P2-12-10: Low TCR Diversity (Divpenia) Is a Prognosis Factor of Overall Survival in Metastatic Breast Cancer.

Background: We already showed that lymphopenia ( Patients and methods: The ImmunTraCkeR® assay (ImmunID, Grenoble, France), which analyzes through semi quantitative multiplex-PCR the V-D-J combinatorial diversity of TCR-beta chain (TRB), was used to investigate diversity of T cell repertoire on cryopreserved blood samples from a retrospective cohort of MBC patients before chemotherapy administration (n=66). Univariate and multivariate analysis were performed. We then validated our score on a prospective cohort (n=67) using the same eligibility criteria (MBC patients before first line chemotherapy administration). Results: Using a 33% cutoff for divpenia in our retrospective cohort (T cell diversity below 33%) (average diversity for healthy people is 70%), divpenia was associated with a median OS of 10 months vs 22 months for patients with diversity >33% (logrank p value=0.04). The NDL® score (Numeration Diversity Lymphocytes representation) that combines lymphocyte numeration with TRB diversity, demonstrated that lympho-divpenia (T cell diversity below 33% and lymphopenia below lGiga/L) was associated with a poor OS compared to patients with either lymphocyte 33% or lymphocyte >1000/μL & diversity 1000/μL and diversity >33% (p=0.015). In multivariate analysis, including performance status (PS), hemoglobin level, polynuclear neutrophil count (PNN), age, and liver metastasis, NDL® score was identified as an independent prognostic factor for OS. In our prospective validation cohort, NDL® score was also identified as a prognostic factors for OS (p=0,007), as well as lymphopenia ( Conclusion: We showed that Divpenia and NDL® score are prognostic factors for OS in MBC patients. In order to confirm these results, a prospective clinical trial is ongoing on a larger cohort of MBC and lung cancer patients. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-12-10.