Tirbanibulin for Actinic Keratosis: Insights into the Mechanism of Action

Clinical and experimental aspects of tirbanibulin treatments

Tirbanibulin is a topical medication approved in 2020 as a 5 day topical treatment for actinic keratosis, a precancerous skin lesion characterized by the hyperproliferation of atypical keratinocytes. Tirbanibulin exerts its effects through dual mechanisms: microtubule inhibition, which disrupts cell division, and Src kinase inhibition, which interferes with cancer-associated signaling pathways. Although its primary use is in AK, these mechanisms suggested potential therapeutic applications in a broader range of epithelial cancers. In this literature review, we explored tirbanibulin's application in not only actinic keratosis, but also in squamous cell carcinoma and basal cell carcinoma. We addressed the relevant findings obtained in recent papers to evaluate tirbanibulin's safety, efficacy, side effects, real-life clinical experiences, and its potential in anti-aging and skin lightening therapies on patients. In summary, we highlighted the preclinical and clinical evidence on the use of tirbanibulin as an effective and safe treatment option beyond AK. Graphical Abstract.

An Overview of Actinic Keratoses: Understanding Etiology, Diagnosis, and Treatment Approaches

Actinic keratoses (AK) are common cutaneous lesions located in skin areas chronically exposed to UV radiation, with the potential of progressing into invasive squamous cell carcinoma (SCC). Since it is not possible to predict which AK lesions will become SCC or when will that happen, treating all AK is generally recommended. There is a wide range of therapies available for AK and new drug approvals have joined the therapeutic armamentarium in recent years. These changes in the available treatments for AK require a review of the scientific evidence available and the current status of AK diagnosis and management in Spain.

The Skin-Lightening Power of Tirbanibulin 1% Ointment

BACKGROUND

Tirbanibulin 1% ointment has been licensed to treat non-hyperkeratotic actinic keratosis (AK) on the face and scalp in adults. Recent evidence suggests that, besides the antineoplastic effect, tirbanibulin may also confer substantial cosmetic benefits to patients.

METHODS

We report a single-center retrospective study of patients affected by solar lentigines (SLs) and AKs in the context of field cancerization treated with tirbanibulin 1% ointment.

RESULTS

Among 42 patients, 35% (n = 15) experienced complete clearance of SLs, while partial clearance was observed in 50% (n = 21) of patients. Regarding AKs, complete and partial clearance were observed in 52% (n = 22) and 40% (n = 17) of patients, respectively. Major study limitations are the small sample size and the absence of a control group.

CONCLUSIONS

Our results suggest that tirbanibulin 1% ointment may offer the dual benefit of treating AKs while simultaneously lightening aesthetically bothersome and difficult-to-treat lesions like SLs with just 5 days of application.

Safety and tolerability of tirbanibulin ointment 1% treatment on 100 cm2 of the face or scalp in patients with actinic keratosis: A phase 3 study

Background

Tirbanibulin is approved for actinic keratosis (AK) field treatment up to 25 cm2. However, AK often affects larger areas; thus, AK treatments for larger fields are needed.

Objective

Evaluate the safety and tolerability of tirbanibulin when applied to a field of approximately 100 cm2.

Methods

Phase 3, multicenter, open-label, single-arm study among adult patients having a treatment field on the face or balding scalp of approximately 100 cm2 with 4-12 AKs. Patients received tirbanibulin to cover the treatment field once daily (5 consecutive days). Safety was assessed by evaluating treatment emergent adverse events and tolerability by composite score of 6 local tolerability signs (LTS).

Results

A total of 105 patients were included. The most common LTS were erythema (96.1%) and flaking/scaling (84.4%), being mostly mild-to-moderate severity, and resolved/returned to or close to baseline by Day 29. The only severe LTS were erythema (5.8%) and flaking/scaling (8.7%). Most frequent treatment emergent adverse events were application site pruritus (10.5%) and application site pain (8.6%). Mean total number of AKs decreased from 7.7 AKs at baseline to 1.8 AKs at Day 57. Mean percent of change (reduction) from baseline in lesion count was 77.8% at Day 57.

Limitations

No control group. No long-term follow-up.

Conclusion

Safety and tolerability profiles in patients treated with tirbanibulin up to 100 cm2 were consistent with those previously reported over smaller field. Tirbanibulin could be used on a larger field (>25 cm2).

