Elotuzumab Enhances CD16-Independent NK Cell-Mediated Cytotoxicity against Myeloma Cells by Upregulating Several NK Cell-Enhancing Genes.

Multiple myeloma (MM) is an intractable hematological malignancy caused by abnormalities in plasma cells. Combination therapy using antibodies and natural killer (NK) effectors, which are innate immune cells with safe and potent antitumor activity, is a promising approach for cancer immunotherapy and can enhance antitumor effects. Elotuzumab (Elo) is an immune-stimulatory antibody that targets the signaling lymphocytic activation molecule family 7 (SLAMF7) expressed on the surface of MM and NK cells. We confirmed that Elo strongly promoted NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) against SLAMF7-positive MM cells in a CD16-dependent NK cell line, and also activated expanded NK cells derived from peripheral blood mononuclear cells of healthy donors and patients with MM in the present study. However, the antitumor effects and genes involved in the direct promotion of NK cell-mediated activation using Elo in CD16-independent NK cells are not clearly known. In this study, we demonstrated that Elo pretreatment significantly enhanced CD16-independent NK cell-mediated cytotoxicity in both SLAMF7-positive MM.1S and SLAMF7-negative K562, U266, and RPMI 8226 tumor cells. Upon direct simulation of CD16-independent NK cells with Elo, increased levels of CD107a degranulation and IFN-γ secretion were observed along with the upregulation of granzyme B, TNF-α, and IL-1α gene expression. The enhanced NK cell function could also be attributed to the increased expression of the transcription factors T-BET and EOMES. Furthermore, the augmentation of the antitumor effects of CD16-independent NK cells upon pretreatment with Elo enhanced the expression of CRTAM, TNFRSF9, EAT-2, and FOXP3 genes and reduced the expression of HSPA6. Our results suggest that Elo directly promotes the cytotoxic function of CD16-independent NK cells against target cells, which is associated with the upregulation of the expression of several NK cell-enhancing genes.

[Effective therapy with cyclophosphamide, doxorubicin, vincristine, and prednisolone chemotherapy with obinutuzumab for follicular lymphoma in leukemic phase].

The patient, a 56-year-old lady, also exhibited numerous lymphadenopathy, hepatosplenomegaly, hyperleukocytosis (167,200/µl, aberrant lymphocytes 91.5%), and fever. A lymph node biopsy revealed follicular lymphoma (FL), grade 1. Peripheral blood tumor cells did not express CD10, which was a distinctive characteristic of the lymph node specimen. To prevent tumor lysis syndrome (TLI), CHOP was delivered without an anti-CD20 antibody, but afterward, residual lymphoma cells were found in peripheral blood (>80%). As a result, obinutuzumab (Obi) was given on day 8 following the second round of CHOP, and the tumor cells in the peripheral blood vanished without any major side effects like TLI. She underwent six chemotherapy sessions before receiving maintenance therapy with Obi and achieving a full metabolic response. According to reports, leukemic FL exhibits negative CD10 expression in peripheral blood lymphoma cells, while leukemic mantle cell lymphoma also shows this trait. Therefore, it is important not to confuse the two types in diagnosis. Leukemic FL with significant leukocytosis is reportedly uncommon and has a bad prognosis. Our case indicates that CHOP with Obi would be a good alternative for cases like yours, however, there have been a few cases recorded. Further case accumulation or investigation is warranted.

The levels of serum soluble CD86 are correlated with the expression of CD86 variant 3 gene and are prognostic indicators in patients with myeloma.

