PEGylated liposomes for diagnosis of polyethylene glycol allergy

BACKGROUND

Polyethylene glycol (PEG) is a nonprotein polymer that is present in its native (unbound) form as an excipient in a range of products. It is increasingly being utilized clinically in the form of PEGylated liposomal medications and vaccines. PEG is the cause of anaphylaxis in a small percentage of drug reactions; however, diagnosis of PEG allergy is complicated by the variable and poor diagnostic performance of current skin testing protocols.

OBJECTIVE

We assessed the diagnostic performance of PEGylated lipid medications as an alternative to currently described tests that use medications containing PEG excipients.

METHODS

Nine patients with a strong history of PEG allergy were evaluated by skin testing with a panel of PEG-containing medications and with a PEGylated lipid nanoparticle vaccine (BNT162b2). Reactivity of basophils to unbound and liposomal PEG was assessed ex vivo, and specificity of basophil responses to PEGylated liposomes was investigated with a competitive inhibition assay. More detailed information is provided in this article's Methods section in the Online Repository available at www.jacionline.org.

RESULTS

Despite compelling histories of anaphylaxis to PEG-containing medications, only 2 (22%) of 9 patients were skin test positive for purified PEG or their index reaction-indicated PEG-containing compound. Conversely, all 9 patients were skin test positive or basophil activation test positive to PEGylated liposomal BNT162b2 vaccine. Concordantly, PEGylated liposomal drugs (BNT162b2 vaccine and PEGylated liposomal doxorubicin), but not purified PEG2000, consistently induced basophil activation ex vivo in patients with PEG allergy but not in nonallergic controls. Basophil reactivity to PEGylated nanoparticles competitively inhibited by preincubation of basophils with native PEG2000.

CONCLUSION

Presentation of PEG on the surface of a lipid nanoparticle increases its in vivo and ex vivo allergenicity, and improves diagnosis of PEG allergy.

Polythylene glycol severe allergy and SARS-CoV-2 vaccines: usefulness of testing with PEG 1500 extract

Summary

Background. Polyethylene glycol (PEG) is being used for first time as an excipient for mRNA anti-SARS-CoV-2 vaccines containing PEG 2000, highlighting it as a potential cause of anaphylaxis. Methods. We evaluated 126 patients with moderate-high risk of allergy to SARS-CoV-2 vaccines referred to our department from March-December 2021. Skin tests were performed with PEG 1500 extract (Roxall), using a stepwise approach, with readings at 30 minutes: prick tests with 0.1%, 1% and 10% concentrations; if negative, intradermal tests with 0.0001%, 0.001% and 0.01% concentrations. The same protocol was applied to 5 healthy controls Results. Six patients had positive immediate intradermal tests with PEG 1500, all with severe PEG allergy: one with a near-fatal anaphylaxis after glucocorticoid injection containing PEG 3350 and five with systemic allergic reactions after mRNA vaccines containing PEG 2000 (Pfizer-BioNTech or Moderna). One patient developed anaphylaxis during intradermal test. These six patients were negative to polysorbate 80. The remaining 120 patients had negative tests to PEG 1500; seven had positive tests to polysorbate 80. All controls had negative tests. Conclusions. To our knowledge this is the first study describing the allergy work-up testing with PEG 1500 commercial extract in the scope of SARS-CoV-2 vaccination. The algorithm designed for skin tests revealed to be a useful tool. Severe PEG allergy was diagnosed in 5% of patients, contraindicating PEG-containing vaccines. PEG allergy was excluded in one hundred patients that afterwards took SARS-CoV-2 vaccines containing PEG 2000. Investigation should be conducted in specialized drug allergy centers..

The Polysorbate containing AstraZeneca COVID-19 vaccine is tolerated by polyethylene glycol (PEG) allergic patients

BACKGROUND

Polyethylene glycol (PEG) is the excipient found in the mRNA COVID-19 vaccines. We previously demonstrated PEG allergy was a cause of severe anaphylaxis to the Pfizer/BioNTech COVID-19 vaccine. PEG is widely used in many household products, cosmetics and medicines. However PEG allergy is rare, there have been few confirmed cases of PEG allergy. The excipient of potential concern in the AstraZeneca COVID-19 vaccine is polysorbate 80 (PS80). Cross-reactivity between PEG and polysorbate has been suggested, based on their composition and skin-test data. The aim of this study was to determine whether PEG-allergic patients could be vaccinated with the PS80 containing AstraZeneca COVID-19 vaccine.

