2/87) of patients in the mitapivat and placebo arms, respectively (2-sided p=0.0003). The key secondary endpoints TRR3 and TRR4 were defined as a ≥33% and ≥50% reduction in transfused RBC units, respectively, from Week 13 through Week 48 compared with baseline. TRR3 was achieved in 14.6% (n=25/171) versus 1.1% (n=1/87) of patients in the mitapivat and placebo arms, respectively (2-sided p<0.0001), and TRR4 was achieved in 7.6% (n=13/171) versus 1.1% (n=1/87) of patients in the mitapivat and placebo arms, respectively (2-sided p=0.0056). 

The results for the primary and key secondary endpoints were not driven by any of the individual prespecified subgroups, including but not limited to genotype and baseline transfusion burden, highlighting the overall robustness of the efficacy results.

Further, 17 patients (9.9%) in the mitapivat arm compared with one patient (1.1%) in the placebo arm achieved the secondary endpoint of transfusion independence (transfusion-free for 8 or more consecutive weeks through Week 48). Three patients in the mitapivat arm did not receive any transfusions during the 48-week double-blind period.

Overall, during the 48-week double-blind period, incidence of adverse events (AEs) was similar across the mitapivat and placebo arms. The proportion of patients with any treatment-emergent adverse events (TEAEs) was 90.1% (n=155) in patients on mitapivat and 83.5% (n=71) in patients on placebo. The most frequent TEAEs that occurred in at least 10% of patients on mitapivat were headache, upper respiratory tract infection, initial insomnia, diarrhea and fatigue. Serious treatment-emergent adverse events were reported in 11.0% (n=19) and 15.3% (n=13) of patients on mitapivat and placebo, respectively; 2.3% (n=4) and 1.2% (n=1), respectively, were considered treatment-related. There were 5.8% (n=10) of patients on mitapivat and 1.2% (n=1) on placebo with TEAEs leading to treatment discontinuation. The TEAEs leading to discontinuation of mitapivat, each of which occurred in one patient, were diarrhea, paresthesia oral, concurrent anxiety and insomnia, initial insomnia, supraventricular tachycardia, fatigue, hyper-transaminasemia, hepatitis C, hepatic cancer, and renal mass. The TEAE that led to discontinuation of the one patient on placebo was blood creatine phosphokinase increased.