Severe aplastic anemia (SAA) is a lifethreatening bone marrow failure disorder that can be treated with bone marrow transplantation, immunosuppressive therapy, and high-dose cyclophosphamide. Here, we report long-term follow-up on 67 SAA patients (44 treatment-naive and 23 refractory) treated with high-dose cyclophosphamide. At 10 years, the overall actuarial survival was 88%, the response rate was 71% with the majority being complete, and the actuarial event-free survival was 58% in 44 treatmentnaive SAA patients. Patients with refractory SAA fared less well after high-dose cyclophosphamide therapy; at 10 years, overall actuarial survival, response, and actuarial event-free survival rates were 62%, 48%, and 27%, respectively. High-dose cyclophosphamide is highly effective therapy for severe aplastic anemia. Large randomized controlled trials will be necessary to establish how results of high-dose cyclophosphamide compare with either bone marrow transplantation or standard immunosuppressive regimens, such as antithymocyte globulin and cyclosporine. (Blood. 2010;

High-dose cyclophosphamide therapy without bone marrow transplantation produces durable treatment-free remission in severe aplastic anemia. This approach deserves further study in patients with severe aplastic anemia who are not suitable candidates for allogeneic bone marrow transplantation.

Background Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal, hematopoietic stem cell disorder that manifests with hemolytic anemia and bone marrow failure. Eculizumab has been shown to improve anemia, decrease intravascular hemolysis, and reduce the risk of thrombosis. Design and methods This is a retrospective, single-center study of patients treated with eculizumab and categorized according to response criteria. Complete response (CR) was defined as transfusion independence with normal hemoglobin for age/sex, absence of symptoms, and lactate dehydrogenase <1.5 times the upper limit of normal. A good partial response (GPR) was defined as decreased transfusions from pretreatment and lactate dehydrogenase <1.5 upper limit of normal without thrombosis. These patients did not achieve normal hemoglobins for age and sex. A suboptimal response was defined as unchanged transfusion needs and persistent of symptoms. Results Thirty patients with PNH clones were treated with eculizumab and classified as complete responders (four patients), good partial responders (16), and suboptimal responders (10) over 863 patient-months of treatment. Complete responders had a decrease in red cell clone size, while good partial responders had an increase. Thirteen patients treated did not meet inclusion criteria for the clinical trials of eculizumab due to lack of transfusions or thrombocytopenia; eight had at least a GPR. Conclusions Eculizumab is efficacious in patients with PNH, but responses can vary and may depend on underlying marrow failure, underlying inflammatory conditions and red cell clone size following treatment. Normalization of hemoglobin with decrease in red cell clone size may predict CR.

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by a lack of the terminal complement inhibitor CD59 on erythrocytes that renders these cells susceptible to chronic hemolysis. Eculizumab blocks terminal complement resulting in reductions in hemolysis, thrombotic events, renal impairment and transfusion requirement, as well as improvement in quality of life. The standard dosing regimen for eculizumab is 600 mg/week for 4 weeks (induction); 900 mg one week later; and then 900 mg every 14 ± 2 days (maintenance). This regimen maintains eculizumab levels >35 μg/mL, which is sufficient to completely and consistently block complement-mediated hemolysis in patients with PNH. In PNH clinical trials, 900 mg of eculizumab every 14 ± 2 days effectively and consistently blocked complement-mediated hemolysis in 98% of patients (n=195). During the studies, 10–15% of patients experienced an increase in hemolysis (elevation of LDH) near the end of the 14-day dosing interval with a return of pre-eculizumab symptoms such as hemoglobinuria, dysphagia, abdominal pain, or fatigue. The dosing interval was reduced to 12 days, as specified by label, resulting in sustained complement blockade, control of hemolysis and resolution of symptoms in nearly all patients. Three of the original 195 patients (2%) were not consistently blocked with the approved dosing regimen. Alternative eculizumab dosing regimens were investigated in these patients to assess their effectiveness and safety. Two different dosing regimens were employed; both included a maintenance phase with 1200 mg every 14 days. One regimen also included an induction period of 900 mg weekly for 5 doses. LDH, pharmacokinetics (PK), and clinical signs of complement breakthrough were monitored. The time from first eculizumab treatment to initial breakthrough on the 900 mg every 14 days ranged from 2 to 19 mo., and the reduction in the dosing interval to 900 mg every 12 days, as specified in the label, did not adequately control hemolysis in each of these 4 patients. Patient 1 was managed for 6 mo. with 900 mg every 12 days before experiencing additional complement breakthrough episodes (Figure, panel A). LDH levels (closed diamonds) reached 9234 U/L (ULN, 430-450 U/L) and breakthrough symptoms occurred 2 days prior to the next dose. The patient was re-induced with 900 mg eculizumab every 7 days for 5 weeks followed by 1200 mg every 14 days. Trough levels of eculizumab increased (open circles) each week during the induction phase (42.7 – 81.8 μg/ml) resulting in an immediate reduction in LDH to near normal levels. A maintenance dose of 1200 mg every 14 days in this patient resulted in sustained complement blockade. Patient 2 experienced breakthrough hemolysis after 19 mo. of standard dosing. Complement breakthrough occurred during a post-cholecystectomy infective endocarditis. After an adjustment to 900 mg every 12 days did not control complement breakthrough (Figure, panel B), the dose was changed to 1200 mg every 14 days without re-induction. This regimen resulted in sufficient levels of eculizumab to consistently reduce hemolysis to near normal levels. Further episodes of hemoglobinuria and other symptoms of hemolysis were not observed. Two additional patients received 1200 mg every 14 days without re-induction, one following complement breakthrough on the approved dose and the other due to the convenience of the 14 day interval with the 1200 mg dose. Complete complement blockade has been maintained in these patients for 8 mo. and 12 mo. to date, respectively. After 1 year of sustained complement blockade with the 1200 mg maintenance dose, patient 1 again demonstrated a breakthrough. Complement inhibition is now being maintained in this patient by a 1200 mg dose every 14 days with an additional 1200 mg dose in between the 14 day dosing interval every 4–5 doses. There were no reported adverse events in any of the four patients in which the 1200 mg dosing regimens were administered. In summary, these data demonstrate good correlation between eculizumab and LDH levels, suggesting that a breakthrough in complement activity due to insufficient drug levels can be monitored by levels of LDH near the end of the dosing interval. These results illustrate that two alternative-dosing regimens are well tolerated and can be effectively employed in the small percentage of PNH patients in which complement inhibition is not consistently maintained using the standard dose. Figure Figure