We previously showed that cell-surface CD86 expressed on multiple myeloma (MM) cells contributed to not only tumor growth but also antitumor cytotoxic T-lymphocyte responses mediated by induction of IL-10-producing CD4+ T cells. The soluble form of CD86 (sCD86) was also detected in serum from patients with MM. Thus, to determine whether sCD86 levels are a useful prognostic factor, we investigated the association of serum sCD86 levels with disease progression and prognosis in 103 newly diagnosed patients with MM. Serum sCD86 was detected in 71% of the patients with MM but was only rarely detected in patients with monoclonal gammopathy of undetermined significance and healthy controls, and the level was significantly increased in patients with advanced-stage MM. When we examined differences in clinical characteristics according to the level of serum sCD86, those in the high (≥2.18 ng/mL, n = 38) group exhibited more aggressive clinical characteristics, with shorter overall survival times compared with those in the low (<2.18 ng/mL, n = 65) group. On the other hand, it was difficult to stratify the patients with MM into different risk groups based on the expression levels of cell-surface CD86. The levels of serum sCD86 were significantly correlated with the expression levels of the messenger RNA (mRNA) transcripts of CD86 variant 3, which lack exon 6, resulting in a truncated transmembrane region, and its variant transcripts were upregulated in the high group. Thus, our findings suggest that sCD86 can be easily measured in peripheral blood samples and is a useful prognostic marker in patients with MM.

Very Early Increased Platelet Count within a Week after Initiation of High-Dose Dexamethasone Treatment Is Associated with Long-Term Response in Newly Diagnosed Immune Thrombocytopenia Patients.

To evaluate the long-term efficacy of high-dose dexamethasone (HD-DXM) treatment for immune thrombocytopenia (ITP), we retrospectively analysed 36 newly diagnosed ITP patients treated with HD-DXM as a first-line treatment. An initial response was obtained in 23 (63.9%) patients, including 11 with a complete response (CR) and 12 with a partial response (PR). Six months after HD-DXM treatment, 26 of 33 (78.8%) evaluable patients achieved objective responses, including 18 CR and 8 PR. Among 13 patients without initial response, very early increased platelet count within a week (VEIP) was observed in 7 patients, 5 (71.4%) of whom achieved a response at 6 months. In 29 patients who had available platelet count within a week, patients showing VEIP revealed longer survival than those who did not (p = 0.026). HD-DXM was an effective treatment for newly diagnosed ITP patients. VEIP after HD-DXM treatment initiation was associated with a long-term objective response in newly diagnosed ITP patients.

Circulating cell-free DNA in the peripheral blood plasma of patients is an informative biomarker for multiple myeloma relapse.

BACKGROUND: Multiple myeloma (MM) is an incurable hematological malignancy. Despite the introduction of several novel drugs, most patients relapse. Biomarkers to identify the early signs of relapse will make it possible to adjust the therapeutic strategy before the disease worsens. Although understanding genetic changes is important for the treatment of MM, currently known biomarkers of relapse, including serum free-light chains and monoclonal paraproteins, are not associated with genetic changes. METHODS: We therefore performed a multicenter study to examine the usefulness of circulating cell-free DNA (cfDNA) present in the peripheral blood (PB) plasma of patients as a biomarker for MM relapse. RESULTS: We identified several driver mutations by combined analysis of next-generation sequencing and existing databases of candidate oncogenes. Furthermore, relapse was detected more sensitively by monitoring the circulating cfDNA with these driver mutations than by conventional serum free-light chain examination. CONCLUSION: These results suggest the potential utility of cfDNA in the PB plasma of patients as a relevant early biomarker for MM relapse.

High PRAME expression is associated with poor survival and early disease progression in myelodysplastic syndromes with a low bone marrow blast percentage.

