Photodynamic therapy serves many medical, aesthetic purposes

Las Vegas - The safety and versatility of photodynamic therapy (PDT) make it a worthwhile addition for dermatologists not yet providing this treatment, according to Amy Forman Taub, M.D., who spoke at the 2011 annual meeting of the American Society of Cosmetic Dermatology and Aesthetic Surgery.

For starters, Dr. Taub says PDT provides a nonablative treatment option for severe photodamage. "Instead of using a fractional CO₂ laser to get rid of a patient's brown, mottled skin that's also a bit wrinkly and dull, PDT can provide very good result with less downtime," she says.

Short of ablative or nonablative fractional treatments, PDT is the best option for such patients, says Dr. Taub, who is assistant clinical professor of dermatology at Northwestern University Medical School, Chicago, and medical director of Advanced Dermatology, Lincolnshire, Ill.

"It's also one of the best treatments - if not the best treatment - for reduction of pore size," a common concern among patients, she says. Although there is debate regarding whether aesthetic treatments can indeed shrink pore size, "PDT makes pores appear smaller."

Additionally, she says she considers PDT the best procedural treatment for acne. In fact, "PDT is one of the most underutilized acne treatments in the United States." Because it's not covered by insurance, "It's expensive. And it's tough to get teenagers to stay indoors for two days after treatment," she adds.

PDT causes 48 hours of photosensitivity, "And with PDT, patients are more likely to have downtime than if they underwent traditional intense pulsed light (IPL) treatments without it," Dr. Taub says. "Patients might have some redness that's more prolonged, or eyen some crusting or a burning sensation." Such downtime if it occurs typically lasts two to three days, she says. "But if there's a lot of photodamage, or the patient doesn't follow postprocedural instructions to avoid sunlight, downtime can last up to a week."

PDT is also useful for sebaceous gland hyperplasia, which is very difficult to treat, Dr. Taub says. Somewhat similarly, she says that for the small subset of patients with an oily form of rosacea, "I've found that PDT works better than anything. These patients don't seem to respond to typical rosacea medications. Even with laser by itself, I've found that they don't always respond. Yet when you perform a laser treatment with PDT, they seem to do extremely well."

Along with treating nonmelanoma skin cancers, some literature suggests that PDT can prevent development of skin cancers (Willey A, Mehta S, Lee PK. Dermatol Surg. 2010;36(5):652-658).

Furthermore, Dr. Taub says that whatever the indication, most dermatologists need not buy extra equipment to perform PDT.

“Many dermatologists already have an intense pulsed light device, for instance. IPL works very well for most PDT indications, probably better than blue or red light alone," she says.

Clinical studies
A clinical trial has shown that PDT performed with IPL and Levulan (aminolevulinic acid HCl/ALA, DUSA) achieved statistically significant improvements over IPL alone in all parameters used to measure photodamage, Dr. Taub says (Gold MH, Bradshaw VL, Boring MM, et al. Dermatol Surg. 2006;32(6):795-801; discussion 801-803). In particular, she says, IPL-PDT provided superior improvement in crows' feet, skin roughness, mottled hyperpigmentation, telangiectasias and response of actinic keratoses (AKs) to treatment.

Other research performed with Metvixia (methyl aminolevulinate/MAL, Galderma) and red light has shown that PDT produces dermal changes that induced collagen production (Choi JY, Park GT, Na EY, et al. J Dermatol Sci. 2010;58(3):198-203. Epub 2010 Apr 4). In this study, she says, mice that underwent PDT with red light and hexaminyl levulinate showed immediate increases in inflammatory factors in the skin, and long-term promotion of collagen production.

"That may account for some of the improvements we're seeing clinically," she says.

Overall, Dr. Taub says that in her experience, IPL-PDT works best for rejuvenation and acne treatments. Conversely, "I believe that blue light is best for medical indications such as AKs. Pulsed dye laser works for acne, oily rosacea or sebaceous gland hyperplasia," she says.

