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ExPeCT™ Expansion and Persistence of CAR T Assay

Test Code: 33285

CAR T Chimeric Antigen Receptor

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Clinical and Procedure
Clinical Utility

For Hematology/Oncology patients this assay provides interventional data which may provide information on the expansion and persistence of the genetically modified T-cells used as therapeutic treatment for specific lymphomas and leukemias (Chimeric Antigen Receptor T-cell therapy or CAR T). However, some patients fail CAR-T therapy due to lack of cell expansion or persistence. Eurofins Viracor has developed and validated a multiplexed quantitative real-time PCR (qPCR) assay targeting the single chain variable fragment (scFv) FMC63 for the longitudinal monitoring of CD19-directed CAR T-cell therapy. 

Ideally, a pre-transfusion samples of the CAR T cells in the infusion bag and patient’s blood should be collected to establish a baseline and then monitored longitudinally. Subsequently several sources recommend routine monitoring for the first year and then annually up to five years.   


The successes with chimeric antigen receptor (CAR) T cell therapy involving patients with pre-B cell acute lymphoblastic leukemia (ALL) or B cell lymphomas have revolutionized anticancer therapy, providing a potentially curative option for patients who are refractory to standard treatments. FDA approvals of anti-CD19 CAR T cell products for both ALL and certain types of B cell lymphoma (the first approved gene therapies in the USA). CD19-targeted CAR-T cells, which have been engineered to recognize the CD19 (specifically the FMC63 scFv region) cell surface molecule of malignant B cells, show remarkable efficacy in patients with B cell acute lymphoblastic leukemia. Some patients relapse due to the CAR-T therapy not persisting in the body, leading to antigen loss, tumor escape (frameshift mutation), or exhaustion. 

In the clinical setting, long-term remission in patients with hematological malignancies is associated with sustained persistence of CAR T cells.  In the clinical oncology setting, CAR T cell expansion and persistence correlates with response and attaining remission in patients.  Because of this observation, establishing a reliable and direct method of tracking CAR T cell numbers is particularly important, not only in the estimation of effectiveness of CAR T cell therapy, but in terms of safety evaluation in post-infusion monitoring. Serious side effects of clinical CAR T cell therapy have been noted, one of the most severe being cytokine release syndrome (CRS) and is associated with CAR T cell expansion in vivo.  In addition, a major concern for recipients of allogenic CAR T cells is GvHD.  

The persistence/expansion of CAR T cells is key for determining anti-tumor efficacy, which depends on several factors such as structure of CAR T therapeutic, the manufacturing process, the lymphodepletion regimen, the infused cell phenotype, tumor burden, and disease. Persistence of CAR T-cell population is considered a critical factor of anti-tumor efficacy (therapy effectiveness).  Understanding the limitations of anti-CD19 CAR T cell therapy is critical to realizing the full potential of this treatment approach.  Growing experience with these agents has revealed that remissions will be brief in a substantial number of patients owing to poor CAR T cell persistence and/or cancer cell resistance resulting from antigen loss or modulation.  The Viracor ExPeCT™ anti-CD19 (FMC63) CAR T expansion and persistence assay is a monitoring tool to evaluate and validate the efficacy of anti-CD19 FMC63 CAR T therapy. 

CAR T cells are regulated as a gene therapy product under the FDA’s framework for biological products.


Viracor's ExPeCT anti-CD19 (FMC63) CAR T Expansion and Persistence Monitoring qPCR assay is not expected to cross-react with human genomic DNA or commensal organisms present in whole blood specimens, as determined by in silico specificity analysis. Specificity against human genomic DNA was demonstrated experimentally during validation, with no CAR vector signal detected in negative whole blood specimens.

Turnaround Time

24 hours from receipt of specimen, performed Monday - Saturday

Specimen Information
Specimen Type Test Code CPT Code NY Approved Volume Assay Range Special Instructions
whole blood 33285 80299 No

2 mL (min 0.5 mL)

2.072 to 1.392 x 107 CAR vector copies/µg DNA

100.0 to 6.250E+08 CAR vector copies/mL DNA

  • Collect in EDTA - do not centrifuge.
  • Can be shipped at ambient or frozen temperature. Monday through Friday.
  • Specimens shipped at ambient temperature must be received within 96 hrs. of collection.
    • 7 days ambient
      (15 to 25 C)
    • 7 days refrigerated
      (2 to 8 C)
    • 186 days frozen(6 months)
      (-90 to -64 C)

2.072 to 1.392 x 107 CAR vector copies/µg DNA

100.0 to 6.250E+08 CAR vector copies/mL DNA


Ship Monday through Friday. Friday shipments must be labeled for Saturday delivery. All specimens must be labeled with patient's name and collection date. A Viracor Eurofins test requisition form must accompany each specimen. Multiple tests can be run on one specimen. Ship specimens FedEx Priority Overnight® to: Viracor Eurofins, 18000 W 99th St. Ste, #10, Lenexa, KS 66219.

