The purpose of this study is assess the safety and tolerability of lemuteporfin topical solution (LTS) with exposure to red light (PDT), when applied to the backs of healthy volunteers.

This is an open-label, safety study in healthy volunteers. Two cohorts, of 6 subjects each, will be enrolled (total subjects = 12). Each subject will have test areas identified on the back and receive a single LTS, vehicle solution and red light (PDT) applied to the test areas on the back. Subjects will be followed for safety at study visits occurring on Day 1 (baseline and treatment), Day 2, and Day 7.

Inclusion Criteria:

1. Healthy adults 18 years of age or older
2. Fitzpatrick skin types I-IV

Exclusion Criteria:

1. Current pregnancy or lactation.
2. Presence of severe facial acne, acne fulminans or conglobata, or nodulocystic acne.
3. Poor skin condition on the back, including erythema, dryness, sunburn, dermatological malignancies, infections, cuts, abrasions, tattoo, excess of hair or any other skin condition
4. Subjects who have used any agents known to produce significant photosensitivity reactions (tetracyclines, phenothiazines, trimethoprim, etc.) within 2 weeks of Day 1 or 5 half-lives, whichever is longer.
5. Subjects who have used any medicated topical therapy on the back within 3 days of Day 1.
6. Chronic treatment with low dose aspirin, a non-steroidal anti inflammatory drug (NSAID), or an anticoagulant regimen such as warfarin (Coumadin).
7. Abnormal findings on screening ECG deemed clinically significant by the Investigator.
8. Active participation in an experimental therapy study or experimental therapy within 30 days of Day 1.
9. Screening clinical chemistry or hematology laboratory value that is considered clinically significant, in the opinion of the Investigator.
10. Subjects who are a poor medical risk because of other systemic diseases or active uncontrolled infections.