Flow cytometric minimal residual disease assessment in multiple myeloma

W świetle wysokiej skuteczności nowych metod leczenia szpiczaka plazmocytowego oraz zwiększającego się odsetka osiąganych całkowitych remisji (CR) ocena minimalnej choroby resztkowej (MRD) jest obecnie istotną metodą określającą głębokość odpowiedzi. Wieloparametryczna cytometria przepływowa (MFC) jest obecnie najczęściej wykorzystywaną metodą monitorowania MRD w szpiku kostnym pacjentów ze szpiczakiem plazmocytowym, jednak w tym celu można również stosować metody molekularne. Rodzaj protokołu stosowanego przy badaniu MRD metodą MFC może istotnie wpływać na uzyskiwane wyniki, jednak obecnie jest już dostępny wystandaryzowany i wysoce czuły protokół cytometrii następnej generacji (NGF). Wykazano, że głębokość odpowiedzi oceniona na podstawie pomiaru MRD koreluje z przeżyciem wolnym od progresji (PFS) oraz przeżyciem całko¬witym (OS) chorych na szpiczaka plazmocytowego. Ponadto ujemny wynik badania w kierunku MRD jest lepszym czynnikiem prognostycznym w odniesieniu do PFS oraz OS niż osiągnięcie CR. Z tych względów wynik oceny MRD, uzyskany wysoce czułą oraz powtarzalną metodą MFC, jest potencjalnie użytecznym klinicznie biomarkerem do oceny skuteczności różnych strategii leczniczych i może być podstawą do podejmowania decyzji terapeutycznej oraz użytecznym czynnikiem prognostycznym w szpiczaku plazmocytowym.Minimal residual disease (MRD) assessment in light of the effectiveness of new multiple myeloma (MM) treatment modalities and related to it increasing ratios of achieved complete remissions (CR), becomes an important tool in recognition of the depth of the response. Multiparametric flow cytometry (MFC) is currently the most popular method for monitoring of MRD presence in bone marrow of MM patients; however, molecular techniques may also be used for MRD assessment. The choice of protocol utilized for MFC-MRD measurement can significantly affect the obtained results, nevertheless standardized and highly sensitive approach of next generation flow (NGF) is already available. The depth of response based on MRD assessment was shown to be an inde-pendent predictor of progression-free survival (PFS) and overall survival (OS). Furthermore, the MRD-negative status surpasses the prognostic value of CR achievement for PFS and OS. Thus, MRD status detected by highly sensitive and reproducible MFC is potentially a clinically applicable biomarker for evaluation of different treatment strategies efficacy potentially influencing treatment decisions, and acting as prognostic factor in MM patients

Increased T regulatory cells are associated with adverse clinical features and predict progression in multiple myeloma.

Background: Regulatory T (Treg) cells play an important role in the maintenance of immune system homeostasis. Multiple myeloma (MM) is a plasma cell disorder frequently associated with impaired immune cell numbers and functions. Methods: We analyzed Treg cells in peripheral blood (n = 207) and bone marrow (n = 202) of pre-malignant and malignant MM patients using flow cytometry. Treg cells and their subsets from MM patients and healthy volunteers were functionally evaluated for their suppressive property. A cohort of 25 patients was analyzed for lymphocytes, CD4 T cells and Treg cells before and after treatment with cyclophosphamide, thalidomide plus dexamethasone (CTD). Results: We found elevated frequencies of Treg cells in newly diagnosed (P<0.01) and relapsed MM patients (P<0.0001) compared to healthy volunteers. Also, Treg subsets including naive (P = 0.015) and activated (P = 0.036) Treg cells were significantly increased in MM patients compared to healthy volunteers. Functional studies showed that Treg cells and their subsets from both MM and healthy volunteers were similar in their inhibitory function. Significantly increased frequencies of Treg cells were found in MM patients with adverse clinical features such as hypercalcemia (.10 mg/dL), decreased normal plasma cell (<5%) count and IgA myeloma subtype. We also showed that MM patients with >5% of Treg cells had inferior time to progression (TTP) (13 months vs. median not reached; P = 0.013). Furthermore, we demonstrated the prognostic value of Treg cells in prediction of TTP by Cox regression analysis (P = 0.045). CTD treatment significantly reduced frequencies of CD4 T cells (P = 0.001) and Treg cells (P = 0.018) but not Treg cells/CD4 T cells ratio compared to pretreatment. Conclusions: Our study showed immune deregulation in MM patients which is evidenced by elevated level of functionally active Treg cells and patients with increased Treg cells have higher risk of progression

Functionally suppressive CD8 T regulatory cells are increased in patients with multiple myeloma: a cause for immune impairment.

