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MO05 - Prognostic and Predictive Biomarkers II (ID 95)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Medical Oncology
- Presentations: 1
MO05.09 - Activation of the classical complement pathway: a novel biomarker for the early diagnosis and prognosis of lung cancer (ID 964)
16:15 - 17:45 | Author(s): D. Ajona
Numerous diagnostic and prognostic molecular markers have been proposed for lung cancer. However, genetic heterogeneity has limited the success of these initiatives. This limitation may be overcome by the use of biomarkers related to the host response to cancer. In this study we tested the capacity of lung cancer cells to activate the complement system and evaluated the diagnostic performance of complement-activation fragments. We demonstrate for the first time that lung cancer cells efficiently activate the classical complement pathway and that fragments of complement activation are of value for detection and prognosis of lung cancer at a very early stage.
We first assessed complement activation in bronchial epithelial and lung cancer cell lines. C4d, a degradation product of complement activation, was determined in 90 primary lung tumors; in bronchoalveolar lavage supernatants from 50 patients with lung cancer and 22 non-malignant respiratory diseases; and in plasma samples from different cohorts, including: advanced (n=133) and early (n=84) non-small cell lung cancer patients, subjects with inflammatory lung diseases (n=133) and asymptomatic individuals enrolled in a lung cancer CT-screening program (n=190; 32 of them with lung cancer).
Lung cancer cells treated with normal human serum activated complement and deposited C3 more efficiently than non-malignant bronchial epithelial cells. Incubation of cells with different buffer conditions, complement depleted sera and complement inhibitors showed that lung cancer cells bind C1q and activate complement through the classical complement pathway. In a set of lung cancer cell lines, a significant correlation was found between C1q binding and C4 or C3 deposition. The presence of phosphatidylserine inhibited C1q binding and diminished complement activation. Based on these results, C4d, a classical pathway-derived split product, was evaluated as a possible diagnostic or prognostic biomarker in lung cancer. Many lung primary tumors (adenocarcinomas and squamous cell carcinomas) deposited C4d. More importantly, survival was decreased in patients with high C4d deposition in their tumors (HR=3.06; 95% CI=1.18-7.91). Moreover, C4d levels were increased in bronchoalveolar lavage fluid from lung cancer patients as compared to patients with non-malignant respiratory diseases (0.61 ± 0.87 vs. 0.16 ± 0.11 µg/ml, respectively; P<0.001). C4d levels in plasma samples from lung cancer patients at both advanced (III and IV) and early (I and II) stages were also increased compared with control subjects (4.13 ± 2.02 vs. 1.86 ± 0.95 µg/ml, P<0.001; and 3.18 ± 3.20 vs. 1.13 ± 0.69 µg/ml, P<0.001, respectively). In addition, C4d plasma levels were associated with shorter survival in patients at advanced (HR=1.59; 95% CI=0.97-2.60) and early stages (HR=5.57; 95% CI=1.60-19.39). Plasma C4d levels were dramatically reduced after surgical removal of lung tumors. Finally, plasma C4d levels were associated with increased lung cancer risk in asymptomatic individuals: OR=4.38; 95% CI=1.61-11.93.
Lung tumors activate the classical complement pathway and generate C4d, a stable complement split product. Moreover, C4d is increased in biological samples from lung cancer patients, is associated with poor prognosis, and may be of clinical value for the early detection of lung cancer.
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