New Method for Early Detection of Pancreatic Cancer—A Protease-Activated Nanosensor Assay

Background

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the leading causes of cancer-related deaths worldwide. Due to its nonspecific early symptoms, most patients are diagnosed at advanced stages, resulting in limited treatment options and poor prognosis. Although early detection and treatment can significantly improve patient survival rates, there is currently no early detection method approved by the U.S. Food and Drug Administration (FDA). The existing clinical biomarker CA 19-9 is primarily used to monitor disease burden, but its low positive predictive value in early detection limits its application in general population screening. Therefore, there is an urgent need to develop a highly specific, sensitive, and easy-to-use early detection method.

Proteases play a crucial role in cancer progression, particularly in tumor cell invasion and metastasis, as they degrade the extracellular matrix to facilitate cancer spread. PDAC is particularly suitable for protease-based early detection because the progression of PDAC is closely related to the activity of various secreted proteases. Based on this, researchers proposed using serum protease activity as an early detection biomarker for PDAC and developed a rapid, high-throughput detection method combined with nanotechnology, termed “PAC-MANN.”

Source of the Study

This research was conducted by a team of researchers, including Jose L. Montoya Mira, Arnaud Quentel, and others from institutions such as Oregon Health & Science University (OHSU) and Stanford University. The study was published on February 12, 2025, in the journal Science Translational Medicine. The research team combined expertise in biomedical engineering, oncology, surgery, and other fields to develop a non-invasive detection method based on protease activity, aiming to improve the early diagnosis rate of PDAC.

Research Process and Experimental Design

1. Protease Substrate Screening

The study first screened a series of protease-cleavable peptide probes using the Charge-Changing Protease (CCP) assay to distinguish PDAC patients from healthy controls and non-cancerous pancreatic disease patients. Researchers designed 12 peptide probes containing 38 unique cleavage sites and 18 shared sites. By screening serum samples from 6 PDAC patients and 6 healthy controls, 8 probes showing significant signals in PDAC samples were selected and further optimized into 6 probes for subsequent experiments.

2. Protease Activity Differentiating Cancer and Non-Cancer States

Next, the researchers applied these 6 probes to serum samples from 67 PDAC patients, 11 chronic pancreatitis patients, 21 pancreatic neoplasm patients (including Intraductal Papillary Mucinous Neoplasm, IPMN, and Pancreatic Intraepithelial Neoplasia, PanIN), and 67 healthy controls. The results showed that all probes could significantly distinguish PDAC patients from healthy controls, and most probes also displayed different protease activity in pancreatitis and neoplasm patients.

3. Identification of Specific Proteases

Using liquid chromatography-mass spectrometry (LC-MS), the researchers further identified the cleavage sites of these probes and found that the Matrix Metalloproteinase (MMP) family, particularly MMP2, exhibited significant activity in PDAC serum. Inhibition experiments confirmed that MMP2 is the primary protease in PDAC serum.

4. Development of the PAC-MANN Nanosensor Assay

Based on the above results, the researchers developed a rapid magnetic nanosensor assay called PAC-MANN. This assay uses fluorescent signals to reflect protease activity in serum, requiring only 8 microliters of serum. In a longitudinal study, researchers found that the PAC-MANN signal decreased by an average of 16% after tumor resection, indicating that this method can be used to monitor treatment response.

5. Blinded Validation Study

Finally, the researchers conducted a blinded validation study involving 356 participants, including 170 healthy controls, 110 PDAC patients, 45 pancreatitis patients, and 31 pancreatic neoplasm patients. The results showed that the PAC-MANN assay achieved 98% specificity and 73% sensitivity in distinguishing PDAC from non-cancer diseases. When combined with CA 19-9, the detection sensitivity further improved, reaching 85% for early-stage PDAC (Stage I).

Key Results and Conclusions

1. Accuracy of Protease Activity Detection

The study confirmed that serum protease activity in PDAC patients is significantly higher than in healthy controls and other non-cancer pancreatic diseases, particularly in MMP2 activity. This provides a new biomarker for early detection of PDAC.

2. Advantages of the PAC-MANN Assay

The PAC-MANN assay is rapid, high-throughput, and requires minimal sample volume. Compared to the traditional CA 19-9 assay, it shows higher sensitivity in early-stage PDAC detection. It is particularly effective for patients with low CA 19-9 expression.

3. Clinical Application Potential

PAC-MANN can be used not only for early PDAC screening but also for monitoring treatment response, as its signal changes correlate with reduced tumor burden after surgery and chemotherapy.

Research Highlights

1. Innovative Detection Method: The PAC-MANN assay combines protease activity and nanotechnology, providing a highly sensitive, low-cost tool for early PDAC detection.
   
2. Scientific Value: This study is the first to systematically identify the key protease MMP2 in PDAC serum and validate its role in cancer detection.
   
3. Clinical Application Prospects: This method is suitable for screening high-risk populations and can significantly improve the early diagnosis rate of PDAC, thereby enhancing patient outcomes.

Summary

This study developed a protease-activated nanosensor assay, PAC-MANN, offering an efficient and reliable tool for early PDAC detection. When combined with the traditional biomarker CA 19-9, it further enhances the detection capability for early-stage PDAC, demonstrating significant scientific value and clinical application potential. In the future, this method is expected to be promoted in high-risk and general populations, contributing to improving the survival rate of pancreatic cancer patients.