Abstract 53: Expression of EBV in the non-neoplastic cell population in trephine biopsies of patients with multiple myeloma is associated with a significant survival advantage

Abstract

Abstract Introduction: Multiple myeloma (MM) is a plasma cell (PC) disorder of the elderly, affecting predominantly males. Therapeutic advancement during the last decade has improved overall survival. Crosstalk between malignant PCs and the microenvironment is considered to play an important role in the development of resistance to treatment and relapse. Epstein Barr virus (EBV) is the first B-lymphotropic herpes virus identified for its association with human tumors. Reports relating an association of EBV to MM are few and inconsistent. It has been proposed that initiation of viral lytic cycle in EBV infected B cells is preceded by X-Box binding Protein-1 (XBP-1) mediated differentiation, resulting in a subset of EBV expressing infected PCs. Increased incidence of EBV expressing MM cases have been observed in immune-compromised patients. However, the significance of EBV in the bone marrow (BM) of MM patients has not been fully elucidated. The aim of our study was to evaluate prevalence of EBV in association with MUC1, XBP-1, ALDH1, and B-cell lineage markers (CD20, CD45, CD56, and CD138) in bone marrow trephine biopsies of patients with MM and to assess if there was any association with prognosis in a cohort of 151 MM patients at a single tertiary teaching hospital institution in Pakistan. Methodology: Formalin-fixed, paraffin-embedded trephine blocks of 151 MM cases diagnosed from 2007-2015 were evaluated for immunohistochemical (IHC) expression of MUC1, XBP-1, and EBV along with stem cell marker (ALDH1) and B-cell lineage markers (CD20, CD45, CD56, and CD138). Clinicopathologic details and follow-up data were collected from patients' medical records. Data was analyzed on SPSS 19. Five-year survival was estimated by Kaplan Meier curve for patients with follow-up available for 5 years or more (n=75). Results: Mean age at diagnosis was 57 years (range 30-89) with male preponderance (68.2%). Women (60.4%) with MM presented at an earlier age (median age 55 years, range 42-78) and difference in age of presentation was found to be significant (p value 0.04). Bone lesions were identified in 68.9% of patients at presentation. Stage I, II, and III disease was identified in 32.4%, 23.4%, and 44.1 % of patients, respectively (ISS staging system). Relapse was observed in 79.6% of patients and was significantly correlated with the expression of XBP-1 (p value 0.035). CD56 was expressed in 60.3% of cases and was significantly associated with cases diagnosed after the age of 57 years (p value 0.003). Expression of MUC1 was observed in 62.3% of tumors and 70% of MUC1-positive tumors also expressed XBP-1 (p value 0.06). Although the number of cases expressing EBV in the MM tumor cell population was only 7.2%, we detected EBV in 80.2% of the cases in the adjacent non-neoplastic cells with conspicuous expression in megakaryocytes. Five-year survival analysis (n=75) showed that expression of EBV+ in non-neoplastic cells was associated with significantly improved outcome with an advantage of 1.8 years (95% CI 3.32-4.4) as compared to EBV- cases (p value < 0.005). Among the XBP-1+ tumors, lack of EBV expression in non-neoplastic cells significantly correlated with adverse outcome (95%CI, 0.70-2.6) (p value < 0.005). Conclusions: To the best of our knowledge, this is the first study reporting expression of EBV in non-neoplastic cell population in BM trephines of MM patients. Salient conclusions of our study are as follows: 1. Expression of EBV in the surrounding tumor microenvironment of trephine biopsies of patients with MM is associated with a significant survival advantage; 2. Patients with MM in Pakistan present at a comparatively earlier age; 3. XBP1 expression was associated with relapse. Citation Format: Sheerien Rajput, Khurram Minhas, Iqbal Azam, Sadia Habib, Azhar Hussain, El-Nasir Lalani. Expression of EBV in the non-neoplastic cell population in trephine biopsies of patients with multiple myeloma is associated with a significant survival advantage [abstract]. In: Proceedings of the Second AACR Conference on Hematologic Malignancies: Translating Discoveries to Novel Therapies; May 6-9, 2017; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(24_Suppl):Abstract nr 53.