Bevacizumab is the most likely cause of this patient's clinical picture. This patient presents with classic features of thrombotic microangiopathy (TMA), including microangiopathic hemolytic anemia, a low platelet count, and kidney dysfunction. Chemotherapeutic agents known to be associated with TMA include mitomycin C, gemcitabine, tyrosine kinase inhibitors, mammalian target of rapamycin (mTOR) inhibitors (sirolimus, everolimus), and anti-vascular endothelial growth factor (VEGF) inhibitors. VEGF inhibitors are an important class of drugs used in treating metastatic cancer, and they are able to induce a form of microangiopathy very similar to preeclampsia/eclampsia that is associated with severe hypertension and kidney failure. VEGF inhibition by endogenous factors is thought to play a key role in development of preeclampsia/eclampsia, and two VEGF inhibitors, bevacizumab and sunitinib, have been linked to TMA, which typically subsides after stopping the drug. Patients typically present with an insidious onset of kidney failure and hypertension (new or exacerbated). There tends to be a variable amount of proteinuria and a relatively bland urine sediment. The cancer is not typically overt (to differentiate from cancer-associated TMA, in which there are widely metastatic lesions at the time of diagnosis of TMA). Plasmapheresis is not usually effective for treatment of VEGF inhibitor–associated TMA and is not indicated.

The other chemotherapeutic agents (5-fluorouracil, leucovorin, oxaliplatin) being administered are not associated with TMA.