Originally published Oct. 8
Researchers from Myriad Genetics, MD Anderson Cancer Center, and elsewhere published a validation study involving the myPlan Lung Cancer Test in Clinical Cancer Research last month.
The myPlan Lung Cancer Test, developed by Myriad, gauges 31 cell cycle proliferation genes and 15 housekeeper genes and yields a score that delineates the risk that a patient with a Stage I/II lung adenocarcinoma will die within five years after surgical resection of their tumor.
In the study, researchers retrospectively tested more than 250 early-stage lung cancer patients from the Director's Consortium in the US, and another 200 samples from a Japanese database. Using quantitative PCR, researchers tested the same gene signature on around 380 formalin-fixed paraffin-embedded primary tumors.
"In univariate analysis the [myPlan Lung] score was a strong predictor of cancer specific survival in both cohorts" from the US and Japan, the researchers, led by MD Anderson's Ignacio Wistuba, reported in the paper. Multivariate analysis showed that the test score was the "dominant prognostic marker" compared to other clinical variables, such as age, stage of disease, gender, smoking status, and tumor size.
When using a quantitative PCR platform to analyze a third cohort, the test score was still significantly prognostic for survival. In these FFPE tumor samples, the test score was again the most significant predictor of outcome compared to clinical variables, and no clinical variables substantially interacted with the genetic test score.
The study authors reported that an increase in the test score was associated with a heightened risk of dying from lung cancer with a hazard ratio of 2.1. Comparatively, low test scores were "clearly associated with improved outcome," they wrote in the paper.
The researchers also analyzed samples from a cohort of 200 patients from MD Anderson in order to gauge whether the myPlan Lung Cancer Test score was predictive for treatment benefit. In this cohort, 46 patients had received adjuvant therapy. Their analysis showed that patients with high scores had significantly greater absolute treatment benefit than those with low test scores.
Given these findings, Wistuba and colleagues concluded that "the CCP score is a significant predictor of lung cancer death in early stage lung adenocarcinoma treated with surgery and may be a valuable tool in selecting patients for adjuvant treatment."
In discussing the gene panel underlying the myPlan Lung Cancer Test, the study authors highlighted that by focusing on cell cycle proliferation genes, Myriad has chosen to interrogate an important characteristic of tumor cells. When cells divide, the expression of cell cycle proliferation genes is elevated, the researchers pointed out. As such, the myPlan test score speaks to the aggressiveness of a tumor by capturing how actively the cells are dividing.
"In contrast, other prognostic profiles aggregate the highest ranked genes in survival analysis from a single training data set into a prognostic score. Inevitably, these lists contain genes that appear correlated with outcome due to statistical noise rather than true biological association," Wistuba and colleagues wrote. "Not surprisingly, many of these signatures lack robustness when applied to additional data sets."
The myPlan test, according to the study authors, may be particularly useful in determining disease prognosis in Stage I adenocarcinoma patients who are largely not given adjuvant systemic therapy after surgery, despite five-year survival rates of less than 50 percent.
"Most of these deaths are likely due to occult disease at the time of surgery and those cases would be expected to benefit from systemic therapy. Heterogeneity of patients for whom surgery was curative likely contributes to the failure to show a treatment benefit in Stage I patients," the study authors wrote. "This highlights the need for prognostic markers to identify patients with an increased risk of death not captured by current clinical evaluation tools."
Myriad is planning to launch the myPlan Lung Cancer Test later this fiscal year.
Once on the market, Myriad's myPlan test will compete with Life Technologies' Pervenio Lung RS. Life Tech's PCR-based test, launched last September, measures the expression of 14 genes and is intended to be used to gauge which early-stage non-small cell lung cancer patients with small, but aggressive tumors are at heightened risk of death (PGx Reporter 2/6/2013). Life Tech has initiated a prospective trial to investigate whether the Pervenio test score is predictive for which patients will benefit from adjuvant chemotherapy.
"The present study distinguishes itself from the 14 gene score by focusing on a gene set that is directly related to a well-established feature of tumor cells," Wistuba and colleagues wrote in the Clinical Cancer Research paper on the myPlan Lung Cancer Test. "In addition, the choice of outcome measure is more relevant to the intended clinical application. For the purpose of informing treatment decisions in resectable lung cancer, association with overall survival is less informative than prediction of lung-cancer specific survival."