Contact Sensitization and Phototoxic and Photoallergic Potential of Tirbanibulin 1% Ointment in Healthy Volunteers.

Tirbanibulin 1% ointment is approved for the topical treatment of actinic keratosis, applied once daily for 5 days. Three phase 1 randomized, single-center, controlled, within-subject comparison studies were conducted to evaluate the sensitization (KX01-AK-006), phototoxic (KX01-AK-008), and photoallergic (KX01-AK-009) potential of tirbanibulin 1% ointment in healthy adults. In KX01-AK-006 and KX01-AK-009, subjects received repeated applications of tirbanibulin or vehicle for induction (followed by irradiation in KX01-AK-009) and an additional application for the challenge on naïve sites. In KX01-AK-008, subjects received single applications, followed by irradiation. Sensitization was defined as a reaction scoring 3 at naïve sites, recurring at rechallenge. Photoallergy was assessed based on the dermal response of erythema + edema at naïve sites. Phototoxicity was assessed based on the average dermal response score (days 3‒4). Adverse events were collected. In KX01-AK-006, none of the 229 subjects scored 3 at naïve sites. In KX01-AK-008, none of the 31 subjects developed edema, not meeting the criteria for phototoxicity. In KX01-AK-009, none of the 59 subjects showed reactions compatible with photoallergy. Mild-to-moderate contact irritations were reported. The evidence provided by these phase 1 studies showed that tirbanibulin 1% ointment lacks sensitization and phototoxic or photoallergic potential, and supports the safety of its topical application.

Topical Tirbanibulin, a Dual Src Kinase and Tubulin Polymerization Inhibitor, for the Treatment of Plaque-Type Psoriasis: Phase I Results.

Plaque-type psoriasis is a common skin disorder. Tirbanibulin (KX01) is a new Src kinase inhibitor with potent antiproliferative activity against keratinocytes and has been approved for treatment of actinic keratosis. This Phase I study investigates the safety and activity of KX01 ointment in patients with plaque-type psoriasis. We recruited 28 patients from two medical centers in Taiwan. This study was performed in four stages. Double-blind treatments were randomized in stages I (KX01 0.01% + placebo, two rounds of two-week treatment) and II (KX01 0.1% + placebo, four weeks) and open-labelled in stages III (KX01 1%, five days) and IV (KX01 1%, five days weekly for four weeks). The safety, tolerability, KX01 concentration, target area score, physician global assessment, and disease relapse were determined. Most treatment-emergent adverse events were mild-to-moderate application site reactions. Three (50.0%) subjects from the stage IV group showed ≥50% reduction in the target area score (TAS50), while two subjects (33.3%) showed a clinically meaningful improvement in the physician global assessment score. KX01 0.01%, 0.1%, and 1% were safe and well-tolerated. KX01 1% at four weeks showed a promising activity for the treatment of plaque-type psoriasis.

Phase 1 Maximal Use Pharmacokinetic Study of Tirbanibulin Ointment 1% in Subjects With Actinic Keratosis.

Tirbanibulin is a novel tubulin polymerization and Src kinase signaling inhibitor. This study was designed to fully characterize tirbanibulin pharmacokinetics (PK) when applied topically under maximal use conditions. This was an open-label, parallel-group PK safety study of tirbanibulin ointment 1% applied to 25 cm2 of the face or balding scalp in adults with actinic keratosis (AK). Eligible subjects self-applied tirbanibulin once-daily for 5 days. PK sampling occurred on days 1, 3 and 4 at 0 hour (before dosing), and on day 5 at prespecified time points up to 24 hours after application. Safety assessments included adverse events and local skin reactions were evaluated up to day 29. Eighteen subjects (face or scalp, n = 9 each) completed the study. Subjects were White (100%), of mean [range] age 66.4 [43-83] years, predominantly men (83.3%) with Fitzpatrick skin type I to III (94.4%); baseline AK lesion count, mean [range] 8.2 [6-14]. All subjects had quantifiable but low plasma concentrations of tirbanibulin. On day 5, overall mean (standard deviation) maximum concentration (Cmax ) was 0.26 (0.23) ng/mL (or 0.60 nM), median time to maximum concentration was 6.91 hours, and mean (standard deviation) area under the plasma concentration-time curve from time 0 to 24 hours was 4.09 (3.15) ng ∙ h/mL. Four subjects experienced a total of 5 treatment-emergent adverse events that resolved. Mild to moderate erythema, flaking, or scaling in the treatment area peaked around day 8 before resolving or returning to baseline by day 29. In conclusion, under maximal use conditions, tirbanibulin ointment 1% for 5 days in the treatment of AK on the face or scalp was well tolerated and resulted in low systemic exposure with subnanomolar plasma concentrations.

Phase 3 Trials of Tirbanibulin Ointment for Actinic Keratosis.

