Modulation of γ-secretase activity holds potential for the treatment of Alzheimer’s disease. Most NSAID-derived γ-secretase modulators feature a carboxylic acid, which may impair blood–brain barrier permeation. The structure activity relationship of 33 carbazoles featuring diverse carboxylic acid isosteres or metabolic precursors thereof was established in a cellular amyloid secretion assay. The modulatory activity was observed for acidic moieties and metabolically labile esters only, which supports our hypothesis of an acid-lysine interaction to be relevant for this type of γ-secretase modulators.