Background: Alemtuzumab is a lymphocyte-depleting induction agent used in kidney transplantation among high-risk highly sensitized recipients, or low-risk candidates on a steroid-withdrawal regimen. Although alemtuzumab is effective in preventing hyperacute rejection, it can result in prolonged lymphocyte depletion, which can be magnified with the routine use of antimetabolites and anti-infectives post-transplant. Here we assessed the dosing, tolerability, and outcomes in administering alemtuzumab induction via IV vs. SQ route in pediatric kidney transplant recipients.
Methods: A multicenter analysis of 119 patients <21 years old who received a kidney transplant and alemtuzumab induction was conducted. Dosing differences were evaluated by total dose and dose by body weight. Tolerability was defined by the development of leukopenia (WBC <3.0 x103/uL) or neutropenia (ANC <1.5 x103/uL); differences in total mycophenolate mofetil dose were also assessed. Outcomes in the first-year post-transplant were defined by eGFR, hospitalizations, bacterial infections, viral infections (BK, CMV, EBV), and rejection. 
Results: 83 recipients received IV alemtuzumab compared to 36 who received SQ. Mean age at transplant was 12.5 yrs (standard deviation (SD) 6.0), with a slightly older population in the SQ group, 14.0 yrs (SD 5.5) vs. 11.9 yrs (SD 6.1) (P=0.07). More patients were highly sensitized (PRA >30%) in the SQ group, 14 (38.9%) vs. 10 (12.1%) (P=0.002). Total dose and dose by weight was higher in the SQ group, 22.3 mg (SD 8.9) vs. 14.9 mg (SD 9.5), and 0.57 mg/kg (SD 0.21) vs. 0.36 mg/kg (SD 0.18 mg), respectively. Mycophenolate dosing was higher in the IV group at 1-, 3-, 6-, and 12-months post-transplant; there were no differences in the incidence of leukopenia and neutropenia at the same time points, and eGFR remained similar between the groups (Table 1). There were no significant differences between the groups in the development of bacterial infections, viral infections (BK, CMV, EBV), hospitalization, or rejection in the first-year post-transplant. 

Conclusion: Despite the higher total and weight-based dose of alemtuzumab used in the SQ group, there were no differences in the measured outcomes, compared to IV alemtuzumab. Overall, alemtuzumab is well tolerated during the first-year post-transplant as an induction agent in the subsets of pediatric kidney transplant population in which it is used.