Hypersensitivity Reaction of Gemtuzumab Ozogamicin (Mylotarg™) Associated with Platelet Transfusion: Two Case Reports.

Introduction

Gemtuzumab ozogamicin (Mylotarg™) is a monoclonal antibody developed for the treatment of myeloid leukemias. Mylotarg is composed of a recombinant humanized IgG₄ kappa antibody conjugated with a cytotoxic antitumor antibiotic, calicheamicin. It binds specifically to the CD33 antigen, which is expressed on the surface of leukemic myeloblasts and immature normal cells of myelomonocytic lineage. It is approved for the treatment of CD33 positive AML in first relapse in patients >= 60 years of age and are not considered candidates for cytotoxic chemotherapy. Hypersensitivity reactions, including anaphylactoid reactions, anaphylactic shock, dyspnea, and severe hypotension, have been reported during clinical use of gemtuzumab ozogamicin. Infrequently, hypersensitivity reactions have been fatal. It is unknown if the risk of hypersensitivity reaction increases with administration of blood products in the same day of Mylotarg infusion. We are reporting 2 cases of severe hypersensitivity reaction to Mylotarg on 2 patients who received platelete transfusion in the same day.

Case reports:

Case number 1: A 75 year old male diagosed with AML with normal cytogenetics in April 2005. Relapse was noted in March 2006. He was admitted for Mylotarg infusion at a dose of 9mg/m2 which was started at 11:00 a.m. after receiving the appropriate premedications and finished at 1:00 p.m. without any signs of distress or reaction. He received 6 units of platelets at 6:40 p.m. At 1:00 a.m. the next morning he went into severe respiratory distress and died shortly after that in the ICU.

Case number 2: A 68 y/o male with the history of NHL in 1991, received CHOP chemotherapy in 1991 and 1992, now has secondary AML (diagnosed in October 2005 and underwent chemo in November 2005, and relapsed after induction and consolidation. He was admitted for Mylotarg infusion. Initially he received 6 units of platelets at 8:30a.m. Mylotarg was started at 10:15a.m. and finished at 12:10p.m.No signs of distress or reaction post infusion. At 2:30 p.m. the patient started having chills, rigors with fever, tachycardia, hypertension and hypoxia (pO2 86%). The patient was treated with Solu-medrol, Benadryl, Tylenol and Demerol. The reaction ceased with no further adverse events

Conclusion:Mylotarg is known to cause hypersensitivity reaction, but it is unknown if the risk of this reaction increases with blood products transfusion around the time of Mylotarg transfusion. We are reporting these 2 cases to draw attention to this serious observation.