Filsuvez in Moderate-to-Severe Epidermolysis Bullosa Simplex

Inclusion Criteria: * Subject has a documented diagnosis and confirmed clinical history of EBS. The Investigator will determine subject eligibility based on historical phenotypic presentation of EBS symptoms along with genetic/diagnosis documentation in order to determine EBS severity. * The following skin conditions are required: * A minimum area of \~3% BSA containing active blisters/erosions, and freshly ruptured blisters across 50% of the TLA (as assessed by the PI). Skin erosions, keratoderma, fissures and/or erythema may also be present. * Subjects will be permitted to treat their feet to assess plantar blister surface area but blistering on the feet is not a requirement for study inclusion. * TLA may not be infected (as assessed by PI) or have been treated with a topical antibiotic within 14 days. * If the subject is a woman of childbearing potential (WOCBP) (Need to verify current labeling on use during pregnancy) * Has a negative urine pregnancy test at baseline. * Agrees to use an approved effective form of birth control with failure rates \<1% per year (e.g., implant, injectable, combined oral contraceptive, intrauterine contraceptive device, sexual abstinence, vasectomized partner) during participation in the study. * Is not nursing. * Subject's laboratory values (blood and urine) are within the range of normal or abnormal values are within normal levels for the disease and in the opinion of the PI the values are not clinically relevant for study participation. * Subject is in good, general health and free of any known disease state or physical condition which, in the investigator's opinion, might interfere evaluation of the EBS lesions during study or which exposes the subject to an unacceptable risk by study participation. * Over the duration of the study, the subject agrees to not use any other topical therapies and/or impregnated dressings within the TLAs (e.g., medicated cleansers, CBD oil, MediHoney, Silvadene cream 1%, topicals containing antimicrobials, keratin, and/or collagen, lipid-colloid or polymeric membrane dressings, and/or hydrogels). * Subject and/or legally appointed and authorized representative must be able and willing to follow study procedures and instructions to maintain compliance throughout the study period. * The subject, parent, or legally appointed and authorized representative must have read, understood and signed an Institutional Review Board/Ethics Committee (IRB/EC) approved Informed Consent and Assent Form if applicable. Exclusion Criteria: * Subject's use of prior or concomitant medication or medical treatments/procedures: * Any investigational drug or therapy within 30 days. * Systemic steroidal therapy within 30 days. * Topical steroidal therapy in TLA within 14 days (Note: inhaled and ophthalmic products containing steroids are allowed). * Systemic antibiotic therapy within 7 days. * Currently receiving chemotherapy or radiation. * Surgery within the previous 2 weeks (except for minor surgery, cosmetic or dental procedures as determined by the investigator). * Started to take chronic medications (NSAIDs, antihistamines, etc.) at least 30 days prior to starting study medication. * Subject's medical history includes: * Cancer that is currently undergoing treatment. * Current systemic or ongoing skin infection. * HIV/AIDS. * Non-EBS skin disease (e.g., psoriasis, atopic dermatitis, etc.), or condition (e.g., sunburn) that, in the opinion of the investigator, might put the subject at undue risk by study participation or interferes with the study medication application or the study assessments. * An illness (e.g., neurological, cardiovascular, respiratory, hepatic, renal, or metabolic disease), condition, or situation that in the opinion of the principal investigator is likely to interfere with the subject's participation in or completion of the study. * Factors present in the subject and/or his/her legal representative that could interfere with study compliance such as inability to attend scheduled study visits or to perform study protocol procedures. * Subject is a member of the investigational team or his/her immediate family. * Other unspecified reasons that, in the opinion of the Investigator, make the subject unsuitable for enrollment.