therapy despite their poor status, researchers reported.
Positive findings on the test, known as DetermaIO, were “associated with efficacy of response to ICI therapy in advanced NSCLC patients,” Matthew G. Varga, PhD, manager of scientific affairs at Oncocyte, said in an interview. “These data suggest that DetermaIO warrants further study in poor performance status patients as it has the potential to identify likely responders to ICI therapy.”
Oncocyte, which is developing the test, presented the findings in a poster at the annual meeting of the Society for Immunotherapy of Cancer.
According to Dr. Varga, “DetermaIO is an RT-qPCR test that can be applied to FFPE [formalin-fixed, paraffin-embedded] tissue specimens to quantify the relative gene expression of 27 genes and subsequently applies our proprietary algorithm to generate an IO score based on the gene expression profile. The DetermaIO score is a binary IO+ or IO– score, representing likely responder or nonresponder, respectively.”
The test was originally developed for triple negative breast cancer, Dr. Varga said, and it’s been validated in non–small cell lung cancer, metastatic urothelial carcinoma, and metastatic colorectal carcinoma.
For the study, the researchers retrospectively tracked associations between DetermaIO score and either progression-free survival (PFS) or overall survival (OS) in 147 patients in Canada with NSCLC who were treated with ICI monotherapy. All had programmed death-ligand 1 (PD-L1) ≥ 50%.
Overall, outcomes were poor: The median survival was 12.7 months, and median PFS was 7.0 months. These outcomes were even worse in those who underwent therapy as a second- line treatment: The median survival was 9.7 months, and median PFS was 4.4 months.
“DetermaIO was significantly associated with PFS at hazard ratio [HR] = 0.55, 95% [confidence interval] CI, 0.32-0.94, P = .028. In our analyses, a hazard ratio less than 1 suggests lower risk – i.e, that DetermaIO+ patients have lower risk of an event – death or progression – compared to a DetermaIO– patient,” Dr. Varga said. “The association for overall survival was not statistically significant, but it was suggestive of clinically meaningful benefit.”
He added that “we could identify likely responders from nonresponders, suggesting that the DetermaIO score adds both independent and incremental data to the existing gold standard biomarker. The objective response rate for all first-line patients – n = 78 – was 44.9%. Twenty-two DetermaIO– tumors had a 23% response rate (5 partial responses) whereas of the 56 DetermaIO+ patients, the response rate was 54% (2 complete response and 28 partial responses).”
A score on the test, he said, was not associated with OS or PFS in patients who received second-line or later treatment.
The study was not designed to evaluate the predictive power of the test. “For a biomarker to be defined as predictive requires a formal test of interaction between a treatment group (ICI monotherapy, for example) vs. a control group (chemo-only or other regimen),” Dr. Varga explained. “In our analysis, there was no group of patients who did not receive ICI monotherapy. Thus a test for interaction and a predictive claim cannot be made.”
The test is available for at no cost via an early access program, Dr. Varga said, and Oncocyte is getting ready to seek Medicare coverage. The ultimate cost of the test, he said, is unknown.
Oncocyte funded this study. Dr. Varga and several other study authors are Oncocyte employees, and another author is a paid consultant to the company.