Inhibition of interleukin‐1 with rilonacept is not effective in cold urticaria—Results of a randomized, placebo‐controlled study

Abstract Background Cold urticaria (ColdU) is characterized by pruritic wheals following exposure of the skin to cold. Many patients show insufficient response to antihistamines, the first line treatment. Based on the high efficacy of interleukin‐1(IL‐1)‐inhibition in cold‐induced urticarial autoinflammatory diseases, we assessed the effects of rilonacept, an IL‐1 inhibitor, in ColdU patients unresponsive to standard treatment. Methods In this randomized, double‐blind, placebo‐controlled two‐center study, we included 20 patients with ColdU. In the first part, patients received 320 mg rilonacept or placebo (1:1) followed by weekly doses of 160 mg rilonacept or placebo for 6 weeks. In the second part, all patients received weekly 160 mg or 320 mg rilonacept for 6 weeks, open‐label. The primary endpoint was change in critical temperature threshold (CTT). Secondary endpoints included changes in quality of life impairment (Dermatology Life Quality Index, DLQI), differences of inflammatory mediators upon cold provocation and safety assessment over the study period. Results Baseline mean CTTs were 20.2°C (placebo) and 17.3°C (rilonacept). Mean CTTs did not change significantly during the 6‐week double‐blind treatment (placebo – 0.45°C; rilonacept +0.89°C). IL‐6, IL‐18 and HSP‐70 blood levels showed interindividual variability without significant changes during hand cold water bath provocation in placebo‐ or rilonacept‐treated patients. In contrast, DLQI significantly improved in the rilonacept (mean DLQI reduction of 3.8; p = 0.002) but not in the placebo group (mean DLQI reduction of 0). Comparing baseline with the rilonacept open‐label treatment, there were no changes in CTTs or DLQI scores. Conclusion IL‐1 inhibition with rilonacept did not improve ColdU, but demonstrated a good safety profile. Clinical Trial Registration EudraCT number: 2012‐005726‐30. ClinicalTrials.gov identifier: NCT02171416.


| BACKGROUND
Acquired cold urticaria (ColdU) is characterized by pruritic wheals and/or angioedema following exposure of the skin to cold. Skin symptoms typically arise minutes after exposure to cold objects, liquids or air and are usually limited to cold-exposed skin areas. 1 However, extensive cold exposure for example, swimming in cold water can lead to generalized urticarial symptoms and systemic reactions such as dyspnea, hypotension and loss of consciousness. 2 In addition, consumption of cold foods and beverages can result in oropharyngeal angioedema. 3,4 ColdU can, therefore, be a lifethreatening disease. 5,6 ColdU is the second most prevalent subtype of chronic inducible urticaria with an estimated incidence of 0.05% in Central Europe. 7 It affects young adults most frequently but may occur at any age. 7,8 ColdU is a self-limited disease with approximately 50% of patients experiencing remission after 6 years. 8 The exact pathogenesis of ColdU is not completely understood.
The development of wheals and angioedema is thought to be driven by the activation and degranulation of cutaneous mast cells with subsequent release of various inflammatory mediators including histamine, leukotrienes and cytokines after cold exposure of the skin. [9][10][11][12] Current treatment strategies in ColdU comprise the avoidance of cold exposure and the use of H1 antihistamines. 13 Antihistamine treatment in ColdU patients significantly reduces cutaneous histamine release as well as levels of interleukin (IL)-6, a downstream effector of IL-1β, and IL-8 after cold exposure. 14 However, many patients with ColdU show insufficient response to treatment with antihistamines, even at high doses. 15,16 The reasons for this are currently unknown. 8 In antihistamine non-responders, anti-IgE treatment with omalizumab may be an effective treatment option. 17 Nevertheless, omalizumab is not approved for ColdU, and not all ColdU patients treated with omalizumab show improvement.
Novel and better treatment options for patients with ColdU are needed, and several are currently being explored or in clinical development. 12,[18][19][20][21] Different systemic autoinflammatory diseases present with coldinduced wheals. The best known entity is cryopyrin-associated periodic syndrome (CAPS), for which IL-1-targeting drugs have been shown to be highly effective. [22][23][24] Familial cold autoinflammatory syndrome (FCAS) is a subform of CAPS and characterized by coldinduced urticarial rash, fever, arthralgia and fatigue. 25 IL-1β is the pivotal proinflammatory cytokine in many autoinflammatory diseases and accounts for fever and systemic inflammation. Rilonacept is a dimeric fusion protein that inhibits both, IL-1α and IL-1β. It is licensed in the US for the treatment of CAPS including FCAS and Muckle-Wells-syndrome (MWS) in adults and children aged 12 years and older. In CAPS patients, rilonacept shows favorable effects on systemic symptoms and cold-induced urticarial rash. 22 Of note, anti-IL-1 treatment was reported to be beneficial in other chronic inflammatory dermatologic conditions including a patient with acquired ColdU with inadequate symptom control and multifactorial autoinflammatory diseases presenting with wheals such as Schnitzler syndrome and adult-onset Still's disease (licensed use in Europe for anakinra and canakinumab for the last-mentioned). [26][27][28] We hypothesized that patients with acquired ColdU who are unresponsive to antihistamines may benefit from IL-1 inhibition.
Therefore, the objective of this study was to assess the efficacy and safety of rilonacept in patients with ColdU who are not successfully treated with antihistamines.

