Potent anti-myeloma efficacy of dendritic cell therapy in combination with pomalidomide and programmed death-ligand 1 blockade in a preclinical model of multiple myeloma.

Dendritic cell (DC)-based vaccines are recognized as a promising immunotherapeutic strategy against cancer; however, the efficacy of immunotherapy with DCs is controlled via immune checkpoints, such as programmed death-ligand 1 (PD-L1). PD-L1 expressed on DC and tumor cells binds to programmed death-1 (PD-1) receptors on the activated T cells, which leads to the inhibition of cytotoxic T cells. Blocking of PD-L1 on DC may lead to improve the efficacy of DC therapy for cancer. Here we demonstrated that DC vaccination in combination with pomalidomide and programmed death-ligand 1 (PD-L1) blockade inhibited tumor growth of a multiple myeloma (MM) mouse model. DCs + pomalidomide with dexamethasone + PD-L1 blockade significantly inhibited immune immunosuppressive factors and promoted proportions of immune effector cells in the spleen and tumor microenvironment. Additionally, functional activities of cytotoxic T lymphocytes and NK cells in spleen were enhanced by DCs + pomalidomide with dexamethasone + PD-L1 blockade. Taken together, this study identifies a potential new therapeutic approach for the treatment of MM. These results also provide a foundation for the future development of immunotherapeutic modalities to inhibit tumor growth and restore immune function in MM.

5-diphenylacetamido-indirubin-3'-oxime as a novel mitochondria-targeting agent with anti-leukemic activities.

Current treatment for leukemia largely depends on chemotherapy. Despite the progress in treatment efficacy of chemotherapy, a poor outcome consequent upon chemoresistance against conventional anti-cancer drugs still remains to be solved. In this study, we report 5-diphenylacetamido-indirubin-3'-oxime (LDD398) as a novel mitochondria-targeting anti-leukemic agent, which is a derivative of indirubin used in traditional medicine. Treatment with LDD398 resulted in caspase activation, cell death, and growth arrest at G2/M phases in leukemia cells. Interestingly, LDD398 quickly collapsed mitochondrial membrane potential (MMP) within 1 h, accompanied by cytochrome c release into cytosol and severe depletion of cellular ATP. However, the LDD398-induced cellular events was significantly mitigated by blockage of mitochondrial permeability transition pore (MPTP) opening with chemical and genetic modifications, strongly supporting that LDD398 executes its anti-leukemic activity via an inappropriate opening of MPTP and a consequent depletion of ATP. The most meaningful finding was the prominent effectiveness of LDD398 on primary leukemia cells and also on malignant leukemia cells resistant to anticancer drugs. Our results demonstrate that, among a series of indirubin derivatives, LDD398 induces leukemia cell death via a different mode from indirubin or conventional chemotherapeutics, and can be employed as a potent anti-cancer agent in the treatment for newly diagnosed and relapsed leukemia.

Analysis of gene profiles involved in the enhancement of all-trans retinoic acid-induced HL-60 cell differentiation by sesquiterpene lactones identifies asparagine synthetase as a novel target for differentiation-inducing therapy.

All-trans retinoic acid (ATRA) is one of the most useful drugs in the treatment for acute promyelocytic leukemia (APL), but its adverse effects, which include drug resistance and hypercalcemia are obstacles to achieving complete remission. Our previous study showed that some sesquiterpene lactones (STLs), i.e., helenalin (HE) and parthenolide (PA) but not sclareolide (SC), enhance ATRA-induced differentiation of HL-60 APL cells with no unexpected effects, but the precise mechanism on underlying this synergism is not yet fully understood. In this study, we investigated the distinctive transcriptional profile of cells treated with effective STL compounds, which were identified by comparing the profile with that of cells treated with SC. Genome-wide approaches using cDNA microarrays showed that co-treatment with the differentiation-enhancing STLs HE and PA maximized the transcriptional variation regulated by the suboptimal concentration of ATRA in HL-60 cells. Of the genes of interest, asparagine synthetase was remarkably downregulated by ATRA co-treated with either HE or PA, but not with SC. In an additional analysis for the role of asparagine synthetase, ATRA-mediated HL-60 cell differentiation was enhanced when asparagine in the culture media was depleted by an addition of L-asparaginase, indicating that downregulation of asparagine synthetase gene expression may be involved in the enhanced cell differentiation by STL compounds. These results provide useful insight into differentiation-inducing therapy in the treatment of leukemia.

Korean guideline for iron chelation therapy in transfusion-induced iron overload.

