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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rituximab, a chimeric monoclonal antibody that binds specifically to the CD20 antigen, induced objective responses in 50% of patients with low-grade or follicular B-cell lymphoma. Because most nonfollicular B-cell lymphomas also express the CD20 antigen, we conducted a phase II study to evaluate the efficacy and tolerability of this new agent in patients with more aggressive types of lymphoma. Patients with diffuse large B-cell lymphoma (DLCL), mantle cell lymphoma (MCL), or other intermediate- or high-grade B-cell lymphomas according to the Working Formulation were included in this prospective randomized phase II study if they were in first or second relapse, if they were refractory to initial therapy, if they progressed after a partial response to initial therapy, or if they were elderly (age >60 years) and not previously treated. The patients received 8 weekly infusions of rituximab at the dose of 375 mg/m2 in arm A or one infusion of 375 mg/m2 followed by 7 weekly infusions of 500 mg/m2 in arm B. Patients were evaluated 2 months after the last rituximab infusion. Fifty-four patients were randomized from 9 centers in Europe and Australia (28 in arm A and 26 in arm B). A total of 5 complete responses (CR) and 12 partial responses (PR) were observed among the 54 enrolled patients, with no difference between the two doses. In an intent-to-treat analysis, the CR rate was 9% (CI95%, 3% to 20%) and the PR rate was 22% (CI95%, 12% to 36%), for an overall response rate of 31% (CI95%, 20% to 46%). An analysis of prognostic factors showed that response rates were lower in patients with refractory disease, patients with lymphoma not classified as DLCL, and patients with a tumor larger than 5 cm in diameter. DLCL and MCL patients had response rates of 37% and 33%, respectively. The median time to progression exceeded 246 days for the 17 responding patients. The most frequently reported adverse events were related to an infusion syndrome and were mild: 19% of the patients had a grade 3 related adverse event, slightly more in arm B, and only 1 patient had a grade 4 related adverse event in arm A. Two patients (3.7%) withdrew from treatment because of severe adverse events, one patient in each arm. In this first trial of rituximab in DLCL and MCL, patients experienced a significant clinical activity with a low toxicity. Rituximab has significant activity in DLCL and MCL patients and should be tested in combination with chemotherapy in such patients.
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PMID:Rituximab (anti-CD20 monoclonal antibody) for the treatment of patients with relapsing or refractory aggressive lymphoma: a multicenter phase II study. 973 Oct 49

Rituximab is a chimeric antibody with human gamma-1 and kappa constant regions and murine variable regions. It recognizes the CD20 antigen, a pan B-cell marker. Therapeutic trials in patients with B-cell non-Hodgkin's lymphoma (NHL) have shown significant efficacy with a primary response rate of 50%, and a secondary response rate of 44% after repeat treatments in prior responders. The selection for proliferating tumor cells that no longer express CD20 may compromise repeated treatment. We have identified a patient who developed a transformed NHL that lost CD20 protein expression after two courses of therapy with rituximab. In a pretreatment lymph node biopsy, 83% of B cells (as defined by CD19 and surface immunoglobulin) expressed surface CD20. A biopsy from the recurrent tumor after two courses of rituximab revealed a diffuse large cell NHL where 0% of B cells expressed CD20 with no evidence of bound rituximab. Cytoplasmic staining showed no CD20 protein. Sequencing of immunoglobulin heavy chain cDNA identified identical variable sequences in the initial and recurrent lymphomas, confirming the association between the two tumors. Literature and database review suggests that approximately 98% of diffuse large cell lymphomas express CD20, which suggests that these tumors rarely survive without CD20. This is the first identified case of loss of CD20 expression in a lymphoma that has relapsed after rituximab therapy, although several other cases have since been identified. Considering the significant number of patients treated with anti-CD20 antibodies, this may occur only rarely and is unlikely to preclude recurrent therapy with anti-CD20 antibodies in the majority of patients. However, because many patients have relapsed after anti-CD20 antibody therapy and have not been biopsied to identify clones with down-regulated CD20 antigen, we do not currently know the true frequency of this phenomenon. When possible, patients should undergo evaluation for CD20 expression before repeated courses of anti-CD20 therapy.
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PMID:Therapy of B-cell lymphoma with anti-CD20 antibodies can result in the loss of CD20 antigen expression. 1065 64

