Photodynamic elimination of clonogenic Ph+ chronic myeloid leukemia cells.

Benzoporphyrin derivative (BPD) and light is a potent photosensitizer. We investigated this modality as a means to selectively eliminate clonogenic Ph(+) chronic myeloid leukemia (CML) cells. BPD at 10 ng/ml and 10.8 J/cm2 broad spectrum light eliminates from 5 to 6 logs of Ph(+) EM-2 cells. Long-term marrow culture studies of treated mixtures of normal and CML cells indicate that multipotent progenitor cell viability is retained while cells transcribing BCR-ABL are not detected. We conclude that BPD and light may offer a means of providing CML autografts potentially free of Ph(+) clonogenic cells.