In Vivo Study to Assess the Recovery and Survival of Radiolabeled Autologous INTERCEPT Apheresis Platelet Components Suspended in 100% Plasma Stored for up to 7 Days

The study will be performed in two stages. Stage 1 is a randomized, 2-period crossover design. Test platelets stored for 7 days will be radiolabeled based on either the BEST or Variant 1 methods (depending on the period and randomization scheme for the Test platelets) for 12 healthy subjects. The recovery and survival for Test platelets prepared with the BEST and Variant 1 methods will be compared with each other and against the fresh platelet Control. With agreement from the FDA (BQ200481, July 8, 2020), completion of Stage 1 is not required.

Stage 2 is a single arm design. Test platelets from 24 healthy subjects, stored for 7 days, will be prepared for radiolabeling following the Variant 1 methodology. The recovery and survival for Test platelets will be compared against the fresh platelet Control. Stage 1 subjects with evaluable Variant 1 method data will contribute to the requirement of the 24 subjects for Stage 2.

For both stages, the study population will consist of healthy subjects who meet the FDA, AABB, and site-specific research donor eligibility criteria for apheresis platelet donation. Apheresis platelets will be collected in 100% plasma on the Trima Accel® Automated Blood Collection system.

Each study apheresis collection will be processed using the INTERCEPT Blood System for Platelets. Platelet components containing 3.0 to 7.9 x10^11 platelets in 300 to 420 mL of plasma will be processed using the INTERCEPT Dual Storage (DS) set. The INTERCEPT process will begin on either the day of collection (Day 0) or the day following donation (Day 1); illumination must occur within 24 hours after the end of collection. Test platelets components will be stored for up to 7 days, from day of collection, in 100% plasma.

During each stage samples for in vitro platelet testing will be collected prior to INTERCEPT treatment (Day 0/1), post INTERCEPT treatment and at the end of storage, Day 7 (see In vitro evaluation of platelets below).

At the end of storage, an aliquot of Test platelets will be aseptically removed from each subject's INTERCEPT platelet storage container for preparation of samples for radiolabeling using either the BEST (Stage 1) or Variant 1 (Stages 1 and 2) methodology. The in vitro quality of the Test platelet sample used for radiolabeling will be assessed prior to and following the pre-radiolabeling platelet sample preparations. The indices to be measured in Stage 1 are volume, pH22°C, CD62P, platelet count, red blood cell (RBC) count and white blood cell (WBC) count. Assessments of these indices will enable the determination of platelet processing recovery for each sample preparation method and evaluation of RBC and WBC contamination in samples prior to radiolabeling. In Stage 2 platelet processing recovery during sample preparation will be calculated from volume and platelet count and pH22°C, will be measured in the sample prior to radiolabeling.

On the day corresponding to the end of storage for the Test component, healthy subjects will return to the site, and 43 mL of whole blood (WB) will be drawn into a syringe containing 9 mL of Anticoagulant Citrate Dextrose Solution, Formula A (ACD A). The sample will be used to prepare Control platelets following the BEST methodology. Test and Control platelets will be randomly radiolabeled with either 51Cr (approximately10-30μCi) as sodium radiochromate (Na251CrO4) or 111In (approximately 10-30 μCi) as indium oxine, depending upon the randomization assignment and period as applicable. Subjects will be randomized with equal probability to the radiolabeling sequences (111In/51Cr vs. 51Cr/111In) for Test/Control. The isotope labels will be assigned randomly with equal probability that Control and Test platelets will be labeled with each isotope, and the same randomization assignment of isotope labels will be utilized for both apheresis collections for the same subject in Stage 1. After radiolabeling, the autologous Control and Test platelet samples will be simultaneously infused into the subject (approximately 10 30 mL). A negative pregnancy test for females of childbearing potential is required before infusion.

Blood samples will be drawn immediately before infusion and for radioactivity measurements at 1 hour ± 15 min and 2 hours ± 15 min post-infusion (Day 0), and 6 more samples will be drawn at 1, 2, 3, 4 (or 5 or 6), 7 or 8, and 11±1 days post-infusion (DPI), at approximately the same time of day as the radiolabeled platelet infusion was administered (±4 hours). The exact time of each sample draw will be recorded.

For subjects enrolled in Stage 1, there will be a minimum washout period of four weeks between the two study periods (e.g., four weeks after the last blood sample at 11±1 DPI, in Period 1). Subjects will be monitored for safety (adverse events) from the first apheresis procedure until 24 hours after the last DPI blood sample is drawn.