Regulatory T-Cells and Multiple Myeloma: Implications in Tumor Immune Biology and Treatment.

Multiple myeloma (MM) is associated with both cellular and humoral immune deficiencies and, despite significant advances in treatment, remains an incurable disease. Regulatory T-cells (Tregs) represent a critical subset of CD4 T-cells, characterized by CD4 + CD25+ Forkhead box P3+ (FoxP3+) phenotype, able to control peripheral tolerance and responses to foreign and tumor antigens. Tregs are elevated in various types of cancer, including hematological malignancies; in MM, data regarding Tregs function and numbers and their correlation with survival parameters are controversial. Advances in cancer biology have shown that the tumor microenvironment plays an important role in tumor progression. In MM, the highly immunosuppressive nature of the bone marrow microenvironment has been significantly elucidated in the past decade and it is now well acknowledged that targeting only the tumor clone may not be able to cure MM. Tregs within the tumor microenvironment might play a significant role in the suppression of antitumor immune responses against cancer cells and are considered to predict poor outcome in cancer patients; nonetheless the exact prognostic significance of this cell subpopulation in malignancies is still a matter of debate. In this review, we discuss the role of Tregs as an essential cell population of the MM immune microenvironment.

Evaluation of regulatory T cells (Tregs) alterations in patients with multiple myeloma treated with bortezomib or lenalidomide plus dexamethasone: correlations with treatment outcome.

The exact role of regulatory T cells (Tregs) in multiple myeloma (MM) has not been yet determined. Data regarding alterations of Tregs during therapy with novel agents (NA), i.e., bortezomib and lenalidomide are conflicted and limited. We evaluated prospectively alterations of Tregs and searched for correlations with disease characteristics, response, and outcome in 29 patients with active MM treated with either bortezomib-dexamethasone (BD; 11 patients) or lenalidomide-dexamethasone (LenDex, 18 patients). Additionally, we recorded changes of lymphocytes subsets and cytokines related to Tregs function and MM biology, i.e., interleukin (IL) 6, 2, 17, and TGF-ß. Compared with controls, patients had significantly higher median levels of Tregs%, IL-6, and IL-17 (p < 0.001). Median CD4 T and B cells frequencies were significantly lower, whereas CD8 T and natural killers were increased compared to controls. In BD group, no significant alterations of Tregs% were observed. Patients treated with LenDex, displayed a significant reduction of Tregs% (p < 0.001) especially those who achieved at least very good partial response (≥vgPR) (p = 0.04). Lymphocyte subsets or cytokines did not significantly change during therapy. In summary, Tregs% are higher in patients with active MM compared with controls, and they significantly decrease after treatment with LenDex but not with BD; After therapy with LenDex, Tregs reduction between baseline and major response correlated with achievement of ≥vgPR suggesting a possible predictive role, that may contribute to therapeutic strategy.

Lack of survival improvement with novel anti-myeloma agents for patients with multiple myeloma and central nervous system involvement: the Greek Myeloma Study Group experience.

Involvement of the central nervous system (CNS) is a rare complication of multiple myeloma (MM). Herein, we have described the incidence, characteristics, prognostic factors for post CNS-MM survival, and outcome of CNS-MM and explored the efficacy of novel agents (NA) (thalidomide, bortezomib, lenalidomide) in this setting. Between 2000 and 2013, 31 (0.9 %) out of 3408 newly diagnosed symptomatic MM patients, consecutively diagnosed and treated during the same period in 12 Greek centers, developed CNS-MM (M/F 15/16, median age 59 years, range 20-96 years; newly diagnosed/relapsed-refractory 2/29; median time to CNS-MM diagnosis 29 months). Clinical and laboratory characteristics were retrospectively recorded. Twenty-six percent of patients had circulating plasma cells (PCs) or plasma cell leukemia (PCL) at CNS-MM and 39 % had skull-derived plasmacytomas, suggesting hematological and contiguous spread. Treatment for CNS-MM was offered in 29/31 patients and 11/29 responded (NA 18/29, additional radiotherapy 9/28, intrathecal chemotherapy 13/29). The median post CNS-MM survival was 3 months (95 % CI 1.9-4.1) and did not differ between patients treated with NA and/or radiotherapy vs. others. In the multivariate analysis, prior treatment of MM with NA, extramedullary disease (EMD) during MM course (i.e., plasmacytomas, circulating PCs, or documented PCL) and abnormally high LDH at MM diagnosis were independent prognostic factors, whereas treatment of CNS-MM with NA did not predict for post CNS-MM survival. Despite the relatively limited number of patients due to the rarity of CNS-MM, our results suggest that NA do not seem to improve post CNS-MM survival. Patients with EMD display shortened post CNS-MM survival and should be followed thoroughly.

