Interleukin-2 for Refractory Chronic Spontaneous Urticaria

The goal of this clinical trial is to learn if human interleukin-2 (IL-2) works to treat moderate to severe chronic spontaneous urticaria in adults who remain symptomatic despite oral antihistamine treatment (refractory CSU). It will also learn about the safety of IL-2. The main questions it aims to answer are: Does IL-2 alleviate the symptoms of urticaria in patients? What medical problems do participants have when given IL-2? Researchers will compare IL-2 to a placebo (a look-alike and smell-like substance that contains no IL-2) to see if IL-2 works to treat refractory, moderate to severe CSU. Participants will: Receive IL-2 or a placebo intramuscular injections for 3 rounds at Week 0, 4 and 8, in which each round includes one injection daily for seven consecutive days. Visit the clinic for checkups and tests at Week 2, 4, 8, 12 and 24. Keep a diary of their symptoms and the number of tablets of oral antihistamines.

Background: Urticaria is a common disorder characterized by localized edema due to dilation and increased permeability of small blood vessels in the skin and mucous membranes. The primary clinical manifestations include wheals and pruritus. Chronic spontaneous urticaria (CSU) is defined as recurrent, transient (\<24 hours), pruritic wheals on the skin and mucosa lasting for more than 6 weeks, with or without angioedema, excluding chronic inducible urticaria. Among patients with chronic urticaria, about 2/3 have CSU. Although the pathogenesis of CSU remains unclear, increasing evidence suggests an autoimmune feature of this disorder. Oral antihistamines are the primary treatment for CSU, yet some patients continue to experience symptoms despite treatment with standard or double doses. Recent studies have shown that human IL-2 (Interleukin-2) can be effective in a proportion of CSU patients refractory to antihistamine treatment, without significant side effects. Therefore, in this clinical trial we aim to evaluate the therapeutic effect and safety of this new therapeutic method. Study Design: This is a randomized, placebo-controlled, multi-center clinical trial to evaluate the safety and efficacy of IL-2 treatment in CSU patients who remain symptomatic despite oral antihistamine treatment. Methods: CSU patients who meet the inclusion criteria will receive IL-2 or placebo intramuscular injections in combination with their current antihistamine regimen (either a single antihistamine or a combination of two to three antihistamines at a dose of at least the standard dosage). Endpoints include clinical response, quality of life, and safety profiles.