New blood test could simplify cancer treatment decisions for lung cancer patients

Immune Checkpoint Inhibitors: A Game Changer in Lung Cancer Treatment

Lung cancer is a leading cause of cancer-related deaths worldwide, but recent advancements in treatment have given patients new hope. One such advancement is the use of immune checkpoint inhibitors (ICIs). These drugs work by targeting proteins like PD-L1 and its receptor, PD-1, which cancer cells use to evade the immune system. By blocking these proteins, ICIs help the immune system recognize and attack cancer cells, significantly improving survival rates for patients with non-small-cell lung cancer (NSCLC).

The Challenge of Assessing PD-L1 Expression

To determine which patients will benefit most from ICIs, doctors need to measure the level of PD-L1 expression in tumor cells. Currently, this requires taking a tissue sample from the tumor through a biopsy or fine needle aspiration. However, obtaining enough tissue for accurate testing can be difficult, and not all patients are able to undergo these procedures.

A Promising Solution: Liquid Biopsies

A new study by researchers at the University of Queensland suggests that liquid biopsies could offer a simpler and less invasive way to measure PD-L1 levels. Liquid biopsies involve analyzing blood samples, which is much easier than traditional tissue biopsies. The study explored the use of a mesoporous gold sensor (MGS) assay to measure the phosphorylation status of PD-L1 in extracellular vesicles (EVs) found in the plasma of NSCLC patients.

What Are Extracellular Vesicles?

Extracellular vesicles are tiny particles released by cells into the blood. They can carry proteins, such as PD-L1, from the cells they originate from, including cancer cells. By examining these vesicles, scientists can gather information about the tumor without needing a direct tissue sample.

The Study’s Key Findings

The study involved two groups of NSCLC patients and found a strong correlation between the levels of phosphorylated PD-L1 in EVs (EV pPD-L1) in the blood and the PD-L1 levels in tumor tissues. This correlation was consistent regardless of the stage of the cancer. Notably, plasma levels of PD-L1 alone did not show this correlation, highlighting the importance of measuring EV pPD-L1.

  • Detection Sensitivity: The MGS assay used in the study provided high sensitivity in detecting PD-L1 levels due to its advanced design, which includes a large surface area and superior electro-conductive properties.
  • Correlation with Tumor PD-L1: The study found a nearly perfect linear correlation (Pearson’s r = 0.99) between EV pPD-L1 levels in plasma and tumor PD-L1 levels.
  • Patient Selection: About 64% of patients showed detectable levels of EV pPD-L1, suggesting that this method could be widely applicable for selecting patients for ICI therapy.

Advantages of the New Method

The most significant advantage of this new testing method is its rapid turnaround time—less than 24 hours. This quick processing means that it could be easily integrated into routine diagnostic evaluations, helping doctors make faster and more accurate decisions about ICI therapy for their patients.

Future Implications

This study is a promising step towards making cancer treatment more accessible and personalized. The use of liquid biopsies could reduce the need for invasive procedures, making it easier for patients to get the treatment they need. Furthermore, the ability to quickly and accurately measure PD-L1 levels could lead to better outcomes for patients with NSCLC by ensuring they receive the most appropriate therapy.

As the study authors suggest, the next step is to test this method in larger, randomized controlled trials to confirm its effectiveness and reliability. If successful, this approach could revolutionize how we assess and treat lung cancer, providing a less invasive, quicker, and more accurate method for guiding treatment decisions.

Shanmugasundaram KB, Ahmed E, Miao X, Kulasinghe A, Fletcher JA, Monkman J, Mainwaring P, Masud MK, Park H, Hossain MSA, Yamauchi Y, Sina AAI, O’Byrne K, Wuethrich A, Trau M. (2024) A Mesoporous Gold Sensor Unveils Phospho PD-L1 in Extracellular Vesicles as a Proxy for PD-L1 Expression in Lung Cancer Tissue. ACS Sens [Epub ahead of print]. [abstract]

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