Abstract PO2-12-07: Risk of anaphylaxis associated with the use of pertuzumab or other biologics with potential for use outside the hospital
Authors: Sanglier Thibaut , Chambers Tom , Harton Joanna , Wahyudi Laurentia , Genevray Magali , Restuccia Eleonora , Droz-Perroteau Cécile , Dang Chau 
Published: May 2024

Abstract
BACKGROUND
Intravenous (IV) pertuzumab (P) and trastuzumab (H) are approved in the US for the treatment of HER2-positive breast cancer. P and H are also approved as a fixed-dose combination for SC injection (pertuzumab, trastuzumab, and hyaluronidase-zzxf; PH FDC SC). PH FDC SC may offer the possibility of treatment outside a hospital setting by a healthcare professional. Anaphylactic reactions can be a concern with the use of biologics. PH is also frequently initiated with six to eight cycles of taxanes, which can also be associated with anaphylaxis. We used administrative claims data to evaluate the risk of anaphylaxis associated with the real-world administration of PH or other biologic drugs in the real world.
Our objective was to evaluate the risk of anaphylaxis associated with the administration of P and to contextualize the risk estimate by using other biologics that can be used outside the hospital as a benchmark.
METHODS
Cohorts of incident users were selected using retrospective records from a US healthcare claims database (IQVIA). Patients included were privately insured in the US, aged 16 to 65 years, and initiated a treatment of interest between 2012 and 2021. Possible and severe anaphylactic events (PAEs) were identified using the algorithm developed by the US Food and Drug Administration (FDA) Sentinel Initiative and updated with ICD10 codes (PMID: 34181291). PAEs were attributed to a drug if it occurred on the day of administration or the day after. The prevalence proportion (PP) of PAE was used to approximate the risk of anaphylaxis at each cycle. A sensitivity analysis using the proportion of prior P use amongst the cases of PAE beyond cycle 1 in the H cohort was conducted to approximate how many cases of PAE could have been missed at cycle 1 of P due to a depletion of susceptibles (as P IV and H may be administered sequentially in any order, patients with a PAE from H would not receive scheduled P and thus be excluded from the P cohort).
RESULTS
A total of 1,919,748 patients constituted 27 cohorts. Of them, 184,414 patients initiated monoclonal antibodies (mAbs) in 12 cohorts of which 12,264 and 184 initiated P IV and PH FDC SC, respectively. In the P IV cohort, seven PAE events were observed up to cycle 6 and none after. The PP at cycle 1 of P was 1.63 per 10,000 patients (95% confidence interval [CI] = 0.45, 5.94). The risk was comparable to that of other mAbs where anaphylaxis risk is described as uncommon/rare (Table). Accounting for a potential depletion of susceptibles increased the PP at cycle 1 of P to 2.45/10,000 (95% CI = 0.83, 7.19). No PAEs were reported in patients treated with PH FDC SC.
CONCLUSIONS
Using one of the largest datasets available, results suggest the risk of PAE with P administration could be within the range of what is observed with other mAbs that can be administered outside of the hospital. All events were observed when patients are expected to receive treatment at the hospital due to taxane administration. No PAE events were identified for PH FDC SC, but there were few patients in this cohort. Efforts are ongoing to identify a larger cohort treated with PH FDC SC.
Risk of anaphylaxis by mAb
* According to summary of product characteristics.
† ≥1/1,000 to &lt;1/100.
‡ ≥1/10,000 to &lt;1/1,000.
CI = confidence interval; H = trastuzumab; IV = intravenous; P = pertuzumab;
PH FDC SC = pertuzumab, trastuzumab, and hyaluronidase-zzxf.
Citation Format: Thibaut Sanglier, Tom Chambers, Joanna Harton, Laurentia Wahyudi, Magali Genevray, Eleonora Restuccia, Cécile Droz-Perroteau, Chau Dang. Risk of anaphylaxis associated with the use of pertuzumab or other biologics with potential for use outside the hospital [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-12-07.