Tumor Mutation Burden Study Shows Viability of In-House Testing

Tumor Mutation Burden Study Shows Viability of In-House Testing

As laboratories increasingly look to bring advanced molecular testing in-house, the results of a new retrospective clinical research study show that tumor mutation burden (TMB) assessments performed in a French hospital’s clinical laboratory using the Oncomine Tumor Mutation Load Assay provides comparable results and predictive value to a commonly ordered, commercial next-generation sequencing (NGS) panel that is available only as an outsourced test.

The study, led by Dr. Paul Hofman, head of the laboratory of clinical and experimental pathology at Pasteur Hospital in Nice, France, found a high degree of correlation in the ability of the Oncomine assay to assess predictive response in non-small cell lung cancer (NSCLC) and melanoma patients. The study will be featured as a poster (abstract 4889) during the American Association for Cancer Research (AACR) 2019 Annual Meeting in Atlanta, March 29-April 3.

TMB has emerged as a focus of clinical trials aiming to harness genomic data to more effectively identify patients who may benefit from immune checkpoint inhibitor therapy. Because these trials primarily rely on outsourced testing, which can pose logistical and cost issues, the authors sought to compare outsourced results with data derived from in-house TMB assessment.

“Results can take up to 20 days or more when a patient’s sample is sent out for TMB analysis,” said Dr. Hofman. “With the Oncomine Tumor Mutation Load Assay, we were able to secure results in as little as seven days. This shortened turnaround time enables faster access to test results and placement for patients into applicable clinical studies.”

The study assessed TMB status in randomly selected formalin-fixed paraffin-embedded (FFPE) samples from 51 NSCLC and 25 melanoma patients who were previously treated with checkpoint inhibitors. When results from samples assessed in-house were compared to outsourced sample results, correlation scores were high for both NSCLC (R2 = 0.88) and melanoma (R2 = 0.95). Prediction of a durable clinical response by receiver operating characteristic was comparable between Oncomine Tumor Mutation Load Assay (AUC = 0.70) and the outsourced test (AUC = 0.74). Additionally, analysis could not be performed in 22 percent and 8 percent of NSCLC and melanoma cases, respectively, due to stringent sample requirements of the outsourced test, according to the study.

“Among the problems with outsourcing samples are limited control over data analysis parameters, access to raw data and its ownership, and slow turnaround times,” said Luca Quagliata, global head of medical affairs for clinical NGS and oncology, Thermo Fisher Scientific. “Slow turnaround time becomes even more problematic if the test cannot return results because higher quantities of sample are required or the material is degraded. This study clearly shows that in-house testing, combined with very low sample requirements of Oncomine gene panels, including the Tumor Mutation Load Assay, help overcome these obstacles….