van Nunen S

Quantifying the allergenic potency of mammalian meat sources, an important step in providing a framework for improved management of mammalian meat allergy after tick bite (alpha-gal syndrome/AGS).

A systematic review of tick removal techniques: Relationship to outcomes of tick-induced allergic reactions and tick-borne illnesses.

Australia has the highest prevalence worldwide of tick-induced allergies (mammalian meat and tick allergy/anaphylaxis). Inappropriate tick removal techniques are known to trigger tick anaphylaxis. This study aimed to ascertain the evidence for the effectiveness of tick removal methods and their relationship to the outcomes of tick-induced allergies and tick-borne illnesses. The design involved is a systematic literature review. Scopus, Embase, and Medline were searched (September 20, 2023) for studies of tick removal techniques and for outcomes of tick-induced allergic reactions and tick-borne illnesses. Two reviewers reviewed abstracts and full texts. Included studies were appraised (Joanna Briggs Institute critical appraisal tools), and data were extracted, tabulated, and evaluated. Six studies investigated a relevant outcome, all of low or moderate quality. Tick-killing in situ before removal resulted in allergic reactions in only 3/61 patients and no anaphylaxis. 23/28 who presented to the Emergency Department following removal with tweezers had allergic reactions (one anaphylaxis). When those with known tick anaphylaxis killed ticks in situ before removal there was no subsequent anaphylactic reaction. A significant decrease in disease transmission and/or seropositivity ( and/or ) was shown with crushing ticks or gentle pressure before removal with fine-tipped forceps, forceps alone, and surgical tweezers. Manipulation before removal with tweezers made no difference to seropositivity. Few studies worldwide have examined outcomes of tick removal techniques. Tick-killing in situ reduces recurrent tick anaphylaxis in Australians. Early removal with forceps may be effective where tick-borne disease is of greater concern. Further studies of tick-killing in situ focusing upon disease transmission should be prioritized.

A protocol for pre-treatment testing for antibodies to galactose-alpha-1,3-galactose to mitigate the risk of cetuximab hypersensitivity reactions - a retrospective cohort review.

Cetuximab improves survival in KRAS wildtype metastatic colorectal cancer. However, high rates of hypersensitivity reactions (HSRs) limit its use, with HSR rates up to 10-20 %. A major driver of cetuximab HSR is from pre-formed IgE antibody response to galactose-1,3-alpha-galactose (alpha-gal). Evidence from retrospective studies supports alpha-gal pre-screening in this setting. This study reports the impact of prospective alpha-gal antibody screening on cetuximab HSR. Records were reviewed across three medical oncology centres that have adopted alpha-gal antibody screening measures. Data for patients with metastatic colorectal cancer treated with cetuximab were retrieved. All centres assessed alpha-gal levels using the ImmunoCAP® immunoassay. Due to variability in alpha-gal screening practices across study sites, a standardised protocol was applied to all cases. This protocol allowed cetuximab administration if alpha-gal levels were ≤0.10 kUA/L, but prohibited it if alpha-gal levels were >0.10 kUA/L in favour of panitumumab administration. Patients were allocated to either the Alpha-gal Pre-screening Applied ('Pre-screening') or Alpha-gal Pre-screening Not Applied ('Reference') cohorts based on protocol requirements being met. The primary outcome between these patient groups was the incidence of cetuximab HSRs. Of 254 assessable patients, 39 underwent the pre-treatment screening protocol. Of the Pre-screening group, 3% (n=1/39) experienced a cetuximab HSR compared to 16% (n=35/215) in the Reference group (Odds ratio (OR) 0.14; 95% CI 0.0033-0.86, p= 0.02). Patients with alpha-gal antibody titres >0.10 kUA/L were more likely to experience a cetuximab HSR (OR 69.71; 95% CI 5.18-4296.81, p=0.0001). Pre-treatment screening for alpha-gal antibodies significantly reduces the incidence of cetuximab HSRs. A testing threshold of 0.10 kUA/L is effective in identifying patients at risk. Implementing this protocol can improve the safety of cetuximab therapy in high-risk populations. Hypersensitivity reactions (HSRs) limit cetuximab use in KRAS wildtype advanced colorectal cancer, with a significant driver being pre-formed IgE antibodies against galactose-1,3-alpha-galactose (alpha-gal). Our multicentric retrospective study assessed the impact of prospective alpha-gal antibody screening on HSR incidence following cetuximab administration. Of 254 assessable patients, pre-treatment alpha-gal antibody screening significantly reduced the incidence of cetuximab HSRs (3% vs 16%; OR 0.14, p=0.02). Our findings support pre-treatment alpha-gal screening to improve safety of cetuximab therapy in high-risk populations.

Newly Recognized α-Gal Syndrome in the Upper Midwestern United States.

