A phase I randomized trial to assess the effect on skin infiltrate thickness and tolerability of topical phosphodiesterase inhibitors in the treatment of psoriasis vulgaris using a modified psoriasis plaque test

Clinical pharmacokinetics and pharmacodynamics of topical non-biological therapies for psoriasis patients

INTRODUCTION

Psoriasis is a chronic inflammatory cutaneous disease that causes patients psychosocial distress. Topical therapies are utilized for mild-to-moderate disease and for more severe disease in conjunction with systemic therapies. Topical corticosteroids are a cornerstone of treatment for psoriasis, but long-term use can cause stria and cutaneous atrophy and as well as systemic side effects such as topical steroid withdrawal. Non-steroidal topical therapies tend to be safer than topical corticosteroids for long-term use.

AREAS COVERED

We conducted a literature review on the pharmacokinetic (PK) and pharmacodynamic (PD) properties of topical therapies for psoriasis. We discuss how the PK and PD characteristics of these therapies inform clinicians on efficacy and toxicity when prescribing for patients.

EXPERT OPINION

Topical corticosteroids, used intermittently, are very safe and effective. Long-term, continuous use of topical corticosteroids can cause systemic side effects. Several generic and newly approved non-steroidal options are available, but no head-to-head studies compare the effectiveness of the generics (vitamin D analogs, tacrolimus, pimecrolimus) against the newer therapies (roflumilast, tapinarof). Patients often do not respond to topical therapies due to poor adherence to treatment regimens. For patients resistant to topical treatment, phototherapy or systemic therapy may be an option.

New and Emerging Oral/Topical Small-Molecule Treatments for Psoriasis

The introduction of biologic therapies has led to dramatic improvements in the management of moderate-to-severe psoriasis. Even though the efficacy and safety of the newer biologic agents are difficult to match, oral administration is considered an important advantage by many patients. Current research is focused on the development of oral therapies with improved efficacy and safety compared with available alternatives, as exemplified by deucravacitinib, the first oral allosteric Tyk2 inhibitor approved for the treatment of moderate to severe psoriasis in adults. Recent advances in our knowledge of psoriasis pathogenesis have also led to the development of targeted topical molecules, mostly focused on intracellular signaling pathways such as AhR, PDE-4, and Jak-STAT. Tapinarof (an AhR modulator) and roflumilast (a PDE-4 inhibitor) have exhibited favorable efficacy and safety outcomes and have been approved by the FDA for the topical treatment of plaque psoriasis. This revision focuses on the most recent oral and topical therapies available for psoriasis, especially those that are currently under evaluation and development for the treatment of psoriasis.

Pharmacokinetics of Roflumilast Cream in Chronic Plaque Psoriasis: Data from Phase I to Phase III Studies

BACKGROUND

Most patients with chronic plaque psoriasis receive topical treatment; however, available options lack a balance of efficacy with long-term safety and tolerability. Roflumilast cream 0.3% is a highly potent phosphodiesterase 4 (PDE4) inhibitor approved by the US FDA for treatment of psoriasis.

OBJECTIVE

The aim of this study was to define the pharmacokinetic (PK) profile of roflumilast delivered topically from a phase I maximal usage study and data from phase II and phase III studies.

METHODS

PK data for roflumilast and the active metabolite, roflumilast N-oxide, were determined from a phase I PK and safety maximal usage study of roflumilast cream 0.3% applied once daily for 14 days in patients with plaque psoriasis affecting body surface area (BSA) ≥20% (N = 26). Serial plasma samples were obtained on Days 1 and 15 to determine maximum plasma concentration (C_max) and area under the concentration-time curve (AUC). Plasma concentrations were also assessed at Weeks 3, 4, and 5 for terminal half-life (t_½). Concentrations of roflumilast and roflumilast N-oxide in skin were assessed at Day 28 for 14 patients with psoriasis in a phase I/IIa study of once-daily roflumilast cream 0.5% and 0.15% for 28 days. Systemic exposure (C_trough and AUC) of roflumilast and roflumilast N-oxide in two phase III trials (DERMIS-1, n = 245; DERMIS-2, n = 250) of roflumilast cream 0.3% for 8 weeks was assessed at Weeks 4 and 8.

RESULTS

Bioavailability of roflumilast cream 0.3% after topical administration was 1.5%. Unlike after oral dosing, the plasma concentration-time curve was flat, with a peak-to-trough ratio of 1.2. Roflumilast N-oxide concentrations were eightfold higher than roflumilast concentrations. The t_½ in adult patients was 4.0 days for roflumilast and 4.6 days for roflumilast N-oxide following the last dose administered. Steady state was reached by Day 15. Concentrations of roflumilast in skin were, on average, 126- and 61.8-fold higher than corresponding mean plasma C_trough following administration of roflumilast cream 0.15% and 0.5% daily for 28 days. Roflumilast N-oxide was quantifiable in only one skin sample (N = 27). Following 8 weeks of treatment in DERMIS-1, mean plasma C_trough of roflumilast was 1.78 ng/mL, and 9.86 ng/mL for roflumilast N-oxide. In DERMIS-2, mean plasma C_trough was 1.72 ng/mL and 10.2 ng/mL, respectively. In the maximal usage study (mean BSA: 27.5%), eight patients (30.8%) experienced adverse events (AEs) and all were mild or moderate, with no reports of diarrhea, headache, insomnia, or application-site pain; no patients discontinued treatment due to an AE.