METHOD

Eight patients with PEG allergy were identified by the allergy clinic at Cambridge University Hospital. Patients underwent skin prick testing to PS80 (20%) and to the AstraZeneca COVID-19 vaccine prior to vaccination.

RESULTS

All eight patients allergic to PEG tolerated the AstraZeneca COVID-19 vaccine, even in 2 patients where the PS80 skin prick test was positive and 1 with a positive skin prick test to the AstraZeneca COVID-19 vaccine.

CONCLUSION

Patients allergic to PEG, previously denied COVID vaccination, may now be safely vaccinated with the PS80 containing AstraZeneca vaccine and need only avoid the PEG-containing mRNA COVID-19 vaccines. This opens up the possibility that these patients will also tolerate other vaccines containing PS80 such as the Janssen/Johnson and Johnson COVID-19 vaccine. Clinical cross-reactivity between PEG and PS80 did not occur in this vaccine setting.

First-Dose mRNA COVID-19 Vaccine Allergic Reactions: Limited Role for Excipient Skin Testing

BACKGROUND

The Centers for Disease Control and Prevention state that a severe or immediate allergic reaction to the first dose of an mRNA COVID-19 vaccine is a contraindication for the second dose.

OBJECTIVE

To assess outcomes associated with excipient skin testing after a reported allergic reaction to the first dose of mRNA COVID-19 vaccine.

METHODS

We identified a consecutive sample of patients with reported allergic reactions after the first dose of mRNA COVID-19 vaccine who underwent allergy assessment with skin testing to polyethylene glycol (PEG) and, when appropriate, polysorbate 80. Skin testing results in conjunction with clinical phenotyping of the first-dose mRNA COVID-19 vaccine reaction guided second-dose vaccination recommendation. Second-dose mRNA COVID-19 vaccine reactions were assessed.

RESULTS

Eighty patients with reported first-dose mRNA COVID-19 vaccine allergic reactions (n = 65; 81% immediate onset) underwent excipient skin testing. Of those, 14 (18%) had positive skin tests to PEG (n = 5) and/or polysorbate 80 (n = 12). Skin testing result did not affect tolerance of the second dose in patients with immediate or delayed reactions. Of the 70 patients who received the second mRNA COVID-19 vaccine dose (88%), 62 had either no reaction or a mild reaction managed with antihistamines (89%), but 2 patients required epinephrine treatment. Three patients with positive PEG-3350 intradermal (methylprednisolone) testing tolerated second-dose mRNA COVID-19 vaccination. Refresh Tears caused nonspecific skin irritation.

CONCLUSIONS

Most individuals with a reported allergic reaction to the first dose of mRNA COVID-19 vaccines, regardless of skin test result, received the second dose safely. More data are needed on the value of skin prick testing to PEG (MiraLAX) in evaluating patients with mRNA COVID-19 vaccine anaphylaxis. Refresh Tears should not be used for skin testing.

Polyethylene Glycol-Induced Systemic Allergic Reactions (Anaphylaxis)

Polyethylene glycols (PEGs) or macrogols are hydrophilic polymers found in everyday products such as foods, cosmetics, and medications. We present 5 cases of confirmed PEG allergy, which to our knowledge is the largest case series to date. Four of the 5 cases developed anaphylaxis to medications containing PEGs, with 1 near-fatal case resulting in cardiac arrest. Skin tests were undertaken to the index medications and to PEGs of different molecular weights. Three were confirmed with positive skin prick test result to PEG, 1 confirmed with a positive intradermal test result, and 1 confirmed after positive oral challenge. Two patients developed anaphylaxis following intradermal test to PEG and 1 a systemic allergic reaction (without hypotension or respiratory distress) following PEG skin prick tests. Before diagnosis, all 5 patients were mislabeled as allergic to multiple medications and their clinical management had become increasingly challenging. An algorithm is proposed to safely investigate suspected PEG allergy, with guidance on PEG molecular weights and skin test dilutions to minimize the risk of systemic allergic reaction. Investigation carries considerable risk without knowledge and informed planning so should only be conducted in a specialist drug allergy center.