We investigated the clinical implications of preferentially expressed antigen in melanoma (PRAME) expression in bone marrow cells of 116 patients with myelodysplastic syndromes (MDS). Quantitative RT-PCR was carried out to examine the PRAME expression level. High PRAME expression was observed in MDS patients classified into higher revised International Prognostic Scoring System (IPSS-R) risk categories (Very high and High) with a high bone marrow blast percentage (5% or higher). Kaplan-Meier analysis demonstrated that high PRAME expression is significantly associated with a poorer overall survival (OS) in MDS patients with a low bone marrow blast percentage (less than 5%) (log-rank test p = .0014) and those classified into lower IPSS-R risk categories (Very Low, Low, and Intermediate) (log-rank test, p = .0035). In contrast, there was no significant association between PRAME expression and OS in MDS patients with a high bone marrow blast percentage or those classified into higher IPSS-R risk categories. In addition, high PRAME expression was associated with early disease progression in MDS patients with a low bone marrow blast percentage. This study suggested PRAME expression to be a prognostic factor in MDS.

Successful Rituximab Treatment in Thrombotic Thrombocytopenic Purpura Patients Complicated by Other Autoimmune Disorders: Two Case Reports.

We herein report two cases of thrombotic thrombocytopenic purpura (TTP) complicated by other autoimmune disorders, autoimmune hepatitis and immune thrombocytopenia, respectively. In both cases, corticosteroids were continuously administered for the treatment of preceding autoimmune disorders. However, a sufficient objective response for TTP was not obtained by plasma exchange and corticosteroid treatment. Once a week rituximab (375 mg/m2) treatment for 4 times was initiated within 2 weeks from the diagnosis. Both patients achieved a sufficient response, and have never had any recurrence as of the last follow-up dates. The early introduction of rituximab could be an effective treatment option in TTP patients complicated with other autoimmune disorders.

Correction to: Fractionated ifosfamide, carboplatin, and etoposide with rituximab as a safe and effective treatment for relapsed/refractory diffuse large B cell lymphoma with severe comorbidities.

In the published online paper, the data "p = 0.144" was not deleted from the line "Median and mean number of prior treatments (range)" in Table 4.

Fractionated ifosfamide, carboplatin, and etoposide with rituximab as a safe and effective treatment for relapsed/refractory diffuse large B cell lymphoma with severe comorbidities.

Although treatment outcomes for diffuse large B cell lymphoma (DLBCL) have improved with the introduction of rituximab, approximately half of patients experience relapsed/refractory (r/r) disease. Furthermore, no standard salvage therapy has yet been established to date, while limitations in treatment options exist due to toxicity and restricted tolerability among elderly patients and/or those with comorbidities. The ICE (ifosfamide, cyclophosphamide, and etoposide) regimen is often used as salvage therapy for r/r DLBCL. Several modified ICE regimens not requiring continuous ifosfamide infusion are available, which can be used in outpatient clinics. This study analyzed the efficacy and toxicity of fractionated ICE with rituximab (f-R-ICE) as a salvage regimen among 47 patients with relapsed/refractory DLBCL (median age upon f-R-ICE initiation, 71 years). The whole cohort had an overall (ORR) and complete response rate of 53.1% (n = 25) and 25.5% (n = 12), respectively, and an estimated 1-year overall survival after f-R-ICE initiation of 57%. Comorbidities were evaluated using the Charlson Comorbidity Index (CCI) upon f-R-ICE initiation. Patients with low CCI scores (68%) had a higher ORR than those with high CCI scores (36.4%) upon f-R-ICE initiation (P = 0.042). In contrast, no significant differences in overall survival (OS) were observed between the low and high CCI groups (1-year OS 56.6% vs. 52.2%; median OS 24 vs. 22.8 months) after initiating f-R-ICE. Our results suggest that f-R-ICE is a safe and effective salvage therapy for r/r DLBCL and can be used for older patients and/or those with high CCI scores in outpatient clinics.

SLAMF3-Mediated Signaling via ERK Pathway Activation Promotes Aggressive Phenotypic Behaviors in Multiple Myeloma.

