A Controlled, In Vivo, Pilot Study to Assess the Recovery and Survival of Radiolabeled Autologous INTERCEPT Treated 7-Day Stored Apheresis Platelet Components in 35% Plasma and 65% InterSol and 7-Day Stored Apheresis Platelet Components in 100% Plasma

Overview

The objective of this study is to test the hypothesis that INTERCEPT platelet components stored for 7 days retain sufficient viability for therapeutic efficacy. The post-infusion recovery and lifespan of 7-day old INTERCEPT platelet components stored in 35% plasma and 65% InterSol or stored in 100% plasma, will be measured in comparison to "fresh" radiolabeled platelets according to FDA guidance for platelet testing (FDA 1999).

The two stages of this pilot study consist of the following: single or double-dose platelet apheresis collection, pathogen inactivation with INTERCEPT treatment, storage for 7 days, collection of fresh platelets, radiolabeling, infusion of fresh and stored INTERCEPT treated radiolabeled autologous platelets, and collection of blood samples for assessment of platelet recovery and survival (lifespan). In Stage A, apheresis platelets will be collected using the Amicus separator and stored for 7 days in 35% Plasma and 65% InterSol. In Stage B, apheresis platelets will be collected using the Trima separator and stored for 7 days in 100% plasma. Procedures for both stages will be as follows: On Day 0, each healthy volunteer subject has apheresis platelets collected. INTERCEPT treatment will begin on either the day of donation (Day 0) or before the end of the day following donation (Day 1). Platelets will then be stored for 7 days after collection (Day 7). Aliquots for in vitro platelet function will be taken on Day 0/1 after INTERCEPT treatment and Day 7. An aliquot for bacterial detection will be taken on Day 5. On Day 7, healthy volunteers will return to the laboratory, and 43 mL of blood will be drawn into a syringe containing 9 mL of Anticoagulant Citrate Dextrose Solution, Formula A (ACD-A). Fresh platelets will be prepared from this sample. An aliquot (10-20 mL) of the stored (INTERCEPT treated) platelets will be aseptically removed from each subject's test container. Previously stored (Test) and fresh (Control) platelets will be radiolabeled according to randomization assignment with either 51Cr (≤20 μCi) as sodium radiochromate (Na251CrO4), or 111In (≤15 μCi) as indium oxine, following the labeling and washing procedures outlined by the Biomedical Excellence for Safer Transfusion (BEST) Collaborative. The isotope labels will be determined by a random number table such that equal numbers of fresh and stored (INTERCEPT treated) platelets will be labeled with each isotope. Aliquots of the fresh and stored platelets will be radiolabeled in tubes with the standard techniques. After radiolabeling, the autologous fresh and stored platelets will be simultaneously infused into the subject (approximately 10-30 mL). Negative bacteria detection test and negative pregnancy test for females of childbearing potential are required before infusion. Blood samples for radioactivity measurements will be drawn at 0 (pre-infusion), 0.5, 1, and 2 hours post-infusion, and then 6 more samples will be drawn 1, 2, 3, 4 (or 6), 7±1, and 10±1 days post-infusion. In addition, when logistically feasible, an additional sample will be obtained 5 days post-infusion (optional). Radioactivity measurements Samples will be obtained from the radiolabeled fresh and stored platelets before infusion and used as a radioactive standard. By measuring the volume infused, the total dose of radioactivity infused will be calculated. In vitro elution of the label from the transfused platelets will be determined by two elution assessment methods, as well as the in vivo elution of radioactivity from the serial blood samples obtained post-infusion of the labeled platelets. The standard as well as the subject's whole-blood samples will be corrected for elution and also for the residual activity in the cellular fraction on Day 8. The first four data points post-infusion will be used to calculate in vivo recoveries and survivals after all radioactive corrections have been made. The radioactivity of the samples will be determined by use of a gamma counter. A multiple-hit model, with a computerized program "COST," will be used to estimate the recovery and survival of the radioactively labeled platelets.