Mild skin photosensitivity in cancer patients following injection of Photochlor (2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a; HPPH) for photodynamic therapy.
OBJECTIVE
To measure skin photosensitivity in cancer patients infused with the new second-generation photodynamic sensitizer Photochlor (2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a). A major disadvantage of using the clinically approved photosensitizer Photofrin is potentially prolonged and sometimes severe cutaneous phototoxicity.


METHODS
Forty-eight patients enrolled in Phases 1 and 2 clinical trials underwent two or more exposures to four graded doses (44.4, 66.6, 88.8 or 133.2 J/cm2) of artificial solar-spectrum light (SSL) before and after administration of Photochlor at a dose of 2.5, 3, 4, 5 or 6 mg/m2 .


RESULTS
The most severe skin response, experienced by only six of the subjects, was limited to erythema without edema and could only be elicited by exposure to the highest light dose. Conversely, eight subjects had no discernible reaction to SSL at any light dose. For nearly all the patients, the peak skin response was obtained when the interval between sensitizer injection and exposure to SSL was 1 day and, generally, their sensitivity to SSL decreased with increasing sensitizer-light interval. For example, a 2-day sensitizer-SSL interval resulted in less severe reactions than those obtained with the 1-day interval in 79% of the subjects, while 90% of the subjects exposed to SSL 3 days after Photochlor infusion had responses that were less severe than those obtained with either the 1- or 2-day sensitizer-SSL interval.


CONCLUSIONS
Photochlor, at clinically effective antitumor doses, causes only mild skin photosensitivity that declines rapidly over a few days.
Department of Cell Stress Biology (Photodynamic Therapy Center), Roswell Park Cancer Institute, Buffalo, NY 14263, USA. david.bellnier@roswellpark.org
David A
DA
Bellnier
William R
WR
Greco
Hector
H
Nava
Gregory M
GM
Loewen
Allan R
AR
Oseroff
Thomas J
TJ
Dougherty
D017323:Dihematoporphyrin Ether / Q000009:adverse effects* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000188:drug therapy*; D010778:Photochemotherapy; D010787:Photosensitivity Disorders / Q000139:chemically induced*; D017319:Photosensitizing Agents / Q000009:adverse effects* / Q000627:therapeutic use; D012867:Skin / Q000187:drug effects / Q000528:radiation effects; D014466:Ultraviolet Rays
D017319:Photosensitizing Agents; D017323:Dihematoporphyrin Ether