The use of serotherapy to treat patients with plasma cell dyscrasias (PCDs) has been sought by us and others. Candidate antigens that have been targeted or proposed for targeting in PCDs include the immunoglobulin idiotype, CD19, CD38, CD54, CD126, HM1.24, and Muc-1 core protein. Unfortunately, many of these antigens are not ideal for use in serotherapy since they are not selectively expressed, are either shed or secreted, or have not been fully characterized. Serotherapy with an anti-CD19 monoclonal antibody (B4) conjugated to a blocked ricin toxin had no significant activity in patients with multiple myeloma (MM). Circulating CD20+ clonotypic B cells have been detected in the circulation of most MM and Waldenstrom's macroglobulinemia (WM) patients. Plasma cells from most WM patients express CD20, but most MM patient plasma cells either lack CD20 or express it weakly. In view of recent successes with anti-CD20-directed serotherapy in other B-cell malignancies, we initiated a phase II trial to study the anti-CD20 monoclonal antibody rituximab (Rituxan; IDEC Pharmaceuticals, San Diego, CA, and Genentech, Inc, San Francisco, CA) in patients with MM. We describe two PCD patients (one with WM and one with MM) who responded to therapy. By flow cytometric analysis, CD20+ plasma cells and B cells present in the bone marrow and peripheral blood of a patient with MM disappeared with response to rituximab therapy. However, residual CD20- tumor cells remained in the bone marrow following rituximab therapy, and after 6 months this patient progressed with CD20- myeloma cells. As a potential strategy to overcome this limitation, we demonstrated that interferon-gamma at pharmacologically achievable levels induced CD20 expression on these CD20- plasma cells, consistent with our recent findings that interferon-gamma is a potent inducer of CD20 expression on MM patient plasma cells and B cells. We also characterize a response to rituximab with a decrease in paraprotein and resolution of anemia in a patient with WM whose response to rituximab is ongoing after 19+ months. This preliminary experience supports the potential use of serotherapy targeting CD20 in PCDs. Our studies further suggest that interferon-gamma may enhance CD20 expression on MM plasma cells, thereby increasing their susceptibility to anti-CD20 monoclonal antibody therapies.
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PMID:Treatment of plasma cell dyscrasias by antibody-mediated immunotherapy. 1056 Oct 24

Accumulating data are showing that the humoral immune response against tumors could favor tumor progression. However, no B lymphocyte pathology has been reported in cancer. Using anti-IgM Ab we nonspecifically depleted B cells in tumor-bearing mice, a treatment that resulted in significant reduction of tumor burden. We analyzed the B lymphocyte phenotype of abdominal lymph nodes and peripheral blood from advanced colon cancer patients by flow cytometry, and compared the B cell phenotype with that found in samples from normal donors. In both lymph nodes and peripheral blood of cancer patients, abnormal populations of B lymphocytes appeared that express an increased CD21 and/or sTn antigens on their cell surface. All patients showed a reduction of CD19+ cells. In a limited clinical test, we analyzed the effects of a partial B cell depletion with Rituximab. The treated patients did not develop any side-effects; the CD21-hyperpositive lymphocytes were reduced, but the proportion of sTn-positive lymphocytes remained unaffected. Apparent reduction of the tumor burden was reported in 50% of the patients when the treatment was ended.
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PMID:B lymphocyte pathology in human colorectal cancer. Experimental and clinical therapeutic effects of partial B cell depletion. 1063 Mar 6

Pretargeted radioimmunotherapy (PRIT) was investigated in patients with non-Hodgkin's lymphoma (NHL). The PRIT approach used in this study is a multi-step delivery system in which an antibody is used to target streptavidin to a tumor associated antigen receptor, and subsequently biotin is then used to target 90Y radioisotope to the tumor localized streptavidin. A chimeric, IgG1, anti-CD20 antibody, designated C2B8 or Rituximab, was conjugated to streptavidin (SA) and administered to patients with NHL. Thirty-four hours later, a clearing agent, synthetic biotin-N-acetyl-galactosamine, was administered to remove non-localized conjugate from the circulation. Finally, a DOTA-biotin ligand, labeled with 111In for imaging and/or 90Y for therapy was administered. Ten patients with relapsed or refractory NHL were studied. In three patients, the C2B8/SA conjugate was radiolabeled with a trace amount of 186Re in order to assess pharmacokinetics and biodistribution using gamma camera imaging. Seven patients received 30 or 50 mCi/m2 90Y DOTA-biotin. Re-186 C2B8/SA images confirmed that the conjugate localized to known tumor sites and that the clearing agent removed > 95% of the conjugate from the circulation. Radiolabeled biotin localized well to tumor. Unbound radiobiotin was rapidly excreted from the whole body and normal organs. The mean tumor dose calculated was 29 +/- 23 cGy/mCi 90Y and the average whole body dose was 0.76 +/- 0.3 cGy/mCi 90Y, resulting in a mean tumor to whole body dose ratio of 38:1. Only grade I/II non-hematologic toxicity was observed. Hematologic toxicity was also not severe; i.e., five of the seven patients who received 30 or 50 mCi/m2 of 90Y-DOTA-biotin experienced only transient grade III (but no grade IV) hematologic toxicity. Although six of ten patients developed humoral immune responses to the streptavidin, these were delayed and transient and hence may not preclude retreatment. Six of seven patients who received 30 or 50mCi/m2 90Y achieved objective tumor regression, including three complete and one partial response. The estimate of tumor to whole body dose ratio (38:1) achieved with PRIT in these NHL patients is higher than has been achieved in other studies using conventional RIT. Toxicity was mild and tumor response encouraging. PRIT clearly deserves additional study in patients with NHL.
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PMID:Pretargeted radioimmunotherapy (PRIT) for treatment of non-Hodgkin's lymphoma (NHL): initial phase I/II study results. 1074 Jun 47

