Multiplexed 'CAR Pooling' accelerates evaluation of anticancer cell therapy receptors

By Nick Paul Taylor, The Science Advisory Board contributing writer

November 14, 2022 -- A multiplexed approach to testing chimeric antigen receptors (CARs) could accelerate the identification of the most clinically promising cell therapies, according to a paper published November 9 in the journal Science Translational Medicine.

CAR T-cell therapies are already approved and improving outcomes in patients with some blood cancers. However, there remains scope to better the efficacy of existing products, both by improving response rates and durability in existing indications and by expanding into new settings, notably solid tumors. The use of alternative costimulatory domains is one possible way to improve outcomes.

Second-generation CARs contain 4-1BB or CD28 intracellular domains to support immune activation but it is unclear if they are the best options in all settings. To address the uncertainty, researchers at the University of California, San Francisco developed a repetitive stimulation assay to "mimic the protracted stress and exhaustion of chronic antigen exposure on T cells in difficult-to-eliminate tumors."

The scientists used the assay to evaluate a signaling domain library of 40 inhibitory and stimulatory domains from innate and adaptive immune cells. Performing a suite of pooled assays in primary human CD4 or CD8 T cells containing the CAR library generated data on the CAR T cell costimulation landscape.

Using the approach, which the team dubbed "CAR Pooling," the scientists identified B cell-activating factor receptor (BAFF-R) as a potent costimulatory domain from the tumor necrosis factor (TNF) receptor family that enhanced T-cell proliferation and cytotoxicity in vitro. The discovery that domains primarily associated with the B cell lineage enhanced T cells was a surprise enabled by the speed of CAR Pooling.

"Our method makes the process of testing new receptor-based therapeutics much faster. This not only allows the researchers to save time, but also to explore designs they wouldn't have been able to test individually. We would never have chosen to test BAFF-R if we weren't utilizing CAR Pooling," co-first author Camillia Azimi said in a statement.

The researchers validated BAFF-R in a xenotransplant mouse model of multiple myeloma. Replacing the 4-1BB intracellular signaling domain with BAFF-R in a B cell maturation antigen (BCMA)–specific CAR improved survival in the mouse model. BCMA is the target of two Food and Drug Administration (FDA)-approved CAR T-cell therapies.

Having developed CAR Pooling, the researchers plan to use the approach to test more receptors. The team could use the approach to find the best receptors for different settings, recognizing that the optimal approach may differ between glioblastoma and melanoma, for example.

New type of CAR T cells provide on-off switch to improve cell therapy safety, efficiency
Researchers at Boston University have created on and off switches for chimeric antigen receptor (CAR) T cells, enabling them to control the activity of...
Soluble BCMA acts as decoy receptor to curb blood cancers in mice: study
A soluble version of B-cell maturation antigen (BCMA), a B-cell surface receptor, may act as a decoy to stop two proteins driving the growth of blood...
CAR-NK cells hold promise for solid tumors
A new cancer immunotherapy that leverages the ability of natural killer (NK) cells to discriminate between cancer and normal cells has shown promise in...

Copyright © 2022 scienceboard.net


Conferences
Glasgow International Health Festival
January 25-26, 2023
Glasgow
Connect
Science Advisory Board on LinkedIn
Science Advisory Board on Facebook
Science Advisory Board on Twitter