Immunoglobulin E Sensitization to Mammalian Oligosaccharide Galactose-α-1,3 (α-Gal) Is Associated With Noncalcified Plaque, Obstructive Coronary Artery Disease, and ST-Segment-Elevated Myocardial Infarction.

Treating known risk factors for coronary artery disease (CAD) has substantially reduced CAD morbidity and mortality. However, a significant burden of CAD remains unexplained. Immunoglobulin E sensitization to mammalian oligosaccharide galactose-α-1,3-galactose (α-Gal) was recently associated with CAD in a small observational study. We sought to confirm that α-Gal sensitization is associated with CAD burden, in particular noncalcified plaque. Additionally, we sort to assess whether that α-Gal sensitization is associated with ST-segment-elevated myocardial infarction (STEMI) Methods: We performed a cross-sectional analysis of participants enrolled in the BioHEART cohort study. We measured α-Gal specific-immunoglobulin E antibodies in serum of 1056 patients referred for CT coronary angiography for suspected CAD and 100 selected patients presenting with STEMI, enriched for patients without standard modifiable risk factors. CT coronary angiograms were assessed using coronary artery calcium scores and segmental plaque scores. α-Gal sensitization was associated with presence of noncalcified plaque (odds ratio, 1.62 [95% CI, 1.04-2.53], =0.03) and obstructive CAD (odds ratio, 2.05 [95% CI, 1.29-3.25], =0.002), independent of age, sex, and traditional risk factors. The α-Gal sensitization rate was 12.8-fold higher in patients with STEMI compared with matched healthy controls and 2.2-fold higher in the patients with STEMI compared with matched stable CAD patients (17% versus 1.3%, =0.01 and 20% versus 9%, =0.03, respectively). α-Gal sensitization is independently associated with noncalcified plaque burden and obstructive CAD and occurs at higher frequency in patients with STEMI than those with stable or no CAD. These findings may have implications for individuals exposed to ticks, as well as public health policy. Registration: URL: https://www.anzctr.org.au; Unique identifier: ACTRN12618001322224.

Genetic and structural basis of the human anti-α-galactosyl antibody response.

Humans lack the capacity to produce the Galα1-3Galβ1-4GlcNAc (α-gal) glycan, and produce anti-α-gal antibodies upon exposure to the carbohydrate on a diverse set of immunogens, including commensal gut bacteria, malaria parasites, cetuximab, and tick proteins. Here we use X-ray crystallographic analysis of antibodies from α-gal knockout mice and humans in complex with the glycan to reveal a common binding motif, centered on a germline-encoded tryptophan residue at Kabat position 33 (W33) of the complementarity-determining region of the variable heavy chain (CDRH1). Immunoglobulin sequencing of anti-α-gal B cells in healthy humans and tick-induced mammalian meat anaphylaxis patients revealed preferential use of heavy chain germline IGHV3-7, encoding W33, among an otherwise highly polyclonal antibody response. Antigen binding was critically dependent on the presence of the germline-encoded W33 residue for all of the analyzed antibodies; moreover, introduction of the W33 motif into naive IGHV3-23 antibody phage libraries enabled the rapid selection of α-gal binders. Our results outline structural and genetic factors that shape the human anti-α-galactosyl antibody response, and provide a framework for future therapeutics development.

Increased rates of cetuximab reactions in tick prevalent regions and a proposed protocol for risk mitigation.

Cetuximab is an anti-epidermal growth factor receptor mouse-human chimeric monoclonal antibody used to treat advanced colorectal cancers. Initial data suggest that severe infusion reactions occurred in 4.5%, many on first exposure. The majority of those with anaphylactic reactions possess predeveloped IgE antibodies to galactose-alpha-1,3-galactose. It is thought that the vector for preexposure to alpha-gal is antigen inoculation via tick bites. This retrospective study reviews the experience of two community cancer centers in high tick exposure areas in Sydney with cetuximab anaphylaxis and proposes a protocol to avoid this. Severe cetuximab infusion reactions occurring in the Northern Cancer Institute Frenchs Forest and St Leonards clinics, Sydney, from May 2014 to February 2019 were recorded. Area of residence was then compared to areas of known high tick prevalence. A total of 87 patients received cetuximab in this period. Six patients (6.9%) experienced at least a grade 3 reaction, three females, age range 41-72 years (median 57.5 years). All were receiving cetuximab for metastatic colorectal cancer and their anaphylaxis occurred with the first infusion in all cases. These cases support the existing theory of increased rates of cetuximab anaphylaxis in areas of high tick prevalence. Given this, we recommend the following protocol for patients being considered for cetuximab therapy: known mammalian meat allergy as an absolute contraindication; all patients receiving cetuximab should have RAST (ImmunoCAP ) testing for alpha-gal specific-IgE-specific antibodies before first infusion and those who test positive to be considered alternate therapy.