Clinical relevance of MDM2 SNP 309 and TP53 Arg72Pro in follicular lymphoma

TP53 Arg72 as a favorable prognostic factor for Chinese diffuse large B-cell lymphoma patients treated with CHOP

Background

TP53 Arg72Pro (SNP rs1042522) is associated with risk of non-Hodgkin lymphoma (NHL). Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of NHL. However, the relationship between this SNP and prognosis of DLBCL in Asians is unknown.

Methods

Genotyping of TP53 Arg72Pro was done in 425 Chinese DLBCL patients. Two hundred and eighty-nine patients were treated with R-CHOP, and 136 patients received CHOP or CHOP-like as frontline regimen. Three hundred and ninety-six patients were assessable for the efficacy.

Results

Patients with Arg/Arg and Arg/Pro at codon 72 of TP53 had a higher complete response rate (61% vs. 44%, P = 0.007) than those with Pro/Pro. In the subgroup treated with CHOP or CHOP-like therapy, patients with Arg/Arg and Arg/Pro showed a higher 5-year overall survival (OS) rate than those with Pro/Pro (68.8% vs. 23.2%, P = 0.001). Multivariate Cox regression analysis revealed TP53 Arg72 as a favorable prognostic factor in this group. However, the combination of rituximab with CHOP significantly increased the 5-year OS rate of patients with Pro/Pro to 63%.

Conclusion

This study revealed TP53 Arg72 as a favorable prognostic factor for Chinese DLBCL patients treated with CHOP or CHOP-like as frontline therapy.

Genetic variation in cell death genes and risk of non-Hodgkin lymphoma

Background

Non-Hodgkin lymphomas are a heterogeneous group of solid tumours that constitute the 5^th highest cause of cancer mortality in the United States and Canada. Poor control of cell death in lymphocytes can lead to autoimmune disease or cancer, making genes involved in programmed cell death of lymphocytes logical candidate genes for lymphoma susceptibility.

Materials and Methods

We tested for genetic association with NHL and NHL subtypes, of SNPs in lymphocyte cell death genes using an established population-based study. 17 candidate genes were chosen based on biological function, with 123 SNPs tested. These included tagSNPs from HapMap and novel SNPs discovered by re-sequencing 47 cases in genes for which SNP representation was judged to be low. The main analysis, which estimated odds ratios by fitting data to an additive logistic regression model, used European ancestry samples that passed quality control measures (569 cases and 547 controls). A two-tiered approach for multiple testing correction was used: correction for number of tests within each gene by permutation-based methodology, followed by correction for the number of genes tested using the false discovery rate.

Results

Variant rs928883, near miR-155, showed an association (OR per A-allele: 2.80 [95% CI: 1.63–4.82]; p_F = 0.027) with marginal zone lymphoma that is significant after correction for multiple testing.

Conclusions

This is the first reported association between a germline polymorphism at a miRNA locus and lymphoma.

Host genetics in follicular lymphoma

The role of inherited (host) genetic susceptibility in the pathogenesis of follicular lymphoma (FL) is reviewed. First degree relatives of FL patients are at an increased risk of FL, suggesting a role for inherited factors. While there have been no linkage studies in FL families, candidate gene and genome-wide association studies have identified several risk loci which have been confirmed in independent studies. These include regions on 6p21.32-33 and TNF family members. Host genetics has also been hypothesized to influence treatment response, disease progression and overall survival. Early leads in FL prognosis include pathways that regulate immune function, antibody-dependent cellular cytotoxicity, chemotaxis, and one-carbon metabolism, although few of these associations have been independently confirmed. While the use of host genetics to identify individuals at high risk of FL or to predict FL treatment response and prognosis appears to be very promising, it is not yet ready for the clinic.

No association between the TP53 codon 72 polymorphism and risk or prognosis of Hodgkin and non-Hodgkin lymphoma

The role of the TP53 gene's R72P polymorphism in non-Hodgkin lymphoma (NHL) has been analyzed in several studies but it has not been studied in Hodgkin lymphoma (HL). We have evaluated the role of R72P in 340 NHL and 298 HL patients. There was no difference in the R72P frequency between analyzed lymphoma cases and 749 controls. We found no association of R72P with the risk of NHL and HL development [OR(ArgPro/ProPro)=0.9 (95% CI 0.7-1.2) and 1.2 (95% CI 0.9-1.5), respectively] or with survival. Our results support the evidence that R72P is not a prognostic factor in Caucasian NHL patients, and they indicate its irrelevance for HL development or prognosis.

Prognostic impact of the MDM2SNP309 allele in leukemia and lymphoma

A T-to-G germline single nucleotide polymorphism in the promoter region of MDM2 (SNP309) has been reported to markedly accelerate tumor formation in humans suggesting that it may represent a powerful cancer predisposing allele. Since its first description in 2004, a large number of retrospective analyses involving a wide variety of human malignancies have been reported, showing conflicting results regarding the impact of Mdm2SNP309 status on cancer risk and response to cancer therapy. Here, we appraise the available information on the effect of Mdm2SNP309 in lymphoma and leukemia and discuss the factors that likely account for the conflicting results observed in the studies reported to date.

Prognostic impact of the MDM2SNP309 allele in leukemia and lymphoma

A T-to-G germline single nucleotide polymorphism in the promoter region of MDM2 (SNP309) has been reported to markedly accelerate tumor formation in humans suggesting that it may represent a powerful cancer predisposing allele. Since its first description in 2004, a large number of retrospective analyses involving a wide variety of human malignancies have been reported, showing conflicting results regarding the impact of Mdm2SNP309 status on cancer risk and response to cancer therapy. Here, we appraise the available information on the effect of Mdm2SNP309 in lymphoma and leukemia and discuss the factors that likely account for the conflicting results observed in the studies reported to date.