The Use of Chimeric Antigen Receptor-Modified T Cells to Aid in Leukemia Treatment

James StockwellNovember 29, 2012

Overview

Manuscript summary Chronic Lymphoid Leukemia (CLL)

Background Genetically engineering T cells Patient treatment history Engineered T cell therapy and results Future applications

Manuscript Summary

Investigators designed a lentiviral vector to express a chimeric antigen receptor to the B Cell CD19 antigen

This vector was transformed into the T Cells of a patient with chronic lymphocytic leukemia (CLL).

These genetically engineered T Cells were propagated and injected into the patient

Despite some severe toxicity due to the amount of cells destroyed by treatment, the patient showed no signs of cancerous cells 10 months after treatment.

Porter D, Levine B, Kalos M, Bagg A, June C. Chimeric Antigen Receptor–Modified T Cells in Chronic Lymphoid Leukemia. N Engl J Med 2011; 365:725-733

Disease Overview

CLL is a common form of leukemia and is caused when B cells grow out of control

CLL is generally considered incurable, however life expectancy after diagnosis is 8 to 25 years

Common mutations Deletion of a portion of chromosome 17p.

• This mutation generally indicates significantly shorter intervals between treatments

Deletion of a portion of chromosome 11 Trisomy 12 Deletion of a portion of chromosome 13

Design of the Vector

• A lentivirus vector was used to express a chimeric antigen receptor (CAR) composed of three components:– Antigen recognition domain of an anti-CD19

antibody

– Intracellular domain of the CD3-zeta chain

– CD137 (4-1BB) signaling domain

• T cells were collected from the patient by leukapheresis, cryopreserved, and subsequently tranformed with the CAR vector

Vector Map

Patient Disease History

1996 – patient diagnosed with stage I CLL

2002 – first treatments with two cycles of rituximab plus fludarabine resulting in normalized blood counts

2006 – Patient received four cycles of the same treatment with similar results

2009 (February) – Bone marrow showed persistent infiltration with CLL. Cytogenetic analysis showed that 170 of 200 cells had p53 deletions on chromosome 17p. Treatment with one round of rituximab and bendamustine followed by three rounds of bendamustine alone showed only marginal effectiveness

Patient Treatment with CART19

In December of 2009, T cells from the patient were removed by leukaphoresis and cryopreserved

T cells were transduced with lentiviral vector Four days before infusion the patient received

chemotherapy to deplete lymphocytes. Three days later the patient showed that 40% of the bone marrow was involved in CLL

Treatment with engineered T cells was conducted over 3 consecutive days, with an increasing amount of cells infused each day.

Treatment Results

Fourteen days after the initial infusion the patient began to exhibit a fever

On day 22 the patient was diagnosed with tumor lysis syndrome and hospitalized for 4 days

By day 23 there was no evidence of CLL in the bone marrow

CLL Remission remained sustained for the 10 months between treatment and the publication of the manuscript

Bone Marrow Analysis

• Comparison of bone marrow biopsy specimens from Day 1 and Day 23 show transition from hypercellular to normal .

• Analysis of the bone marrow at 6 months shows continued remission

Progression of Tumor Lysis Syndrome

Increased levels of creatinine, LDH, and uric acid correspond to the onset of tumor lysis syndrome

Future Applications

Replacing the anti-CD19 portion of the chimeric antigen receptor with any number of proteins can create genetically engineered T cells capable with any number of applications– Pre-programmed for specific viruses such as

HIV, HSV, Hepatitis– Cancer cells expressing specific receptors

References

• Porter D, Levine B, Kalos M, Bagg A, June C. Chimeric Antigen Receptor–Modified T Cells in Chronic Lymphoid Leukemia. N Engl J Med 2011; 365:725-733

• Kalos M, Levine BL, Porter DL, et al. T cells with chimeric antigen receptors have potent antitumor effects and can establish memory in patients with advanced leukemia. Sci Transl Med 2011;3:95ra73-95ra73

• Gross G, Waks T, Eshhar Z. Expression of immunoglobulin-T-cell receptor chimeric molecules as functional receptors with antibody-type specificity. Proc Natl Acad Sci U S A 1989;86:10024-10028

• Milone MC, Fish JD, Carpenito C, et al. Chimeric receptors containing CD137 signal transduction domains mediate enhanced survival of T cells and increased antileukemic efficacy in vivo. Mol Ther 2009;17:1453-1464

• Irving BA, Weiss A. The cytoplasmic domain of the T cell receptor zeta chain is sufficient to couple to receptor-associated signal transduction pathways. Cell 1991;64:891-901