Evaluation of the effectiveness and safety of combined oral and topical photoprotection with a standardized extract of Polypodium leucotomos (Fernblock®) in a Moroccan population with xeroderma pigmentosum

Xeroderma pigmentosum (XP) is a rare autosomal‐recessive genodermatosis resulting from a DNA‐repair defect syndrome. The purpose was to evaluate the prevention on new malignant lesions in patients taking a supplement with Fernblock® (Polypodium leucotomos extract [PLE]) and secondarily correlation with the photoprotective behavior.


| INTRODUC TI ON
Xeroderma pigmentosum (XP) is a rare autosomal-recessive genodermatosis.The prevalence varies from one per million in the USA; 1 to one per 10,000 in Tunisia. 2 This study focusses particularly on XP patients in Morocco where the disease is widely prevalent. 3ere are different forms of XP, depending on the underlying genetic defect.Molecular abnormalities appear with high heterogeneity among patients.Nucleotide excision repair (NER) recognizes an extremely wide range of photolesions, including UV-induced cyclopyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs). 4To date, XP has been classified into seven variants with NER defects, named XP A-G, with other variants such as XP-V with normal NER but a deficiency with respect to DNA replication after ultraviolet radiation (UVR)-induced DNA damage. 1,5The XPC, XPD, and XPA variants represent the most frequent forms responsible for about 90% of XP patients worldwide. 6,7The genomic alterations lead to DNA repair defects and therefore to an accumulation of photoproducts and reactive oxygen species (ROS) that can be premutagenic. 8For this reason, XP patients are at high risk of different types of skin cancer, 9 with 10,000-fold greater risk of developing NMSC as compared to the general population, and a 2000-fold greater risk of developing melanoma. 10Skin cancer usually appears at an early age, reported to be the mean age 9 years for NMSC and 22 years for melanoma. 10In Morocco, the average age of onset of the first tumor was 7.7 years. 11agnosis of XP is based on family history and clinical evaluation, which includes dermatological (photosensitivity, early freckling, lentiginous pigmentation since childhood, skin cancer, and premature aging), 5 ophthalmological, neurological, and otorhinolaryngologic examination. 10A confirmation of the diagnosis can be achieved by functional cell-based test systems, as well as genetic sequencing to determine the specific genetic defect. 9,10ere is currently no cure for XP, but prophylaxis of skin cancer and early treatment of sun-induced skin lesions are key to improve the quality of life of patients and extend the period free from skin cancer.XP patients should be encouraged to use sun protection consisting of broad-spectrum sunscreen and applied it every 2 h in sufficient quantity.They should use sunscreen containing antioxidant actives and DNA repair enzymes (photolyase and/ or endonuclease), [12][13][14][15] UV-protective clothing, wide-brimmed hats, sunglasses, and UV-window filters. 4XP patients should also undergo periodical dermatological evaluation and subsequent specific treatment if needed. 4,161][22][23] Other preventive treatments in XP patients include: systemic retinoids such as isotretinoin, 24 oral nicotinamide (NAM), 16,25 and oral antioxidants. 26Some studies showed on average a reduction in skin cancers of 63% with isotretinoin, 24 of 23% with NAM 25 and more than 50% with oral antioxidants. 26e of the most studied antioxidant compounds with proven anticarcinogenic efficacy is Fernblock®, a standardized aqueous extract from the leaves of Polypodium leucotomos (PLE) rich in phenolic compounds with antioxidant effects. 27Fernblock® prevents and repairs UVR-induced DNA damage, prevents DNA mutations and preserves the skin's immune system. 28,29In this study, we sought to assess the efficacy and safety of treatment with oral and topical photoprotection based on Fernblock® to prevent the appearance of NMSC lesions and improve the quality of life in patients with XP.

| MATERIAL S AND ME THODS
This was a prospective, single-center, and open cohort study conducted over a 12-month period at the Dermatology Department of the University Hospital of Casablanca.All patients included and/or their guardians gave their written consent and met the inclusion criteria: diagnose of XP, be over 12 years old, willing to comply with the correct photoprotection measures, not have active lesions at the time of inclusion, not having any other dermatosis that difficult skin evaluation, agree to sign the informed consent for the study and take, and transfer the necessary photographs.
Patients received initial treatment to remove lesions if present.
Optimal photoprotection behavior was explained to patients and/ or their guardians and registered in the following visits as optimal if all the following points were met: sun avoidance (sleeping during the day and going out at night), anti-UV glasses, hats, long-sleeved clothing if going outdoors, topical full-spectrum sunscreen applied regularly and repeatedly, and window foils with UV filters.
Regarding the protective treatment, topical and oral photoprotection, patients were instructed to take two capsules (each of which containing 480 mg Fernblock® and, among other ingredients, 5 μg vitamin D (Heliocare Ultra D® Capsules) daily in the morning.All patients had to apply sunscreen with a SPF50+ featuring chemical filters and Fernblock® (Heliocare Ultra Gel SPF 50+®) every 2 h during sun exposure.The study period lasted 12 months.The demographic, clinical, and dermatoscopic patient data were collected at the beginning of the study (baseline, T0).Although it had been established that periodic visits would be carried out every 3 months for detailed clinical and dermatoscopic examinations (listed on Table 1), as well as for the detection of any secondary effects.Due to the consequences of the COVID-19 pandemic, some of the visit schedules were modified and some patients were lost due to lack of follow-up.The work of the "Association de Solidarité avec Enfants de la Lune au Maroc" was of great assistance in ensuring timely delivery of the treatment products to the recruited volunteers.Any adverse events were registered.

| Statistical treatment
To correlate photoprotective behavior (Yes/No) to the appearance of lesions (Yes/No), the contingency table for both variables was calculated.As descriptors, the frequencies of injury conditioned to the photoprotective attitude have been used and, as a measure of the effect, said probabilities have been used to calculate the relative risk.

