Chimeric Antigen Receptor T Cell Therapy (or CAR-T therapy)

Chimeric Antigen Receptor T cell therapy (or CAR-T therapy) is the latest and most exciting anti-cancer therapy to make the news in recent months. The FDA has approved two such therapies: Kymriah (Novartis) for acute lymphoblastic leukemia; and Yescarta (Kite) for diffuse large B cell lymphoma.  This treatment strategy uses the patient’s own immune system, specifically the T cells, to destroy the tumor. The T cell is engineered with a new molecule on its cell surface, a modified T cell receptor, so that it recognizes and kills the cancer cells and in addition recruits the rest of the immune system to eliminate the tumor.  The results from clinical trials utilizing CAR-T are promising, they show a very effective and efficient treatment with less severe side effects than those associated with chemo- or radiation therapy.

T cells are extracted from the patient and infected with replication deficient retro- or lentiviruses that carry the gene for the engineered T cell receptor. This gene is then incorporated into the nucleic DNA of the patient’s T cells resulting in a “chimeric” T cell, having the cellular immune functions of the host T cells, but engineered to readily recognize and kill cancer cells. These chimeric T cells are then cultured to obtain the actual therapeutic, essentially a bag of CAR-T cells numbering usually in the hundreds of millions, suspended in growth media. These cells are then transfused back into the patient where the CAR-T cells seek and destroy the cancerous cells, usually within 2-4 weeks.  Another advantage of CAR-T cell therapy is that this therapeutic can develop into dormant memory T cells that will monitor the patient for possible relapse of the same cancer.  Should relapse occur, the CAR-T cells become active again and proceed to destroy the reoccurring cancer cells.

Ensuring the safety and efficacy of this therapeutic, especially because a retrovirus is used during production, is critical. Monitoring the possibility of reversion of the replication deficient retroviruses is needed during production and treatment and can be monitored using RT-PCR and cell based assays. The therapeutic needs to be characterized by immunophenotyping, usually by flow cytometry, and tested for the presence of the T cell receptor gene, testing routinely performed using qPCR. The patient symptoms are monitored carefully during the 2-4 weeks post infusion, when the CAR-T therapeutic is seeking and destroying the tumor, to ensure that any serious side effects can be mitigated. Immunoassays (ELISA, MSD, Luminex) are used to measure cytokines and potential anti-therapeutic antibodies generated by the patient’s immune system. Long term follow-up of the patient also involves monitoring the persistence of the CAR-T cells in the memory compartment of the cellular immune system.  These can be detected by qPCR or cell based proliferation assays.

This novel approach to cancer treatment requires novel methods to monitor and quantify the progression and effects of the therapeutic. 

Cambridge Biomedical Inc. offers these qPCR, flow cytometry and immunoassay capabilities at the quality and regulatory levels required for clinical trial study sample testing:

  • PBMC collection from the patient (Leukopheresis)
    • Immunophenotyping of patient PBMC (Flow)
    • HLA phenotyping (Flow/PCR)
  • Transduction of PBMC with T cell receptor construct (CAR T gene)
    • RCR/RCL testing of T cell therapeutic product (product release testing) (PCR/Cell Based)
    • CAR T gene monitoring (transduction efficiency testing) (PCR)
    • Immunophenotyping of T cell therapeutic product (Flow)
  • Infusion of programmed CAR T cells into patient
    • CRS monitoring (MSD/Luminex/ELISA)
  • Patient monitoring
    • CAR T gene monitoring (persistence testing) (PCR)
    • RCR/RCL testing of T cell therapeutic product (safety testing) (PCR/Cell Based)
    • Humoral Immunogenicity testing (MSD/Luminex/ELISA)
    • Cellular Immunogenicity testing (Flow)
    • ADA (MSD/Flow)

 

 Maloy M. Mangada, PhD

Maloy M. Mangada, PhD

Dr. Mangada is Associate Director of Scientific Services at Cambridge Biomedical and serves as the lead immunologist directing a team of accomplished scientists in the development and validation of novel high and low complexity assays.  He has more than 20 years’ experience with biomarker assay development, including 15 years of flow cytometry assay development and validation.  Dr Mangada has a PhD in Molecular Virology, an MS in Molecular Biology and Biotechnology and a BS in Applied Physics. He undertook a Post-Doctoral Research Fellowship, studying T cell immunology at the University of Massachusetts Medical School, USA.