Clinical assessment of the use of topical liquid diclofenac following laser microporation of cutaneous neurofibromas in individuals with neurofibromatosis type 1

Background

Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder with a prevalence of 1:3000 births and a wide variety of clinical manifestations. Cutaneous neurofibromas (cNF) are among the most common visible manifestations of NF1 and present a major clinical burden for patients. NF1 patients with cNF often report decreased quality of life, emotional well-being and physical comfort. Developing effective medical therapies for cNF has been identified as a priority for the majority of adults with NF1.

Methods

The study was an open, controlled and prospective proof-of-concept clinical trial. The topical treatment consisted of two steps: cNF microporation using a laser device followed by topical application of one drop of diclofenac 25 mg/mL on the surface of the cNF (T neurofibroma = treatment) or physiological saline (C neurofibroma = control) and reapplied twice daily for 3 days. Neurofibroma assessments included visual and dermatoscopy observations noting color and presence of necrosis, presence of flaccidity, measurements in two dimensions, photographs, and histopathology after excision. The primary efficacy variable was the presence of tissue necrosis. The primary safety variable was the occurrence of treatment-related adverse events.

Results

Six patients were included in the study. The treatment resulted in transitory topical changes (healing of the microporation grid with formation of scintillating tissue layer, hyperemia and desquamation), with no statistically significant variation in the dimensions of the T and C neurofibromas in relation to pretreatment measurements. There was no necrosis in the T or C neurofibromas. In the histopathological analysis, there was no significant difference in the distribution of chronic (lymphocytic) inflammatory infiltrate in the papillary reticular dermis (subepithelial), type of infiltrate (diffuse, perivascular, or both), presence of fibrosis, and presence of atrophy among the T and C neurofibromas. No adverse events attributable to the use of diclofenac were reported during the treatment period.

Conclusions

Treatment did not result in significant alterations in terms of presence of tissue necrosis, size, or histopathological features in the T neurofibromas or in comparison to the C neurofibromas. Topical diclofenac with laser microporation was well-tolerated, with no adverse events attributable to diclofenac reported. Whether these observations are due to minimal systemic and neurofibroma exposure remain to be explored in dosage studies with larger patient groups.

Trial registration

ClinicalTrials.gov (NCT03090971) retrospectively registered March 27, 2017.

Laser irradiation of ocular tissues to enhance drug delivery

Scleral and corneal membranes represent substantial barriers against drug delivery to the eye. Conventional hypodermic needles-based intraocular injections are clinically employed to overcome these barriers. This study, for the first time, investigated a non-invasive alternative to intraocular injections by laser irradiation of ocular tissues. The P.L.E.A.S.E.® laser device was applied on excised porcine scleral and corneal tissues, which showed linear relationships between depths of laser-created micropores and laser fluences at range 8.9-444.4 J/cm². Deeper and wider micropores were observed in scleral relative to corneal tissues. The permeation of rhodamine B and fluorescein isothiocyanate (FITC)-dextran were investigated through ocular tissues at different laser parameters (laser fluences 0-44.4 J/cm² and micropore densities 7.5 and 15%). Both molecules showed enhanced permeation through ocular tissues on laser irradiation. Maximum transscleral permeation of the molecules was attained at laser fluence 8.9 J/cm² and micropore density 15%. Transcorneal permeation of rhodamine B increased with increasing either laser fluence or micropore density, while that of FITC-dextran was not affected by either parameter. The transscleral water loss increased significantly after laser irradiation then returned to the baseline values within 24 h, indicating healing of the laser-created micropores. Laser irradiation is a promising technique to enhance intraocular delivery of both small and large molecule drugs.

Laser-assisted skin delivery of immunocontraceptive rabies nanoparticulate vaccine in poloxamer gel