Efficacy and tolerability of tirbanibulin 1% ointment in the treatment of cancerization field: a real-life Italian multicenter observational study of 250 patients

BACKGROUND

Tirbanibulin 1% ointment is approved for the field treatment of Olsen grade I actinic keratoses (AKs) of the face and scalp.

METHODS

We performed a multicenter retrospective study involving 15 dermatologic units in Italy to investigate the efficacy and tolerability of tirbanibulin in a real-life setting. 250 patients were enrolled. Tirbanibulin, 1% ointment, was applied daily for five consecutive days. The efficacy of treatment was measured with modifications of the Actinic Keratosis Area and Severity Index (AKASI). A satisfactory response was defined by complete (100% reduction in the number of lesions) or partial clearance (75-99%) of treated AKs.

RESULTS

Overall, the AKASI score was significantly reduced in the studied population (mean, from 4.1 ± 2.7 to 1.4 ± 1.5; P < 0.001). A satisfactory response was observed in 222 (88.8%) cases. The proportion of satisfactory responses was higher when follow-up was performed after 8 weeks (34/35, 97.1%). The reduction in AKASI was significant in patients with Olsen grade II or III lesions (from 5.3 ± 2.8 to 1.6 ± 1.6; P < 0.001). A satisfactory response was observed in 91/104 (87.5%) cases. AKASI reduction was also significant in patients with trunk or limb AKs (from 7.0 ± 1.3 to 2.0 ± 1.6; P = 0.018) since a satisfactory response was observed in 7/8 (87.5%) cases. Tirbanibulin was well tolerated; all adverse events (AEs) included transient local reactions at the site of treatment. Overall, 231 patients had at least one AE. Only 7 (2.8%) grade 4 AEs were recorded.

CONCLUSION

Our retrospective study confirmed that tirbanibulin 1% ointment is effective and well tolerated in a real-life setting and is also promising for Olsen grade II and grade III AKs and AKs localized on difficult-to-treat areas.

Utilizing fractional lasers and tirbanibulin ointment to treat squamous and basal cell carcinomas

Keratinocyte carcinoma is the most common form of cancer in the United States. Often treated by surgical excision, electrodessication and curettage, or Mohs surgery, treatment can frequently leave patients with a scar and can be time consuming and inconvenient for both patients and healthcare providers. Utilizing non-ablative fractional laser therapy followed by tirbanibulin ointment, we treated 30 basal and/or squamous cell carcinomas on 23 patients over the age of 50 with varying skin types. Multiple areas of the face and body, and carcinomas at differing stages, were treated. We maximized the depth of penetration of the fractional laser by using bulk heating methods while simultaneously optimizing cosmetic results. This is an ongoing study as we continue to track the progress of our participants. Thus far, no clinical or histological recurrence of carcinoma has been found in any of the treated sites.

Developing a questionnaire for assessing clinician- and patient-reported outcomes in actinic keratosis: Results from an expert panel

Background

Current assessments on topical treatment attributes in actinic keratosis (AK) do not evaluate safety, effectiveness, and satisfaction from both clinician and patient perspectives, creating an unmet need for more comprehensive AK-specific measures that fully capture the patient experience.

Objective

To develop an actinic keratosis-specific expert panel questionnaire (AK-EPQ) of patient-reported outcomes and clinician-reported outcomes for use in research studies.

Methods

Using interviews of patients with AK and targeted literature reviews, a 9-person consensus panel of dermatologists with expertise in AK treatment was convened to develop the AK-EPQ to assess AK-specific patient-reported outcomes and clinician-reported outcomes.

Results

Nine expert advisers achieved consensus on 11 AK-EPQ items that encompass patient and clinician perspectives of treatment-related local skin reactions, clinical and cosmetic outcomes associated with AK, and satisfaction with treatment; the AK-EPQ will be first implemented in the Patient-Reported Outcomes for Actinic Keratosis study (NCT05260073).

Limitations

The AK-EPQ does not directly measure quality of life, although it can be used with validated quality of life instruments.

Conclusion

The newly developed AK-EPQ elicits insights into the patient and clinician experience with AK treatments. Comparative probing of these perspectives may help optimize precision medicine in AK treatment.

