PHOENIX – after only one treatment, according to preliminary results of an ongoing prospective trial that compared several treatment modalities.
“Neurofibromatosis type 1 is the most common single-gene disease of mankind, but there is so much we have yet to learn about it,” study author Patricia Richey, MD, who practices Mohs surgery and cosmetic dermatology in Washington, D.C., said in an interview in advance of the annual conference of the American Society for Laser Medicine and Surgery, where she presented the results during an abstract session. Dr. Richey also conducts research for the Wellman Center for Photomedicine and the Dermatology Laser and Cosmetic Center at Massachusetts General Hospital, Boston, and is working with R. Rox Anderson, MD, director of the Wellman Center, on this project. In his words, she said, “the lack of better treatments for cNF is a ‘problem worth solving.’ ”
Dr. Patricia Richey
“The accepted and widely available treatments for cNF result in scars and hypopigmentation. Our treatments do not,” she added. Since the epidermis overlying cNF is normal, “there is no reason to use nonselective or surgical methods and destroy a perfectly good epidermis when you don’t need to.”
Four treatments vs. controls
For the study, Dr. Richey and colleagues enrolled 19 adults with a total of 307 cNFs measuring 2-4 mm in size to receive one of four treatments: electrocautery with an insulated radiofrequency needle; 755-nm alexandrite laser with negative pressure (8-mm spot size, 100 J/cm2 fluence, 3-ms pulse duration); 980-nm diode laser (delivered via 8-mm sapphire skin-contact window), and intratumoral injection of 10 mg/mL deoxycholic acid at a volume approximately equal to that of the tumor. The average age of the participants was 49 years and 15 were female.
The investigators applied 5% lidocaine/prilocaine for 40 minutes to treatment sites before randomizing the tumors to treatment or to the control arm (no treatment). They compared safety, tolerability (including pain scores), and efficacy of each modality as measured by the change in cNF volume/height via three-dimensional imaging and clinical improvement via physician assessment at 6 months. All 19 participants have completed the 6-month assessment.
All modalities reduced or eliminated some of the cNFs by 6 months after treatment, with statistically significant reductions in height and volume across all four treatments. A wide variation of responses was observed. Specifically, the mean tumor volume changes for each modality, compared with controls, were –33.4% versus –5.1% among those treated with the 755-nm alexandrite laser; –24.9% versus –9.2% among those treated with the 980-nm diode laser, –23.3% versus –0.8% among those treated with insulated-needle radiofrequency coagulation, and –29.4% versus –3.7% among those treated with deoxycholic acid.
The variation in responses “may be due to histologic diversity of cNF or may indicate a need for more fine-tuned dosimetry, or a combination,” Dr. Richey said. “Our future trials will address this. We will also be treating all skin types in our upcoming trials.”
No adverse events categorized as higher than grade 2 occurred in any of the treatment groups, and no signs of regrowth or growth stimulation have been observed to date.
Tolerability of treatments
As for general tolerability, the 980-nm laser treatment caused moderate to severe pain; the alexandrite laser caused mild pain; insulated-needle radiofrequency coagulation caused mild pain, though more than deoxycholic acid injections or alexandrite laser, and pain associated with the deoxycholic acid injections was minimal.
When residual neurofibroma tumor was present histologically, its appearance was similar to that of untreated tumors in controls. There was no evidence of atypia, mitosis, or tumor inflammation, and mild fibrosis was present at the sites of prior tumor.
“It was surprising that all four modalities did work to some extent,” Dr. Richey said, noting that the lack of ulceration with deoxycholic acid injection “was pleasantly surprising.” Treatment with the 980-nm diode laser “was a bit more painful than we anticipated.”
The positive results of this trial has raised “more questions for us to answer. We have three additional trials in the works to fine tune these treatments and optimize dose/delivery, with the end goal of treating younger people.”
Dr. Richey said that she was “amazed” by how motivated the enrollees were to participate in the trial, noting that many patients with cNF undergo general anesthesia to have dozens of tumors surgically removed at once. “They pay $10,000-$20,000 on average out of pocket, as this surgery is considered cosmetic,” she said.
Dr. Jeffrey S. Dover
“This very important study could lead to effective, relatively noninvasive, therapy for small neurofibromas,” said Jeffrey S. Dover, MD, codirector of SkinCare Physicians in Chestnut Hill, Mass., who was not involved with the study and was asked to comment on the results.
“Remarkably, all four treatments worked to varying degrees, but of all the treatments, the selective alexandrite laser appeared to achieve the best results. Further study will be needed to see just how effective these treatments are, and to determine the best and safest treatment parameters. Given how common this autosomal dominant disease is, and how disfiguring neurofibromas become as they enlarge, a well-tolerated noninvasive nonsurgical treatment with limited side effects is highly sought after.”
The study, which was named the best clinical abstract at the meeting, was supported by the Neurofibromatosis Therapeutic Acceleration Program. Dr. Anderson is supported in part as the Lancer Endowed Chair in Dermatology at MGH. Dr. Dover reported having no relevant disclosures.