| RE SULTS
Twenty-six patients with XP were first recruited, but four patients were lost before starting protective treatment due to difficulties in obtaining follow-up and another four patients were excluded because their initial lesions could not be removed.The remaining 18 patients, all met the inclusion criteria detailed in the materials and methods section.Thirteen of them were treated with either surgical or cryotherapy treatment before starting the protective treatment and five patients did not need any treatment as they did not have initial lesions.The patients had neither extensive skin grafts nor multiple fibrous scars.
The 18 patients who completed the study had a mean age of 17 ± 5 years, 11 (61.1%) were women and seven (38.88%) men, and skin phototype III was the most frequent (64%).Of these 18 patients, 60% came from rural areas.
Among the 18 patients who finished the study, 11 patients did not develop new lesions over the course of the study, while seven did.The seven patients with new lesions had presented a higher number of lesions upon enrollment (average of nine per patient) with respect to those who did not develop lesions (average of four per patient) upon enrollment.During the study, the seven patients who developed new lesions did so within the first 6 months of the study and the total number of new lesions was 12, which means an average of 1.70 per patient.Of these new lesions, two were non-suspicious lesions (lentigos that were identified clinically and confirmed by dermoscopy), five were actinic keratosis, four were basal cell carcinoma, and one was an in situ squamous cell carcinoma.The 11 patients who completed the study without new lesions represented 61.1% of the population studied and it should be noted that more than 60% (seven patients) of them adopted photoprotective behavior very close to ideal, while of the seven patients who developed lesions, only 30% (two patients) adopted a correct photoprotective behavior whereas 70% (five patients) did not adopt the recommended photoprotective behavior (Figure 1).No side effects were reported.
To correlate photoprotective behavior (Yes/No) to the appearance of lesions (Yes/No), the contingency table for both variables was calculated, resulting in the lack of an optimal photoprotective behavior increased the probability of developing lesions by 2.5 times with a 95% confidence interval (0.645 and 9.69; Figure 2).

| DISCUSS ION
Failure in DNA-repair system in XP patients leads to accumulation of mutations and consequent activation of numerous intracellular pathways that eventually lead to the development of malignant skin lesions. 4,13rnblock® provides four levels of skin protection against damage caused by exposure to UV, visible (VIS), and infrared (IR) TA B L E 1 Parameters evaluated at the different study times.

Baseline (T0) T3m T6m T12m
Informed consent signature The figure shows the number of patients recruited, lost and, of those who completed the study, those with or without development of new lesions.New lesions only were developed within the first 6 months.
It was previously believed that CPDs generation occurred only within picoseconds after cutaneous exposure to UVB radiation.
However, it is now known that CPDs production continues for several hours after UVA exposure in melanin-containing murine melanocytes; these CPDs are known as dark-CPDs. 23,38In this regard, Fernblock® can successfully reduce the elevated production of reactive species, demonstrating its antioxidant and both oxygen and nitrogen species scavenging properties, 4 as well as inflammation (COX-2). 34,39With respect to the preservation of skin immunity by Fernblock®, its incorporation in sunscreens markedly decreased sunburn cells and prevented Langerhans cell (CD1a+) depletion in human volunteers as shown by Shalka et al. 40,41 In our study, after 1 year of dual (oral and topical) sun protection practice, 11 out of 18 patients remained clear of lesions being seven patients who developed new malignant lesions, indicating a lesion-free rate of 61.1%.Patients with XP who do not adopt appropriate photoprotection measurements may develop hundreds of skin cancers on sun-exposed areas. 9We believe that the pho-

ACK N O WLE D G E M ENTS
We thank Cantabria Labs Maroc for the support of the study and to the "Association de Solidarité avec Enfants de la Lune Au Maroc" for its help at the logistical level of the study.

CO N FLI C T O F I NTER E S T S TATEM ENT
M. Truchuelo and S. Gonzalez are consultants for Cantabria Labs.
Maria Vitale is an employee of Cantabria Labs.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available on request from the corresponding author.The data are not publicly available due to privacy or ethical restrictions.
toprotection behavior and use of the topical and oral treatment with Fernblock® were decisive in decreasing the relative risk of NMSC development observed in this study.Patients following almost ideal photoprotection were 2.5 times less likely to develop NMSC lesions.We believe that in this vulnerable population, even patients undergoing NMSC in the past could obtain significant protection from this regimen and, therefore, the better their quality of life.As dermatologists, we would encourage the use of oral and topical photoprotection with Fernblock® in particular, XP patients.In conclusion, the best treatment to prevent the large number of skin cancers experienced by XP patients remains prevention by solar photoprotection.This study evaluated the efficacy of a safe preventative sun protection regimen consisting of a combination of broad-spectrum topical sunscreen and oral supplementation with Fernblock®, obtaining promising results without side effects.This natural botanical extract has broad scientific support and the benefits reported in this study derive from its multiple preventive and repairing activities (antioxidant, immunomodulatory, prevention of DNA damage, and preservation of skin architecture) against suninduced cell damage.Studies in a larger population of XP patients could confirm the positive results observed in this study.

F I G U R E 2
(A) Patient with a history of five lesions; she completed the 12-month study treatment period without lesions.Patient from urban setting and with ideal photoprotective behavior.(B) Patient with four cutaneous lesions at recruitment who developed basal cell carcinoma 1 month into the study.Patient from urban setting and without ideal photoprotective behavior.(C) Patient with a history of numerous lesions.She developed squamous cell carcinoma in situ within 6 months of beginning the study.Patient from a rural setting and without optimal photoprotective behavior.(D) Patient with four lesions at the start of treatment who finished the study without lesions.Patient from urban setting and with ideal protective behavior.