Reditus ‘on the front lines in the fight against cancer

Reditus Laboratories is excited to bring on our first biomarker as we move to the forefront of malignancy and precision pathology.

The test will determine whether patients with certain cancers are good candidates for a specific cancer treatment and soon will be available at Reditus.

PD-L1 IHC 22C3 pharm Dx is the name of the test, by Agilent Dako, that Reditus Laboratories will be performing to determine whether Keytruda (pembrolizumab) could be beneficial in treating patients with cancer.

When Reditus begins the testing early this spring, it will be for patients with non-small cell lung cancer (NSCLC). By the end of 2023, Reditus hopes to use the test to also determine whether Keytruda would be beneficial for patients with triple-negative breast cancer, gastric or gastroesophageal (GEJ) adenocarcinoma, esophageal squamous cell carcinoma (ESCC), cervical cancer, urothelial carcinoma and head and neck squamous cell carcinoma (HNSCC).

Offering the PD-L1 test is another example of Reditus becoming a full-service laboratory, said Lorin Heiser, Reditus histology supervisor, and Mark Potts, Reditus histology technical supervisor and digital pathology technologist.

“We will be the only laboratory in our area offering this,” Potts said. Currently, Central Illinois oncologists send specimens to reference labs out of state and it takes typically one to two weeks to get results, Potts said. With Reditus, results will be available in 24 to 72 hours, Heiser and Potts said.

Faster turnaround time for results means that oncologists and their patients will know sooner whether they are eligible for Keytruda and treatment could begin sooner. For patients battling cancer, the sooner treatments begin, the better it is for patients’ physical, mental and emotional health.

“This allows us to expand our new tumor testing capability into multiple directions,” Potts said. “We’re proud that Reditus is on the front lines of this specific targeted therapy.”

PD-L1 (Programmed death-ligand 1) is a protein expressed in the membrane of many different types of cells, including tumor cells. PD-L1 allows tumor cells to disguise themselves as normal tissue.

“PD-L1 expression can only be seen through the use of immunohistochemical (IHC) staining,” Heiser said.

PD-L1 IHC 22C3 pharmDx is an FDA-approved, qualitative immunohistochemical assay intended to detect the PD-L1 protein in formalin-fixed, paraffin-embedded (FFPE) cancer specimens using the AutostainerLink 48 by Agilent Dako.

“With this test, if a patient is diagnosed with, for example, non-small cell lung cancer, we can perform this test on the tumor tissue and the level of PD-L1 expression is used to determine if treatment with Keytruda is indicated for the patient or not,” Heiser said.

The process begins when histology technicians take tissue from oncologists and put the tissue in a mold that results in a solid block of paraffin with the tissue inside. Histology technicians use a microtome to cut ribbons of sections of the block that are four microns thick, or the thickness of one cell. Sections are transferred to glass slides.

Slides are brought to the Dako PT Link and placed in a target retrieval solution, as shown by Heiser in the first photo. The solution exposes antigen antibody binding sites.

Then, the slides are put on the Dako AutostainerLink 48, as demonstrated by Heiser in the second photo. That facilitates antibody staining for PD-L1 expression. The third photo shows a finished slide.

In the fourth photo, Potts scans the slide to make a digital image.

In the fifth photo, the slide is digitized for on-screen analysis.

“That produces a digital image in which the tumor is digitally analyzed for presence or absence of PD-L1 expression,” Potts said.

In the sixth and seventh photos, Potts analyzes the slides. “Cells outlined in blue are negative for PD-L1 expression,” he said. “Cells outlined in red are positive for PD-L1 expression.”

The eighth photo is a pathologist’s review of the slide.

After analysis, the patient’s analysis report and slides are given to the pathologist for review and sign out. The results are then sent to the patient’s oncologist.

Oncologists who are interested in sending patient specimens to Reditus should contact Dr. Lorine LaGatta, Reditus medical director.

“We’re on the front lines in the fight against cancer,” Potts said.