NEWPORT BEACH, CALIF. – Offering photodynamic therapy is a smart move for any dermatology practice, but also it requires common sense. That starts with making sure you treat only appropriate candidates.
“They can’t be intimidated by the thought of light or looking red, and you have to go into depth ahead of time as far as managing reactions, as well as long-term expectations,” Neal Bhatia, MD, said at the annual meeting of the Pacific Dermatologic Association. That includes reviewing any oral medications they’re taking, as well as topical products they may be using on their face or scalp.
“I like to do this treatment on Fridays so it gives patients the weekend to stay indoors for the next 48 hours, which is really what they need to optimize the response rate,” said Dr. Bhatia, director of clinical dermatology at Therapeutics Clinical Research in San Diego. “The other part of this is managing your staff. Make sure they have enough time to check in on the patients while they’re incubating away from light, as well as to review the post-treatment plan. And make sure they have a comfortable chair. Some patients might feel claustrophobic if you lay them down and put the light above them. Others might like to lay down for the procedure versus sitting down.”
His checklist for treatment day includes a reminder for patients to bring a wide-brimmed hat to shield the treated lesions from ambient light, as well as a book, computer, or paperwork to pass the time. He also advises putting together a take-home bag for patients that includes topical anesthetics, moisturizers, and sunscreen. In his clinical experience, prior to photodynamic therapy (PDT), there is no reason for patients to discontinue medications that are sensitizing in the UV spectrum such as antibiotics, diuretics, anti-hypertensives, since PDT works in the 410-417 nm range. “If you are concerned, you can hold the drugs the day before [the procedure], the day of, and maybe the day after, but that’s really all you need,” he said.
Dr. Bhatia discussed combinations with 5-fluorouracil (5-FU) before and after PDT, imiquimod plus aminolevulinic acid–PDT (ALA-PDT), and ingenol mebutate plus ALA-PDT. Antihistamines may play a role in helping to reduce the anticipated ALA-PDT response (J Invest Dermatol. 2006;126:2296-301). Dr. Bhatia explained that the edema component is generated by mast cell release and can be uncoupled using selected H1-antihistamines, which can provide symptom relief without compromising efficacy. “Some studies talk about reducing erythema and edema based on the presence of mast cells and the surge of mast cells within first 48 to 72 hours,” he said. “Symptomatic relief is going to mean a lot to that patient who’s getting red, feeling itchy, and feeling swollen, but we don’t want to stop the reaction pattern and the efficacy by undoing what we’ve created as a response.”
It may seem counterintuitive, but direct tissue cooling after PDT appears to have a negative impact on perforin conversion, “to the point where it actually reduces the efficacy and treatment when you do direct tissue cooling,” Dr. Bhatia said. One study showed found significantly less resolution of actinic keratosis (AK) lesions treated with direct tissue cooling, compared with those who did not receive tissue cooling (J Photochem Photobiol B. 2011;103:1-7). In addition, there was a failure of conversion and optimization of the accumulated protoporphyrin IX when direct tissue cooling was used.
“That’s not to say a handheld fan or a fan in the room or aerating, making sure they have enough oxygen around the treatment area [isn’t useful],” Dr. Bhatia said. “I’m talking about the direct tissue cooling that we use with the pulsed laser device, or the Zimmer cooler. You get better conversion when you have a warming device, compared with contact cooling.”
Dr. Bhatia predicted that in the future, microneedle pre-treatment of human skin is going to gain popularity as a PDT adjunct. On early study of microneedling found that it improved 5-ALA and 5-MAL–induced protoporphyrin IX production for topical photodynamic therapy without increasing pain or erythema (Pharm Res. 2010;27:2213-20). “I think that’s very important,” he said.
Dr. Bhatia disclosed having affiliations with Biofrontera and Dusa, the two main manufacturers of PDT in the United States.