Compositions, methods and kits for diagnosis of lung cancer
Methods are provided for identifying biomarker proteins that exhibit differential expression in subjects with a first lung condition versus healthy subjects or subjects with a second lung condition. Also provided are compositions comprising these biomarker proteins and methods of using these biomarker proteins or panels thereof to diagnose, classify, and monitor various lung conditions. The methods and compositions provided herein may be used to diagnose or classify a subject as having lung cancer or a non-cancerous condition, and to distinguish between different types of cancer (e.g., malignant versus benign, SCLC versus NSCLC).
1. A method of determining the likelihood that a pulmonary nodule in a subject is not lung cancer, comprising:
(a) contacting a blood sample obtained from the subject with a proteolytic enzyme to produce peptide fragments from a panel of proteins present in the blood sample, wherein the panel comprises ALDOA, FRIL, LG3BP, TSP1, and COIA1;
(b) combining the produced peptide fragments from the panel from step (a) with labeled, synthetic peptide fragments which correspond to the produced peptide fragments from the panel;
(c) performing selected reaction monitoring mass spectrometry to measure the abundance of the peptide fragments from step (b);
(d) calculating a probability of lung cancer score based on the peptide fragment measurements of step (c); and
(e) ruling out lung cancer for the subject if the score in step (d) is lower than a pre-determined score.
2. The method of claim 1 , wherein said panel further comprises at least one protein selected from the group consisting of PEDF, MASP1, GELS, LUM, C163A and PTPRJ.
3. The method of claim 1 , wherein when lung cancer is ruled out, the subject does not receive a treatment protocol.
4. The method of claim 3 , wherein said treatment protocol is a pulmonary function test (PFT), pulmonary imaging, a biopsy, a surgery, a chemotherapy, a radiotherapy, or any combination thereof.
5. The method of claim 4 , where said imaging is an x-ray, a chest computed tomography (CT) scan, or a positron emission tomography (PET) scan.
6. The method of claim 1 , wherein said pulmonary nodule has a diameter of less than or equal to 3 cm.
7. The method of claim 1 , wherein said pulmonary nodule has a diameter of about 0.8 cm to 2.0 cm.
8. The method of claim 1 , wherein said score is calculated from a logistic regression model applied to the peptide fragment measurements.
9. The method of claim 1 , wherein said score is determined as P s =1/[1+exp(−α−Σ i=1 N β i *{hacek over (I)} i,s )], where is logarithmically transformed and normalized intensity of transition in said sample (s), β i is the corresponding logistic regression coefficient, α was a panel-specific constant, and N was the total number of transitions in said panel.
10. The method of claim 1 , wherein the determining the likelihood that a pulmonary nodule is not lung cancer is determined by the sensitivity, specificity, negative predictive value or positive predictive value associated with the score.
11. The method of claim 1 , wherein said score determined in step (d) has a negative predictive value (NPV) of at least about 80%.
12. The method of claim 1 , wherein the selected reaction monitoring mass spectrometry is performed using a compound that specifically binds the peptide fragments being detected.
13. The method of claim 12 , wherein the compound that specifically binds to the peptide fragments being measured is an antibody or an aptamer.
14. The method of claim 1 , wherein the subject is at risk of developing lung cancer.
15. The method of claim 1 , wherein the proteolytic enzyme is trypsin.