Emerging drugs for psoriasis

Modeling clinical efficacy of the S1P receptor modulator ponesimod in psoriasis

BACKGROUND

Ponesimod is currently the only S1P receptor modulator studied in psoriasis. In a dose-finding study, the active doses showed similar efficacy.

OBJECTIVE

Prediction of efficacy at lower doses to aid clinical phase 3 planning with respect to dose selection, duration of treatment, and patient inclusion criteria based on pharma-co-kinetic/pharmacodynamic (PK/PD) modeling and simulation.

METHODS

The dose-finding study treated 326 patients (67 on placebo, 126 on 20mg, and 133 on 40mg) over 16 weeks. PK/PD modeling of steady-state trough concentrations and longitudinal PASI scores was employed to characterize data and simulate scenarios.

RESULTS

PASI score continually decreased with time on ponesimod treatment, reaching a plateau at 16 weeks. Absolute and relative (percent) PASI score change was larger in patients with higher PASI score at baseline. Doses below 10mg were predicted to show lower efficacy than doses of 10mg and higher.

CONCLUSION

Concentration-response modeling was able to predict the efficacy of doses that were not studied. In psoriasis patients, a dose of 10mg (not administered in the study) was predicted to show efficacy similar to 20mg. Disease status (PASI score at baseline) as study inclusion criterion has pronounced influence on study outcome.

Humanized anti-CD2 monoclonal antibody treatment of plaque psoriasis: efficacy and pharmacodynamic results of two randomized, double-blind, placebo-controlled studies of intravenous and subcutaneous siplizumab

New biologic therapies focused primarily on cytokine pathways, some targeting T cell-mediated immune responses, are being developed for the treatment of psoriasis. Siplizumab is a humanized anti-CD2 monoclonal antibody that interferes with costimulation necessary for T cell activation and proliferation. We assessed the biological activity, serum concentrations, and pharmacodynamic effects of siplizumab in patients with plaque psoriasis. Two multicenter, phase II randomized, double-blind, placebo-controlled studies were conducted: one study randomized 124 patients to one of two intravenous (IV) doses (0.012 and 0.04 mg/kg) of siplizumab, given every 2 weeks x 8 doses; the other study randomized 420 patients to one of three subcutaneous (SC) dose regimens of siplizumab given weekly (5 mg for 12 weeks, 5 mg for 6 weeks, and 7 mg for 4 weeks) or placebo for 12 weeks. Adults with plaque psoriasis involving > or =10% of the body surface area and who were not receiving psoriasis therapy were eligible. Treatment with siplizumab resulted in reductions in psoriasis severity, but most of the effects were not statistically significant compared with placebo. Statistically significant differences among IV siplizumab-treated and placebo groups were observed at study day 28, with greater psoriasis area and severity index (PASI) score reductions from baseline in the siplizumab groups. The difference in PASI50 response rates between the 0.04 mg/kg siplizumab and placebo groups was also statistically significant at day 28. A trend toward clinical improvement was observed in SC siplizumab-treated groups. Significant reductions in circulating absolute lymphocyte counts and CD2+ (CD3+, CD8+, and CD16+/56+), but not CD2- (CD19+ and CD14+), lymphocyte populations were observed. These changes were not accompanied by concomitant reductions in infiltrating CD3+ lymphocytes in psoriatic lesions, epidermal thickness, or keratin 16 (K16) and intercellular adhesion molecule (ICAM) expression. The effect of siplizumab did not differentially affect CD45RO+ and CD45RA+ lymphocytes. Low or undetectable mean trough serum concentrations of siplizumab following IV or SC treatment were observed. Pharmacokinetic data coupled with higher-than-expected placebo clinical response rates may partly explain siplizumab's marginal clinical activity. Higher doses of siplizumab may be required to detect significant improvements in psoriasis; however, further development of this agent was not planned.

Cutaneous manifestations in inflammatory bowel diseases: eight cases of psoriasis induced by anti-tumor-necrosis-factor antibody therapy

BACKGROUND

Ulcerous rectocolitis and Crohn's disease are the best known forms of inflammatory bowel disease (IBD). Skin manifestations are not uncommon in IBD and may be divided into specific cutaneous signs, aspecific cutaneous signs, and cutaneous signs caused by drugs used for IBD therapy. The specific signs (fistulas, rhagades and ulcers) are the result of the diffusion of the intestinal inflammatory process into the skin. Aspecific cutaneous signs (stomatic aphthosis, erythema nodosum, pyoderma gangrenosum, Sweet's syndrome, vasculitis, bullous diseases) are quite frequently found in those suffering from IBD, but also in apparently healthy subjects, and may sometimes be the first sign of the intestinal disease. Cutaneous manifestations due to drugs vary in clinical aspect and are the direct consequence of the therapies adopted, which in IBD patients can be quite numerous: steroids, immunosuppressants, 5-aminosalicylic acid, biological agents, antibiotics.

OBJECTIVE AND METHODS

Due to the frequent finding of cutaneous manifestations in patients affected by IBD, a collaboration was set up between the Dermatological Clinic of the University of Bologna and the Center for the Study of IBD of the same university hospital. The aim was to diagnose the cutaneous signs appearing during IBD and to establish their etiopathogenesis in order to assess whether they were the result of epiphenomena of the IBD or side effects of the therapies adopted.

RESULTS

The cutaneous manifestations we observed can be divided into three distinct groups: signs that were specific to the basic disease, aspecific signs and finally signs attributable to the drugs used for therapy. Particular attention was given to the aspecific signs and those consequential to therapy. The aspecific cutaneous signs seen in our clinic generally reflect those reported in the literature. The cutaneous manifestations due to drugs were further divided into three groups: rosacea, acneiform dermatitis and psoriasis-like dermatitis. The most notable aspect of our series is the high number of patients presenting psoriasiform-type dermatitides with a generally widespread diffusion.

CONCLUSION

We would like to draw attention to the fact that all patients with psoriasis had been undergoing treatment with drugs inhibiting tumor necrosis factor alpha (TNF-alpha) as part of IBD therapy. In all cases, the cutaneous reaction started after the third or fourth infusion of the biological drug. Anti-TNF-alpha agents have also been successfully used to treat psoriasis in the last few years. The reason for this apparently paradoxical effect of the therapy is still unclear.