Evaluating the Efficacy and Safety of 4% 5-Fluorouracil Cream in Patients with Actinic Keratosis: An Expert Opinion.

Actinic keratosis is a lesion that develops in sun-exposed areas of the skin and is considered to be a precancerous condition or an early in situ squamous cell carcinoma. Treatment of actinic keratosis is important for reducing skin cancer risk, with treatment choice based on patient-, lesion- and treatment-related considerations. Of the topical treatments used for field-directed therapy, those containing 5-fluorouracil are among the most effective and widely prescribed. The most recently developed topical 5-fluorouracil preparation (Tolak®; Pierre Fabre, France) contains 4% 5-fluorouracil in an aqueous cream. This narrative review discusses data on 4% 5-fluorouracil cream to treat actinic keratosis, and provides the authors' expert opinion on issues associated with it use. The effect of the cream has been evaluated in phase 2 and 3 trials of adult patients with actinic keratosis on the face, ears or scalp. These trials included patients with severe baseline disease, defined by high lesion counts and large-size treatment fields, which possibly affected the proportion of patients who were able to achieve complete clearance. Other efficacy parameters (e.g. percentage change in lesion count, ≥ 75% clearance of lesions or clinically significant changes in validated severity scales) should also be assessed to fully evaluate 4% 5-fluorouracil treatment efficacy in these patients. Nevertheless, 4% 5-fluorouracil is associated with high efficacy, a low level of recurrence and a satisfactory safety profile.

Severity of Local Skin Reactions with 4% 5-Fluorouracil Plus Emollient versus 4% 5-Fluorouracil Alone in Patients with Actinic Keratosis: A Single-Blind Randomised Trial.

INTRODUCTION: Topical 5-fluorouracil (5-FU)-containing treatments are effective for actinic keratosis (AK); however, they frequently lead to transient local skin reactions (LSRs), which often result in treatment non-adherence. METHODS: The aim of this international, phase IV clinical trial was to investigate whether addition of an emollient to topical 4% 5-FU would reduce the frequency and severity of LSRs over 4 weeks of treatment (intervention group) compared with 4% 5-FU alone (control group) in patients with AK. The primary objective was to assess the severity of LSRs (i.e. erythema, flaking/scaling, crusting, swelling, vesiculation/pustulation and erosion/ulceration) at week 4 of treatment (or before, in case of a major local reaction). Key secondary objectives were LSR total scores at weeks 2 and 8, the scores of individual LSR items at each visit, and the proportions of patients with 100% and ≥ 75% AK lesion clearance at week 8. RESULTS: In total, 141 patients were included in the efficacy analysis (71 in the intervention group and 70 in the control group). There were no statistically or clinically significant differences between the treatment groups in terms of LSR total score at week 4 (overall and by subgroups defined by the number of lesions and patient age at baseline), scores of individual LSR items at any time point, and AK lesion clearance rates at week 8. LSR scores with topical 4% 5-FU alone were lower than expected. Skin reactions were the most common treatment-emergent adverse events in both groups, leading to treatment discontinuation in nine patients (12.3%) in the intervention group and seven (9.9%) in the control group. No new safety signals were observed with the addition of an emollient to 4% 5-FU. CONCLUSIONS: Daily emollient applications during the 4-week treatment course did not impact the safety and efficacy profile of 4% 5-FU.

The Overall Number of Actinic Keratosis Lesions Is Not Predictable by the Number of Visible Lesions: Consequences for Field-Directed Therapies.

Actinic keratoses are keratotic lesions occurring on skin areas extensively damaged by sunlight. Using data from a previously published Phase III randomized, controlled clinical trial in patients with at least 5 actinic keratoses, we explored the potential link between the number of visible actinic keratosis lesions before any treatment and the total number of lesions of the field cancerization as revealed by 5-fluorouracil cream. Our analysis suggests that the baseline number of visible actinic keratoses is a poor indicator of the real number of lesions in the field of cancerization, reinforcing the need to explain the field cancerization concept to patients. (Curr Ther Res Clin Exp. 2022; 82:XXX-XXX) © 2022 Elsevier HS Journals, Inc.

Intensity of Local Skin Reactions During 5-Fluorouracil Treatment Related to the Number of Actinic Keratosis Lesions: A Post Hoc, Exploratory Analysis.

INTRODUCTION: Actinic keratoses (AK) are epithelial lesions caused by chronic skin exposure to ultraviolet light that can progress into squamous cell carcinoma. Although several treatments are effective, they are associated with severe skin reactions, which might be related to the extent of the disease. This study aimed to examine the relationship between the severity of local skin reactions during treatment with 5-fluorouracil 4% cream and the number of AK lesions at baseline. METHODS: This post hoc analysis pooled data from two multicentre randomised phase III studies (HD-FUP3B-048, HD-FUP3B-049) in patients with AK treated with topical 5-fluorouracil 4% once daily (OD) or 5% twice daily (BID) for 4 weeks. First, we compared the severity, assessed using a numerical rating scale, of the local skin reactions between 5-fluorouracil 4% and 5%. Then, we investigated the relationship between the number of lesions at baseline and severe skin reactions with 5-fluorouracil 4% OD. RESULTS: Safety data were included from 397 patients who had received 5-fluorouracil 4% (348 in study HD-FUP3B-048, 49 in study HD-FUP3B-049) OD and 342 (HD-FUP3B-048) who had received 5-fluorouracil 5% BID. For most skin reactions, severe ones were more common in patients treated with 5-fluorouracil 5% cream BID than in those treated with 5-fluorouracil 4% cream OD (P < 0.05). With 5-fluorouracil 4% OD, the incidence of severe erythema was significantly higher in patients with at least 10 lesions (46%) than in patients with 5-10 lesions (28%; P < 0.001). Similar results were observed for the other local skin reactions. CONCLUSION: Treatment with 5-fluorouracil 4% cream OD was associated with less severe local skin reactions than 5-fluorouracil 5% BID. The number of AK lesions at baseline seems to have predictive value regarding the severity of local skin reactions that appear during treatment.

In order to prevent recurrence of actinic keratosis lesions and their progression to invasive squamous cell carcinoma, topical treatment of actinic keratosis often involves treating the field of cancerisation to clear visible and subclinical lesions. The occurrence of local adverse skin reactions during treatment can affect patient adherence to therapy and therefore compromise efficacy. A thorough understanding of the relationships between changes in lesions, actinic keratosis remission and tolerability of topical treatments over time is necessary to manage patient expectations, ensure treatment adherence and optimise clinical outcomes. This exploratory study used pooled data from two pivotal phase III studies to compare local skin reaction severity between 5-fluorouracil 4% cream applied once daily and 5-fluorouracil 5% cream applied twice daily, then to examine the relationship between the severity of local skin reactions during treatment and the number of actinic keratosis lesions at baseline. Local skin reactions appeared to be more severe in patients with more than 10 actinic keratosis lesions at baseline than in those with 5 to 10 lesions. Using a cut-off value of 10 lesions pre-treatment, healthcare practitioners can forewarn patients accordingly of potentially more severe local adverse skin reactions in order to motivate them to complete their treatment, thus ensuring treatment efficacy. If patients are likely to experience intolerable severe skin reactions, practitioners can plan to introduce an appropriate rescue treatment.