Background: Acquired SAA is a potentially life-threatening bone marrow failure disorder that is usually immune-mediated. SAA can be effectively treated with bone marrow transplantation (BMT), immunosuppressive therapy (IST), or CY. BMT can cure the disease but ideally requires a matched sibling donor. IST has a high response rate, but up to 50% of patients relapse, become dependent on cyclosporine, or develop secondary clonal disease such as paroxysmal nocturnal hemoglobinuria (PNH) or myelodysplastic syndromes (MDS). We previously showed that CY induces durable remissions in the majority of SAA patients, but concern has been raised about the safety of this approach. Methods: Since 1996, we treated 38 previously untreated, and 17 IST failed, SAA patients with CY (50 mg/kg/d x 4) followed by daily G-CSF (5 ug/kg/day) until the neutrophil count (ANC) reached 1000/dl. Response was defined as ANC &gt; 1000/dl and transfusion independence without growth factor support for &gt; 3 months. Relapse was defined as no longer meeting criteria for response. PNH was monitored by flow cytometry. Results: The median age of the newly diagnosed patients was 40 (range 2–68) years. With a median follow-up of 41 (range, 6 – 111) months, 33/38 patients survive (actuarial survival of 86%, 95% CI 72–95%) with 28 (74%, 95% CI 58–85%) achieving remission, most being complete. Median time to ANC of 500, last platelet and red cell transfusion was 50, 99, and 181 days, respectively. Before treatment, 15 patients met criteria for very (v) SAA (ANC &lt; 200). Mortality within 6 months after CY occurred in 4 (10.5%) patients, all with vSAA; 1 additional patient died from bacterial sepsis 18 months after CY. 22/23 (96%) SAA patients survive (20 in remission) compared to 11/15 (73%) with vSAA (10 in remission). Eight patients had a severe infection at the time of beginning treatment and 5 survive in remission. PNH screening revealed a PNH population ranging from 0.5–40% of granulocytes in 12 patients, and all 12 achieved a durable remission (p = 0.039). No patient in this series has progressed to PNH or MDS, and the PNH clone is regressing in all 12 patients. Two patients have relapsed. One patient, whose first remission lasted 5 years, was retreated with CY into a persisting second complete remission 3 years ago; another patient recently relapsed 3 years after achieving remission. Ten of the 17 patients who failed IST (median age of 31, range 6–58) are alive and nine are in remission. Conclusions: Cy is safe and highly effective therapy for both untreated and relapsed SAA. Relapses after CY are rare and progression to PNH or MDS in previously untreated patients has not been observed in this series with now 15 patients out beyond 5 years. The presence of a PNH population may be a favorable risk factor, perhaps by excluding non-immune mediated forms of SAA. Figure Figure