Sensitive Test to Detect Efzofitimod’s Target Developed
Test could show how NRP2 production relates to pulmonary sarcoidosis, researchers say
Researchers have developed a highly selective and sensitive test to detect neuropilin-2 (NRP2), the therapeutic protein target of efzofitimod, an experimental treatment for pulmonary sarcoidosis by aTyr Pharma.
Using immunohistochemical (IHC) detection methods, the new antibody-based tool — created in collaboration with Michael Muders, at the University Hospital Bonn, Germany — will shed light on how NRP2 expression (production) relates to pulmonary sarcoidosis and potentially could be a biomarker to classify and monitor patients.
“This unique antibody developed by the aTyr research team and optimized for IHC in collaboration with the Muders lab provides a highly specific and sensitive detection method for NRP2 that will facilitate characterization of the target receptor for efzofitimod in patient tissue samples,” Leslie Nangle, PhD, vice president at aTyr Pharma, said in a press release. “This may provide an extremely useful clinical tool, potentially aiding in patient selection or stratification, thereby enabling thoughtful understanding of NRP2 expression as it relates to relevant disease states.”
Pulmonary sarcoidosis is marked by the formation of granulomas, small clumps of inflammatory cells that trigger inflammation, in the lungs. During inflammation, NRP2 levels are elevated in immune cells, including those in granulomas. By modulating NRP2 activity, efzofitimod seeks to dampen immune responses associated with lung inflammation.
Data from a now complete Phase 1/2 study (NCT03824392) demonstrated that efzofitimod was generally well tolerated and improved lung function compared to a placebo.
Recently, aTyr announced plans for EFZO-FIT, a Phase 3 clinical trial (NCT05415137) that aims to enroll 264 adults with pulmonary sarcoidosis, ages 18–75. The study’s goal is to determine whether efzofitimod can reduce the use of glucocorticoids, which can cause harmful side effects over the long term.
IHC detection is widely used to identify and localize specific proteins in patient tissue samples. It relies on creating an antibody that’s highly selective towards its protein target, which can then be stained and visualized.
However, the availability of reagents for IHC detection of the NRP2 protein in tissues is limited and commercially available anti-NRP2 antibodies tend to show low selectivity, leading to proteins other than NRP2 being stained.
aTyr presented the new test’s development in a poster at the European Respiratory Society (ERS) International Congress 2022. The poster, “A novel neuropilin-2 (NRP2) antibody for immunohistochemical staining of patient tissue samples,” can also be viewed on the company’s website.
The research team first generated a panel of anti-NRP2 antibodies by immunizing mice. One antibody, dubbed aNRP2-36v2, was chosen for further testing due to its high selectivity and strong NRP2 binding.
Tests confirmed aNRP2-36v2 bound to human NRP2, recognized two forms of the protein called NRP2a and NRP2b, and did not cross-react with human NRP1 or NRP2 from mice, rats, or monkeys. The team also identified the specific location where the antibody binds to NRP2.
Using IHC detection, aNRP2-36v2 showed strong and specific staining of cells that produce NRP2, but not to those without the protein.
A commercial anti-NRP2 antibody was also less specific than aNRP2-36v2 and a lack of NRP1 binding was confirmed by a lack of staining of cells producing this protein. Specificity was demonstrated by aNRP2-36v2 staining being absent after adding excess NRP2 protein or reducing NRP2 expression in tissues.
Finally, IHC staining of sarcoidosis patient tissues from skin and lung biopsies showed high levels of NRP2 production within granulomas, but not in the surrounding tissue. Tests also showed granulomas primarily composed of immune macrophage cells also express NRP2. This antibody was suitable for co-staining with other antibodies targeting different proteins.
“We are using this antibody to further understand the biology of key immune cells that make up these sarcoid granuloma structures and hope it may lead to identification of biomarkers for sarcoidosis and other indications in which NRP2 plays a role,” the researchers concluded.
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