Development of CAR-T Cells for Drug Delivery Systems

CAR-T cells are living drugs with proliferative capacity and unique cellular kinetic characteristics. Traditional pharmacokinetic parameters and pharmacokinetic models are not applicable to CAR-T cells, influenced by factors such as antigen-dependent amplification, infusion product heterogeneity, and tumor microenvironment. CD Formulation offers the development of CAR-T cells for drug delivery. We offer hydrogel-based CAR-T cell delivery platforms designed to enhance local T cell expansion after in vivo administration by co-encapsulating immunostimulatory signals with CAR-T cells.

What are CAR-T Cells?

CAR-T cell therapy begins by extracting T cells from a patient's own blood, cultured in vitro and genetically engineered to transfer genetic material with specific antigen recognition structural domains and T cell activation signals into T cells, which are then purified, amplified and fed back into the body, capable of expressing artificial receptors that specifically recognize specific tumor target antigens and thus kill tumor cells. To make CAR-T cells, the collected T cells are genetically processed in the laboratory to generate specific receptors called chimeric antigen receptors (CARs). These CARs enable T cells to recognize antigens (or markers) on the surface of cancer cells and activate the ability of T cells to kill these cancer cells CAR-T cells are delivered primarily by intravenous infusion and are highly effective in treating blood cancers because the T cells can easily detect and eradicate cancer cells. Biomaterial scaffolds for local delivery of CAR-T cells and cytokines require that cytokines be specially formulated in the biomaterial in microsphere or insoluble form to prevent rapid release.

Development of CAR-T Cells

CD Formulation offers biomaterial platforms designed for CAR-T cell-based delivery services.

• Design of polymeric nanoparticle (PNP) hydrogels for CAR-T cell delivery platforms

The dynamic polymer network within PNP hydrogels can be designed to be small enough to provide prolonged protein retention while still being able to permeate immune cells. As a result, our team can perform designs that co-encapsulate immunostimulatory signals with CAR-T cells, which will enhance local T-cell expansion after in vivo administration. The self-assembled, entropy-driven cross-linking within these PNP hydrogels produces temperature-invariant mechanical properties, and their physical cross-linking can be easily injected through a needle or catheter.

• CAR-T cell proliferation studies

Relative signals are measured after 2 days of cell culture by adding the relevant reagents to each well, mixing, standing, and then reading the luminescence signal with an integration time of 1 second. Relative growth was calculated using a calibration curve generated by testing various known cell loads in the hydrogel.

• CAR-T cell hydrogel release studies

CAR-T cells are loaded into PNP hydrogel preparations and the hydrogels are injected into the transwell inserts. Transwells are gently placed in a 24-well plate with medium gently added underneath. Incubate the experiment according to standard culture conditions. At each time point, the medium is gently removed, the cells within the medium are counted, and the transwell wells are placed into new wells containing fresh medium. At the end of the assay, the contents of the transwell are diluted, cells are counted, and viability is recorded.

• CAR-T cell kinetic characteristics

After intravenous infusion, CAR-T cells are distributed to various tissues, resulting in a temporary decrease in circulating CAR-T cell density; CAR-T cells proliferate and expand to several orders of magnitude and reach peak concentrations (C_max) within 2-3 weeks after infusion; finally, CAR-T cells undergo activation-induced death and the number of CAR-T cells decreases, while a small percentage of CAR-T cells are maintained for several months to years of memory cell phenotype to produce sustained antitumor activity.