Clinical features, outcome, and prognostic factors for survival and evolution to multiple myeloma of solitary plasmacytomas: a report of the Greek myeloma study group in 97 patients.

Solitary plasmacytoma (SP) is a rare plasma cell dyscrasia characterized by the presence of bone or extramedullary plasma cell tumors. The treatment of choice is local radiotherapy (R/T) ± surgical excision. The role of adjuvant chemotherapy (C/T) or novel agents (NA) is uncertain. Data related to prognostic factors are inconclusive. Herein, we describe the clinical features, survival and prognosis of 97 consecutive patients, 65 with bone SP (SBP), and 32 with extramedullary SP (SEP), diagnosed and treated in 12 Greek Myeloma Centers. Objective response rate (≥PR) and complete response (CR) was 91.8% and 61.9%, respectively, and did not differ between the 2 groups. Overall, 38 patients relapsed or progressed to multiple myeloma (MM). After a median follow-up of 60 months, 5 and 10-year overall survival (OS) probability was 92% and 89% in SEP and 86% and 69% in SBP, respectively (P = 0.2). The 5- and 10-year MM-free survival (MMFS) probability was 90% and 70% for patients with SEP vs. 59% and 50% for patients with SBP, respectively (P = 0.054). Overall, the 5- and 10-year OS probability, plasmacytoma relapse-free survival (PRFS), progression-free survival and MMFS was 84% and 78%, 72% and 58%, 58% and 43%, and 70% and 59%, respectively. In the multivariate analysis, prolonged PRFS and young age were positive predictors of OS. Achievement of CR was the only positive predictor of PRFS. Immunoparesis was the only negative predictor of progression to MM. The addition of C/T or NA-based treatment increased toxicity without offering any survival advantage over R/T.

Erythropoiesis-stimulating agents are associated with reduced survival in patients with multiple myeloma.

The impact of erythropoiesis-stimulating agent (ESA) on cancer patients' survival has recently become a matter of extensive discussion. Studies in solid tumors demonstrated that ESA adversely affects survival. This issue has not been sufficiently studied in patients with multiple myeloma. In this study, which included 323 multiple myeloma patients followed in our Institution between 1988 and 2007, we demonstrated by using a proportional hazards model including multiple covariates (age, LDH, Hb, platelets, serum creatinine, ISS score, beta2 microglobulin, and ESA administration) that ESA administration is associated with reduced survival (hazards ratio: 1.88, 95% CI: 1.28-2.77). Anemia, which is considered a predictor for survival, platelets, serum creatinine, ISS score, and LDH, were not significant, whereas, age and beta2 microglobulin confirmed their predicting value in the multivariate analysis. With a median follow-up of 31 months (range 1-238), the median survival of patients in the ESA group was 31 months (95% CI: 25-37), whereas in the group without ESA administration it was 67 months (95% CI: 55-79) (P < 0.001). The median progression-free survival for patients in the ESA group was 14 months (95% CI: 12-16), and for the group without ESA it was 30 months (95% CI: 24-36) (P < 0.001). These results indicate that ESA may have a detrimental impact on MM patients' outcomes and, thus, in this context, they should be used with rigorous criteria.

Response of primary plasma cell leukemia to the combination of bortezomib and dexamethasone: do specific cytogenetic and immunophenotypic characteristics influence treatment outcome?

Plasma cell leukemia (PCL) is a rare and aggressive form of plasma cell dyscrasias. Its special biological characteristics may play an important role in the poor outcome when treated with conventional therapy or even with stem cell transplantation. New treatment approaches based on the biology of this disease are mandatory. Here we present three cases of primary PCL with adverse cytogenetics (deletion 13q14 and translocation 4;14) and specific immunophenotypic features (CD27 antigen strong expression) in which excellent response and sustained remission was achieved with the combination of bortezomib and dexamethasone. The possible role of these biological characteristics is been analyzed.