Biomedical subjects

Michael J Keating

Publications and source records attributed to Michael J Keating.

95 records · Page 6Linked to original sources

PubMed2002

Epstein-Barr virus-positive B-cell lymphoproliferative disorders arising in immunodeficient patients previously treated with fludarabine for low-grade B-cell neoplasms.

We describe five patients with treated low-grade B-cell neoplasms who subsequently developed Epstein-Barr virus (EBV)-positive B-cell lymphoproliferative disorders (BLPDs). The low-grade B-cell neoplasms were B-cell chronic lymphocytic leukemia in four patients and splenic marginal zone lymphoma in one patient. All patients had received treatment with fludarabine for the low-grade B-cell neoplasm, and three had also received Campath-1H. The EBV-BLPDs arose 2-12 months after completion of fludarabine therapy and morphologically resembled the EBV-BLPDs that occur in the setting of iatrogenic immunodeficiency. Molecular genetic studies showed that these lesions were clonally distinct from the low-grade B-cell neoplasm in three of four cases assessed. Two patients did not receive therapy for the EBV-BLPD. The lesions regressed spontaneously in both patients but recurred in one. One patient underwent surgical excision and remains without evidence of the EBV-BLPD. One patient received aggressive multiagent chemotherapy with a complete response initially, but the EBV-BLPD recurred after 12 months. One patient received antiviral therapy and responded completely but died 2 months later of an opportunistic infection. We conclude that patients with low-grade B-cell neoplasms treated with fludarabine, possibly in combination with other immune suppressive agents, may subsequently develop EBV-BLPDs that morphologically resemble other iatrogenic immunodeficiency-associated BLPDs. Most are clonally distinct from the underlying low-grade B-cell neoplasm. A subset of these lesions may regress without systemic therapy.

Antineoplastic Agents↗

PubMed2002

Emerging information on the use of rituximab in chronic lymphocytic leukemia.

Rituximab (Rituxan; Genentech, Inc, South San Francisco, CA, and IDEC Pharmaceuticals, San Diego, CA) is a chimeric monoclonal antibody that targets mature B cells in most lymphoid B-cell malignancies. While rituximab was approved by the US Food and Drug Administration for the treatment of recurrent B-cell lymphoma, initial studies suggested that it had less activity in small lymphocytic lymphoma, the nodal counterpart of chronic lymphocytic leukemia (CLL). Two studies have now investigated the activity of higher-dose and more intensive therapy with rituximab in CLL. They have shown a dose-response relationship and a higher response rate than previously seen in the lower-dose studies. This is presumably caused by the overcoming of lower antigen density on CLL cells compared with lymphoma cells, and the shorter half-life of rituximab in small lymphocytic lymphoma. There is now evidence that CD20 is shed into the plasma in patients with CLL, which may explain the shorter half-life of the antibody in small lymphocytic lymphoma/CLL. The higher dose may then be effective in overcoming this so-called "antigen sink." Toxicity was uncommon except in previously untreated patients and those with atypical forms of CLL such as mantle cell lymphoma and prolymphocytic leukemia. There is now evidence in vitro of additive or synergistic activity of rituximab with a variety of chemotherapeutic agents including fludarabine and cyclophosphamide. Combinations of fludarabine with rituximab or these two drugs combined with cyclophosphamide have given very high complete response rates in series of patients with both previously untreated and treated CLL. It is apparent that rituximab is playing a significant role in the management of patients with CLL as salvage therapy and is a potential potentiating agent for combined chemoimmunotherapy strategies for front-line or relapsed patients with CLL.

Antibodies, Monoclonal↗

PubMed2002

UCN-01 (7-hydroxystaurosporine) inhibits DNA repair and increases cytotoxicity in normal lymphocytes and chronic lymphocytic leukemia lymphocytes.

Elevated DNA repair processes represent resistance mechanisms to the treatment of malignancies with alkylating agents. Recently, the cell cycle checkpoint abrogator, UCN-01, was reported to inhibit nucleotide excision repair in cell-free systems. We hypothesized that if UCN-01 was combined with DNA-damaging agents, UCN-01 might inhibit the damage repair processes, thereby enhancing cytotoxicity in quiescent cells. Here, we investigated the effect of UCN-01 on DNA repair and viability of quiescent normal lymphocytes and chronic lymphocytic leukemia lymphocytes treated with UV or the cyclophosphamide prodrug 4-hydroperoxycyclophosphamide (4-HC). DNA damage repair kinetics were determined as DNA single strand breaks by the alkaline single cell gel electrophoresis (comet) assay and by [3H]thymidine incorporation. Pretreatment with UCN-01 inhibited DNA repair initiated by UV or 4-HC in normal lymphocytes as well as chronic lymphocytic leukemia lymphocytes in a concentration-dependent manner at clinically relevant levels (50-300 nM). This inhibition was demonstrated by the decreases in incision capability, DNA resynthesis, and in rejoining, suggesting that UCN-01 inhibits the multiple sites of the repair processes. The higher UCN-01 concentration (300 nM) maximized the inhibitory effects and enhanced the UV- or 4-HC-induced cytotoxicity, as determined by annexin V binding or Hoechst 33342 staining. This enhancement was not obtained by the lower concentrations that incompletely inhibited the repair, suggesting the close association between the inhibition of the repair and the enhancement of the cytotoxicity. Our findings suggest that UCN-01 may be a good candidate for combination strategies of cancer treatment.

Alkaloids↗

PubMed2002

Rituximab in B-cell disorders other than non-Hodgkin's lymphoma.

Rituximab is a human/mouse chimeric monoclonal antibody that binds to the CD20 antigen and is expressed at all stages of B-cell development. Rituximab has demonstrated efficacy as monotherapy and in combination with chemotherapy in the treatment of both indolent and aggressive non-Hodgkin's lymphoma (NHL). Rituximab treatment results in rapid depletion of B-cells and this has led to the consideration of other B-cell disorders as candidates for rituximab therapy. Recent studies have demonstrated the efficacy of rituximab in a variety of such disorders, including chronic lymphocytic leukemia (CLL), post-transplant lymphoproliferative disorder (PTLD), Waldenström's macroglobulinemia (WM), multiple myeloma (MM), idiopathic thrombocytopenic purpura (ITP), hairy-cell leukemia (HCL) and cold agglutinin disease (CAD). In patients with CLL, increasing the dose and/or frequency of rituximab treatment has given improved response rates compared with the standard dose schedule used in NHL, and combination immunochemotherapy has yielded an overall response rate of 92% (with a 60% complete response rate). Clinical trials have also demonstrated evidence of efficacy for rituximab in PTLD, WM and relapsed or refractory ITP. Efficacy of rituximab in CAD and relapsed or refractory HCL has also been demonstrated in small studies and case reports. Available data thus indicate that rituximab can be an effective therapy in a wide range of CD20+ lymphoid disorders.

Anemia, Hemolytic, Autoimmune↗

PubMed2002

TAD: a web interface and database for tissue microarrays.

Tissue microarrays are increasingly important tools that bring high-throughput technology to traditional pathology laboratories. In many cases, each spot on a tissue microarray is scored by a skilled pathologist and recorded manually. TAD consists of an Active Server Page web interface to a relational database that automates recording scores and linking them with clinical data for future interpretation. TAD is an open source application that can be installed locally.

Computational Biology↗