Several biologics targeting different
cytokines and receptors, including
T-cell receptors, have been approved for
psoriasis treatment.
Siplizumab, a humanized anti-CD2
monoclonal antibody, may potentially provide an alternative
therapy for
psoriasis. Its safety profile and immunogenicity was examined in adults with plaque
psoriasis. Two multicenter phase II randomized, double-blind, placebo-controlled studies: one tested two intravenous (I.V.) doses (0.012 and 0.04 mg/kg) of
siplizumab every 2 weeks x 8 doses (124 patients); the second study tested three subcutaneous (S.C.) dose regimens of
siplizumab (5 mg x 12 weeks, 5 mg x 6 weeks + placebo x 6 weeks, 7 mg x 4 weeks + placebo x 8 weeks), and placebo x 12 weeks (420 patients). Adverse events (AEs) and laboratory values were monitored. Immunogenicity was determined by anti-
siplizumab antibodies quantification. In both studies,
siplizumab exhibited an acceptable safety profile; most common AEs judged to be
siplizumab related were
lymphopenia,
chills, and
headache, reported at a higher frequency in the
siplizumab-treated vs. placebo group.
Siplizumab-related reductions in absolute lymphocyte count did not result in clinical evidence of immune suppression. Anti-
siplizumab antibodies were detected after exposure to
siplizumab; however, there was no evidence of an association between antibody development and AEs.
Siplizumab exhibited an acceptable safety profile in adult patients with plaque
psoriasis when administered as multiple I.V. or S.C. doses. Higher, clinically relevant doses of
siplizumab would need to be tested to fully assess its safety.