A Study of NGM621 in Participants With Geographic Atrophy

Geographic atrophy lesion area was measured by a non-invasive imaging technique called fundus autofluorescence (FAF). FAF refers to the spontaneous emission of light by certain substances within the eye when exposed to a specific wavelength of light and involves quantifying the area and progression of atrophic lesions. The minimal GA lesion area is zero, the maximal GA lesion area is unknown. The higher the GA lesion area, the worse the visual outcome.

Geographic atrophy lesion area was measured by fundus autofluorescence (FAF). FAF refers to the spontaneous emission of light by certain substances within the eye when exposed to a specific wavelength of light and involves quantifying the area and progression of atrophic lesions.

Best Corrected Visual Acuity Score is the best possible vision an eye can achieve with corrective lenses, typically glasses or contact lenses. BCVA was assessed by the Early Treatment of Diabetic Retinopathy Study (ETDRS) chart at a starting distance of 4 meters. ETDRS letter score is calculated when >20 letters are read correctly at 4.0 meters; the visual acuity letter score is equal to the total number of letters read correctly at 4.0 meters plus 30. If <20 letters are read correctly at 4.0 meters, the visual acuity letter score is equal to the total number of letters read correctly at 4.0 meters (number of letters recorded on line 1.0), plus the total number of letters in the first six lines read correctly at 1.0 meter. Therefore, the ETDRS letter score could result in a score of 0-100, where lower scores indicate better vision.

The change from baseline in BCVA is being report with negative scores indicating an improvement in vision.

Low Luminance Visual Acuity Score measures vision in low-light conditions. It was assessed by the Early Treatment of Diabetic Retinopathy Study (ETDRS) chart at a starting distance of 4 meters.

ETDRS letter score is calculated when >20 letters are read correctly at 4.0 meters; the visual acuity letter score is equal to the total number of letters read correctly at 4.0 meters plus 30. If <20 letters are read correctly at 4.0 meters, the visual acuity letter score is equal to the total number of letters read correctly at 4.0 meters (number of letters recorded on line 1.0), plus the total number of letters in the first six lines read correctly at 1.0 meter. Therefore, the ETDRS letter score could result in a score of 0-100, where lower scores indicate better vision.

A lower (negative) LLVA score compared to baseline indicates a decline in visual acuity. A higher (positive) LLVA score compared to baseline indicates an improvement in visual acuity.

Low Luminance Deficit (LLD) Score was assessed by the Early Treatment of Diabetic Retinopathy Study (ETDRS) letters at a starting distance of 4 meters. ETDRS letter score is calculated when >20 letters are read correctly at 4.0 meters; the visual acuity letter score is equal to the total number of letters read correctly at 4.0 meters plus 30. If <20 letters are read correctly at 4.0 meters, the visual acuity letter score is equal to the total number of letters read correctly at 4.0 meters (number of letters recorded on line 1.0), plus the total number of letters in the first six lines read correctly at 1.0 meter. Therefore, the ETDRS letter score could result in a score of 0-100, where lower scores indicate better vision.

A LLD is the difference between standard visual acuity and LLVA, with a LLD >13 ETDRS letters suggesting potential visual abnormality. The change from baseline in LLD is being report with negative scores indicating an improvement in vision.

Average binocular reading speed was assessed by Minnesota Low-Vision Reading Test (MNRead) or Radner reading charts. The change from baseline in average binocular reading speed is reported with a higher (positive) reading speed (wpm) indicates better reading ability, while a lower (negative) reading speed indicates poorer reading ability.

Binocular critical print size was assessed by the Minnesota Low-Vision Reading Test (MNRead) or Radner reading charts. MNRead uses a logarithmic scale (LogMAR) to represent print sizes, with each step representing a 0.1 LogMAR difference. The chart ranges from +1.3 LogMAR (equivalent to 20/400 at 40 cm) to -0.5 LogMAR (equivalent to 20/6 at 40 cm). The change from baseline in binocular critical print size is being reported with a higher (positive) LogMAR value for critical print size indicating that a person needs larger print sizes to maintain their maximum reading speed, while a lower (negative) LogMAR value indicates that they can read smaller print sizes at their maximum speed.

Binocular reading acuity was assessed by the Minnesota Low-Vision Reading Test (MNRead) or Radner reading charts. MNRead uses a logarithmic scale (LogMAR) to represent print sizes, with each step representing a 0.1 LogMAR difference. The chart ranges from +1.3 LogMAR (equivalent to 20/400 at 40 cm) to -0.5 LogMAR (equivalent to 20/6 at 40 cm). Binocular reading acuity is the smallest print size (in LogMAR) that a person can read easily and accurately. The change from baseline in binocular reading acuity is being reported with a higher LogMAR value for reading acuity indicates poorer reading ability, while a lower LogMAR value indicates better reading ability.

The Functional Reading Independence (FRI) Index Composite Score is a 7-item patient questionnaire developed to evaluate the effect of geography atrophy on a patient's ability to independently perform reading activities. The FRI Index yields mean scores ranging from 1-4, with 1=unable to do and 4=totally independent. The FRI Index composite score is calculated by averaging the item-level scores across the seven questions, higher sores indicate better FRI. The change from baseline in FRI is being reported with lower (negative) values indicating a decline in FRI.

The National Eye Institute Visual Functioning Questionnaire Composite Score is calculated by averaging the scores of the 11 vision-targeted subscales, excluding the general health rating question, on a scale of 0 to 100, with higher scores indicating better vision-related function. The change from baseline is being reported with a negative value indicating a decline in vision function.

Systemic Complement Activity is a blood test that measures the overall activity of the complement system, a group of proteins crucial for the immune system's function. Low CH50 levels can be associated with certain infections. CH50 levels of 41 to 90 hemolytic units per mL (U/mL) is considered normal. The change from baseline in CH50 is being reported.

The incidence of anti-drug antibody (ADA) was assessed in serum.