Inhibitory receptors have been proposed to modulate the in vivo cytotoxic response against tumor targets for both spontaneous and antibody-dependent pathways. Using a variety of syngenic and xenograft models, we demonstrate here that the inhibitory FcgammaRIIB molecule is a potent regulator of antibody-dependent cell-mediated cytotoxicity in vivo, modulating the activity of FcgammaRIII on effector cells. Although many mechanisms have been proposed to account for the anti-tumor activities of therapeutic antibodies, including extended half-life, blockade of signaling pathways, activation of apoptosis and effector-cell-mediated cytotoxicity, we show here that engagement of Fcgamma receptors on effector cells is a dominant component of the in vivo activity of antibodies against tumors. Mouse monoclonal antibodies, as well as the humanized, clinically effective therapeutic agents trastuzumab (Herceptin(R)) and rituximab (Rituxan(R)), engaged both activation (FcgammaRIII) and inhibitory (FcgammaRIIB) antibody receptors on myeloid cells, thus modulating their cytotoxic potential. Mice deficient in FcgammaRIIB showed much more antibody-dependent cell-mediated cytotoxicity; in contrast, mice deficient in activating Fc receptors as well as antibodies engineered to disrupt Fc binding to those receptors were unable to arrest tumor growth in vivo. These results demonstrate that Fc-receptor-dependent mechanisms contribute substantially to the action of cytotoxic antibodies against tumors and indicate that an optimal antibody against tumors would bind preferentially to activation Fc receptors and minimally to the inhibitory partner FcgammaRIIB.
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PMID:Inhibitory Fc receptors modulate in vivo cytotoxicity against tumor targets. 1074 35

Anti-CD20 monoclonal antibodies have been successfully employed in the clinical treatment of non-Hodgkin's lymphomas in both unmodified and radio-labeled forms. Previous publications have demonstrated that the antitumor effects of unmodified anti-CD20 mAb are mediated by several mechanisms including antibody-dependent cellular cytotoxicity, complement-mediated cell lysis, and induction of apoptosis by CD20 cross-linking. In this report, we demonstrate induction of apoptosis by three anti-CD20 monoclonal antibodies [1F5, anti-B1, and C2B8 (Rituximab)]. The magnitude of apoptosis induction was greater with the chimeric Rituximab antibody than with the murine 1F5 and anti-B1 antibodies. Apoptosis could be enhanced with any of the antibodies by cross-linking with secondary antibodies (or Fc-receptor-bearing accessory cells). The signaling events involved in anti-CD20-induced apoptosis were investigated, including activation of protein tyrosine kinases, increases in intracellular Ca2+ concentrations, caspase activation, and cleavage of caspase substrates. Our results indicate that anti-CD20-induced apoptosis can be attenuated by PP1, an inhibitor of protein tyrosine kinases Lck and Fyn, chelators of extracellular or intracellular Ca2+, and inhibitors of caspases, suggesting that anti-CD20-induced apoptosis may involve modulation of these signaling molecules. We also demonstrated that varying the expression of Bc1-2 did not affect the magnitude of anti-B1-induced apoptosis, possibly because of the sequestering effects of other Bc1-2 family members, such as Bad. These studies identify several of the signal-transduction events involved in the apoptosis of malignant B cells that transpire following ligation of CD20 by anti-CD20 antibodies in the presence of Fc-receptor-expressing cells or secondary goat anti-(mouse Ig) antibodies and which may contribute to the tumor regressions observed in mouse models and clinical trials.
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PMID:Signaling events involved in anti-CD20-induced apoptosis of malignant human B cells. 1075 75

