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Amitabha Mazumder

Publications and source records attributed to Amitabha Mazumder.

13 recordsLinked to original sources
PubMed2007

Bortezomib disrupts tumour-dendritic cell interactions in myeloma and lymphoma: therapeutic implications.

Recent studies have shown that the interactions between tumour and dendritic cells (DCs) promote clonogenic growth of lymphoproliferative tumours, particularly myeloma. The present study showed that the proteasome inhibitor, bortezomib, disrupts this interaction. Targeting the drug to DCs was required for optimal suppression of tumour growth, including primary myeloma tumour progenitors in clonogenic assays. Bortezomib lead to dose-dependent induction of apoptosis in both myeloid and plasmacytoid DCs, and the sensitivity of DCs to bortezomib was comparable with that of tumour cells. These data suggest that disruption of tumour-DC interactions may contribute to the clinical effects of bortezomib.

Apoptosis↗
PubMed2006

Enhancement of clonogenicity of human multiple myeloma by dendritic cells.

Infiltration by dendritic cells (DCs) is a common feature of most human tumors. Prior studies evaluating the interaction of DCs with tumors have focused largely on their immunologic properties (for review see Banchereau, J., and R.M. Steinman. 1998. Nature. 392:245-252). In this study, we show that the clonogenicity of several human tumor cell lines and primary tumor cells from myeloma patients is enhanced by their interactions with DCs. Myeloma cells cultured in the presence of DCs have an altered phenotype with an increased proportion of cells lacking terminal plasma cell differentiation marker CD138. DC-tumor interaction also leads to the up-regulation of B cell lymphoma 6 expression in myeloma cells. Effects of DCs on myeloma cells are inhibited by blockade of the receptor activator of NF-kB (RANK)-RANK ligand and B cell-activating factor-APRIL (a proliferation-inducing ligand)-mediated interactions. Together, these data suggest that tumor-DC interactions may directly impact the biology of human tumors, particularly multiple myeloma, and may be a target for therapeutic intervention.

Bone Marrow↗
PubMed2006

Enhancement of ligand-dependent activation of human natural killer T cells by lenalidomide: therapeutic implications.

Natural killer T (NKT) cells are CD1d-restricted glycolipid reactive innate lymphocytes that play an important role in protection from pathogens and tumors. Pharmacologic approaches to enhance NKT cell function will facilitate specific NKT targeting in the clinic. Here we show that lenalidomide (LEN), a novel thalidomide (Thal) analog, enhances antigen-specific expansion of NKT cells in response to the NKT ligand alpha-galactosylceramide (alpha-GalCer) in both healthy donors and patients with myeloma. NKT cells activated in the presence of LEN have greater ability to secrete interferon-gamma. Antigen-dependent activation of NKT cells was greater in the presence of dexamethasone (DEX) plus LEN than with DEX alone. Therapy with LEN/Thal also led to an increase in NKT cells in vivo in patients with myeloma and del5q myelodysplastic syndrome. Together these data demonstrate that LEN and its analogues enhance CD1d-mediated presentation of glycolipid antigens and support combining these agents with NKT targeted approaches for protection against tumors.

Antigen Presentation↗
PubMed2006

Thalidomide and lenalidomide in multiple myeloma.

Multiple myeloma is a treatable but not necessarily a curable plasma-cell cancer. After decades of minimal progress, two new classes of drugs with novel mechanisms of action - immunomodulatory drugs (thalidomide and lenalidomide) and proteasome inhibitors (bortezomib) - have been introduced for the treatment of this disease. Thalidomide and lenalidomide have shown great activity as single agents and in combination with glucocorticoids for the treatment of chemotherapy-refractory myeloma. Thalidomide - and more recently lenalidomide - in combination with dexamethasone have shown promising results as induction therapy. These drugs can easily be combined with other chemotherapeutic agents to potentiate the anti-myeloma effect. The immunomodulatory function of these drugs can be successfully exploited to control residual disease during remission. Thus, both thalidomide and lenalidomide have ushered in a new era of optimism in the management of this incurable cancer.

Humans↗
PubMed2006

Plasmacytoma in the breast with axillary lymph node involvement: a case report.

Plasmacytic tumors in the breast are extremely rare neoplasms that can mimic mammary adenocarcima. A literature review revealed approximately 43 reports worldwide of plasmacytic tumors in the breast since 1928, the majority with a synchronous diagnosis of multiple myeloma. We discuss management of a 78-year-old man with plasmacytoma in the breast who underwent a left total mastectomy and axillary lymph node dissection. This report characterizes the histologic and immunochemical characteristics of plasmacytoma in the breast and reviews the consensus on treatment. This could be the first recorded account of plasmacytomas in the breast with axillary lymph node involvement and extracapsular extension of tumor.

Aged↗
PubMed2005

Bortezomib therapy alone and in combination with dexamethasone for previously untreated symptomatic multiple myeloma.

