Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER

Thompson WR, Manuel R, Abbruscato A, et al. · Genetics in Medicine

The longest human exposure to daily subcutaneous elamipretide: 186 adverse events in 10 patients, 49 judged treatment-related, dominated by injection-site erythema and pruritus (80% each) and pain (70%); two discontinued for urticaria or drug eruption; three serious events judged unrelated, no deaths. Six-minute-walk distance was 96.1 m above pre-drug baseline at week 168 (p = 0.003) and hand-held dynamometry strength 37.9–60.3 N above it (p < 0.05 at every visit), while the total fatigue score's improvement (-1.21) did not reach significance (p = 0.21); all of it uncontrolled.

Population

10 Barth syndrome patients (all male, mean age 19, 33–86 kg) continuing from TAZPOWER into the open-label extension; 8 reached week 168

Intervention

Elamipretide 40 mg subcutaneous daily for up to 168 weeks

Comparator

None (comparison to pre-drug baseline)

Limitations

Open-label, no control arm, 10 patients, and a data gap between weeks 72 and 168 during the pandemic; three Stealth BioTherapeutics employees among the authors and the trial funded by Stealth; efficacy claims rest on baseline comparison.