Basic principle of aminolevulinic acid-mediated photodynamic therapy
Basic principle of aminolevulinic acid-mediated photodynamic therapy
The addition of exogenous aminolevulinic acid bypasses the first regulatory step (ie, feedback inhibition by heme [dashed arrow]) in the heme synthesis pathway, thereby allowing PPIX to build up to high levels. Activation of PPIX by light causes free radical-based photochemistry that ultimately kills the cancer cell.