The Psoriasis Area and Severity Index Score (PASI) is a physician assessment that combines the assessment of the severity of and area affected by psoriasis into a single score in the range 0 (no disease) to 72 (maximal disease).The efficacy of EDP1815 will be measured using the mean percentage change in PASI from baseline to week 16.

The Psoriasis Area and Severity Index Score (PASI) is a physician assessment that combines the assessment of the severity of and area affected by psoriasis into a single score in the range 0 (no disease) to 72 (maximal disease). The efficacy of EDP1815 will be measured using the mean percentage change from baseline in PASI from baseline at weeks 4, 8, and 12.

The Psoriasis Area and Severity Index Score (PASI) is a physician assessment that combines the assessment of the severity of and area affected by psoriasis into a single score in the range 0 (no disease) to 72 (maximal disease). The efficacy of EDP1815 will be measured using the mean absolute change from baseline in PASI from baseline at weeks 4, 8, 12, and 16.

The efficacy of EDP1815 will be measured using the achievement of PASI-50 at weeks 4, 8, 12, and 16. PASI-50 is defined by at least a 50% reduction from baseline in the PASI score.

The efficacy of EDP1815 will be measured using the time to first achievement of PASI-50

The efficacy of EDP1815 will be measured using the achievement of PASI-75 at week 16. PASI-75 response is defined by at least a 75% reduction from baseline in the PASI score.

The efficacy of EDP1815 will be measured using the achievement of PASI-90 at week 16.PASI-90 response is defined by at least a 90% reduction from baseline in the PASI score.

The efficacy of EDP1815 will be measured using the achievement of PASI-100 at week 16. PASI-100 response is defined as achieving a complete resolution of all disease.

The efficacy of EDP1815 will be measured using the achievement of PGA of 0 or 1 with a ≥2-point improvement from baseline at Week 16 [PGA = Physician's Global Assessment]. The National Psoriasis Foundation Psoriasis Score version of a PGA is calculated by averaging the total body erythema, induration, and desquamation scores. Erythema, induration, and desquamation will be scored on a 6-point scale, ranging from 0 (clear) to 5 (severe): the total PGA score is defined as the average of the erythema, induration, and desquamation scores. PGA score of 0 or 1 is defined as clear or almost clear of psoriasis.

The efficacy of EDP1815 will be measured using the achievement of PGA of 0 at Week 16 [PGA = Physician's Global Assessment]. The National Psoriasis Foundation Psoriasis Score version of a PGA is calculated by averaging the total body erythema, induration, and desquamation scores. Erythema, induration, and desquamation will be scored on a 6-point scale, ranging from 0 (clear) to 5 (severe): the total PGA score is defined as the average of the erythema, induration, and desquamation scores. PGA score of 0 or 1 is defined as clear or almost clear of psoriasis. A PGA 0 is defined as clear or no signs of psoriasis.

[PGA = Physician's Global Assessment, BSA = Body Surface Area]. The National Psoriasis Foundation Psoriasis Score version of a static Physicians Global Asessment (PGA) is calculated by averaging the total body erythema, induration, and desquamation scores. Erythema, induration, and desquamation will be scored on a 6-point scale, ranging from 0 (clear) to 5 (severe): the total PGA score is defined as the average of the erythema, induration, and desquamation scores.

Body surface area (BSA) measures the total area of the body affected by psoriasis. Psoriasis that occurs on less than 5 percent of the BSA is considered mild to moderate psoriasis. Psoriasis affecting more than 5 percent of the BSA is considered moderate to severe psoriasis.

The efficacy of EDP1815 will be measured using the mean percentage change from baseline in PGA x BSA at Weeks 4, 8, 12, and 16.

[PGA = Physician's Global Assessment, BSA = Body Surface Area]. The National Psoriasis Foundation Psoriasis Score version of a static Physicians Global Asessment (PGA) is calculated by averaging the total body erythema, induration, and desquamation scores. Erythema, induration, and desquamation will be scored on a 6-point scale, ranging from 0 (clear) to 5 (severe): the total PGA score is defined as the average of the erythema, induration, and desquamation scores.

