Lemuteporfin is a newly introduced, light-sensitive drug for use in combination photodynamic therapy (PDT). It acts on mitochrondria to initiate the apoptotic cascade resulting in cell death (apoptosis). The photosensitizer was highly potent, killing cells at low nanomolar concentrations upon exposure to activating light. The cellular uptake of lemuteporfin was rapid with maximum levels reached within 20 min. Mitogen-activated lymphoid cells accumulated more of the lemuteporfin than their quiescent equivalents, supporting selectivity. Lemuteporfin had been in phase II clinical trials for the treatment of benign prostatic hypertrophy. It is in phase I clinical trials for the treatment of acne rosacea.