Allumera update
As for the new photosensitizer Allumera (hexyl aminolevulinate HCl, Photocure), Dr. Taub says physicians should use red light because that's the light source used in its pivotal Food and Drug Administration trials. Dr. Taub says she tried Allumera with blue light on one of her employees, "And she had a reaction that lasted three weeks. Blue light offers much higher efficacy in terms of photosensitizer activation, even though it doesn't penetrate as deeply."

Moreover, Dr. Taub says that although she has seen modest-to-moderate cosmetic improvement achieved by Allumera and red light in photos of patients treated with this regimen, "In my opinion, it's not something we should start experimenting with in terms of treating AKs.

Allumera was not FDA-approved as a drug - it’s a cosmeceutical," so it faced less stringent FDA requirements.

Procedural details
For ALA-PDT in her office, Dr. Taub says, “We first cleanse the skin with a Clarisonic (Clarisonic Inc.) brush. Then we use an acetone scrub" with a cleaning pad that slightly roughs up the patient's skin. "After that, I lightly wipe the acetone off with alcohol," so that the cleaner doesn't interfere with the drug's activity.

"Then we apply the photosensitizer. For photorejuvenation, usually we incubate for 30 minutes," she says. "Then we use IPL, at the normal settings we would use for the patient's skin type if we were just doing photorejuvenation without ALA." As such, "IPL is not indicated for skin types five or six. For those, you would need to use blue or red light."

A typical ALA-PDT treatment cycle consists of three treatments spaced one month apart, she adds. To treat acne, Dr. Taub uses water-based microdermabrasion before performing PDT as described above.

Improving PDT results requires increasing either the concentration or the absorption of the photosensitizer, Dr. Taub says. In the former area, researchers applied ALA to the entire face of 10 patients with acne, then treated one side with infrared light for 15 minutes before irradiating the entire face with red light. On the infrared-treated side, she says, "Patients on average achieved a 73 percent reduction in acne after one treatment with ALA, infrared and red light (Barolet D, Boucher A. Lasers Surg Med. 2010;42(2):171-178).”

Heating the skin, as infrared light does, is believed to increase the production of protoporphyrin IX, thereby producing more yield per patient, Dr. Taub says. Taking this idea one step further, she says it might be worth investigating the efficacy of applying infrared light before blue or red light, which work for acne on their own, without any photosensitizer. This way, "Maybe we would get better results than with blue or red light by themselves, and we wouldn't need the photosensitizer," which could make treatment easier for teenagers, she says.

Microneedling
Dr. Taub says microneedling can increase photosensitizer absorption. "The idea is that you're basically puncturing holes in the epidermis to increase absorption of the ALA. But you're not puncturing far enough into the dermis that you're causing pain or bleeding."

In a proof-of-concept study, investigators performed microneedling with a 0.3 mm-long needle before applying ALA. After an hour of incubation, UV photography showed uniform fluorescence; subsequent treatments with IPL plus red light and broadband pulsed light achieved very impressive results in all parameters measured (Clementoni MT, B-Roscher M, Munavalli GS. Lasers Surg Med. 2010;42(2):150-159).

Accordingly, Dr. Taub says microneedling could increase the effectiveness of each treatment and possibly reduce the number of treatments required.

"We're starting to use microneedling in our clinic. But it results in a little more downtime, perhaps up to a week," she says. In traditional PDT, abnormal tissue preferentially absorbs photosensitizers. "Now we're talking about absorption through the entire skin."

However, Dr. Taub says that in her experience, microneedling provides better and more even rejuvenation. "And even if a patient had AKs, you might have a higher yield," she says. "Most studies show patients can achieve 80 percent to 90 percent improvement in AKs after two treatments. If you could get 95 percent improvement after one treatment, even with a little more downtime, that would be great," though it hasn't been proven.

Disclosures: Dr. Taub has been a consultant and clinical researcher for DUSA. She currently has an article in press at Cosmetic Dermatology.