The signaling lymphocytic activation molecule family 3 (SLAMF3) is a member of the immunoglobulin superfamily expressed on T, B, and natural killer cells and modulates the activation and cytotoxicity of these cells. SLAMF3 is also expressed on plasma cells from patients with multiple myeloma (MM), although its role in MM pathogenesis remains unclear. This study found that SLAMF3 is highly and constitutively expressed on MM cells regardless of disease stage and that SLAMF3 knockdown/knockout suppresses proliferative potential and increases drug-induced apoptosis with decreased levels of phosphorylated ERK protein in MM cells. SLAMF3-overexpressing MM cells promote aggressive myeloma behavior in comparison with cytoplasmic domain-truncated SLAMF3 (ΔSLAMF3) cells. SLAMF3 interacts directly with adaptor proteins SH2 domain-containing phosphatase 2 (SHP2) and growth factor receptor bound 2 (GRB2), which also interact with each other. SLAMF3 knockdown, knockout, ΔSLAMF3, and SHP2 inhibitor-treated MM cells decreased phosphorylated ERK protein levels. Finally, serum soluble SLAMF3 (sSLAMF3) levels were markedly increased in advanced MM. Patients with high levels of sSLAMF3 progressed to the advanced stage significantly more often and had shorter progression-free survival times than those with low levels. This study revealed that SLAMF3 molecules consistently expressed on MM cells transmit MAPK/ERK signals mediated via the complex of SHP2 and GRB2 by self-ligand interaction between MM cells and induce a high malignant potential in MM. Furthermore, high levels of serum sSLAMF3 may reflect MM disease progression and be a useful prognostic factor. IMPLICATIONS: SLAMF3 may be a new therapeutic target for immunotherapy and novel agents such as small-molecule inhibitors.

Clinical impact of serum soluble SLAMF7 in multiple myeloma.

The signaling lymphocytic activation molecule family (SLAMF7; also known as CS1 or CD319) is highly expressed on plasma cells from multiple myeloma (MM) as well as natural killer (NK) cells and is a well-known therapeutic target of elotuzumab. The objective of this study was to evaluate the clinical significance of serum soluble SLAMF7 (sSLAMF7) levels in patients with MM (n=103) and furthermore the impact of sSLMF7 on the antitumor activity of anti-SLAMF7 antibody. Thirty-one percent of MM patients, but not patients with monoclonal gammopathy of undetermined significance and healthy controls, had detectable levels of serum sSLAMF7, which were significantly increased in advanced MM patients. Further, MM in sSLAMF7-postive patients exhibited aggressive clinical characteristics with shorter progression-free survival times in comparison with sSLAMF7-negative patients. In responders to MM therapy, the levels of sSLAMF7 were undetectable or decreased compared with those before treatment. In addition, the anti-SLAMF7 antibody-mediated antibody-dependent cellular cytotoxicity of NK cells against MM cell lines was inhibited by recombinant SLAMF7 protein. Thus, our findings suggest that high concentrations of sSLAMF7, which could transiently suppress the therapeutic effects of elotuzumab, may be a useful indicator of disease progression in MM patients.

L265P mutation of the MYD88 gene is frequent in Waldenström's macroglobulinemia and its absence in myeloma.

