Open-Label Extension Trial to Characterize the Long-term Safety and Tolerability of Elamipretide in Subjects With Genetically Confirmed Primary Mitochondrial Myopathy (PMM)

This open-label, non-comparative, extension trial will enroll subjects with genetically
confirmed PMD who have completed the End-of-Study Visit in the SPIMM-202 trial. Subjects who
do not discontinue or withdraw from the trial will receive treatment with 40 mg SC
elamipretide for the shortest of the following: 260 weeks; regulatory approval and commercial
availability of elamipretide in the subject's respective country; or termination of the
clinical development for elamipretide in subjects with PMD.

Inclusion Criteria:

- Investigator determines the subject can, and subject agrees to, adhere to the trial
requirements for the length of the trial including self-administration (by subject or
trained caregiver) of the study drug

- Subject completed the End-of-Study Visit in SPIMM-202

Exclusion Criteria:

- Subject has any prior or current medical condition that, in the judgment of the
Investigator, would prevent the subject from safely participating in and/or completing
all trial requirements

- Subject has received any investigational compound (excluding elamipretide) and/or has
participated in another interventional clinical trial within 30 days prior to the
SPIMM-203 Baseline Visit (excluding SPIMM-202) or is concurrently enrolled in any
non-interventional research of any type judged to be scientifically or medically
incompatible with the trial as deemed by the Investigator in consultation with the
Sponsor

- Subject experienced an adverse reaction attributed to study drug resulting in
permanent discontinuation of study drug in the SPIMM-202 trial.

- Female subjects who are pregnant, planning to become pregnant, or lactating

- Subject has undergone an in-patient hospitalization within the 1 month prior to the
SPIMM-203 Baseline Visit