Safe administration of rituximab for follicular lymphoma after obinutuzumab infusion-related reaction.

Obinutuzumab is a novel glycoengineered, type-II anti-CD20 monoclonal antibody that was recently developed to treat follicular lymphoma (FL), the most prevalent subtype of indolent B-cell lymphoma. Several intensely hypermetabolic lesions (SUVmax: 40) were identified in the post-mediastinal and paraaortic lymph nodes by 18F-FDG-PET maximum-intensity projection images of a 58-year-old man who presented with systemic lymphadenopathy. A biopsy at the time of laparotomy definitively diagnosed grade 1 FL. The patient was given the recommended standard premedication, comprising acetaminophen (1000 mg), diphenhydramine (50 mg), and dexamethasone (20 mg), and then started on six cycles of obinutuzumab plus cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP). However, the patient developed severe hypotension and dyspnea about 15 min after starting obinutuzumab. It was difficult to differentiate between a possible allergic reaction and infusion-related reaction. A pleural effusion was drained to reduce the tumor burden, after which a single course of CHOP was started. Rituximab (R) was added 10 days later without incident, and the patient completed six cycles of the R-CHOP therapy without adverse events. We conclude that R-CHOP was safe for administration to patients who react to infused obinutuzumab. Such patients should be carefully monitored during R infusion, given the risk of cross-reactivity.