Seraseq® Blood TMB Mix Score 7

INTRODUCTION

In immuno-oncology, the goal is to enable a patient’s immune system to locate and eliminate cancerous cells. The immune system may normally protect against cancer – except when cancers manage to evade it – since immunocompromised individuals have a higher likelihood of developing cancer. Checkpoint inhibitors, which have recently improved the prognosis for a significant number of cancer patients, work by blocking inhibitory molecules such as PD-L1 and CTLA-4 that may be allowing cancers to evade the adaptive immune system. However, by taking the brakes off the immune system, the use of checkpoint inhibitors is associated with a significant risk of developing autoimmune disease. Additionally, frequently checkpoint inhibitors are not effective.

In order to maximize the safety and efficacy of checkpoint inhibitors, it is beneficial to identify patients who are likely to respond to their use. Since the adaptive immune system can detect changes to proteins, it is thought that the number of somatic mutations that lead to such changes may be correlated with efficacy. The metric of non-silent somatic mutations per megabase of coding DNA has been termed tumor mutational burden (TMB), which has shown some correlation to the efficacy of checkpoint inhibitors. Assessments of TMB are being added to many NGS assays to enable their use for patient selection in I-O clinical trials, and perhaps as companion diagnostics to these therapies. However, it is also known that TMB scores can differ significantly between assays and especially around levels that may be clinical decision points.

To improve and harmonize the measurement of TMB, we have generated and characterized tumor-normal human cell lines, fragmented and sized to ctDNA fragment sizes, and determined their Blood TMB scores by a targeted NGS panel.

The Blood TMB reference materials are formatted as ctDNA (purified mix) in three different tumor fractions.

Blood TMB Reference Standards
Reference standards are made from human lung cancer cell lines and their SNP-matched normal cell lines from peripheral blood of the same patients.

• Fragmented and blended at 0%, 0.5% and 2% tumor fractions
• Available as a purified ctDNA mix, and ready as input into WES or targeted NGS library preparation
• Blood TMB scores determined using a targeted NGS panel (TSO500 plasma)
• Manufactured in GMP-compliant and ISO 13485 certified facilities

*Adjusted bTMB Score after correcting for contributions of somatic variants in the 0% (WT) blend. Scores displayed are from a representative batch of material, please see Package Insert for description of performance expectations.

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