L265P mutation in the MYD88 gene has recently been reported in Waldenström's macroglobulinemia; however the incidence has been different according to the methods used. To determine the relevance and compare the incidence by different methods, we analyzed the L265P mutation in bone marrow mononuclear cells from lymphoid neoplasms. We first performed cloning and sequencing in 10 patients: 8 Waldenström's macroglobulinemia; 1 non-IgM-secreting lymphoplasmacytic lymphoma; and 1 low grade B-cell lymphoma with monoclonal IgG protein. The L265P mutation was detected in only 1/8 Waldenström's macroglobulinemia patients (2 of 9 clones). To confirm these results, direct sequencing was performed in the 10 patients and an additional 17 Waldenström's macroglobulinemia patients and 1 lymphoplasmacytic lymphoma patient. Nine of 28 patients (7/25 Waldenström's macroglobulinemia, 1/2 lymphoplasmacytic lymphoma, and B-cell lymphoma) harbored the mutation. We next tested for the mutation with BSiE1 digestion and allele-specific polymerase chain reaction in the 28 patients and 38 patients with myeloma. Aberrant bands corresponding to the mutation were detected by BSiE1 digestion in 19/25 patients with Waldenström's macroglobulinemia (76%), 1/2 lymphoplasmacytic lymphoma and B-cell lymphoma, but not in the 38 myeloma patients. The L265P mutation was more frequent in patients with Waldenström's macroglobulinemia than in those with myeloma (p=1.3x10(-10)). The mutation was detected by allele-specific polymerase chain reaction in 18/25 Waldenström's macroglobulinemia patients (72%). In the 25 Waldenström's macroglobulinemia patients, the L265P was more frequently detected by BSiE1 digestion than by direct sequencing (p=5.3x10(-4)), and in males (15/16, 94%) than in females (4/9, 44%) (p=1.2x10(-2)). No siginificant difference was observed in the incidence of the L265P mutation between BSiE1 digestion and allele-specific polymerase chain reaction (p=0.32). These results suggest that the L265P mutation is involved in the majority of Waldenström's macroglobulinemia. BSiE1 digestion and allele-specific polymerase chain reaction may detect a small fraction of mutated cells in some cases.

[Usefulness of (18)F-FDG PET/CT for detecting lesions in patients with POEMS syndrome].

Many patients with POEMS syndrome have osteosclerotic plasmacytoma. Radiation therapy is useful for patients who have localized lesions, although chemotherapy is necessary for patients who have widespread lesions. Thus, evaluation of these lesions is important to determine the therapeutic strategy. We evaluated the activities of lesions in two patients with POEMS syndrome by (18)F-FDG positron emission tomography (PET)/computed tomography (CT) scan. In the first patient, PET/CT scan revealed osteosclerotic lesions, which were not detected by Ga-scintigraphy or plain X-ray. It also detected residual disease activity and relapse. In the second patient, lymph node involvement was suggested by (18)F-FDG uptake, and plasmacytoma was confirmed by subsequent biopsy. In the extramedullary lesions of this case, FDG uptake was as marked as in myeloma, whereas bone lesion was only detectable by CT scan. In POEMS syndrome, the PET and CT are complementary, and the combined PET/CT scan is considered to be very useful for evaluation of involved lesions.

Inhibition of PRAME expression causes cell cycle arrest and apoptosis in leukemic cells.

The preferentially expressed antigen of melanoma (PRAME) is known as a tumor-associated antigen, but its function in leukemia remains unclear. We investigated the function with small interfering RNA (siRNA)-induced knockdown of PRAME in a K562 cell line. After PRAME siRNA transfection, proliferation was suppressed and cell cycle analysis showed G(0)/G(1) arrest, followed by apoptosis. PRAME siRNA-treated cells also showed changes in the genes affecting erythroid differentiation. We examined the PRAME expression levels and the S phase population of 32 acute leukemia patients at the time of diagnosis and relapse. An increase of the S phase population was accompanied by an increase of PRAME expression at relapse. Our results suggest that PRAME plays an important role in disease progression in acute leukemia.

Level of DNA topoisomerase IIalpha mRNA predicts the treatment response of relapsed acute leukemic patients.

The DNA topoisomerase IIalpha (Topo IIalpha) is known as a target enzyme for many chemotherapeutic agents. We investigated the Topo IIalpha mRNA expression by real-time RT-PCR in 37 paired samples at diagnosis and at relapse of acute leukemic patients in relation to drug sensitivity and clinical outcome. The Topo IIalpha levels in leukemic blasts at relapse were significantly higher than that at diagnosis, especially in ALL. The increase in the Topo IIalpha level at relapse was significant in cases which could not achieve a second remission, but not significant in cases which achieved a second remission. These results suggest that the change of Topo IIalpha expression in leukemic blasts at relapse may predict therapeutic responsiveness.