Antibody Screening Solutions Made Easy - 25

Antibody Screening Solutions Made Easy * To Root Out Cancer Immunotherapies Dig Deeper

of human cells. According to Dr. Freeth, human cell microarray screening is already used for
immunotherapy development by pharmaceutical companies and academic clients. "When
we started the company in 2009, we weren't going to be focused on membrane proteins,"
recalled Dr. Freeth. "We developed where the demand came."
The tool uses an array of expression vectors encoding about 4,500 full-length human plasma
membrane proteins spotted onto slides. Human cells grown over the top overexpress these
proteins on their surface. The client's molecule can then be applied to the slide and the location
of the bindings analyzed (Figure 3). The advantage of human cell microarray screening, Dr. Freeth
maintained, is that it makes use of correctly folded, full-length membrane proteins. Also, these
proteins are expressed in human cells, so they're "very physiologically relevant."
The Retrogenix tool, Dr. Freeth continued, boasts high success rates and generates few false
positives. "We've had seven publications in mostly high-impact journals," he pointed out.
This form of recognition, Dr. Freeth suggested, "really validates the technology."
The tool is being used in immunotherapy for identifying immune checkpoint interactions
(Figure 4), where "the client may have a checkpoint protein of interest, but doesn't know what the
counter receptor or binding partner is." Other applications include identifying off-target effects
that could cause toxicity in chimeric antigen receptor T-cell (CAR-T) therapies. In these therapies,
T cells are taken from patients and engineered to express a protein, the CAR. The modified T cells,
which are now able to activate an immune response, are put back into the patient.
The possibility that human cell microarray screening could be used to advance
immunotherapy while curbing toxicity, noted Dr. Freeth, is "something that's generated
a lot of interest in the last 18 months.
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| GENengnews.com

Figure 4. Identification of a specific off-target receptor
for an immune checkpoint monoclonal antibody.
Retrogenix

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