Bortezomib, as a single agent and in combination with dexamethasone, was examined as first-line treatment in 32 consecutive patients with untreated symptomatic multiple myeloma. Patients received bortezomib 1.3 mg/m(2) for a maximum of six 3-week cycles; oral dexamethasone 40 mg was added if a less than partial response (PR) was achieved after two cycles or a less than complete response (CR) was achieved after four cycles. The response rate (CR + PR) was 88%, with undetectable paraprotein (CR) in 6%, and detectable by immunofixation only in 19% [near (n)CR]. All 32 patients completed the first two cycles of bortezomib alone, of whom 3% achieved CR, 9% nCR, and 28% PR. Ten patients received single-agent bortezomib on study, and dexamethasone was added in 22, leading to 15 improved responses. The most common adverse events >/=grade 2 included sensory neuropathy (31%), constipation (28%), myalgia (28%) and fatigue (25%). Sensory neuropathy grade 2 or 3 was reversible within a median of 3 months in five of 10 patients. Bortezomib treatment did not affect stem cell mobilization in eight or transplantation in six patients. Bortezomib alone or in combination with dexamethasone is an effective induction therapy with a high CR and nCR rate and manageable toxicities in previously untreated patients with myeloma.

Aged↗
PubMed2005

Cyclosporine A, alpha-lnterferon and interleukin-2 following chemotherapy with BCNU, DTIC, cisplatin, and tamoxifen: a phase II study in advanced melanoma.

Preclinical data suggest that one method of inducing autoimmunity to tumor is the administration and subsequent withdrawal of cyclosporine A following chemotherapy and that this effect may be enhanced with interferon and interleukin-2. Consequently, we performed a phase II trial in patients with advanced melanoma to explore this approach. Thirty-three patients were treated with BCNU (150 mg/m2 iv every 8 weeks), cisplatin (25 mg/m2 iv days 1-3) every 4 weeks, DTIC (220 mg/m2 iv days 1-3 every 4 weeks) along with tamoxifen (10 mg po BID days 1-4). Cyclosporine A at 3 mg/kg/day in two divided doses was given on days 4-21, alpha-interferon 1 million units/m2 subcutaneously every other day on days 4-21 and interleukin-2 1 million units/m2 BID subcutaneously days 21-28 were also given. Of the 33 patients, 3 patients (9%) had complete response and 8 patients (24%) had a partial response for a total response rate of 33% (95% confidence interval 18-52%). Median duration of response was 17 months (range 3+ to 24+ months). Six patients continue to show no signs of tumor progression for 3+, 5+, 10+, 24+, 60+, and 72+ months. Toxicity was generally well tolerated and included myelosuppression and fatigue. This regimen is feasible and generally tolerable and has produced an antitumor response rate comparable with inpatient biochemotherapy regimens.

Adult↗
PubMed2003

Generation of tumor cell lysate-loaded dendritic cells preprogrammed for IL-12 production and augmented T cell response.

Dendritic cells (DC) loaded with tumor associated antigens (TAA) are often used for the vaccination of cancer patients; however methodologies for the vaccine preparation have not yet been standardized. The purpose of this work was to optimize the ex-vivo production of functional TAA-loaded DC that would produce interleukin-2 (IL-12) and enhance the T cell response. We generated ex-vivo DC from human monocytes with granulocyte macrophage-colony stimulating factor (GM-CSF) and IL-4, and whole necrotic tumor cells (cell lysates) of cancer cell lines were used as model TAA. DC were loaded with lysates without or with additional tumor necrosis factor-alpha (TNF-alpha), or cytokine combination treatments and tested for functional ability in vitro. Tumor cell lysates alone did not fully mature DC either phenotypically or functionally. After antigen uptake additional maturation signals were necessary. TNF-alpha matured DC phenotypically, but additional interferon-gamma (IFN-gamma) treatment was necessary to achieve functional maturation, the production of significant amounts of IL-12. Since IL-12 production by DC increased during the first 24 h of maturation and declined by 48 h, proper timing of the ex-vivo DC treatment was crucial for the generation of functionally mature antigen-loaded DC. Our results suggest that after allowing 4 h of tumor lysate uptake by immature DC, further treatment with TNF-alpha and IFN-gamma for 24 h provides the optimal conditions to obtain functional TAA-loaded DC. These TAA-loaded cytokine pretreated DC then prime naïve T cells, and enhance both T helper 1 (Th1), Th2 and cytotoxic T lymphocyte (CTL) responses, that are necessary to achieve an effective, specific anti-tumor response.

Antigens, Neoplasm↗
PubMed2003

Long-term survival in patients with human immunodeficiency virus-associated small non-cleaved cell lymphoma: the role for short course intensive chemotherapy.

