Sienna Biopharmaceuticals, Inc. announced the results from a Phase 1b maximal use (MUse) pharmacokinetic (PK) and safety study of SNA-120 (pegcantratinib), a Phase 2b drug candidate being evaluated as a topical, nonsteroidal therapy to treat itch (pruritus) associated with psoriasis. SNA-120 is a topical tropomyosin receptor kinase A (TrkA) inhibitor that blocks nerve growth factor (NGF) signaling, which plays an important role in the pathogenesis of itch and psoriasis. SNA-120 was developed using Sienna’s Topical by Design™ platform, which yields new chemical entities designed to deliver high local drug concentration in the target tissue and minimal to no systemic exposure for patients. SNA-120 directly targets the peripheral itch pathway in the psoriatic plaque. The multicenter, open-label, Phase 1b study evaluated the PK and safety of 0.5% SNA-120 administered topically twice daily (BID) for four weeks. Circulating plasma levels of SNA-120 were measured in a total of 30 male and female subjects 18 years or older who had moderate to severe itch associated with moderate to severe psoriasis covering 20% or more body surface area. Improvements in pruritus and psoriasis were observed in exploratory efficacy analyses. For example, in a post hoc analysis, approximately 57% of subjects had at least a 4-grade improvement in the Itch Numeric Rating Scale (I-NRS). However, these efficacy data should be interpreted with caution, as this was a small, four-week study in patients with high body surface area involved (20% or greater) and no vehicle comparator.