The endeavor to study desensitization in kidney transplantation has not been matched by an effort to investigate strategies to prevent sensitization. In this study ( NCT 02437422), we investigated the safety, impact on sensitization, and pharmacokinetics of SANGUINATE ( SG ), a hemoglobin‐based oxygen carrier, as a potential alternative to packed red blood cells ( PRBC ) in transplant candidates with end‐stage renal disease ( ESRD ). Ten ESRD subjects meeting inclusion/exclusion (I/E) criteria were planned to receive three weekly infusions of SG (320 mg/kg). The study was stopped after five subjects were enrolled, and their data were analyzed after completing a follow‐up period of 90 days. Two subjects had elevated troponin I levels in setting of SG infusion, one of which was interpreted as a non‐ ST elevation myocardial infarction. All other adverse events were transient. SG pharmacokinetic analysis showed mean (SD) C max , T max , AUC , and half‐life of 4.39 (0.69) mg/mL, 2.42 (0.91) hours, 171.86 (52.35) mg h/mL, and 40.60 (11.96) hours, respectively. None of the subjects developed new anti‐ HLA antibodies following SG infusion and throughout the study period. In conclusion, SG is a potential alternative to PRBC s in ESRD patients considered for kidney transplantation as it was not associated with humoral sensitization. Larger studies in highly sensitized patients are required to further evaluate for potential safety signals.

e14085 Background: Anti-Neutropenia Factor - RHO (ANF-RHO) is a novel pegylated version of native human recombinant G-CSF protein. ANF-RHO has distinct biophysical and biological properties that produce a distinct pharmacokinetic (PK) and pharmacodynamic (PD) profile as compared to pegfilgrastim that may be ideally suited for treating febrile neutropenia. Methods: A phase I clinical study was conducted in healthy subjects to assess the PK/PD profile of ANF-RHO. The randomized, placebo controlled, double blind trial assessed the effect of single, ascending dose, subcutaneous injections of 5 to 50 µg/kg ANF-RHO versus fixed dose 6 mg (80 to 100 µg/kg) pegfilgrastim or placebo on average neutrophil count (ANC) and level of CD34+ hematopoietic progenitor cells. Results: ANF-RHO demonstrated a biphasic ANC response in comparison to pegfilgrastim between days 2-7. Mean ANC counts for all ANF-RHO treated subjects showed a time to Cmax (Tmax ) between 6.8 and 7.4 days in contrast to 2.2 days for pegfilgrastim-treated subjects. Comparison of ANC values showed that ANF-RHO subject neutrophil counts increased in a stable and prolonged manner (over 7 days), in contrast to pegfilgrastim that showed a rapid ANC spike (2 days) and then decreased following administration. Assessment of AUC for the PD curves showed that ANF-RHO at10 µg/kg was equivalent to pegfilgrastim at 80-100 µg/kg, demonstrating a ≥ 8-fold potency effect for ANF-RHO over pegfilgrastim, and with a duration of effect lasting beyond 12 days. Conclusions: Because of the unique PK/PD of ANF-RHO, a significantly lower dose may be given on the same day as chemotherapy administration to achieve neutrophil levels sufficient to mitigate severe neutropenia with fewer dose-related side effects. Planning is underway for a phase II study of ANF-RHO with a focus on reducing or preventing the occurrence and severity of neutropenia resulting from the use of myelo-suppressive chemotherapy. Days Post-Administration Mean AUC Pegfilgrastim 100µg/kg Mean AUC ANF-Rho 10µg/kg 0 3.7 2.86 2 32.6 10.1 7 15.3 16.8 12 5.2 11 %Change from 0 - 12 39 390