HLA-DR9 and DR14 are associated with the allopurinol-induced hypersensitivity in hematologic malignancy.

Allopurinol, a widely used urate-lowering agent, is a leading cause of severe cutaneous adverse reactions (SCARs), especially in patients with HLA-B*58:01. Despite its routine use for the prevention of tumor lysisrelated hyperuricemia prior to chemotherapy, the risk of allopurinol-induced hypersensitivity has not been investigated in patients with hematologic malignancies. This retrospective cohort study was conducted to investigate the incidence and risk factors of allopurinol-induced hypersensitivity in patients at least 18 years of age with hematologic malignancies. We reviewed 463 patients who had ever taken allopurinol for the prevention of hyperuricemia prior to chemotherapy and had undergone serologic HLA typing as a pre-transplant evaluation from January 2000 to May 2010. Thirteen (2.8%) patients experienced maculopapular eruptions (MPE) and none experienced SCARs. Among subtypes of underlying hematologic malignancies, percentage of chronic myeloid leukemia was significantly higher in the allopurinol hypersensitivity group compared with the tolerant group (23.1% (3/13) vs. 5.9% (26/440), P = 0.044). According to HLA subtypes, the incidence of allopurinol-induced MPE was 4.0% in HLA-B58 (+) patients (2/50) and 2.7% in HLA-B58 (−) patients (11/403) but this difference was statistically insignificant. In contrast to HLA-B58, the frequencies of DR9 and DR14 were significantly higher in the allopurinolinduced MPE group compared with the allopurinol tolerant group (38.5% (5/13) vs. 13.6% (53/443), P = 0.019, and 38.5% (5/13) vs. 15.6% (41/440), P = 0.038, respectively). In conclusion, HLA-DR9 and DR14, but not HLA-B58, are associated with hypersensitivity reaction by allopurinol when administered in patients with hematologic malignancy prior to chemotherapy.