Abstract 2548: Retrospective prediction of clinical response to standard-of-care therapies in acute myeloid leukemia by an ex vivo drug sensitivity assay using cryopreserved primary samples
Authors: Patil Lokesh , Gu Christine J. , Anderson Wade , Long Nicola , Johnson Kara , Tognon Cristina , Lacher Markus D. 
Published: March 2024

Abstract
Background: Assessing drug efficacy in primary acute myeloid leukemia (AML) patient cells is crucial for pinpointing drug targets and rationally selecting therapies for patients. We have previously shown that our flow cytometry-based predictive precision medicine platform (PPMP) predicts patient outcomes for standard-of-care (SOC) AML treatments using fresh blood or bone marrow samples with high precision. Here, we wanted to test the feasibility and efficacy of the PPMP on cryopreserved patient-derived leukemic samples. However, cryopreserved leukemic samples are known for exhibiting low viability and cell recovery, rendering their practical utilization often challenging. In this study, we adapt an existing methodology for cryopreservation for patient-derived leukemic cells to investigate the potential of cryopreserved samples as an alternative to fresh samples for ex vivo prediction of treatment outcomes on our PPMP.
Methods: We screened freshly isolated white blood cells from AML patients on the PPMP to assess their response to multiple SOC single agents and combinations. The assay was also run without drug treatments immediately after receiving the fresh sample (≤ 2 days from draw) to establish a phenotype baseline. The cryopreserved samples were processed using a similar protocol, with post-thaw culture times of either 24 or 48 hours in two types of cytokine-containing media. A comparative analysis between untreated fresh and cryopreserved samples determined the optimal post-thaw culture time for cryopreserved samples. Once culture time was optimized, we screened cryopreserved samples on the PPMP with identical SOC drug conditions as the fresh samples and compared the response of leukemic blasts to drug treatment as well as impacts on other phenotypic markers.
Results: Based on our preliminary data, we found that culturing cryopreserved cells for 24 hours post-thaw was sufficient to maintain a minimum cell viability of 80% while closely maintaining a phenotype that recapitulated that of the corresponding fresh samples. In response to drug treatments within the ex vivo assays, preliminary data support a correlation (Decitabine single agent, R2=0.81) between the response profiles of cryopreserved and fresh patient samples as gauged from AUC calculations.
Conclusion: While the preferred method for screening is to use fresh patient samples, many practical constraints make it challenging or unfeasible. The ability of Notable Lab’s high-throughput platform to use cryopreserved samples opens the doors to enhanced retrospective studies leveraging clinically annotated data from biobanks or clinical trials. These retrospective studies provide a substantial reduction in the time needed to conclude such investigations.
Citation Format: Lokesh Patil, Christine J. Gu, Wade Anderson, Nicola Long, Kara Johnson, Cristina Tognon, Markus D. Lacher. Retrospective prediction of clinical response to standard-of-care therapies in acute myeloid leukemia by an ex vivo drug sensitivity assay using cryopreserved primary samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2548.