Exploring New Frontiers: Innovations and Therapeutic Targets in Dermatology

The focus of dermatology has increasingly shifted towards exploring new and innovative approaches [...].

Tirbanibulin decreases cell proliferation and downregulates protein expression of oncogenic pathways in human papillomavirus containing HeLa cells

Tirbanibulin 1% ointment is a synthetic antiproliferative agent approved in 2021 by the European Union for treating actinic keratoses (AK). Topical tirbanibulin has clinically resolved HPV-57 ( +) squamous cell carcinoma (SCC), HPV-16 ( +) vulvar high-grade squamous intraepithelial lesion, epidermodysplasia verruciformis, and condyloma. We examined how tirbanibulin might affect HPV oncoprotein expression and affect other cellular pathways involved in cell proliferation and transformation. We treated the HeLa cell line, containing integrated HPV-18, with increasing doses of tirbanibulin to determine the effects on cell proliferation. Immunoblotting was performed with antibodies against the Src canonical pathway, HPV 18 E6 and E7 transcription regulation, apoptosis, and invasion and metastasis pathways. Cell proliferation assays with tirbanibulin determined the half-maximal inhibitory concentration (IC50) of HeLa cells to be 31.49 nmol/L. Increasing concentrations of tirbanibulin downregulates the protein expression of Src (p < 0.001), phospho-Src (p < 0.001), Ras (p < 0.01), c-Raf (p < 0.001), ERK1 (p < 0.001), phospho-ERK1 (p < 0.001), phospho-ERK2 (p < 0.01), phospho-Mnk1 (p < 0.001), eIF4E (p < 0.01), phospho-eIF4E (p < 0.001), E6 (p < 0.01), E7 (p < 0.01), Rb (p < 0.01), phospho-Rb (p < 0.001), MDM2 (p < 0.01), E2F1 (p < 0.001), phospho-FAK (p < 0.001), phospho-p130 Cas (p < 0.001), Mcl-1 (p < 0.01), and Bcl-2 (p < 0.001), but upregulates cPARP (p < 0.001), and cPARP/fPARP (p < 0.001). These results demonstrate that tirbanibulin may impact expression of HPV oncoproteins via the Src- MEK- pathway. Tirbanibulin significantly downregulates oncogenic proteins related to cell cycle regulation and cell proliferation while upregulating apoptosis pathways.

Topical Pharmacological Treatment of Actinic Keratoses: Focus on Tirbanibulin 1% Ointment

Actinic keratosis (AK) is a frequent precancerous skin lesion that mostly affects chronically sun-exposed areas. Chronic sun damage leads to various mutations in onco-suppressor and oncogenic genes which cause an uncontrolled proliferation of atypical keratinocytes. Untreated AKs may evolve in cutaneous squamous cell carcinoma (cSCC), with the consequent need for dermato-surgical excision or even for systemic immunotherapy in case of invasive/metastatic cSCCs. Epidemiology data on AK prevalence are various, however, the literature unanimously reports an increasing prevalence due to the aging of the population. Clinically AKs appear as a scaly, erythematous macule or papule or hyperkeratotic plaque. Management of AKs and the field of cancerization is important to avoid the natural evolution into squamous cell carcinomas (SCCs). Both physical and topical treatments are approved for managing AKs. Patient compliance with topical regimens is usually low due to the length of the posology and frequent skin adverse events. A recently approved tirbanibulin-based ointment, showed potential for inhibiting cell proliferation and blocking SRC-kinases, implicated in the progression of AKs in SCCs. The advantage of this new treatment is the practical posology, with a daily application for 5 consecutive days on AKs of the face-scalp area. Local skin reactions are usually mild and do not require treatment discontinuation. The short course of this new therapy and its excellent tolerance massively increased patient compliance. This article reviews what is currently known about this new therapy from its mechanism of action to clinical trial outcomes regarding safety, effectiveness, and patient adherence to the treatment.

