Acne vulgaris, or acne, is one of the most prevalent diseases worldwide, with skin conditions being one of the top causes of years lived with disability and non-fatal disease burden. Despite being one of the most prevalent diseases worldwide, the most widely used treatments in acne have changed little in the past 30 years. To date there is still no effective treatment that can prevent and cure this disease. The currently available acne therapies have been discovered several decades ago, and almost no progress was made in developments of novel, breakthrough treatment approaches.

The present randomized, placebo-controlled, dose escalation, Phase 1 trial (ORI-101-PAC) is intended to investigate the safety, tolerability and immunogenicity of an acne vulgaris vaccine (ORI-A-ce001) at three different dose levels in subjects aged ≥18 years suffering from moderate facial acne vulgaris who are otherwise healthy. The present study will also generate preliminary data on efficacy (inflammatory and non-inflammatory acne lesion counts, acne severity), immunogenicity and functionality of the vaccine, as well as a possible impact on skin microbiome composition. Control groups receiving placebo are included. Data from this trial will be used to inform the design of future studies.

Inclusion Criteria: - Male or female subject aged ≥18 years at the time of informed consent signature

• Female subjects of childbearing potential must have a negative serum or urine pregnancy test at Screening and before vaccination and must be willing to practice a highly effective method of contraception during the study
• Subject with a clinical diagnosis of moderate facial acne vulgaris (grade 3 on a 5-grade IGA scale) at Baseline Visit
• Subject must have a maximum of 40 non-inflammatory acne lesions (open and closed comedones) and between a minimum of 20 and a maximum of 70 inflammatory acne lesions (papules and pustules) and a maximum of 1 nodulocystic lesion (nodules and cysts) on the face (e.g., forehead, nose, cheeks, chin, upper lip) at Baseline Visit
• Negative Covid test at Baseline Visit Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply:
• Subject who is pregnant, lactating or is planning a pregnancy during the study period
• Subject who has active nodulocystic acne, acne conglobata, acne fulminans, secondary acne or other forms of acne
• Subject who has more than one facial nodules/cysts (where nodule/cyst is defined as an inflammatory lesion greater than or equal to 0.5 cm in size with or without cystic changes)
• Subject who has any skin pathology or condition that, in the Investigator's opinion, could interfere with the evaluation of the Investigational Medicinal Product (IMP) or requires use of interfering topical, systemic, or surgical therapy
• Subject with excessive facial hair, facial skin disorders, skin reactions that may interfere with the study assessments in the Investigator's opinion or skin infection
• History of Guillain-Barré-Syndrome
• Subject who has used any acne-affecting treatment without an appropriate washout period
• Subject who receives active or passive vaccination within 30 days prior to Baseline - Visit Initiation or change of hormonal contraceptive use within 12 weeks prior to Screening Visit

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org