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Cancer Immunotherapy Biomarkers

PD-L1, TMB, MSI, and emerging predictors of immunotherapy response

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Onkoloji department. Book Appointment →

What is Cancer Immunotherapy Biomarkers?

Cancer immunotherapy biomarkers are tumor or host features that predict response to therapies that activate the immune system, particularly immune checkpoint inhibitors targeting PD-1, PD-L1, and CTLA-4. Their use is now central to oncology decision-making.

Established biomarkers include PD-L1 expression on tumor or immune cells (measured by tumor proportion score or combined positive score), tumor mutational burden (TMB), and microsatellite instability or mismatch repair deficiency (MSI-H/dMMR). Each has approved companion diagnostics that vary by drug and tumor type.

Emerging biomarkers include gene expression signatures, T-cell inflamed phenotype, neoantigen load, gut microbiome composition, and circulating tumor DNA dynamics. Single biomarkers are imperfect, and integrated multi-biomarker approaches are being developed to improve patient selection.

Symptoms

Used to select therapy, not to detect symptoms
Tested on tumor tissue from biopsy or resection
Some biomarkers also measurable in blood (liquid biopsy)
Results guide use of pembrolizumab, nivolumab, and similar agents
Repeat testing may be needed at progression

Risk Factors

Tumor types with high PD-L1, TMB, or MSI-H show greater immunotherapy benefit
Lung, melanoma, urothelial, head and neck, MSI-H tumors are common immunotherapy candidates
Some tumors with low biomarkers still respond, and high biomarkers do not guarantee response
Pre-treatment immunosuppression or steroids may reduce immunotherapy efficacy

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • When deciding on first-line or later therapy for advanced cancer
  • Before starting an immune checkpoint inhibitor
  • When considering tumor-agnostic therapy for MSI-H or TMB-high tumors
  • When pathology reports include biomarker results that need interpretation

Treatment Methods

01
PD-L1 immunohistochemistry with drug-specific scoring
02
Tumor mutational burden by next-generation sequencing
03
Microsatellite instability and mismatch repair testing
04
Gene expression signatures and emerging multiplex assays
05
Liquid biopsy for circulating tumor DNA
06
Multidisciplinary interpretation in molecular tumor boards
07
Integration with clinical features and imaging response

Which Department to Visit?

You can visit our Onkoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.