Clinical Pharmacology for Klisyri
Mechanism Of Action
Tirbanibulin is a microtubule inhibitor. The mechanism of action of KLISYRI for the topical treatment of actinic keratosis is unknown.
Pharmacodynamics
The pharmacodynamics of tirbanibulin in the treatment of actinic keratosis is unknown.
Pharmacokinetics
Absorption
Following topical treatment of a mean daily dose of 348 mg (range: 224 to 435 mg) of KLISYRI to a 100 cm² contiguous area of the face or balding scalp, once daily for 5 consecutive days. On Day 5, systemic exposure to tirbanibulin had a mean±SD maximum plasma concentration (Cmax) of 1.32±0.74 ng/mL and 0.71±0.31 ng/mL, and a mean±SD area under the plasma concentration from time zero to 24 hours (AUC24) of 19.6±8.1 h*ng/mL and 11.7±4.4 h*ng/mL, in subjects who received the face and scalp topical treatment, respectively. The median time to reach Cmax (Tmax) was ~6 hours.
Distribution
Plasma protein binding of tirbanibulin is 88% and is independent of concentrations in the range of 0.01 to 10 μg/mL.
Elimination
Metabolism
Following topical treatment with KLISYRI to adult subjects with actinic keratosis, the plasma concentrations of KX2-5036, KX2-5163, and KX2-5180, three pharmacologically inactive metabolites, were detectable with the highest plasma concentrations of 0.36 ng/mL, 0.42 ng/mL, and 1.70 ng/mL, respectively.
The in vitro study indicated that incubation of 1 or 10 μM tirbanibulin with human hepatocytes generated KX2-5036, KX2-5162 and other unidentified metabolites.
In vitro, tirbanibulin is mainly metabolized by CYP3A4, and to a lesser extent, CYP2C8.
Excretion
Excretion of tirbanibulin has not been fully characterized in humans.
Drug Interactions
Clinical Studies
No clinical studies evaluating the drug interaction potential of KLISYRI have been conducted.
In Vitro Studies
CYP Enzymes
Tirbanibulin and the metabolite KX2-5036 directly or time-dependently inhibited CYP 1A2, 2B6, 2C8, 2C9, 2C19, 2D6, or 3A4 with an IC50 value of >17 μM. Tirbanibulin up to 1 μM (431.5 ng/mL) and the metabolite KX2-5036 up to 3 μM (1024 ng/mL) did not induce CYP 1A2, 2B6, or 3A4. The metabolite KX2-5180 was neither an inhibitor of CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6 or 3A4 with an IC50 value of > 225 nM (85 ng/mL) nor an inducer of CYP1A2, 2B6, and 3A4 at a concentration of 225 nM (85 ng/mL). These findings suggest that KLISYRI has no clinically meaningful effect on the PK of drugs metabolized by CYP 1A2, 2B6, 2C8, 2C9, 2C19, 2D6, or 3A4.
Drug Transporters
Neither tirbanibulin nor the metabolite KX2-5036 was a substrate of MDR1, BCRP, BSEP, MRP2, MATE1, MATE2-K, OAT1, OAT3, OATP1B1, OATP1B3, OCT1 or OCT2. The metabolite KX2-5180 was a substrate of BCRP, but not a substrate for other transporters. Tirbanibulin and the metabolites of KX2-5036 and KX2-5180 inhibited MDR1, BCRP, MRP2, BSEP, MATE1, MATE2-K, OAT1, OTA3, OATP1B1, OATP1B3, OCT1 and/or OCT2 with an IC50 value of >1 μM. The results suggest that KLISYRI has no clinically meaningful effect on the PK of drugs mediated by MDR1, BCRP, MRP2, BSEP, MATE1, MATE2-K, OAT1, OTA3, OATP1B1, OATP1B3, OCT1 and OCT2.