| Study design
This phase II, multi-center, investigator-initiated parallel group study was conducted in two parts. After a 2-week screening period, part A consisted of a 6-week randomized, double-blind, placebo-controlled phase in which the patients were randomized (1:1) to one of two groups: (1) rilonacept or (2) placebo. Patients in the rilonacept group received a loading dose of 320 mg (2 injections of 160 mg), followed by weekly injections of rilonacept 160 mg, subcutaneously. In the open label treatment phase (part B), after unblinding, patients who had received placebo, were treated with rilonacept 160 mg for additional 6 weeks.
Complete rilonacept responders -that is patients without a wheal-and-flare reaction in response to provocation testing with 4°C -were treated with 160 mg. Partial responders -defined as patients with reductions of at least 4°C in critical temperature threshold (CTT, detailed explanation of the method see below) -received 320 mg rilonacept weekly doses. Non-responders-that is patients with CTT increase, maintenance or reduction <4°C to rilonacept -were excluded from the open-label extension. There was an additional 4week follow-up period to monitor safety.

| Patients
Adult patients with symptomatic ColdU, that is, cold-induced wheals and itch for more than 6 weeks, who were resistant to con-

| Critical temperature threshold testing
CTT was defined as the highest temperature at which a wheal reaction was induced by testing for 5 min. To assess CTTs, the TempTest ® 3.0 was applied directly on the volar surface of the forearm at 4, 6,8,10,12,14,16,18,20,22,24, and 26°C simultaneously for 5 min. The CTT was assessed at each visit for each patient.
Non-responders to rilonacept treatment and complete responders to placebo treatment were withdrawn from the study after the end of the double-blind treatment. Subjects who discontinued the study were treated with standard of care by their attending physicians.

| Hand cold water bath
Cold provocation by water bath was performed by immersion of one hand in water of 4°C for 5 min, at week 6 and week 12. This was done under continuous supervision of a healthcare professional and in the presence of adequate emergency measures (emergency medication readily available, i. v. access). Before and after water bath cold provocation (time points 0, +5, +10, +20 min), patients were subjected to blood draws from the cubital vein of the provocation arm.
Blood samples were stored at −80°C and processed for serum and plasma measurements of mast cell mediators. IL-1RA (pg/ml), IL-6 (pg/ml), IL-18 (pg/ml) and heat shock protein (HSP) 70 (pg/ml) were assessed in the serum of the patients. HSP70 was chosen as it is known to modulate various cellular processes, including protein folding, regulation of signaling pathway, degradation of misfolded proteins and the modulation of immune responses. HSP70 is induced by stressors including temperature changes and plays an essential role in environmental stress tolerance and thermal adaptation and has been shown to be significantly elevated in patients with chronic spontaneous urticaria (CSU). 30,31

| Study endpoints
The primary endpoint was the change in CTT from baseline to week 6 in the rilonacept group as compared to the placebo group.

| Rilonacept treatment temporarily improves quality of life in cold urticaria patients
Patient-reported quality of life significantly improved in the rilonacept group (mean DLQI at week 0: 11.9 and after

| Rilonacept treatment does not change serum IL-6, IL-18 and HSP-70 levels in patients with cold urticaria
Post provocation serum levels of the inflammatory mediators IL-6, IL-  Table S1-S2).

| Rilonacept treatment is generally safe in cold urticaria
We observed 67 AEs in 17 patients throughout the study. One AE   8 In addition, we did not use the Cold Urticaria Activity Score (ColdUAS), a patient-reported outcome measure to assess ColdU disease activity, as it was not available at the start of our study. 40

| CONCLUSION
In conclusion, this study shows that rilonacept treatment of ColdU

ACKNOWLEDGMENTS
We thank Melanie Timmler for excellent technical assistance. This investigator-initiated trial was supported by Regeneron Pharmaceuticals.
Open access funding enabled and organized by Projekt DEAL.