Feasibility of trimethoprim/sulfamethoxazole desensitization therapy in hematological diseases

The effectiveness and safety of trimethoprim/sulfamethoxazole (TMP/SMX) desensitization therapy is insufficiently evaluated in hematological diseases. From 2002 to 2019, we retrospectively analyzed 112 patients with hematological diseases who underwent desensitization therapy after TMP/SMX prophylaxis withdrawal due to adverse events. They orally started TMP/SMX at 0.4 mg/2 mg, which was then increased daily to 80 mg/400 mg for 5 or 9 days. Eighty-eight patients (79%) had complete desensitization, and the major reason for failure was rash seen in 21 cases (19%). The cause of desensitization and reasons for failure matched in 22 cases (92%). Pneumocystis pneumonia was not observed throughout the study. In the failure group, the number of eosinophils and alanine aminotransferase (ALT) levels were significantly increased after desensitization. In particular in the failure group, the slight increase in eosinophils was seen through the beginning to halfway during desensitization (36/μL (0-900/μL) and 48/μL (0-2560/μL), respectively, p = 0.025). These data show that TMP/SMX desensitization therapy is effective and safe in hematological diseases. The recurrence of adverse events could help predict desensitization success.