Anti-tumor effects of tirbanibulin in squamous cell carcinoma cells are mediated via disruption of tubulin-polymerization

Topical tirbanibulin is a highly effective and well tolerated novel treatment option for actinic keratoses (AKs). This study aimed to characterize the mode of action of tirbanibulin in keratinocytes (NHEK) and cutaneous squamous cell carcinoma (cSCC) cell lines (A431, SCC-12) in vitro. Tirbanibulin significantly reduced proliferation in a dose-dependent manner in all investigated cell lines, inhibited migration, and induced G2/M-cell cycle arrest only in the cSCC cell lines analyzed, and induced apoptosis solely in A431, which showed the highest sensitivity to tirbanibulin. In general, we detected low basal expression of phosphorylated SRC in all cell lines analyzed, therefore, interference with SRC signaling does not appear to be the driving force regarding the observed effects of tirbanibulin. The most prominent tirbanibulin-mediated effect was on β-tubulin-polymerization, which was especially impaired in A431. Additionally, tirbanibulin induced an increase of the proinflammatory cytokines IL-1α, bFGF and VEGF in A431. In conclusion, tirbanibulin mediated anti-tumor effects predominantly in A431, while healthy keratinocytes and more dedifferentiated SCC-12 were less influenced. These effects of tirbanibulin are most likely mediated via dysregulation of β-tubulin-polymerization and may be supported by proinflammatory aspects.

Topical and Intralesional Immunotherapy for the Management of Basal Cell Carcinoma

Basal Cell Carcinoma (BCC) is the most common type of cancer among the white population. Individuals with fair skin have an average lifetime risk of around 30% for developing BCC, and there is a noticeable upward trend in its incidence rate. The principal treatment objectives for BCC involve achieving the total excision of the tumor while maximizing the preservation of function and cosmesis. Surgery is considered the treatment of choice for BCC for two main reasons: it allows for the highest cure rates and facilitates histological control of resection margins. However, in the subgroup of patients with low-risk recurrence or medical contraindications for surgery, new non-surgical treatment alternatives can provide an excellent oncological and cosmetic outcome. An evident and justified instance of these local therapies occurred during the COVID-19 pandemic, a period when surgical interventions carried out in hospital settings were not a viable option.

Anti-aging Effects of Tirbanibulin 1% Ointment: A Real-Life Experience

INTRODUCTION

Tirbanibulin 1% ointment has been licensed to treat non-hyperkeratotic actinic keratosis (AKs) on the face and scalp in adults to ensure excellent patient tolerability due to the mild side effects and the brief application time compared to other topical therapies on the market. A growing body of evidence suggests that, beyond their primary function, the treatments for AKs and the cancerization field may inadvertently confer substantial cosmetic benefits to patients.

METHODS

We report a single-center retrospective case series of patients referred to the Dermatology Unit of the University Hospital of Messina, Italy, between February and December 2023 seeking treatment for AKs in the context of photodamaged areas in which the application of tirbanibulin 1% ointment induced, besides clearance of AKs, anti-aging effects on both skin texture and solar lentigos.

RESULTS

Seven patients affected by Olsen grade 1-2 AKs experienced a powerful rejuvenating effect in the treated areas, with a marked efficacy in skin lightening and clearance of solar lentigo.

CONCLUSIONS

Tirbanibulin 1% ointment seems able to improve skin aging as a desirable side effect at the site of application for AKs on chronic photodamaged skin. Such preliminary observation needs further confirmation in real-life studies on larger cohorts of patients, to explain the pathogenic mechanisms responsible for such aesthetically relevant results.

Diagnosis and therapy of actinic keratosis

Actinic keratosis (AK) is considered a chronic and recurring in situ skin neoplasia, with a possible transformation into invasive squamous cell carcinoma (SCC). Among others, predominant risk factors for development of AK are UV-light exposure and immunosuppression. Basal epidermal keratinocyte atypia (AK I) and proliferation (PRO score) seem to drive malignant transformation, rather than clinical appearance of AK (Olsen I-III). Due to the invasiveness of punch biopsy, those histological criteria are not regularly assessed. Non-invasive imaging techniques, such as optical coherence tomography (OCT), reflectance confocal microscopy (RCM) and line-field confocal OCT (LC-OCT) are helpful to distinguish complex cases of AK, Bowen's disease, and SCC. Moreover, LC-OCT can visualize the epidermis and the papillary dermis at cellular resolution, allowing real-time PRO score assessment. The decision-making for implementation of therapy is still based on clinical risk factors, ranging from lesion- to field-targeted and ablative to non-ablative regimens, but in approximately 85% of the cases a recurrence of AK can be observed after a 1-year follow-up. The possible beneficial use of imaging techniques for a non-invasive follow-up of AK to detect recurrence or invasive progression early on should be subject to critical evaluation in further studies.

