VEGF 2578 c>a, a Functional Angiogenic Polymorphism, Is Associated with Aggressiveness and Clinical Outcome of Follicular Lymphoma

Introduction: Follicular lymphoma (FL) is the second most prevalent non-Hodgkin lymphoma worldwide, and is characterized by an indolent course and frequent relapses. Better understanding of FL has shown that angiogenesis (AG) has an important role in its progression to a more aggressive form. The most important mediator of AG is the vascular endothelial growth factor (VEGF), which is encoded by a polymorphic gene. It is already known that allele C of the VEGF 2578C/A polymorphism (rs699947) is related to higher serum concentration of VEGF compared to the A allele. The roles of this genetic polymorphism in clinical manifestations and outcome of FL are still unknown, and therefore these were the aims of the present study.

Methods: Our analysis included 86 consecutive FL patients seen at diagnosis at the university hospital. The patients were treated with 6 to 8 cicles of R-CHOP. The clinical data of these patients were obtained from medical records. Genomic DNA was extracted from peripheral blood samples, and genotyping of the VEGF -2578C/A (rs699947) polymorphism was performed with real-time qPCR. Overall-survival (OS) was defined as time from diagnosis until death from any cause or last follow-up. The differences between groups were analyzed by the logistic regression model. Kaplan-Meier and log-rank analyses were used to assess survival information from the patients’ data. Furthermore, we examined survival data using univariate Cox proportional hazards regression, with the respective hazard ratios (HR) and 95% Confidence Intervals (CIs). Adjustement of Cox regression for clinical features was also performed. A p-value smaller than 0.05 was used to denote statistical significance.

Results: The FL patients had a mean age of 56.2 years at diagnosis. The majority of the patients were caucasians (87.6%), and there was an equivalent distribution between genders: 43 male and 43 female patients (50% each). Thirty-nine (45.3%) patients had B-symptoms and 48 (54.7%) had no B-symptoms at diagnosis. Sixty-three (73.2%) patients presented at diagnosis with tumors of III or IV Ann Arbor stage, and 30 (34.8%) had bone marrow infiltration. Follicular Lymphoma International Prognostic Index (FLIPI) was assessed and patients were classified as follows: low-risk FLIPI (≤ 1 point) was seen in 34 cases (39.5%), medium-risk FLIPI (2 points) in 28 cases (32.5%), and high-risk FLIPI ( ≥ 3 points) was seen in 24 patients (27.9%).

The VEGF 2578CC genotype was more common in patients with B-symptoms at diagnosis than in those without B-symptoms (51.2% versus 29.7%, p=0.04). The frequency of VEGF 2578CC genotype was also higher in patients with high-risk FLIPI than in those with medium and low-risk FLIPI (58.3% versus 32.2%, p=0.03). We found no association between genotypes and bone marrow infiltration at diagnosis.

Considering clinical course of the patients, Kaplan Meier curves of OS showed that at 60 months of follow up, B-symptoms at diagnosis (65.2% of OS versus 87.1%, p=0.02), high-risk FLIPI (52.5% of OS versus 90%, p=0.002), and 2578CC genotype (62.1% of OS in 2578CC patients versus 89.4% in 2578CA plus 2578AA patients, p=0.01) had negative impacts on outcome. In univariate Cox analysis, presence of B-symptoms (p=0.03, HR=3.2, 95% CI: 1.09-9.38), high-risk FLIPI (p=0.01, HR= 3.91, 95% CI: 1.38-11.03) and 2578CC genotype (p=0.02, HR=3.70, 95% CI: 1.16-11.82) were also associated with a worse outcome. The prognostic role of the abovementioned polymorphism was still present after adjustment for age (p=0.04, HR=3.23, 95% CI:1.01-10.36) and Ann Arbor stage (p=0.02, HR=3.58, 95% CI:1.1-11.6) in univariate regression. After adjustment for FLIPI status as a whole, only a trend of association of 2578CC genotype with a worse outcome was found in the study (p=0.05, HR=3.24, 95% CI: 0.95-13.05).

Conclusion: Our results present, for the first time, preliminary evidence that FL patients with the VEGF 2578CC genotype, related to higher production of VEGF, are more likely to develop aggressive form of the disease at diagnosis, and to succumb earlier to death. We recognize, however, that our study is based on a small sample size and that more numerous cohorts should be analyzed in order to assess additional associations. Also, further studies, such as correlations between relevant AG genes and tumor vascularization, should be done in order to clarify this issue in the context of FL.