Causes for Rejection

Specimens beyond their acceptable length of time from collection as listed in the specimen handling.


Specimens are approved for testing in New York only when indicated in the Specimen Information field above. The CPT codes provided are based on Eurofins Viracor’s interpretation of the American Medical Association's Current Procedural Terminology (CPT) codes and are provided for informational purposes only. CPT coding is the sole responsibility of the billing party. Questions regarding coding should be addressed to your local Medicare carrier. Eurofins Viracor assumes no responsibility for billing errors due to reliance on the CPT codes illustrated in this material. 

  1. JHOP - February 2022 Vol 12, No 1 - Review Article, CAR T-Cell Therapy, Lymphoma Drew A. Wells, PharmD, BCPS; Jenna Summerlin, PharmD; Zachery Halford, PharmD, BCOP, BCPPS 
  2. Strategies to enhance CAR‑T persistence.  Yue Liu1†, Lingna An1†, Ruihao Huang1†, Jingkang Xiong, Haoyu Yang, Xiaoqi Wang and Xi Zhang Liu et al. Biomarker Research (2022) 10:86  Liu et al. Biomarker Research (2022) 10:86  
  3. Safarzadeh Kozani P, Safarzadeh Kozani P and Rahbarizadeh F (2021). Optimizing the Clinical Impact of CAR-T Cell Therapy in B-Cell Acute Lymphoblastic Leukemia: Looking Back While Moving Forward. Front. Immunol. 12:765097. doi:0.3389/fimmu.2021.765097 
  4. Developing and Monitoring a Standard-of-Care Chimeric Antigen Receptor (CAR) T Cell Clinical Quality and Regulatory Program. 1083-8791/© 2020 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. 
  5. Jafarzadeh L, Masoumi E, Fallah-Mehrjardi K, Mirzaei HR and Hadjati J (2020) Prolonged Persistence of Chimeric Antigen Receptor (CAR) T Cell in Adoptive Cancer Immunotherapy: Challenges and Ways Forward. Front. Immunol. 11:702. doi:10.3389/fimmu.2020.00702 
  6. CAR-T Cells: The Importance of Cell Persistence.   Sep 13, 2021| Russell Garland
  7. The Leukemia & Lymphoma Society. Immunotherapy Facts. Revised December 2019. Accessed October 19, 2021. 
  8. National Cancer Institute. CAR T cells: engineering patient’s immune cells to treat their cancers. Updated: July 30, 2019. Accessed October 20, 2021. 
  9. Brodsky AN. The promise of CAR T cell therapy in 2019 and beyond. Cancer Research Institute [website]. Accessed October 15, 2021. 
  10. Peinelt A, Bremm M, Kreyenberg H, Cappel C, Banisharif-Dehkordi J, Erben S, Rettinger E, Jarisch A, Meisel R, Schlegel PG, Beck O, Bug G, Klusmann JH, Klingebiel T, Huenecke S and Bader P (2022) Monitoring of Circulating CAR T Cells: Validation of a Flow Cytometric Assay, Cellular Kinetics, and Phenotype Analysis Following Tisagenlecleucel. Front. Immunol. 13:830773. doi: 10.3389/fimmu.2022.830773 
  12. Sanber, K., Savani, B. and Jain, T. (2021), Graft-versus-host disease risk after chimeric antigen receptor T-cell therapy: the diametric opposition of T cells. Br J Haematol, 195: 660-668. 
  13. CAR-T cell therapy: practical guide to routine laboratory monitoring. Adrian G Selim, Adrian Minson, Piers Blombery, Michael Dickinson, Simon J Harrison, Mary Ann Anderson. Pathology. 2021 Apr;53(3):408-415. doi: 10.1016/j.pathol.2021.02.002. Epub 2021 Mar 5. 
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