100447 - Feasibility and Impact of an Integrated Allergy-Oncology Clinical Service for Drug Allergy Management

Drug hypersensitivity reactions to anti-cancer therapy and supportive medications in oncology patients may lead to discontinuation of effective treatment and unnecessary drug avoidance. In the absence of structured allergy assessment pathways, inaccurate drug allergy labels may compromise oncologic management. An integrated Allergy–Oncology Clinical Service (AOCS) was established at Queen Mary Hospital in Hong Kong to provide coordinated evaluation and protocolized management of oncology patients with drug allergy labels. This study prospectively evaluated the feasibility and clinical impact of this pilot multidisciplinary service.

Adult oncology patients with documented drug allergy labels referred to the AOCS were prospectively included. Clinical data including age, sex, oncologic diagnosis, disease stage, number of drug allergy labels, culprit drug, clinical manifestations, and details of allergic reactions were collected. Data on allergy assessment, subsequent outcomes, and chemotherapy desensitization were extracted from the electronic Clinical Management System. Feasibility outcomes included completion rate of drug allergy workup and therapeutic optimisation following assessment, including drug de-labelling, identification of alternative medications, and continuation of therapy via desensitization or drug reintroduction.

A total of 129 oncology patients were evaluated. Most patients were female (96/129, 74%), and 22% had more than one drug allergy label (28/129, 22%). Overall, 78% (100/129) consented to drug allergy workup, with a completion rate of 96% (96/100). Therapeutic optimisation following assessment occurred in 98% (94/96) of patients. Systemic anti-cancer therapy (SACT) drug allergy labels were significantly more likely to undergo assessment compared with non-SACT drug allergy labels (46/109, 43% vs 1/58, 2%; p<0.001). Among non-SACT drug allergy labels that were assessed, 74% (45/61) were found to be inaccurate and safely removed. Among patients undergoing chemotherapy desensitization, the completion rate of desensitization courses was 95% (60/63). The overall rate of moderate–severe breakthrough reactions was 14% (9/63), with no statistically significant difference between 1-bag and 3-bag desensitization protocols (7% [2/31] vs 22% [7/32], p=0.148). The 1-bag protocol had a shorter median completion time than the 3-bag protocol (276 vs 418 minutes, p<0.001).

An integrated Allergy–Oncology Clinical Service with protocolised management is feasible and effective in optimizing medication use in oncology patients with drug allergy labels. Structured allergy assessment enables safe continuation of essential chemotherapy, facilitates removal of inaccurate drug allergy labels, and supports safe and efficient chemotherapy desensitization through multidisciplinary collaboration.