While intensive chemotherapy is recommended for the treatment of non-HIV related adult small non-cleaved lymphoma (SNCL), including Burkitt's and Burkitt-like lymphoma, optimal treatment for patients with HIV-associated SNCL is not known. We assessed remissions and survival in a cohort of 44 consecutive HIV positive patients diagnosed with SNCL at our hospital between June 2000 and November 2001 using chart and pathology data. Median follow-up, survival and survival at the median follow-up time were 4.5 months, 4 months and 49% respectively. Of this cohort 39% were complete responders (CR) and 36% were long-term lymphoma-free survivors. Two patients relapsed from CR. Short course intensive chemotherapy (McMaster) was administered to 23 patients; 17 received less intensive conventional combination chemotherapy; and four received single-agent chemotherapy or no treatment. In the McMaster group, 38% (9/23) achieved CR with no relapses. Seven patients (30%) died of toxicity compared with one (6%) in the less intensively treated group. Of the stage I patients, 75% (6/8) achieved long-term CR with half being treated conventionally. Conventional chemotherapy may be curative for early stage HIV-SNCL. In advanced disease, McMaster chemotherapy was found to be associated with substantial early mortality but was curative in a significant number of patients.

Adult↗
PubMed2003

Maturation-dependent expression of C1q binding proteins on the cell surface of human monocyte-derived dendritic cells.

The expression and cell surface levels of many important receptors are dependent on the maturation stage of dendritic cells (DCs), and related to the unique function of immature and mature DCs. In this report, we show, for the first time, that human monocyte-derived DCs express two types of C1q receptors, gC1qR and cC1qR. Furthermore, immature DCs secrete detectable amount of C1q into the culture supernatant. Immature DCs express higher cell surface levels of both C1qRs than mature ones, while the total C1qR protein and mRNA levels remain the same. The following experimental evidence support this conclusion: (1) Inflammatory cytokines and LPS, which induce maturation of DCs, downregulate surface expression of both C1qR molecules. (2) Cytokines and drugs (IL-10, IFN-alpha, Dexamethasone), which keep DCs phenotypically and functionally immature, significantly upregulate the cell surface expression of both C1qRs. (3) Neither of these treatments changed the intracellular gC1qR level nor the gC1qR mRNA levels measured by real time RT-PCR. The elevated surface expression of C1qRs on DCs has been found to be not due to increased apoptosis or cell death as the result of DC treatment. Taken together, these data show that human monocyte-derived DCs express gC1qR and cC1qR, their expression on the cell surface is maturation dependent, and immature DCs secrete C1q. These data strongly suggest the role of C1qRs in immature DC function and in the regulation of immune processes.

Calreticulin↗
PubMed2003

Maturation-dependent expression of C1q-binding proteins on the cell surface of human monocyte-derived dendritic cells.

The expression and cell surface levels of many important receptors are dependent on the maturation stage of dendritic cells (DCs), and related to the unique function of immature and mature DCs. In this report, we show for the first time that human monocyte-derived DCs express two types of C1q-receptors, gC1qR and cC1qR. Furthermore, immature DCs secrete detectable amount of C1q into the culture supernatant. Immature DCs express higher cell surface levels of both C1qRs than mature ones, while the total C1qR protein and mRNA levels remain the same. The following experimental evidence supports this conclusion. (1) Inflammatory cytokines and LPS, which induce maturation of DCs, downregulate surface expression of both C1qR molecules. (2) Cytokines and drugs (IL-10, IFNalpha, dexamethasone) that keep DCs phenotypically and functionally immature significantly upregulate the cell surface expression of both C1qRs. (3) Neither of these treatments changed the intracellular gC1qR level nor the gC1qR mRNA levels measured by real-time RT-PCR. The elevated surface expression of C1qRs on DCs has been found not to be due to increased apoptosis or cell death as the result of DC treatment. Taken together, these data show that human monocyte-derived DCs express gC1qR and cC1qR, their expression on the cell surface is maturation dependent and imature DCs secrete C1q. These data strongly suggest the role of C1qRs in immature DC function and in the regulation of immune processes.

Anti-Inflammatory Agents↗
PubMed2002

Primary Research: Short Communication: Evidence Supporting Rare AIDS-Kaposi's Sarcoma Metastasis In Keeping With Their Vascular Endothelial Evolution.

BACKGROUND: It is postulated that the unusual manifestations of Kaposis's sarcoma cells in nonendothelial brain tissues and on eyeballs in advanced acquired immune deficiency syndrome (AIDS) cases are metastasized AIDS-Kaposi's sarcoma cells arising from vascular endothelial cells. METHODS: Experiments were performed to explore the above hypothesis by testing for intercellular adhesion molecule-1 (CD54 antigens) on cutaneous AIDS-Kaposi's sarcoma cells as well as on AIDS-Kaposi's sarcoma cells isolated from eyeballs as studies have illustrated that, unlike localized Kaposi's sarcoma cells of primary lesions, proliferating Kaposi's sarcoma cells in proximity to primary lesions express a negative or diminished phenotype when evaluated for identical surface antigens. Parallel CD54 antigen tests were done on vascular endothelial cells and monocytes/macrophages as endothelial cells are considered evolutionarily related to Kaposi's sarcoma cells and monocytes/macrophages are ideal CD54 antigen positive controls. RESULTS: Our data showed that only AIDS-Kaposi's sarcoma cells of the eyes did not express CD54 antigens. CONCLUSIONS: We therefore report that our findings support the postulation suggesting AIDS-Kaposi's sarcoma dissemination in advanced AIDS patients in keeping with their vascular endothelial heredity.

Journal Article↗