CAR-T cells can recognize antigens and induced cytotoxic activity to kill tumor cells and their efficacy is closely related to the differences in T cell function. Less differentiated T cells, for example, naive T cells (Tn), T memory stem cells (Tscm) and central memory T cells (Tcm) have more anti-tumor activity than T effector memory cells (Tem) and effector T cells (Teff) -derived CAR-T cells. Studies have shown that different phenotypes of T cells can be obtained by using combination of cytokines. Therefore, selecting appropriate cytokines or combination of cytokines to culture T cells is a feasible method to increase the efficacy of CAR-T cells.

IL-15 can increase CD8+ T memory cell function and antitumor activity

When murine lymphocyte cells were cultured and expanded in vitro with media containing IL-2 and IL-15 respectively, the results showed that T cells cultured with IL-2 mainly differentiated into T effector memory cells (Tem), while the cells cultured with IL-15 mainly differentiated into central memory T cells (Tcm). In terms of function, IL-15 can prompt T cells to secrete more anti-tumor factors such as IFN-γ, TNF-α, IL-10, IL-2, etc^[1].

IL-15 prompts T cells to secrete more antitumor factors
Proc Natl Acad Sci U S A. 2004 Feb 17; 101(7): 1969–1974.

IL-7+15 can increase T memory cell function and antitumor activity of CAR-T cells

Compared with IL-2, IL-7+15 has better expansion effect on CD19-CAR-CD8+ T cells, and helps to retain the expression of CD45RA and CCR7. The effector function and anti-tumor activity is also stronger after antigen-specific stimulation of CAR-T cells, and accompanied by a significant increase in IFN-γ secretion ^[2]

CAR-T cells cultured with IL7+15 have stronger antitumor activity
Blood. 2014 Jun 12; 123(24): 3750–3759.

IL-7+15 expanded CAR-T cells have higher in vivo survival rate

In NSG mice engrafted with a high tumor burden of Raji cells and infused with CAR-T cells we consistently observed that CAR-T cells exposed to IL-2 had a short half-life and disappeared by day 3 post- infusion. In sharp contrast, IL-7 and IL-15 expanded CAR-T cells were detectable for more than 14 days after infusion and accumulated in the spinal cord where tumor cells were primarily localized. Mice infused with IL-7 and IL-15 expanded CAR-T cells had significant delays in disease/paralysis progression.

CAR-T cultured with IL-7+15 has long survival time and strong antitumor activity
Blood. 2014 Jun 12; 123(24): 3750–3759.

IL-15+21 can increase T memory cell function and antitumor activity of CAR-T cells.

In a study of CAIX CAR expanded using IL2, IL7 + 15, or IL15 + 21, respectively. Results showed that T cells proliferated best with IL-15+21, which promoted stronger outgrowth of CD8 + T cells, and could induce activated CAR -T kill-activity.

IL15+21 has the better effect of expansion T cells and enhance the ability of killing tumor
Hum Gene Ther Methods. 2014 Dec 1; 25(6): 345–357.

In conclusion, cytokines such as IL-7, IL-15, IL-21, and IL-2 play an indispensable role in the development of cell therapy. These cytokines are important raw materials of cell therapy and closely relate to clinical therapeutic effect. FDA and Chinese Pharmacopoeia have relevant regulations about the use of these key materials. The FDA CMC recommends using FDA-approved or clinical-grade materials. For Chinese Pharmacopoeia regulations, priority should be given to the use of low-risk materials such as pharmaceutical grade, GMP grade materials as opposed to non-GMP grade materials. Since most of the raw materials are not available in pharmaceutical grade, GMP grade is the first choice for more pharmaceutical companies, but it is worth thinking about how to ensure that it is a real GMP grade raw material.

ACROBiosystems is committed to the development of high-quality reagents that are used in the clinical stage of immune cell therapy. Based on the GMP-grade quality management system platform, combined with the production specifications of cell therapy, we have successfully developed a series of high-quality GMP-grade cytokines such as IL-15, IL-7, IL-21 to support your cell therapy development process.

ACROBiosystems GMP Quality Management System

Designed under ISO 9001:2015 and ISO 13485:2016

The production plant has a drug production license

Pharmaceutical class B+A clean room and automatic filling equipment

Aseptic technique and secondary sterile filtration

Animal-Free materials

Qualified and well-trained personnel

Raw materials and packing materials are registered

Quality-related documents reviewed and approved by QA

Fully batch production and control records

Equipment maintenance and calibration

Validation of analytical procedures

Comprehensive regulatory support files

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Regulatory Support File (RSF)

Automatic separation and purification system

Automatic filling equipment

Verification Data

GMP IL-7/IL15 activity is calibrated against the WHO standard, and can efficiently expand T cells

GMP Human IL-7 (Cat. No. GMP-L07H24) stimulates proliferation of PHA-P-activated human peripheral blood mononuclear cell (PBMC). The EC50 for this effect is 3.821 ng/mL, corresponding to a specific activity of > 1.0 ⅹ10^8 IU/mg, which is calibrated against human IL-7 WHO International Standard (NIBSC code: 90/530) (QC tested).

Protocol

GMP Human IL-15 (Cat. No. GMP-L15H13) stimulates proliferation of CTLL-2 cells. The EC50 for this effect is 1.004 ng/mL, corresponding to a specific activity of > 0.8ⅹ10^7 IU/mg, which is calibrated against human IL- 15 WHO International Standard (NIBSC code: 95/554) (QC tested).

Protocol

GMP Human IL-15 (GMP-L15H13) has high batch-to-batch consistency

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References

[1] Klebanoff CA, Finkelstein SE, Surman DR, et al. IL-15 enhances the in vivo antitumor activity of tumor-reactive CD8+ T cells. Proc Natl Acad Sci U S A. 2004;101(7):1969-1974. doi:10.1073/pnas.0307298101

[2] Xu Y, Zhang M, Ramos CA, et al. Closely related T-memory stem cells correlate with in vivo expansion of CAR.CD19-T cells and are preserved by IL-7 and IL-15. Blood. 2014;123(24):3750-3759. doi:10.1182/blood-2014-01-552174

[3] Lamers CH, van Steenbergen-Langeveld S, van Brakel M, et al. T cell receptor-engineered T cells to treat solid tumors: T cell processing toward optimal T cell fitness. Hum Gene Ther Methods. 2014;25(6):345-357. doi:10.1089/hgtb.2014.051