{
  "abstract": "Background Flow cytometry serves as a critical analytical tool in immunotherapy clinical trials, enabling researchers to assess pharmacodynamic (PD) responses, confirm target engagement, and monitor CAR-T cell expansion and persistence. However, current workflows present significant challenges for global trials using fresh samples. Fresh whole blood must be processed within 24-72 hours of collection, yet sample degradation substantially alters immune profiles. Because samples must be processed quickly, Contract Research Organizations (CROs) have needed to place physical labs near clinical trial sites. Even with this lab infrastructure, 20% of samples still fall outside specifications. Additionally, inter-site variability compromises reproducibility, particularly problematic when cytometry serves as PD endpoints for measuring drug persistence and target engagement. Existing preservation methods maintain sample integrity for only ~1 week and fail to preserve immune cell frequencies comparable to fresh samples. To address these limitations, we developed a three-step preservation kit that provides extended stability, maintains high correlation with live samples, enables centralized batch processing, and achieves Limit of Quantification (LOQ) in the range of established clinical cytometry workflows.Methods We evaluated a no-wash TBNK assay using BD Multitest 6-color reagent with counting beads on stabilized blood samples collected in our three-step preservation kit (TokuKit) and a one-step preservation tube (Cytochex). Blood from three healthy donors was tested, comparing stabilized samples to fresh EDTA blood. Fresh EDTA blood and Cytochex blood were processed according to BD Multitest’s manual whereas TokuKit-collected blood was processed using a modified no-wash protocol. Acquisition was performed on Cytek Aurora using standardized spectral flow configurations. We evaluated absolute cell counts using fluorescent counting beads and compared major lymphocyte subsets for frequency and absolute count. Each condition was run in triplicate with three independent runs by three operators for precision assessment.Results The no-wash TBNK assay combined with TokuKit preservation enables accurate quantification of lymphocyte subsets from stabilized whole blood without centrifugation or regional lab processing. Results demonstrated strong concordance with fresh blood in both cell frequencies and absolute counts, including low-abundance populations.Conclusions The TokuKit addresses critical challenges in multi-site immunotherapy trial cytometry by extending sample stability, eliminating sample failures, and enabling centralized processing to reduce inter-site variability. By removing the need for regional labs, the kit enables standardized TBNK profiling across global trials with improved reproducibility and reduced logistical challenges, supporting more robust and cost-effective clinical trial execution.",
  "authors": [
    {
      "affiliations": [
        "Teiko bio, Salt Lake City, UT, USA"
      ],
      "name": "Carly L Lancaster"
    },
    {
      "affiliations": [
        "Teiko bio, Salt Lake City, UT, USA"
      ],
      "name": "McKenna Coughlin"
    },
    {
      "affiliations": [
        "Teiko bio, Salt Lake City, UT, USA"
      ],
      "name": "Kristina Magee"
    },
    {
      "affiliations": [
        "Teiko bio, Salt Lake City, UT, USA"
      ],
      "name": "Gage S Black"
    },
    {
      "affiliations": [
        "Teiko bio, Salt Lake City, UT, USA"
      ],
      "name": "Lee S Leavitt"
    },
    {
      "affiliations": [
        "Teiko bio, Salt Lake City, UT, USA"
      ],
      "name": "Justin A Jarrell"
    },
    {
      "affiliations": [
        "Teiko bio, Salt Lake City, UT, USA"
      ],
      "name": "Ramji Srinivasan"
    },
    {
      "affiliations": [
        "Teiko bio, Salt Lake City, UT, USA"
      ],
      "name": "Li-Chun Cheng"
    }
  ],
  "title": "50 Assessment of three-step blood preservation kit for pharmacodynamic endpoints by flow cytometry for multi-site, global clinical trials",
  "uid": "174579eb-8974-5ada-ac85-6884cf220daa"
}