CONCLUSION

Topical administration of roflumilast cream 0.3% results in concentrations in skin 126- and 61.8-fold higher relative to plasma, which are much higher than expected to be achievable with oral dosing. PDE4 inhibition in the skin is likely due to roflumilast as compared with its active metabolite, as there is no significant conversion to roflumilast N-oxide in the skin. Consistent with reservoir formation and retention of drug in the stratum corneum, roflumilast is slowly released from the skin (t_½ 4 days) and peak-to-trough ratio is 1.2.

CLINICALTRIALS

GOV IDENTIFIERS

NCT04279119, NCT03392168, NCT04211363, NCT04211389.

Killing all the birds with one drug - is oral roflumilast a novel treatment option for psoriasis?

Psoriasis is a common, chronic inflammatory skin disease associated with a large number of comorbidities. Though management of moderate-to-severe plaque psoriasis has greatly improved in recent years, patients with refractory disease or contraindications to available treatments still constitute therapeutic challenges. Oral roflumilast, a selective phosphodiesterase-4 (PDE-4) inhibitor, is approved for chronic obstructive pulmonary disease. Experimental studies have shown increased PDE-4 activity in psoriatic skin, and inhibition results in down-regulation of key inflammatory cytokines. Based on mode-of-action and available literature, we hypothesize that oral roflumilast is a future treatment for plaque psoriasis. Contrary to most existing psoriasis therapies, roflumilast has a favorable safety profile and holds the potential to improve not only skin manifestations but also commonly seen comorbidities. If efficacy and safety are confirmed in randomized settings, roflumilast can fill in a large unmet need and may represent a novel, relatively inexpensive, and convenient therapy positioned before biologics.

New Topical Therapies for Psoriasis

Psoriasis is a chronic immune-mediated skin disease with a significant impact on patients' quality of life. Mild-to-moderate forms of the disease usually require long-term topical treatment, but prolonged use of corticosteroids and vitamin D analogues is limited by adverse effects. With further understanding of psoriasis pathogenesis, new molecules are emerging aiming to fulfil these clinical needs. Tapinarof, an aryl hydrocarbon receptor modulator, has completed a phase III study and demonstrated good efficacy results, even in long treatment courses, with a favourable safety profile. It additionally appears to have a promising remitting effect as patients presented with an average relapsing time of over 3 months. Roflumilast, a phosphodiesterase type 4 inhibitor, also underwent a phase III study with significant lesion improvement and notable pruritus management, and with no reported side effects. Roflumilast was evaluated as an option for intertriginous areas with good outcomes in a small sample, but larger trials are required. The Janus kinase-signal transducer and activator of transcription pathway has been targeted in recent clinical investigations with promising options, currently with brepocitinib pending phase IIb results. Ongoing preclinical studies involving interleukin-2 inhibition, RNA modulators and amygdalin analogues may lead to forthcoming clinical trials. New topical drugs are successfully emerging and future research comparing them to classical options will dictate their clinical role in the treatment of psoriasis.

Comparison of Occlusive and Open Application in a Psoriasis Plaque Test Design, Exemplarily Using Investigations of Mapracorat 0.1% Ointment versus Vehicle and Reference Drugs

BACKGROUND/AIMS

Psoriasis plaque tests (PPTs) are important tools in the early phases of antipsoriatic drug development. Two distinct PPT design variants (open vs. occluded drug application) are commonly used, but no previous work has aimed to directly compare and contrast their performance.

METHODS

We compared the antipsoriatic efficacy of mapracorat 0.1% ointment and reference drugs reported in 2 separate studies, representing open and occluded PPT designs. The drug effect size was measured by sonography (mean change in echo-poor band thickness), chromametry, and standardized clinical assessment.

RESULTS

Antipsoriatic effects were detectable for the study drugs in both occluded and open PPTs. Differences between the potency of antipsoriatic drugs and vehicle were observable. The total antipsoriatic effect size appeared to be higher in the occluded PPT than the open PPT, despite the shorter treatment duration (2 vs. 4 weeks). Effect dynamics over time revealed greater differences between some study drugs in the open PPT compared to the occluded PPT.

CONCLUSION

Taking the higher technical challenges for the open PPT into account, we recommend the occluded PPT as a standard screening setting in early drug development. In special cases, considering certain drug aspects or study objectives that would require procedural adaptations, an open PPT could be the better-suited design. Finally, both PPT models show clear advantages: classification as phase I studies, small number of psoriatic subjects, relatively short study duration, excellent discrimination between compounds and concentrations, parallel measurement of treatment response, and go/no go decisions very early in clinical development.