CAR-T Cell Production Using the Clinimacs^® Prodigy System

Introduction

Chimeric Antigen Receptor T (CAR-T) cells redirected against tumor antigens are an effective therapy for B cell malignancies refractory to standard treatments. The production of patient-derived CAR-T cells is complicated and thus far is limited to institutions with experienced researchers and expensive GMP facilities, or to those invited to participate in industry sponsored clinical trials. The outsourcing of CAR T-cell production to third party vendors where cells are collected locally, shipped to the manufacturing site, and then sent back to the institution for infusion can be both costly and timely. As a result, CAR-T cell therapies are not widely available and only patients with means to travel to participating sites and with disease that is stable enough to wait the 2-3 months needed to collect and produce CAR-T cells are eligible for these treatments.

At our instution we have explored the use of the CliniMACS^® Prodigy (Miltenyi Biotec, Inc) for the production of CAR-T cells. The CliniMACS^® Prodigy is an automated device that can be used for cell processing within a closed GMP-compliant system. Using the CAR-T system that includes software, specialized tubing sets, and optimized reagents we demonstrate the processing of CAR-T cells, with similar characteristics to those produced in a more traditional manner, in a closed system that is suitable for clinical use without the need for a clean room manufacturing facility.

Methods

In collaboration with Miltenyi Biotec, we obtained pre-release and final versions of the CliniMACS^® Prodigy TCT process software and the TS520 tubing set that allows for cell enrichment, transduction, wash steps, and expansion all within a single set. Starting material was MNC cells recovered from a leukoreduction system chamber (LRSC) used during platelet collections by apheresis. Materials and reagents included MACS CD4 & CD8 reagents for cell enrichment, TransAct CD3/CD28 reagent for activation, lentiviral CD8 TM-41BB-CD3 zeta-cfrag vectors with either CD19 or CD20/CD19 Ab chains (Lentigen Technology Inc., A Miltenyi Biotec Company), TexMACS culture medium-3% HS-IL2, and PBS/EDTA buffer for wash steps. For two experiments, cells after CD4/CD8 enrichment were activated and transduced in 6 well plates and expanded after day 5 in G-Rex gas permerable devices. Total time for line preparation was 14±1 days. Transduction was measured by Protein L expression using flow cytometry. Line function was measured in 51Cr Release assays and by intracellular cytokine production.

Results

Starting cells were washed free of platelets and enriched for CD4+ and CD8+ cells using the Prodigy device. We achieved consistent high levels purity (99±3%) and good recovery (51.0±6%) of CD4+ and CD8+ cells (N=5). The enriched cells were 90±12% CD3+. The approximately 10% non-T cells were CD8+ NK cells, that were largely eliminated after cell activation through CD3/CD28 and expansion. A controlled number of 1 x 10E8 cells enriched for CD4+ plus CD8+ cells were retained in the Prodigy and in 2 experiments a smaller fraction of cells was cultured in 6 well plates for activation and initial transduction. Three preparations were conducted in the Prodigy, one using the CD19 vector and two with the CD19+CD20 vector. Transduction efficiency ranged from 21%-46% of total T cells with a modest preference for CD4+ cells. Expansion ranged from 26-40 fold and all of the lines recognized CD19 and/or CD20 targets based on 51Cr release assays or IFN-gamma production. The paired lines generated on the Prodigy versus manual methods showed similar overall transduction, phenotype, and function as shown in the figure for one representative preparation.

Conclusions

CAR-T cells generated in the Prodigy were similar to those prepared using manual methods in both phenotype and function. This process is timely, requiring 14 days for generation of the target CAR-T cell dose, and does not require outsourcing to third party vendors. All of the Prodigy CAR-T cell preparations met criteria for clinical use in our upcoming Phase I clinical trial. The ability to produce CAR-T cells suitable for clinical use in an entirely closed system without the need for a clean room should allow more centers and patients access to this novel form of immunotherapy.

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