(491) Thrombotic Thrombocytopenic Purpura Presenting as a Bowel Obstruction After Capecitabine/Oxaliplatin

Introduction: Thrombotic thrombocytopenic purpura (TTP) is a life-threatening condition marked by microangiopathic hemolytic anemia, thrombocytopenia, and end-organ damage. Early identification and treatment of TTP is paramount to patient survival. Here we describe a case of TTP with atypical presentation after receiving capecitabine and oxaliplatin.

Description: A 61-year-old man with stage IIa colon adenocarcinoma presented with small bowel obstruction two weeks after the first cycle of chemotherapy with capecitabine/oxaliplatin. Initial labs showed mild anemia and reactive thrombocytosis. The patient then became febrile and encephalopathic with seizures confirmed on EEG. Labs revealed progressive anemia and thrombocytopenia, elevated lactate dehydrogenase, hyperbilirubinemia, low haptoglobin, a negative direct antiglobulin test, elevated creatinine, normal PT/PTT, and normal fibrinogen. 4-5 schistocytes per high power field were noted on the peripheral blood smear. The constellation of clinical symptoms and laboratory findings were highly suspicious for TTP. The PLASMIC score was 5. The patient was given fresh frozen plasma and methylprednisolone; plasmapheresis (PLEX) was promptly started for suspected drug-induced TTP. ADAMTS13 (A Disintegrin And Metalloproteinase with a ThromboSpondin type 1 motif, member 13 activity) sent before the initiation of therapy was low at 37% with an elevated inhibitor titer of 0.8 Bethesda units. The patient underwent five cycles of PLEX followed by one dose of rituximab and a long steroid taper. ADAMTS13 activity normalized to 104% and the inhibitor titers became undetectable. Platelet counts recovered and hemolysis resolved. The patient’s neurocognitive function improved clinically. aHUS/dense deposit disease genetic testing was negative.

Discussion: Chemotherapy-induced TTP is a rare phenomenon with known culprits including gemcitabine and oxaliplatin. This patient developed TTP after receiving capecitabine and oxaliplatin. Notably he presented with small bowel obstruction and thrombocytosis rather than thrombocytopenia. The patient had a positive clinical outcome after prompt initiation of plasmapheresis. We hope to highlight here this rare but serious chemotherapy-related adverse event with an unusual presentation of TTP.