BACKGROUND: The tubulin polymerization and Src kinase signaling inhibitor tirbanibulin is being investigated as a topical treatment for actinic keratosis, a precursor of squamous-cell carcinoma. METHODS: In two identically designed double-blind trials, we randomly assigned, in a 1:1 ratio, adults with actinic keratoses on the face or scalp to receive either topical tirbanibulin or vehicle (placebo) ointment. The ointment was applied by the patients to a 25-cm2 contiguous area containing four to eight lesions once daily for 5 consecutive days. The primary outcome was the percentage of patients with a complete (100%) reduction in the number of lesions in the application area at day 57. The secondary outcome was the percentage of patients with a partial (≥75%) reduction in the number of lesions within the application area at day 57. The incidence of recurrence was evaluated at 1 year. Local reactions were scored with the use of 4-point scale (ranging from 0 [absent] to 3 [severe]). RESULTS: A total of 702 patients were enrolled in the two trials (351 patients per trial). Complete clearance in trial 1 occurred in 44% of the patients (77 of 175) in the tirbanibulin group and in 5% of those (8 of 176) in the vehicle group (difference, 40 percentage points; 95% confidence interval [CI], 32 to 47; P<0.001); in trial 2, the percentages were 54% (97 of 178 patients) and 13% (22 of 173), respectively (difference, 42 percentage points; 95% CI, 33 to 51; P<0.001). The percentages of patients with partial clearance were significantly higher in the tirbanibulin groups than in the vehicle groups. At 1 year, the estimated percentage of patients with recurrent lesions was 47% among patients who had had a complete response to tirbanibulin. The most common local reactions to tirbanibulin were erythema in 91% of the patients and flaking or scaling in 82%. Adverse events with tirbanibulin were application-site pain in 10% of the patients and pruritus in 9%, all of which resolved. CONCLUSIONS: In two identically designed trials, tirbanibulin 1% ointment applied once daily for 5 days was superior to vehicle for the treatment of actinic keratosis at 2 months but was associated with transient local reactions and recurrence of lesions at 1 year. Trials comparing tirbanibulin with conventional treatments and that have longer follow-up are needed to determine the effects of tirbanibulin therapy on actinic keratosis. (Funded by Athenex; ClinicalTrials.gov numbers, NCT03285477 and NCT03285490.).

Prognostic Factors for Communication Improvement in Young Children After Cochlear Implant Surgery.

OBJECTIVE: Our objective was to examine the prognostic factors for post-cochlear implant (CI) communication improvement and determine whether the otologist's and speech-language pathologist's (SLP's) recommendations exhibited the same predictive performance regarding children's post-CI verbal expression acquisition. STUDY DESIGN: Retrospective, diagnostic study. SETTING: Hospital. PATIENTS: The study reviewed 339 medical charts of preschool children who underwent CI surgery before the age of 6 years during 1999 to 2016. After these medical charts were assessed, the cohort comprised of 79 preschool children with pre- and post-CI surgery speech-language assessment reports and medical records. INTERVENTION: A senior SLP and an otologist conducted blind testing of CI candidacy according to the 79 children's pre-CI reports. MAIN OUTCOME MEASURES: Spoken mean length of utterance (MLU). RESULTS: Children with superior skills in comprehending facial and gesture expressions or using gestures or sounds for expression were significantly more likely to receive the SLP's recommendation for CI surgery. The SLP's CI candidacy recommendation, based on background information, communication skill assessments, and magnetic resonance imaging (provided by an otologist), had significant predictive effects. Children recommended by the SLP exhibited a 20 times higher probability of benefiting from CI surgery; such a benefit would be a longer MLU after 2 years. CONCLUSION: CI candidacy testing for young children with prelingual hearing impairment based on a SLP's recommendations provided significant predictive effects. LEVEL OF EVIDENCE: 4 (Evidence from well-designed case-control or cohort studies).

Tirbanibulin Ointment 1% as a Novel Treatment for Actinic Keratosis: Phase 1 and 2 Results.

BACKGROUND: Current field-directed treatments of actinic keratosis (AK), a pre-malignant condition, are often limited by severe local reactions and/or complex treatment. Tirbanibulin, a novel potent anti-proliferative synthetic agent that inhibits tubulin polymerization and Src kinase signalling, is being developed as a convenient, safe, and effective field treatment of actinic keratosis. HYPOTHESIS: A short course of tirbanibulin ointment 1% safely reduces AK lesions. METHODS: In the Phase 1 study, 4 treatment cohorts with forearm lesions received tirbanibulin ointment 1% over 25 or 100 cm2 once daily for 3 or 5 days and were evaluated through day 45. In the Phase 2 study, 2 treatment cohorts with face or scalp lesions received tirbanibulin ointment 1% once daily for 3 or 5 days over 25 cm2 and were evaluated through day 57. Lesion reductions, clearance rates, safety, and pharmacokinetics were assessed. RESULTS: Forearm AK lesions were reduced by day 45 in all Phase 1 cohorts (N=30). Complete AK clearance at day 57 for face/scalp AK lesions in Phase 2 cohorts (N=168) was demonstrated in 43% and 32% of participants of the 5-day and 3-day cohorts, respectively. Adverse reactions were mainly transient mild local erythema and flaking/scaling, pruritus, and pain. Tirbanibulin plasma concentrations were low or undetectable. CONCLUSION: Tirbanibulin ointment 1% was well tolerated and active in AK reduction. Based on activity, the 5-day regimen was selected for Phase 3 development. Clinicaltrials.gov: NCT02337205; NCT02838628 J Drugs Dermatol. 2020;19(11):1093-1100. doi:10.36849/JDD.2020.5576THIS ARTICLE HAD BEEN MADE AVAILABLE FREE OF CHARGE. PLEASE SCROLL DOWN TO ACCESS THE FULL TEXT OF THIS ARTICLE WITHOUT LOGGING IN. NO PURCHASE NECESSARY. PLEASE CONTACT THE PUBLISHER WITH ANY QUESTIONS.

