Time course of platelet count and serum creatinine levels for 2 patients with cancer/chemotherapy–associated TMA treated with terminal complement inhibition. Time (x-axis) is plotted on a logarithmic scale. (A) The course of patient 4 who developed recurrent TMA owing to nonadherence with therapy but was successfully salvaged to continue chemotherapy. Patient 4 presented with renal failure, microangiopathic hemolytic anemia, and a platelet count that was in the high normal range at diagnosis but 50% lower than the patient’s baseline platelet count. On starting eculizumab, platelet count increased within 1 week, and serum creatinine level stabilized. The patient was discharged to continue eculizumab as an outpatient but missed a month of treatment leading to a TMA relapse with thrombocytopenia and worsening renal function, which resolved rapidly with restarting eculizumab. She remained on anti-C5 therapy (eculizumab and later ravulizumab) while receiving taxol and later topotecan and bevacizumab on disease progression without TMA recurrence. (B) The course of patient 6 who responded to eculizumab and was able to discontinue therapy. He presented with renal failure and severe thrombocytopenia with microangiopathic hemolytic anemia. Platelet count started to increase within days of starting eculizumab; urine output increased within 1 week of starting therapy, and serum creatinine decreased within 2 to 3 weeks. He remained on eculizumab while starting androgen deprivation therapy (ADT) (and docetaxel) for prostate cancer. He stopped eculizumab after 12 months of therapy when the prostate cancer was stable on ADT and remains free of TMA recurrence.