BACKGROUND: Multiple myeloma (MM) is a plasma cell malignancy frequently associated with impaired immune cell numbers and functions. In MM, several studies have previously shown that CD4 regulatory T (Treg) cells hamper effector T cell functions and enhance immune dysfunction. In this study, we aimed to prove the presence of functionally suppressive Treg cells expressing CD8 phenotype (CD8 Treg cells) in MM. To the best of our knowledge, this has not been reported previously in MM. METHODS: We analyzed CD8 Treg cells and their transcription factor FoxP3 from 64 newly diagnosed MM patients using flow cytometry and real time-polymerase chain reaction (RT-PCR). RNA profile of cytokines in CD8 Treg cells was also assessed using RT-PCR. CD8 Treg cells from 5 MM patients and 5 healthy donors were functionally evaluated using proliferation assays. RESULTS: CD8 Treg cells (CD8+CD25hi+) were significantly elevated in MM patients (P<0.0001), and their transcription factor FoxP3 expression was also higher in MM (P<0.0001) compared to healthy donors which was evidenced by flow cytometry and RT-PCR analyses. CD8 Treg cells negatively correlated with total lymphocyte count (P = 0.016). Functional studies revealed that CD8 Treg cells isolated from MM patients and healthy donors inhibited proliferation of CD4 T cells in a concentration dependent manner. In the presence of CD8 Treg cells in proliferation assays, level of IFN-γ was decreased but not IL-10. CD4 T cells from MM patients secreted abnormal level of IL-10 compared to healthy donors (P = 0.01) in proliferation assays without CD8 Treg cells. RNA profile of cytokines from CD8 Treg cells did not differ significantly between MM patients and healthy donors. CONCLUSIONS: These findings show the presence of increased number of functionally suppressive CD8 Treg cells in MM patients. We believe that these suppressive CD8 Treg cells might enhance immune impairment and disease progression in MM

Isolation of T regulatory cells and their subsets.

<p>Isolated T lymphocytes were labeled with fluorescent conjugated monoclonal antibodies targeting CD4 and CD25 and sorted by FACS Aria into CD4⁺CD25hi⁺ (Treg cells) and CD4⁺CD25⁻ (conventional T cells). Pre- (A) and post-sorted (B) CD4⁺CD25hi⁺ cells and CD4⁺CD25⁻ cells from a MM patient is shown and purity of sorted cells is represented in percentage. Similarly, to isolate Treg cell subsets, cells were fluorescently labeled for specific antigens (CD4, CD45RA and CD25) and sorted using FACS Aria into four populations: CD4⁺CD25⁺CD45RA⁺ (naïve Treg cells), CD4⁺CD25hi⁺CD45RA⁻ (activated Treg cells), CD4⁺CD25⁺CD45RA⁻ (non-Treg cells) and CD4⁺CD25⁻CD45RA⁺ (naïve CD4 T cells). Pre- (C) and post-sorted (D) Treg cell subsets and naïve CD4 T cells from a MM patient is shown and purity of sorted cells is represented in percentage.</p

Patients’ characteristics.

<p>Footnote: ISS, International staging system; B-J protein, Bence-Jones protein; LDH, lactate dehydrogenase; M protein, monoclonal protein; and BMPCs, bone marrow plasma cells.</p

Univariate Cox regression analysis for factors influencing time to progression in multiple myeloma.

<p>Footnote: CI, confidence interval; ISS, international staging system; M protein, monoclonal protein; β2-M, β2 microglobulin; BMPCs, bone marrow plasma cells; N-PCs, normal plasma cells.</p

Comparison of pre- and post-treatment frequencies of lymphocytes, CD4 T cells and T regulatory cells in relation with treatment response.

<p>Comparison of pre- and post-treatment frequencies of lymphocytes, CD4 T cells and T regulatory cells in relation with treatment response.</p