Discovery of Novel Dual Mechanism of Action Src Signaling and Tubulin Polymerization Inhibitors (KX2-391 and KX2-361).

The discovery of potent, peptide site directed, tyrosine kinase inhibitors has remained an elusive goal. Herein we describe the discovery of two such clinical candidates that inhibit the tyrosine kinase Src. Compound 1 is a phase 3 clinical trial candidate that is likely to provide a first in class topical treatment for actinic keratosis (AK) with good efficacy and dramatically less toxicity compared to existing standard therapy. Compound 2 is a phase 1 clinical trial candidate that is likely to provide a first in class treatment of malignant glioblastoma and induces 30% long-term complete tumor remission in animal models. The discovery strategy for these compounds iteratively utilized molecular modeling, along with the synthesis and testing of increasingly elaborated proof of concept compounds, until the final clinical candidates were arrived at. This was followed with mechanism of action (MOA) studies that revealed tubulin polymerization inhibition as the second MOA.

Hepatic expression of cell proliferation markers and growth factors in giant cell hepatitis: implications for the pathogenetic mechanisms involved.

OBJECTIVES: The aim of this study is to determine whether amitotic division or nuclear proliferation is involved in the formation of giant cells (GCs) in giant cell hepatitis (GCH). PATIENTS AND METHODS: Liver sections from 18 pediatric patients with idiopathic infantile GCH and 12 patients with postinfantile GCH were evaluated for the expression of proliferating cell nuclear antigen (PCNA) and human histone 3 (H3) mRNA, transforming growth factor-alpha (TGF-α), TGF-ß1, hepatocyte growth factor (HGF), and epidermal growth factor receptor (EGFR). RESULTS: Proliferation markers were detected in 1% to 80% in the nuclei of GC and non-GC hepatocytes in 10 of 18 (56%) infantile GCH biopsies and 11 of 12 (92%) postinfantile GCH biopsies, but not in normal liver. The expression of proliferation markers in GCs paralleled that in non-GC hepatocytes (P < 0.05 for both markers). TGF-α and EGFR were detected in both GCs (9/29 and 4/30 patients with infantile or postinfantile GCH, respectively) and non-GC hepatocytes (15/29 and 11/30 patients with infantile or postinfantile GCH, respectively). TGF-ß1 and HGF were detected mainly in sinusoidal cells in 20 of 29 and 10 of 30 patients with infantile or postinfantile GCH, respectively; the expression of HGF was positively correlated with PCNA and H3 mRNA in non-GC hepatocytes and with H3 mRNA in GCs (P < 0.01). CONCLUSIONS: Hepatic expressions of nuclear proliferation markers and growth factors were similar in infantile and postinfantile GCH, nuclear proliferation markers were detected in both GCs and non-GC hepatocytes in a high proportion of patients, and expression of HGF correlated positively with the proliferation markers. These data indicate that nuclear proliferation may contribute to the pathogenesis of GCs in at least a proportion of patients with GCH. A model for the pathogenesis of GCH is proposed.

Expression of Src and FAK in hepatocellular carcinoma and the effect of Src inhibitors on hepatocellular carcinoma in vitro.

The expressions of c-Src and focal adhesion kinase (FAK) were studied in 65 Chinese patients with hepatocellular carcinoma (HCC) by immunohistochemistry using rabbit monoclonal antibodies. Expressions of total Src, an active form of Src, and FAK were found in 44/65 (67.7%), 36/45 (55.4%), and 33/56 (58.9%) HCC cases, respectively. There was a good correlation between the expression of total Src, active form of Src, and FAK in these HCC cases (P < 0.001). Expression of Src was not correlated to any clinical parameters, cancer cell phenotypic markers, and pathologic features apart from a positive correlation with alpha-fetoprotein (P < 0.01). The expression of FAK was correlated with earlier onset and the expression of Ki-67 but not proliferating cell nuclear antigen (PCNA) in these HCC cases. Four liver-cancer-derived cell lines (three derived from HCC and one from hepatoblastoma) were then tested with inhibitors against Src. A small molecule, KX2-391, designed to target the substrate binding pocket of Src, was found to have more broad-spectrum activity and better potency than Dasatinib, an adenosine triphosphate (ATP)-competitive inhibitor in vitro. Our data indicates that Src and FAK expression are both elevated and active in Chinese patients with HCC and that Src may play a key role in supporting HCC progression. Src antagonism with specific inhibitors may be an attractive treatment paradigm for patients with HCC.