Quantification of Siliq levels in patients with psoriasis linked to response rate

Researchers found that monitoring circulating levels of Siliq correlated with clinical response in patients treated for psoriasis, according to a study published in JAMA Dermatology.

“Given the many possible treatment modalities in psoriasis management, an emerging challenge is to estimate the ideal treatment choice for each individual patient,” Christian Enevold, PhD, of the Copenhagen University Hospital in Denmark, and colleagues wrote.

Siliq (brodalumab, Valeant Pharmaceuticals) is a monoclonal fully human antibody of IgG2-isotype targeting the interleukin (IL)-17 receptor A subunit, which targets the broadest possible range of IL-17-mediated signaling.

In their study, Enevold and colleagues recruited 20 patients with plaque psoriasis, all of whom had treatment failure with at least one IL-17A inhibitor. Eighteen patients experienced treatment failure with at least one TNF-alpha or IL-12/23 inhibitor.

Most patients showed notable reductions in PASI scores after brodalumab treatment, with median PASI scores decreasing from 13.5 at baseline to 4.5 at week 4 and to 1.8 at week 12 (P < .001).

After 26 weeks of treatment, five patients discontinued due to insufficient response and one patient discontinued due to an adverse event of worsening psoriasis. After 52 weeks, another three patients discontinued due to insufficient response and two due to severe nausea or back pain. The researchers reported no serious adverse events nor suicidal ideation or behavior.

Patients with quantifiable brodalumab levels of at least 0.05 g/mL had higher PASI reductions compared with patients with subquantifiable levels.

“All samples with quantifiable brodalumab levels corresponded to PASI reductions, and none of the samples showing increases in PASI had quantifiable brodalumab levels,” Enevold and colleagues wrote.

From this, they performed a dichotomization analysis and found that after 12 weeks of therapy, patients with quantifiable drug levels had significantly higher responses (median, 93%; range, 61%-100%; P = .006) compared with those without quantifiable levels.

After 52 weeks, seven patients — all of whom had quantifiable drug levels at 12 weeks — maintained a 75% reduction in PASI scores.

Additionally, the researchers addressed the effects of BMI on response.

“Our data also suggest that brodalumab bioavailability may be more important than BMI with respect to response because all patients with obesity with quantifiable brodalumab levels achieved a 61% or greater reduction in PASI after 12 weeks of therapy,” they wrote. “The BMI, however, remains important because 42% of patients with obesity vs. 88% of patients without obesity had quantifiable brodalumab levels.”