Itch as Major Mediator of Effect of Tofacitinib on Health-Related Quality of Life in Psoriatic Arthritis: A Mediation Analysis

Pain and Inflammation as Mediators of Tofacitinib Treatment Effect on Fatigue in Patients with Ankylosing Spondylitis: A Mediation Analysis

INTRODUCTION

Tofacitinib is an oral Janus kinase inhibitor for treatment of ankylosing spondylitis (AS). Using mediation modelling, we describe interrelationships between fatigue, pain, morning stiffness, C-reactive protein (CRP) and tofacitinib treatment in patients with AS.

METHODS

Data from phase 2 (NCT01786668)/phase 3 (NCT03502616) studies of patients receiving tofacitinib 5 mg twice daily (BID) or placebo were used. Initial models included treatment as the independent binary variable (tofacitinib 5 mg BID versus placebo); fatigue (Functional Assessment of Chronic Illness Therapy-Fatigue [FACIT-F; model A] or Bath AS Disease Activity Index [BASDAI] Q1 [model B]) as the dependent variable; and pain (total back pain/nocturnal spinal pain [model A] or pain measured by BASDAI Q2/3 [model B]), morning stiffness (BASDAI Q5/6) and CRP as mediator variables.

RESULTS

Pooled data from 370/371 patients were included in models A/B. Initial models demonstrated that tofacitinib treatment affects fatigue mainly indirectly via pain and morning stiffness. As a result, initial models were respecified to exclude direct treatment effect and the indirect effect via CRP. For respecified model A, 44.0% of the indirect effect of tofacitinib treatment on fatigue was mediated via back pain/morning stiffness, 40.0% via morning stiffness alone and 16.0% via back pain alone (all P < 0.05). For respecified model B, 80.8% of the indirect effect of tofacitinib treatment on fatigue was mediated via pain/morning stiffness and 19.2% via pain alone (both P < 0.05).

CONCLUSIONS

In tofacitinib-treated patients with AS, improvements in fatigue were collectively mediated through combined treatment effects on morning stiffness and pain.

Examining the Relationships Among Treatment, Pain, and Physical Function in Patients With Osteoarthritis: A Mediation-Modeling Approach

OBJECTIVES

To better understand the relationships among treatment, pain, and physical function (PF).

METHODS

Data were collected from 2 published randomized clinical trials of osteoarthritis patients who received tanezumab or a placebo. PF was measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) PF domain. Pain (WOMAC pain domain) was a mediator of the effect of treatment on PF. A set of mediation models were investigated. Variables were treatment (tanezumab vs placebo), WOMAC pain domain, and WOMAC PF domain. Cross-sectional mediation models were assessed separately at different weeks. Longitudinal mediation models used data from all weeks simultaneously. Results could identify a steady-state period.

RESULTS

The cross-sectional and longitudinal mediation models showed a stable indirect effect of treatment through the pain on PF across time, indicating that a pseudo-steady-state model was appropriate. Therefore, the longitudinal steady-state mediation models were used with all available data assuming relationships among variables in the model being the same at all time points; results showed that the indirect effect of the treatment on PF was 77.8% in study 1 (NCT02697773) and 74.1% in study 2 (NCT02709486), both P <0.0001, whereas the direct effect was 22.2% for study 1 ( P = 0.0003) and 25.9% for study 2 ( P = 0.0019).

DISCUSSION

At least 75% of the treatment effect of tanezumab on physical functioning can be explained by the improvements in pain. However, tanezumab had an additional effect on physical functioning (~25%) that, was independent of improvements in pain. Such independent effects are of considerable interest and require further research to determine their mechanisms.

Effect of Roflumilast Cream (ARQ-151) on Itch and Itch-Related Sleep Loss in Adults with Chronic Plaque Psoriasis: Patient-Reported Itch Outcomes of a Phase 2b Trial

BACKGROUND

Itch is the most bothersome symptom reported by patients with psoriasis. Safe and effective treatments for psoriasis that also address itch are needed.

OBJECTIVES

To report effects of roflumilast cream on itch-related outcomes from a Phase 2b trial.

METHODS

Adults with chronic plaque psoriasis were randomized to roflumilast 0.3%, roflumilast 0.15%, or vehicle once-daily for 12 weeks. Psoriasis severity was assessed via the Investigator Global Assessment (IGA; a 5-point scale assessing plaque thickening, scaling, and erythema ranging from 0 [clear] to 4 [severe]) and ≥ 2 on a modified Psoriasis Area and Severity Index (PASI-HD, which combines severity of lesions and area affected, ranging from 0 [no disease] to 72 [maximal disease], with the actual percentage of the anatomical area involved in those patients with < 10% of anatomical area involved [e.g., 0.1 for 1% to 0.9 for 9%]). Itch was evaluated via Worst Itch Numeric Rating Scale (WI-NRS), Psoriasis Symptom Diary (PSD) Items 1 (severity of itch) and 2 (bother of itch), and itch-related sleep loss NRS scores. Post hoc correlation analyses between WI-NRS and PASI, WI-NRS and itch-related sleep loss, and WI-NRS and DLQI were also performed.

RESULTS

Roflumilast-treated patients had significantly greater improvements than vehicle-treated patients in WI-NRS and PSD Items 1 and 2 beginning at Week 2 and in itch-related sleep loss Weeks 6 through 12. Among patients with baseline WI-NRS ≥ 6, significantly more patients achieved ≥ 4-point improvement with roflumilast than with vehicle as early as Week 2. Itch severity had low correlation with PASI while WI-NRS and IGA were not always aligned.

LIMITATIONS

The first assessment was at 2 weeks, limiting the ability to assess early onset of itch response.

CONCLUSION

Roflumilast cream improved itch and itch-related sleep loss associated with chronic plaque psoriasis.

CLINICALTRIALS

GOV IDENTIFIER

NCT03638258.