Clinical Trial: Study of Sting Challenge and Serological Responses to Jack Jumper Venom Immunotherapy With Inulin as Adjuvant (Jumpvax)

Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Interventional

Official Title: A Dose Ranging Study of Sting Challenge and Specific lgE, and IgG4 Responses to Jack Jumper Ant (JJA) [Myrmecia Pilosula] Venom Immunotherapy (VIT) With and Without Delta-inulin as an Adjuvant.

Brief Summary: The purpose of this study is to assess the potential use of delta-inulin as an adjuvant to facilitate the desired immune response to Jack Jumper Ant (JJA) venom with a lower dose of venom, thus reducing adverse reactions, venom requirements and costs of treatment. Specifically we aim to compare outcomes of in-hospital JJA sting challenges and JJA venom specific IgE, and IgG4 responses to semi-rush JJA VIT at maintenance doses of 25 and 50 mcg of JJA venom, with and without delta-inulin adjuvant.

Detailed Summary:

Background JJA sting appears to be a dominant cause of insect sting anaphylaxis in the cooler areas of southern and eastern Australia where the native ant is prevalent. Immunotherapy for treatment of stinging insect anaphylaxis involves the administration of increasing doses of purified insect venom with the aim of inducing clinical tolerance, but also carrying the risk of allergic reactions to treatment. In a randomised double-blinded, placebo-controlled trial of JJA VIT7 we have shown JJA VIT to be highly effective at preventing JJA sting anaphylaxis, with an objective systemic sting reaction rate in those who were on maintenance JJA VIT < 5% vs 70% for those receiving placebo VIT. Real world experience in Tasmania has supported these findings with objective systemic reaction rates to sting challenges on 50 and 100 mcg maintenance doses respectively 14/130 and 12/126 subjects as against reaction rates to stings in similar subjects without JJA VIT of 70-76% in trial and epidemiological studies.

Although JJA VIT is highly effective at preventing severe objective reactions to JJA stings, its applicability is limited by (1) venom availability with venom collected by venom sac dissection of ants harvested from wild nests with inherent WH&S risks; (2) venom costs, at $2 per microgram of venom (3) as with honey bee VIT difficulties in a significant minority of subjects in achieving maintenance because of immediate generalised allergic reactions (4) prolonged therapy, generally 5 years or longer - for those in whom a previous sting reaction was immediately life-threatening, treatment continues indefinitely for as long as the risk of an accidental sting remains. An adjuvant that would facilitate the wanted immune response to JJA venom has the potential to reduce venom requirements and thereby reduce costs and increase availability of JJA VIT, reduce the number of hospital
Sponsor: Central Adelaide Local Health Network Incorporated

Current Primary Outcome:

• Response to in-hospital JJA sting following 12 months of maintenance treatment [ Time Frame: 15 months ]
  Number of subjects in each group experiencing systemic allergic reaction to in-hospital JJA sting after 12 months of maintenance treatment.
• Specific IgG4 responses to JJA venom during treatment [ Time Frame: 18 months ]
  Specific IgG4 responses (mcgA/L) to JJA venom immunotherapy by group
• Specific IgE responses to JJA venom during treatment [ Time Frame: 18 months ]
  Specific IgE responses (kU/L) to JJA venom immunotherapy by group

Original Primary Outcome: Same as current

Current Secondary Outcome:

• Changes in VST to JJA venom during treatment [ Time Frame: 15 months ]
  Venom skin test responses (concentration of venom which results in a positive intradermal test - mcg/ml) to JJA venom immunotherapy by group
• Adverse reactions to JJA venom immunotherapy [ Time Frame: 18 months ]
  Number of events per group and number of subjects per group experiencing clinical adverse reactions attributable to JJA VIT
• Incidental reactions to field stings during JJA venom immunotherapy [ Time Frame: 18 months ]
  Number of events per group and number of subjects per group experiencing systemic allergic reactions to incidental JJA stings

Original Secondary Outcome: Same as current

Information By: Central Adelaide Local Health Network Incorporated

Dates:
Date Received: February 20, 2017
Date Started: October 2016
Date Completion: December 2019
Last Updated: February 23, 2017
Last Verified: February 2017