A painless skin delivery of vaccine for disease prevention is of great advantage in improving compliance in patients. To test this idea as a proof of concept, we utilized a pDNA vaccine construct, pDNAg333-2GnRH that has a dual function of controlling rabies and inducing immunocontraception in animals. The pDNA was administered to mice in a nanoparticulate form delivered through the skin using the P.L.E.A.S.E.® (Precise Laser Epidermal System) microporation laser device. Laser application was well tolerated, and mild skin reaction was healed completely in 8 days. We demonstrated that adjuvanted nanoparticulate pDNA vaccine significantly upregulated the expression of co-stimulatory molecules in dendritic cells. After topical administration of the adjuvanted nano-vaccine in mice, the high avidity serum for GnRH antibodies were induced and maintained up to 9 weeks. The induced immune response was of a mixed Th1/Th2 profile as measured by IgG subclasses (IgG2a and IgG1) and cytokine levels (IFN-γ and IL-4). Using flow cytometry, we revealed an increase of CD8+ T-cells and CD45R B cells upon the administration of the adjuvanted vaccine. Our previous study used the same pDNA nanoparticulate vaccine through an IM route, and a comparable immune response was induced using P.L.E.A.S.E. However, the vaccine dose in the current study was four-fold less than what was applied through the IM route.We concluded that laser-assisted skin vaccination has a potential of becoming a safe and reliable vaccination tool for rabies vaccination in animals or even in humans for pre- or post-exposure prophylaxis.

Synergistic effects of dendritic cell targeting and laser-microporation on enhancing epicutaneous skin vaccination efficacy

Due to its unique immunological properties, the skin is an attractive target tissue for allergen-specific immunotherapy. In our current work, we combined a dendritic cell targeting approach with epicutaneous immunization using an ablative fractional laser to generate defined micropores in the upper layers of the skin. By coupling the major birch pollen allergen Bet v 1 to mannan from S. cerevisiae via mild periodate oxidation we generated hypoallergenic Bet-mannan neoglycoconjugates, which efficiently targeted CD14⁺ dendritic cells and Langerhans cells in human skin explants. Mannan conjugation resulted in sustained release from the skin and retention in secondary lymphoid organs, whereas unconjugated antigen showed fast renal clearance. In a mouse model, Bet-mannan neoglycoconjugates applied via laser-microporated skin synergistically elicited potent humoral and cellular immune responses, superior to intradermal injection. The induced antibody responses displayed IgE-blocking capacity, highlighting the therapeutic potential of the approach. Moreover, application via micropores, but not by intradermal injection, resulted in a mixed TH1/TH17-biased immune response. Our data clearly show that applying mannan-neoglycoconjugates to an organ rich in dendritic cells using laser-microporation is superior to intradermal injection. Due to their low IgE binding capacity and biodegradability, mannan neoglycoconjugates therefore represent an attractive formulation for allergen-specific epicutaneous immunotherapy.

Transcutaneous delivery of CpG-adjuvanted allergen via laser-generated micropores

BACKGROUND

Two main shortcomings of classical allergen-specific immunotherapy are long treatment duration and low patient compliance. Utilizing the unique immunological features of the skin by transcutaneous application of antigen opens new approaches not only for painless vaccine delivery, but also for allergen-specific immunotherapy. Under certain conditions, however, barrier disruption of the skin favors T helper 2-biased immune responses, which may lead to new sensitizations.

METHODS

In a prophylactic approach, an infra-red laser device was employed, producing an array of micropores of user-defined number, density, and depth on dorsal mouse skin. The grass pollen allergen Phl p 5 was administered by patch with or without the T helper 1-promoting CpG oligodeoxynucleotide 1826 as adjuvant, or was subcutaneously injected. Protection from allergic immune responses was tested by sensitization via injection of allergen adjuvanted with alum, followed by intranasal instillation. In a therapeutic setting, pre-sensitized mice were treated either by the standard method using subcutaneous injection or via laser-generated micropores. Sera were analyzed for IgG antibody subclass distribution by ELISA and for IgE antibodies by a basophil mediator release assay. Cytokine profiles from supernatants of re-stimulated lymphocytes and from bronchoalveolar lavage fluids were assessed by flow cytometry using a bead-based assay. The cellular composition of lavage fluids was determined by flow cytometry.

RESULTS

Application of antigen via micropores induced T helper 2-biased immune responses. Addition of CpG balanced the response and prevented from allergic sensitization, i.e. IgE induction, airway inflammation, and expression of T helper 2 cytokines. Therapeutic efficacy of transcutaneous immunotherapy was equal compared to subcutaneous injection, but was superior with respect to suppression of already established IgE responses.

CONCLUSIONS

Transcutaneous immunotherapy via laser-generated micropores provides an efficient novel platform for treatment of type I allergic diseases. Furthermore, immunomodulation with T helper 1-promoting adjuvants can prevent the risk for new sensitization.