Tempus xF/xF+ Liquid Biopsy

Tempus xF is a 105 gene liquid biopsy circulating tumor DNA (ctDNA) seq panel that detects oncogenic drivers and resistance mutations, and identifies single nucleotide variants (SNVs), insertions and deletions (INDELs), copy number gains (CNGs) and gene rearrangements, all of which help inform precision medicine decisions.

Tempus xF+ is an expanded liquid biopsy panel consisting of 523 genes that detects pathogenic alterations in ctDNA and identifies SNVs, INDELs, CNGs and gene rearrangements.


Data suggests that non-overlapping actionable gene alterations and resistance mechanisms may be detected using complementary tissue and liquid biopsy testing approaches.1,2,3  

  • 9% of patients with actionable variants in a metastatic pan-cancer analysis had unique actionable alterations found in liquid biopsy that were not detected in solid tumor alone.4


 xF / xF+ can also monitor common resistance mechanisms arising from frontline targeted therapies in several cancer types, including lung, breast, ovarian, and colorectal cancers. 

  • EGFR & ALK resistance mutations in lung cancer 5,6
  • ESR1 mutations in breast cancer 7
  • BRCA1/2 reversion alterations in ovarian and breast cancer 8
  • Anti-EGFR resistance mechanisms in colorectal cancer 9


xF results are typically expected within 7 days of specimen retrieval

xF+ results are typically expected within 10 days of specimen retrieval

Ordering Flexibility

Tempus offers a variety of options to customize molecular profiling for patients.

  • xF Liquid Biopsy may be ordered as a standalone test or in combination with xT Solid Tumor
  • Longitudinal testing using xF / xF+ Liquid Biopsy
  • Automatic conversion option from xT to xF in the event of insufficient tumor tissue
  • Streamlined ordering process through Tempus Hub, paper requisition, or directly from your EHR
Access Tempus Hub
image description


view all resources

    xF Validation


    xF+ Validation


    Specimen Guidelines


xF Performance Specifications

Chicago Lab

Variant Class VAF Sensitivity Specificity LOD
Single Nucleotide Variants (SNVs) ≥0.25% 98.5% >99.9% 0.25%
0.10% 66.7%
Insertions and Deletions (INDELs) ≥0.5% 98.5% >99.9% 0.50%
0.25% 75.0%
Copy Number Gains (CNGs) ≥0.5% >99.9% 96.2% 0.50%
0.50% >99.9%
Rearrangements ≥1% 94.40% >99.9% 1%
0.50% 75.00%
Microsatellite Instability High (MSI-H) Status N/A 31.30% >99.9% N/A
Blood Tumor Mutational Burden (bTMB) N/A 39.00% 95.30% N/A

Durham Lab

Variant Class VAF Sensitivity Specificity Limit of Detection
Single Nucleotide Variants (SNVs) ≥0.25% 99.6% >99.9% 0.25%
0.10% 75.6%
Insertions and Deletions (INDELs) ≥0.5% 99.5% >99.9% 0.50%
0.25% 91.1%
Copy Number Gains (CNGs) ≥2.5% >99.9% >99.9% 2.50%
1% 66.70%
Rearrangements ≥1% >99.9% 99.20% 1%
0.50% 98.20%
Microsatellite Instability High (MSI-H) Status N/A 85.70% >99.9% N/A
bTMB will only be reported for samples being run in the Tempus Chicago, Illinois laboratory.

xF+ Performance Specifications

Chicago Lab

Variant Class VAF Sensitivity Specificity LOD
SNVs (Enhanced) ≥0.25% >99.9% >99.9% 0.25%
SNVs (Non Enhanced) ≥1% >99.9% >99.9% 1%
INDELs (Enhanced) ≥0.5% 98.00% >99.9% 0.50%
INDELs (Non Enhanced) ≥2% 87.50% >99.9% 2%
CNGs ≥1% >99.9% 92.00% 1%
Rearrangements ≥1% 96.80% >99.9% 1%
MSI-H Status - 90.00% >99.9% -
bTMB - 78.50% >99.9% -
Financial Assistance

We help provide access to our tests for all patients in financial need

Approval of the financial assistance application is based on your household income and takes into account all life circumstances. Once a financial assistance application is submitted either online or over the phone, you will receive a decision at the time of submission. 

  • Step 1

    Apply for financial assistance online at

  • Step 2

    If approved, you will know immediately about the maximum out-of-pocket cost of your testing.

  • Step 3

    Please contact if you are concerned about out-of-pocket costs and would like to discuss your options.

    All U.S.-based patients are eligible to apply for financial assistance regardless of insurance status. For uninsured and international patients, we offer a self-pay option. If you have any questions, please email

  1. Chae YK, Davis AA, Carneiro BA, et al. Concordance between genomic alterations assessed by next-generation sequencing in tumor tissue or circulating cell-free DNA. Oncotarget. 2016;7(40):65364-65373.
  2. Aggarwal C, Thompson JC, Black TA, et al. Clinical implications of plasma-based genotyping with the delivery of personalized therapy in metastatic non-small cell lung cancer. JAMA Oncol. 2019;5(2):173-180.
  3. Parikh AR, Leshchiner I, Elagina L, et al. Liquid versus tissue biopsy for detecting acquired resistance and tumor heterogeneity in gastrointestinal cancers. Nat Med. 2019;25(9):1415-1421.
  4. Based on a retrospective study involving a cohort of randomly selected patients with breast, colorectal, lung, and prostate cancer. Iams, WT, MacKay M, Ben-Shachar R, et al. Concurrent tissue and circulating tumor DNA molecular profiling to detect guideline-based targeted mutations in a multicancer cohort. JAMA Netw Open. 2024. Clinically actionable variants were identified using indication-matched recommendations from NCCN guidelines.
  5. Jenkins S, Yang JCH, Ramalingam SS, et al. Plasma ctDNA analysis for detection of the EGFR T790M mutation in patients with advanced non-small cell lung cancer. J Thorac Oncol. 2017;12(7):1061-1070.
  6. Horn L, Whisenant JG, Wakelee H, et al. Monitoring therapeutic response and resistance: analysis of circulating tumor DNA in patients With ALK+ lung cancer. J Thorac Oncol. 2019 Nov;14(11):1901-1911.
  7. Bidard FC, Hardy-Bessard AC, Dalenc F, et al. Switch to fulvestrant and palbociclib versus no switch in advanced breast cancer with rising ESR1 mutation during aromatase inhibitor and palbociclib therapy (PADA-1): a randomized, open-label, multicentre, phase 3 trial. Lancet Oncol. 2022;23(11):1367-1377.
  8. Lin KK, Harrell MI, Oza AM, et al. BRCA reversion mutations in circulating tumor DNA predict primary and acquired resistance to the PARP inhibitor rucaparib in high-grade ovarian carcinoma. Cancer Discov. 2019 Feb;9(2):210-219.
  9. Sartore-Bianchi A, Pietrantonio F, Lonardi S, et al. Circulating tumor DNA to guide rechallenge with panitumumab in metastatic colorectal cancer: the phase 2 CHRONOS trial. Nat Med. 2022;28(8):1612-1618.

† “Clinically actionable variants” are assessed as part of the Tempus report generation pipeline.

This is data-driven precision medicine

This is the future of healthcare.