Many Korean patients with transfusion-induced iron overload experience serious clinical sequelae, including organ damage, and require lifelong chelation therapy. However, due to a lack of compliance and/or unavailability of an appropriate chelator, most patients have not been treated effectively. Deferasirox (DFX), a once-daily oral iron chelator for both adult and pediatric patients with transfusion-induced iron overload, is now available in Korea. The effectiveness of deferasirox in reducing or maintaining body iron has been demonstrated in many studies of patients with a variety of transfusion-induced anemias such as myelodysplastic syndromes, aplastic anemia, and other chronic anemias. The recommended initial daily dose of DFX is 20 mg/kg body weight, taken on an empty stomach at least 30 min before food and serum ferritin levels should be maintained below 1000 ng/mL. To optimize the management of transfusion-induced iron overload, the Korean Society of Hematology Aplastic Anemia Working Party (KSHAAWP) reviewed the general consensus on iron overload and the Korean data on the clinical benefits of iron chelation therapy, and developed a Korean guideline for the treatment of iron overload.

Use of azacitidine for myelodysplastic syndromes: controversial issues and practical recommendations.

Azacitidine is recommended for patients with higher-risk myelodysplastic syndromes (MDS) who are not eligible for intensive therapy or for patients with lower-risk MDS who have thrombocytopenia or neutropenia or have anemia that is unresponsive to other therapies. However, standard treatment with azacitidine has not been optimized and many issues about the use of azacitidine remain unresolved. The use of azacitidine is expanding rapidly, but limited comparative clinical trial data are available to (i) define the optimal use of azacitidine in patients with higher-risk MDS or around the time of allogeneic hematopoietic stem cell transplantation, (ii) identify those patients with lower-risk MDS who may benefit from treatment, and (iii) guide physicians on alternative therapies after treatment failure. Increasing evidence suggests that the clinical features, prognostic factors, and cytogenetic profiles of patients with MDS in Asia differ significantly from those of patients in Western countries, so the aim of this review is to summarize the evidence and provide practical recommendations on the use of azacitidine in patients with MDS in the Republic of Korea. Evidence considered in this review is based on published clinical data and on the clinical experience of an expert panel from the acute myeloid leukemia/MDS Working Party of the Korean Society of Hematology.

All-trans retinoic acid inhibits the differentiation, maturation, and function of human monocyte-derived dendritic cells.

All-trans retinoic acid (ATRA) affects on the function of antigen presenting cells with somewhat controversies. We investigated the effects of ATRA on differentiation, maturation and function of human monocyte-derived dendritic cells (DCs). Low dose (10(-14)M) or high dose (10(-6)M) of ATRA was added either when monocytes were differentiated into immature DCs (imDCs) or mature DCs (mDCs) were induced. Apoptotic cell populations were dramatically increased in imDCs or mDCs with increasing concentration of ATRA. The productions of IL-12p40 and IL-12p70 were significantly suppressed in imDCs or mDCs induced by the addition of ATRA in the dose-dependent manner, whereas IL-10 was increased. DCs cultured with ATRA induced the differentiation of naïve T cells towards a helper T cell type 2 (Th2) response and expansion of CD4(+)CD25(+)Foxp3(+) regulatory T cells. Allostimulatory capacity of DCs was suppressed with increasing concentration of ATRA. These findings suggest that ATRA inhibits the effects on the differentiation, maturation and function of human monocyte-derived DCs in vitro and also enhance the differentiation of naïve T cell toward the Th2 type.

Optimization and limitation of calcium ionophore to generate DCs from acute myeloid leukemic cells.

PURPOSE: Calcium ionophore (CI) is used to generate dendritic cells (DCs) from progenitor cells, monocytes, or leukemic cells. The aim of this study was to determine the optimal dose of CI and the appropriate length of cell culture required for acute myeloid leukemia (AML) cells and to evaluate the limitations associated with CI. MATERIALS AND METHODS: To generate leukemic DCs, leukemic cells (4x10(6) cells) from six AML patients were cultured with various concentrations of CI and/or IL-4 for 1, 2 or 3 days. RESULTS: Potent leukemic DCs were successfully generated from all AML patients, with an average number of 1.2x10(6) cells produced in the presence of CI (270 ng/ml) for 2 days. Several surface molecules were clearly upregulated in AML cells supplemented with CI and IL-4, but not CD11c. Leukemic DCs cultured with CI had a higher allogeneic T cell stimulatory capacity than untreated AML cells, but the addition of IL-4 did not augment the MLR activity of these cells. AML cells cultured with CI in the presence or absence of IL-4 showed increased levels of apoptosis in comparison to primary cultures of AML cells. CONCLUSION: Although CI appears to be advantageous in terms of time and cost effectiveness, the results of the present study suggest that the marked induction of apoptosis by CI limits its application to the generation of DCs from AML cells.

Hemolytic anemia as a sequela of arsenic intoxication following long-term ingestion of traditional Chinese medicine.

We report on a 51-yr-old woman who developed intravascular hemolytic anemia caused by arsenic after long-term ingestion of a traditional Chinese medicine (TCM). Twelve years before the admission, she was diagnosed as neurocysticercosis. She has ingested a TCM for about 12 yr instead of undergoing medical therapy for the disease. She was presented with a severe Coombs'-negative hemolytic anemia with hemosiderinuria. The urine arsenic level was elevated suggesting the arsenic intoxication as a cause of the anemia. She was treated successfully with therapeutic red cell exchange without any sequelae.