Diagnose und Therapie aktinischer Keratosen

Actinic keratosis (AK) is considered a chronic and recurring in situ skin neoplasia, with a possible transformation into invasive squamous cell carcinoma (SCC). Among others, predominant risk factors for development of AK are UV-light exposure and immunosuppression. Basal epidermal keratinocyte atypia (AK I) and proliferation (PRO Score) seem to drive malignant turnover, rather than clinical appearance of AK (Olsen I-III). Due to the invasiveness of punch biopsy, those histological criteria are not regularly assessed. Non-invasive imaging techniques, such as optical coherence tomography (OCT), reflectance confocal microscopy (RCM) and line-field confocal OCT (LC-OCT) are helpful to distinguish complex cases of AK, Bowen's disease and SCC. Moreover, LC-OCT can visualize the epidermis and the papillary dermis at cellular resolution, allowing real-time PRO Score assessment. The decision-making for implementation of therapy is still based on clinical risk factors, ranging from lesion- to field-targeted and ablative to non-ablative regimes, but in approximately 85% of the cases a recurrence of AK can be observed after a 1-year follow-up. The possible beneficial use of imaging techniques for a non-invasive follow-up of AK to detect recurrence or invasive progression early on should be subject to critical evaluation in further studies.

Tirbanibulin 1% Ointment for Actinic Keratosis: Results from a Real-Life Study

Background and Objectives: Tirbanibulin 1% ointment is a novel synthetic anti-proliferative agent that inhibits tubulin polymerization. It is approved for treating actinic keratosis (AK) on the face and scalp in adults. It has demonstrated good efficacy, an adequate safety profile and excellent patient adherence in the phase 3 clinical trials, however data about its real-life efficacy and safety are lacking. Here we report the experience of the dermatology unit of the University Hospital of Messina. Materials and Methods: We performed a spontaneous open-label, prospective non-randomized study to assess the effectiveness and safety of tirbanibulin 1% ointment for the treatment of 228 AKs in 38 consecutive patients-28 males (73%) and 10 females (26%)-aged between 52 and 92 years (mean age: 72 ± 8.92 years). Results: Total clearance was recorded in 51% of lesions, while partial clearance was recorded in 73% of lesions. An excellent tolerability profile and high compliance rate were observed, with no treatment discontinuation due to the onset of adverse events. Conclusion: Our real-life experience confirms the effectiveness and safety of tirbanibulin ointment for the treatment of AKs.

Digitally Enhanced Methods for the Diagnosis and Monitoring of Treatment Responses in Actinic Keratoses: A New Avenue in Personalized Skin Care

Non-melanocytic skin cancers represent an important public health problem due to the increasing incidence and the important local destructive potential. Thus, the early diagnosis and treatment of precancerous lesions (actinic keratoses) is a priority for the dermatologist. In recent years, non-invasive skin imaging methods have seen an important development, moving from simple observational methods used in clinical research, to true diagnostic and treatment methods that make the dermatologist's life easier. Given the frequency of these precancerous lesions, their location on photo-exposed areas, as well as the long treatment periods, with variable, imprecise end-points, the need to use non-invasive imaging devices is increasingly evident to complete the clinical observations in the diagnosis and treatment of these lesions, with the aim of increasing accuracy and decreasing the adverse effects due to long treatment duration. This is the first review that brings together all skin imaging methods (dermoscopy, reflectance confocal microscopy, ultrasonography, dermoscopy-guided high frequency ultrasonography, and optical coherence tomography) used in the evaluation of actinic keratoses and their response to different treatment regimens.

Efficacy and safety of tirbanibulin 1% ointment in actinic keratoses: Data from two phase-III trials and the real-life clinical practice presented at the European Academy of Dermatology and Venereology Congress 2022

BACKGROUND

The 31st European Academy of Dermatology and Venereology (EADV) Congress took place between 7th and 10th of September 2022 in Milan, Italy.

OBJECTIVES

We report presented clinical data on the efficacy/effectiveness, safety and tolerability of tirbanibulin 1% ointment that has recently been licensed for actinic keratosis (AK) of the face or scalp in adults.

