Tempus xT CDx Assay

xT CDx is a 648-gene tissue-based NGS-based test for molecular profiling of all solid malignant tumors, that also includes companion diagnostic (CDx) claims for colorectal cancer (CRC) patients.

xT CDx: FDA-approved Next Generation Sequencing CDx
  • Broad tumor profiling for SNVs, MNVs, and INDELs
  • Microsatellite instability (MSI) status designation
  • Tumor normal match
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Companion Diagnostic Indications

Tumor TypeBiomarker(s) DetectedTherapy
Colorectal cancer (CRC)KRAS wild type (absence of mutations in codons 12 or 13)Erbitux® (cetuximab)
Colorectal cancer (CRC)KRAS wild type (absence of mutations in exons 2, 3, or 4) and NRAS wild type (absence of mutations in exons 2, 3, or 4)Vectibix® (panitumumab)
xT CDx Technical Information (FDA Label)

xT CDx is a qualitative Next Generation Sequencing (NGS)-based in vitro diagnostic device intended for use in the detection of substitutions (single nucleotide variants (SNVs) and multi-nucleotide variants (MNVs)) and insertion and deletion alterations (INDELs) in 648 genes, as well as microsatellite instability (MSI) status, using DNA isolated from Formalin-Fixed Paraffin Embedded (FFPE) tumor tissue specimens, and DNA isolated from matched normal blood or saliva specimens, from previously diagnosed cancer patients with solid malignant neoplasms.The test is intended as a companion diagnostic (CDx) to identify patients who may benefit from treatment with the targeted therapies listed in the Companion Diagnostic Indications table in accordance with the approved therapeutic product labeling. Additionally, xT CDx is intended to provide tumor mutation profiling to be used by qualified health care professionals in accordance with professional guidelines in oncology for patients with previously diagnosed solid malignant neoplasms. Genomic findings other than those listed in the Companion Diagnostic Indications table are not prescriptive or conclusive for labeled use of any specific therapeutic product. xT CDx is a single-site assay performed at Tempus Labs, Inc., Chicago, IL. For the complete xT CDx label, including companion diagnostic indications and important risk information, please visit tempus.com/resources/content/document-library/tempus-xt-cdx_technical-information.


xT CDx has demonstrated concordance with orthogonal testing methods.* In precision testing, xT CDx had a positive call rate of 94.5% at a VAF ≥5%. xT CDx concordance for CDx variants was 100.00% and 99.60% based on comparison with each of two FDA-approved comparator methods.

Alteration Type Positive Percent Agreement (PPA) Negative Percent Agreement (NPA)
SNV 99.2% 100.0%
MNV 94.7% 100.0%
Insertion 96.7% 100.0%
Deletion 100.0% 100.0%
MSI** 94.0% 98.0%

*The detection of alterations by xT CDx was compared to results of an externally validated orthogonal method (NGS assay).

**The detection of MSI status by xT CDx was assessed by comparison with results obtained using a validated orthogonal method (IHC staining of MLH1, MSH2, MSH6 and PMS2).


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Tempus operates a CAP/CLIA certified laboratory offering NGS services that go beyond traditional lab partnerships, supporting biomarker discovery, clinical development, and diagnostics throughout the drug development process.

  • Whole transcriptome RNA Sequencing
  • Immunotherapy Platform1
  • Companion Diagnostic (CDx) Development
  • Organoid Modeling

1 Gene expression of key immunotherapy targets,HLA typing and loss of heterozygosity, Neoantigen predictions, T-Cell/B-Cell receptor repertoire

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  • 200+

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  • 90%

    of the top 20 pharma oncology companies*

    *based on publicly available 2020 oncology segment revenue

  • 50%+

    of all Academic Medical Centers in the US are connected to Tempus

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