Body surface area (BSA) measures the total area of the body affected by psoriasis. Psoriasis that occurs on less than 5 percent of the BSA is considered mild to moderate psoriasis. Psoriasis affecting more than 5 percent of the BSA is considered moderate to severe psoriasis.

The efficacy of EDP1815 will be measured using the mean absolute change from baseline in PGA x BSA at Weeks 4, 8, 12, and 16.

The LSS is used to score the severity of psoriasis plaques. The dimensions of scaling, erythema, and plaque elevation are each scored on a scale from 0 (clear) to 4 (very severe), and the total LSS is the numerical sum of the 3-dimensional scores. The efficacy of EDP1815 will be measured using the mean percentage change from baseline in LSS (Lesion Severity Score) at Weeks 4, 8, 12, and 16.

The LSS is used to score the severity of psoriasis plaques. The dimensions of scaling, erythema, and plaque elevation are each scored on a scale from 0 (clear) to 4 (very severe), and the total LSS is the numerical sum of the 3-dimensional scores.The efficacy of EDP1815 will be measured using the mean absolute change from baseline in LSS (Lesion Severity Score) at Weeks 4, 8, 12, and 16.

The DLQI is a patient reported outcomes instrument for assessing the impact of dermatologic conditions on patients' quality of life. The higher the score the more the impact on quality of life. The efficacy of EDP1815 will be measured using mean percentage change from baseline in Dermatology Life Quality Index (DLQI) at Weeks 4, 8, 12, and 16.

The DLQI is a patient reported outcomes instrument for assessing the impact of dermatologic conditions on patients' quality of life. There are 10 questions each scored 0-3, the higher the score the more the impact on quality of life (Total score range 0-30; 0 = no impact, 30 = greatest impact).The efficacy of EDP1815 will be measured using the mean absolute change from baseline in Dermatology Life Quality Index (DLQI) at Weeks 4, 8, 12, and 16

The mNAPSI is a tool for physicians to evaluate the severity of nail bed psoriasis and nail matrix psoriasis by area of involvement in the nail unit. The higher the score the more severe the nail bed psoriasis. The efficacy of EDP1815 will be measured using the mean percentage change in mNAPSI total score (modified Nail Psoriasis Severity Index) from baseline at Weeks 4, 8, 12, and 16

The mNAPSI is a tool for physicians to evaluate the severity of nail bed psoriasis and nail matrix psoriasis by area of involvement in the nail unit. Each fingernail is rated for the presence and severity of seven features to give a total fingernail score of 0-13 (0= no involvement, 13 = greatest involvement). The total mNAPSI score is the sum of the 10 fingernail scores (range 0-130; 0= no involvement, 130= greatest involvement).The higher the score the more severe the nail bed psoriasis. The efficacy of EDP1815 will be measured using the mean absolute change in mNAPSI total score (modified Nail Psoriasis Severity Index) from baseline at Weeks 4, 8, 12, and 16

The efficacy of EDP1815 will be measured by calculating the cumulative incidence of partial relapse at Weeks 20, 24, 28, and 40 for participants who were classified as responders at week 16. Partial relapse is defined as a loss of the PASI-50 response after week 16 and after cessation of study treatment, or commencing a new treatment for psoriasis.

The efficacy of EDP1815 will be measured by calculating the cumulative incidence of complete relapse at Weeks 20, 24, 28, and 40 in participants who were considered as responders at week 16. Relapse is defined as an increase in the severity of the psoriasis as measured by PASI to the baseline value or greater, or commencement of a new treatment for psoriasis.

The efficacy of EDP1815 will be measured by calculating the cumulative incidence of rebound at Weeks 20, 24, 28, and 40 in participants with at least one PASI assessment after the end of treatment. Rebound is defined as an increase in the severity of the psoriasis as measured by PASI to 125% of baseline score or above, or onset of new pustular/erythrodermic psoriasis, within 3 months of cessation of study treatment.