METHODS

Summary of presentations given at the EADV Congress.

RESULTS

Prof. Pellacani presented two post hoc analyses from two phase-III trials with AK patients (NCT03285477 [N = 351] and NCT03285490 [N = 351]): A descriptive analysis of medical history, concomitant medications, and safety results confirming a favourable profile for tirbanibulin showing that number of baseline AK lesions was not correlated to severity of local skin reactions. The latter analysis showed that cases of tirbanibulin application site pain or pruritus were few, and most were found to be mild. Prof. Kunstfeld reported six real-life clinical cases in Austria showing good tirbanibulin effectiveness, safety and tolerability for the treatment of new or recurring AK lesions. Results demonstrated that after 2- to 4-month follow-up, tirbanibulin was well tolerated and effective in AK patients. Presentations by Dr. Patel confirmed good outcomes and tolerability of tirbanibulin in Olsen grade 1-2 AK (N = 12) and porokeratosis patients (N = 4) treated once daily for 5 consecutive days in the United Kingdom. Furthermore, real-world experience in solid organ transplant recipients (N = 2) demonstrated effectiveness of tirbanibulin in skin field cancerization treatment. A symposium sponsored by Almirall was conducted during the congress in which Dr. Hadshiew and Dr. Lear brought together their clinical experience in Germany and the United Kingdom respectively. Interesting clinical cases of 5 consecutive days of tirbanibulin treatment compared to other treatments were discussed with attendees, as well as current treatment needs of AK patients.

CONCLUSIONS

This article provides an overview of presentations and symposium discussions, summarizing key phase-III results and real-life clinical experience with tirbanibulin shared by dermatologists across Europe.

Preliminary Evidence of Efficacy, Safety, and Treatment Satisfaction with Tirbanibulin 1% Ointment: A Clinical Perspective on Actinic Keratoses

BACKGROUND

Actinic keratosis is a common precancerous skin lesion that can progress into invasive squamous cell carcinomas. Many topical treatments for actinic keratoses often have poor tolerability and prolonged duration. Tirbanibulin is a novel synthetic drug with potent antitumor and antiproliferative activities.

METHODS

We conducted a single-center, prospective and observational study using tirbanibulin ointment on a 25 cm2 area for 5 consecutive days on 30 participants with AKs on the face or scalp. They were followed for at least 57 days to assess the safety profile and efficacy of the drug as well as treatment satisfaction. We evaluated six signs of local skin reaction (LSR): erythema, scaling, crusting, swelling, blisters/pustules, and erosions/ulcerations, grading the severity as mild, moderate, or severe. The effectiveness was evaluated both clinically and dermoscopically. The treatment satisfaction was assessed using the Treatment Satisfaction Questionnaire for Medication (TSQM 1.4).

RESULTS

On day 57, 70% of the patients showed a complete clinical and dermoscopic response. The highest scores obtained from the TSQM 1.4 were more evident in the convenience and side effects domains. Most LSRs, including erythema (83.3%), scaling (30%), and swelling (3.3%), occurred on day 8 but resolved spontaneously.

CONCLUSION

Tirbanibulin is a viable therapeutic option with a short regimen treatment and good tolerability, which favors therapy adherence.

Topical Treatments for Basal Cell Carcinoma and Actinic Keratosis in the United States

Skin cancer is an overarching label used to classify a variety of cutaneous malignancies. Surgical excision procedures are the commonly used treatments for these lesions; however, the choice to perform operative intervention may be influenced by other factors. Established research and literature suggest that topical treatments limit the need for surgical intervention and its commonly associated adverse effects, including infection and scarring. In addition, the growing indications for the usage of topical therapies in BCC treatment, as well as their increased availability and therapeutic options, allow for their greater applicability in the dermatology clinic. Certain topical therapies have been highlighted in research, especially those targeting basal cell carcinoma (BCC) and actinic keratosis (AK). There is also a clear correlation between cost and treatment outcomes, considering BCC's ever-growing prevalence and the proportion of excised lesions being reported as malignant. This review will discuss BCC and AK lesion criteria that result in the most successful outcomes using topical treatments, then highlight the various topical treatment options, and finally address their clinical significance moving forward.