Clinical Studies
Actinic Keratosis Of The Face Or Scalp
Two double-blind, vehicle-controlled clinical trials (NCT03285477 and NCT03285490) were conducted with 702 adult subjects with actinic keratosis on the face or scalp. Subjects were randomized 1:1 to KLISYRI or vehicle. Subjects enrolled had 4 to 8 clinically typical, visible, and discrete AK lesions in a contiguous area of 25 cm² on the face or scalp. Subjects had an average age of 70 years (range 45 to 96 years), were predominantly White (99%), male (87%), with Fitzpatrick skin types I or II (72%) and actinic keratosis on the face (68%) or scalp (32%). Treatment groups were comparable across all demographics and baseline characteristics, including AK lesion count and distribution on the face or scalp.
Subjects received 5 consecutive days of once daily treatment with either KLISYRI (353) or vehicle control (349) to the treatment field. Subjects with complete (100%) clearance of AK lesions in the treatment area at Day 57 returned to the clinic for recurrence assessment every 3 months for a total of 12 months post-Day 57.
The primary efficacy endpoint was complete (100%) clearance of AK lesions in the treatment area, defined as the proportion of subjects at Day 57 with no clinically visible AK lesions in the treatment area and the secondary endpoint was partial (≥75%) clearance of AK lesions in the treatment area. Results from both trials are presented below.
Table 3 : Complete (100%) AK Clearance Rates on Day 57 in Adults with AK on the Face or Scalp for the Two Phase 3 Trials (Intent to Treat [ITT] Population)
|
Study 1 |
Study 2 |
KLISYRI
N = 175 n/N (%) |
Vehicle
N = 176 n/N (%) |
Treatment difference (KLISYRI -Vehicle) |
95% Confidence Interval for the Treatment difference |
KLISYRI
N = 178 n/N (%) |
Vehicle
N = 173 n/N (%) |
Treatment difference (KLISYRI -Vehicle) |
95% Confidence Interval for the Treatment difference |
| All subjects |
77/175 (44%) |
8/176 (5%) |
40%a |
(31.6%, 47.5%)a |
97/178 (54%) |
22/173
(13%) |
42% a |
(33.1%, 50.7%)a |
| Face |
60/119 (50%) |
7/121 (6%) |
45% |
-- |
73/119 (61%) |
16/118 (14%) |
48% |
-- |
| Scalp |
17/56 (30%) |
1/55 (2%) |
29% |
-- |
24/59 (41%) |
6/55 (11%) |
30% |
-- |
| a Based on Mantel-Haenszel method |
Table 4 : Partial (≥ 75%) AK Clearance Rates on Day 57 in Adults with AK on the Face or Scalp for the Two Phase 3 Trials (Intent to Treat [ITT] Population)
|
Study 1 |
Study 2 |
KLISYRI
N = 175 n/N (%) |
Vehicle
N = 176 n/N (%) |
Treatment difference (KLISYRI -Vehicle) |
95% Confidence Interval for the Treatment difference |
KLISYRI
N = 178 n/N (%) |
Vehicle
N = 173 n/N (%) |
Treatment difference (KLISYRI -Vehicle) |
95% Confidence Interval for the Treatment difference |
| All subjects |
119/175 (68%) |
29/176 (16%) |
52% a |
(42.9%, 60.3%) a |
136/178 (76%) |
34/173 (20%) |
57% a |
(48.3%, 65.4%) a |
| Face |
90/119 (76%) |
23/121 (19%) |
57% |
-- |
95/119 (80%) |
26/118 (22%) |
58% |
-- |
| Scalp |
29/56 (52%) |
6/55 (11%) |
41% |
-- |
41/59 (69%) |
8/55 (15%) |
55% |
-- |
| a Based on Mantel-Haenszel method |
Efficacy was consistent across sex and age (<65 and ≥65 years) subgroups.
Subjects who achieved 100% clearance of AK lesions in the treatment area at Day 57 continued to be followed for up to 12 months following Day 57 to determine the recurrence rate. Recurrence was defined as the proportion of subjects with any identified AK lesion (new or previous lesion) in the previously treated area who achieved 100% clearance at Day 57. Of the 174 subjects treated with KLISYRI who were followed, the recurrence rate at 12 months post-Day 57 was 73%.