Prurisol for Psoriasis—An Overview

Prurisol (abacavir gylcolate) is a small molecule (<500 molecular weight) that is an ester of Abacavir (abacavir acetate). It acts through immune modulation and PRINSPsoriatic-associated non-protein coding RNA Induced by Stress — reduction, lowering IL-20 and skin cell proliferation rates. The mid-stage drug candidate is being developed utilizing the advantages of the FDA’s 505(b)(2) development plan. This regulatory approach helps expedite a drug’s potential approval as it allows the FDA to rely, in part, on existing long-term safety data of an already approved drug, in this instance, Ziagen — thereby shortening development time and reducing costs.

Key Attributes:

·         Oral dosing
·         Efficacy in a Phase 2 trial in mild-to-moderate chronic plaque psoriasis
·         Bioavailable
·         Excellent in-vivo and in-vitro activity
·         Efficacy in xenograft model

In the Prurisol bioequivalence trial (NCT02101216), AUC values were comparable for both Prurisol and Ziagen (the reference drug), within 80% to 125% equivalence window, indicating equivalent systemic exposure. Also, no serious adverse events, or other significant adverse events, occurred over the course of the study.

In the Prurisol Phase 2 clinical trial (NCT02494479) in mild-to-moderate plaque psoriasis (randomized, double-blind, parallel-group, placebo-controlled), involving 115 patients treated over 12 weeks, 35% of patients in the 200 mg group achieved at least a 2-pt IGA improvement (primary endpoint), from baseline, at 12 weeks. Additionally, among patients with the severest form of psoriasis, those having a baseline IGA score of 3 (“moderate”), the primary endpoint was met in 46% of patients (per protocol) who received 200 mg of Prurisol per day.

Prurisol currently is enrolling ~189 patients in a Phase 2b trial (randomized, double-blind, parallel-group, placebo-controlled) (NCT02949388) in moderate-to-severe cases of psoriasis, with a treatment duration of 12 weeks. Prurisol at 300 mg and at 400 mg is being evaluated against placebo using the PASI scale. Interim results are anticipated to be available in 3Q2017.

The hope is that Prurisol might be shown to be a potential best-in-class oral drug candidate that safely and effectively treats psoriasis, regardless of disease severity.