Advancing the Application of Immuno-Oncology to Improve Patient Care

The proliferation of new biomarkers is one of the biggest successes in the advancement of immuno-oncology (IO) to treat certain types of cancer. Biomarkers are used for the detection and classification of the disease, and certain results can help guide treatment selection.

Up till now, one certain biomarker – the PD-L1 test – has predominantly been one of the primary predictive biomarkers used to guide the treatment of multiple cancers. 

What’s important to know, and commonly misunderstood, is that there isn’t just one test for PD-L1.  There are multiple PD-L1 antibody clones that may be used for testing, and some of these are classified by the FDA as companion diagnostics while others are complementary diagnostics for drugs targeting the PD-1/PD-L1 pathway.

Because of the growing complexity behind PD-L1 testing, clinicians may order the wrong type of PD-L1 test, resulting in the use of an incorrect antibody clone or a different scoring method. As an example, a companion diagnostic PD-L1 test for non-small cell lung cancer is the 22C3 antibody clone. In contrast, the companion diagnostic PD-L1 test for triple negative metastatic breast cancer is the SP142 antibody clone. PD-L1 tests must be ordered based on the type of tumor (e.g., breast versus lung cancer) and the type of drug that may be used on the patient. This ensures that the lab performing the test uses the correct antibody clone and scoring method on the sample.

“The medical community is gaining a deeper appreciation about the complexity of PD-L1 test ordering. They are learning that different antibody clones and scoring methods are used for lung cancer versus breast cancer versus gastric cancer,” says Dr. Joseph Kim, who runs a company called Q Synthesis that specializes in quality improvement initiatives. ASCP is partnering with Dr. Kim to implement its IO education through a series of quality improvement projects in community hospitals nationwide.

“We are seeing a growing number of different kinds of cancers that are being tested for PD-L1; we have to make sure that clinicians and pathologists are ordering and performing the right tests to ensure that patients receive appropriate therapy in a timely fashion,” he says. “If, for example, the PD-L1 22C3 test is ordered for breast cancer, the lab may need to repeat the test using PD-L1 SP142 test. This may result in duplicate test results and treatment delays.”

“Updates on IO Biomarkers”—a new, online educational activity supported by Bristol Myers Squibb—aims to help clinicians and pathologists prevent or correct potential errors in PD-L1 ordering. It is the latest in the IO education projects that ASCP is developing. As part of this project, ASCP and Q Synthesis are working with two cancer centers to enhance communication between oncologists and pathologists and to improve how they are ordering and using IO biomarker tests to ensure that patients are receiving optimal care.

John Summerville, MD, laboratory director at Southside Regional Medical Center, Southern Virginia Regional Medical Center, and Southampton Memorial Hospital, is participating in one of these quality improvement projects.  

His health system is currently using a national reference lab that is able to update its testing options rapidly as new tests or new antibodies become available. The representative from the lab provides updates to Dr. Summerville when a new test becomes available. Additionally, Dr. Summerville’s team holds a weekly oncology conference on Wednesdays where they discuss cases, PD-L1 results or the need for testing to be performed.  

“Our health system is not considering offering our own PD-L1 testing, for a number of reasons. These include the rapid evolution in testing and the complexities involved, including several antibodies specific for restricted tumor sites,” Dr. Summerville said. “Also, our volume is not sufficient to perform our own testing.

“We are working on a few improvement ideas and need to make formal plans to move forward to be sure we are getting this done,” Dr. Summerville said. “We have switched testing for many non-small cell lung cancers to next generation sequencing (NGS); however, the PD-L1 testing is still being done by immunohistochemistry (IHC), in addition to the testing as a part of the NGS, and both results are reported together.”  

For more information on IO biomarkers and implementing IO in your practice, click here.