Pharmacotherapeutic group: Antibiotics and chemotherapeutics for dermatological use, other chemotherapeutics, ATC code: D06BX03
Mechanism of action
Tirbanibulin disrupts microtubules by direct binding to tubulin, which induces cell cycle arrest and apoptotic death of proliferating cells, and is associated with disruption of Src tyrosine kinase signalling.
Clinical efficacy and safety
The efficacy and safety of tirbanibulin applied on the face or scalp for 5 consecutive days was studied in 2 pivotal randomised, double-blind, vehicle-controlled Phase III studies (KX01‑AK-003 and KX01-AK-004) including 702 adult patients (353 patients treated with tirbanibulin and 349 patients treated with vehicle).
Patients had 4 to 8 clinically typical, visible, discrete, non-hyperkeratotic, non-hypertrophic, actinic keratosis lesions within a contiguous 25 cm2 treatment field on the face or scalp. On each scheduled dosing day, the ointment was applied to the entire treatment field. In the tirbanibulin group, the mean age was 69 years (range 46 to 90 years) and 96 % of patients had Fitzpatrick skin type I, II, or III. Efficacy, measured as complete (primary endpoint) and partial clearance rate, was assessed at day 57.
At day 57, patients treated with tirbanibulin had statistically significantly higher complete and partial clearance rates than patients treated with vehicle (p< 0.0001)(see Table 2). Efficacy was less in scalp lesions compared to facial lesions, though still statistically significant (see Table 3).
Table 2: Complete and partial clearance rates at day 57, ITT population (pooled data KX01-AK-003 and KX01-AK-004)
| | Overall (face and scalp) |
| Tirbanibulin 10 mg/g ointment (N=353) | Vehicle (N=349) |
| Complete (100%) clearance ratea | 49%c | 9% |
| Partial (≥75%) clearance rateb | 72%c | 18% |
ITT=Intent-to-Treat
a) Complete clearance rate was defined as the proportion of patients with no (zero) clinically visible actinic keratosis lesions in the treatment field.
b) Partial clearance rate was defined as the percentage of patients in whom 75 % or more of the number of baseline actinic keratosis lesions in the treatment field were cleared.
c) p< 0.0001; compared to vehicle by Cochran-Mantel-Hansel stratified by anatomical location and study.
Table 3: Complete and partial clearance rates at day 57 by anatomical location, ITT population (pooled data KX01-AK-003 and KX01-AK-004)
| Location | Complete (100%) Clearance Rate | Partial (≥75%) Clearance Rate |
| Tirbanibulin 10 mg/g ointment (N=353) | Vehicle (N=349) | Tirbanibulin 10 mg/g ointment (N=353) | Vehicle (N=349) |
| Face n/N % (95% CI) | 133/238 56% (49% - 62%)a | 23/239 10% (6% - 14%) | 185/238 78% (72% - 83%)a | 49/239 21% (16% - 26%) |
| Scalp n/N % (95% CI) | 41/115 36% (27% - 45%)a | 7/110 6% (3% - 13%) | 70/115 61% (51% - 70%)a | 14/110 13% (7% - 20%) |
CI=confidence interval; ITT=Intent-to-Treat
a) p<0.0001; compared to vehicle by Cochran-Mantel-Haenszel stratified by study.
In the individual studies, total and partial clearance rates at day 57 (the primary and key secondary endpoints in these studies) were statistically significantly higher in the group treated with tirbanibulin compared with the vehicle group (p≤0.0003), both overall and by treatment location (face or scalp).
Long‑term efficacy
A total of 204 patients achieved complete clearance of actinic keratosis lesions in the treatment field at day 57 (174 treated with tirbanibulin and 30 treated with vehicle) and were eligible for a 1‑year follow-up period for safety monitoring and to evaluate sustained efficacy by assessing actinic keratosis lesions in the treatment field.
After one year, the recurrence rate in patients treated with tirbanibulin was 73 %. There was a higher recurrence rate for scalp lesions compared to facial lesions. Of the patients who developed recurrences, 86 % had either 1 or 2 lesions. Furthermore, 48 % of patients developing recurrences reported at least 1 lesion that was not identified at the time of the initial treatment (i.e., newly occurring lesions counted as recurrences).
Risk of progression to squamous cell carcinoma (SCC)
By day 57, there were no reports of SCC in the treatment field in patients treated with tirbanibulin (0 of 353 patients) or vehicle (0 of 349 patients). One isolated SCC in the treatment field was reported in 1 patient following the day 57 assessment; this event was considered by the investigator not to be related to treatment with tirbanibulin.
Elderly population
Of the 353 patients treated with tirbanibulin in the 2 randomised, double-blind, vehicle‑controlled Phase III studies conducted, 246 patients (70 %) were 65 years of age or older. No overall differences in safety or efficacy were observed between younger and older patients.
Paediatric population
The European Medicines Agency has waived the obligation to submit the results of studies with Klisyri in all subsets of the paediatric population in the treatment of actinic keratosis (see section 4.2 for information on paediatric use).