Rituximab is a chimeric monoclonal antibody (MAb) directed against the B-cell CD20 antigen that has been approved for therapy of relapsed and resistant follicular non-Hodgkin's lymphoma (NHL). This study describes the development and validation of a highly sensitive, rapid, accurate, precise enzyme-linked immunosorbent assay (ELISA) to measure Rituximab serum concentrations. This study also describes the application of the ELISA method to a pharmacokinetic study in a homogeneous group of patients with follicular lymphoma who received 4 weekly doses of MAb at the standard dose of 375 mg/m2 as consolidation of chemotherapy. In the patients in this study, the median Rituximab serum concentrations increased during therapy, and showed a slow decline during the posttreatment period. The Rituximab elimination half-life of approximately 20 days accounts for the demonstrated accumulation of MAb in serum samples. Because previous pharmacokinetic studies showed a correlation between Rituximab serum levels and tumor response, the ELISA method used in this study, which allows a precise control of serum concentrations, could be useful for predicting the final response to the MAb and for selecting patients able to benefit from higher dosage or repeated drug administration.
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PMID:Rituximab (IDEC-C2B8): validation of a sensitive enzyme-linked immunoassay applied to a clinical pharmacokinetic study. 1085 Mar 96

Dosimetry studies in patients with non-Hodgkin's lymphoma were performed to estimate the radiation absorbed dose to normal organs and bone marrow from 90Y-Zevalin (yttrium-90 ibritumomab tiuxetan, IDEC-Y2B8) treatment in this phase I/II, multicenter trial. The trial was designed to determine the dose of Rituximab (chimeric anti-CD20, Rituxan, IDEC-C2B8, MabThera), the unlabeled antibody given prior to the radioconjugate to clear peripheral blood B cells and optimize distribution, and to determine the maximum tolerated dose of 90Y-Zevalin [7.4, 11, or 15 MBq/kg (0.2, 0.3, or 0.4 mCi/kg)]. Patients received (111)In-Zevalin (indium-111 ibritumomab tiuxetan, IDEC-In2B8 ) on day 0 followed by a therapeutic dose of 90Y-Zevalin on day 7. Both doses were preceded by an infusion of the chimeric, unlabeled antibody Rituximab. Following administration of (111)In-Zevalin, serial anterior/posterior whole-body scans were acquired. Major-organ radioactivity versus time estimates were calculated using regions of interest. Residence times were computed and entered into the MIRDOSE3 computer software program to calculate estimated radiation absorbed dose to each organ. Initial analyses of estimated radiation absorbed dose were completed at the clinical site. An additional, centralized dosimetry analysis was performed subsequently to provide a consistent analysis of data collected from the seven clinical sites. In all patients with dosimetry data (n=56), normal organ and red marrow radiation absorbed doses were estimated to be well under the protocol-defined upper limit of 20 Gy and 3 Gy, respectively. Median estimated radiation absorbed dose was 3.4 Gy to liver (range 1.2-7.8 Gy), 2.6 Gy to lungs (range 0.72-4.4 Gy), and 0.38 Gy to kidneys (range 0.07-0.61 Gy). Median estimated tumor radiation absorbed dose was 17 Gy (range 5.8-67 Gy). No correlation was noted between hematologic toxicity and the following variables: red marrow radiation absorbed dose, blood T(1/2), blood AUC, plasma T(1/2), and plasma AUC. It is concluded that 90Y-Zevalin administered at nonmyeloablative maximum tolerated doses results in acceptable radiation absorbed doses to normal organs. The only toxicity of note is hematologic and is not correlated to red marrow radiation absorbed dose estimates or T(1/2), reflecting that hematologic toxicity is dependent on bone marrow reserve in this heavily pretreated population.
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PMID:Phase I/II 90Y-Zevalin (yttrium-90 ibritumomab tiuxetan, IDEC-Y2B8) radioimmunotherapy dosimetry results in relapsed or refractory non-Hodgkin's lymphoma. 1095 88

The recent clinical trial in lymphoma using tumor antigen-loaded DCs (Hsu et al, Nature Med 1996; 2: 52) demonstrates the efficiency of the use of professional antigen presenting cells (APCs) for taking up, processing and presenting tumor protein in a vaccine strategy in cancer. However, the production of large quantities of clinical grade APCs remains to be resolved. Here, we describe that both dendritic cells (DCs) and macrophages (MOs) can be efficiently differentiated in large numbers from lymphoma patients in spite of their disease and previous therapy. These cells were produced using the VAC and MAK cell processors according to standard operating procedures. DCs and MOs were differentiated from circulating monocytes in gas permeable hydrophobic bags, with 2% autologous serum and in the presence of GM-CSF and IL-13 or GM-CSF alone, respectively. DCs and MOs were then purified by counter flow centrifugation. Phenotypic, morphological and functional analysis showed that cells differentiated from patients with lymphoma present quite similar features to DCs and MOs produced from monocytes of healthy donors. Moreover, we show that MOs, when combined with CD20 antibody (Rituximab), can efficiently engulf tumor cells and propose that a such combination could be used for initiating a clinical trial in lymphoma. Thus, the possibility of producing functional DC and MOs in large amounts in conditions compatible with therapeutic application will allow the development of new immune strategies to eradicate lymphoma.
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PMID:Differentiation of antigen-presenting cells (dendritic cells and macrophages) for therapeutic application in patients with lymphoma. 1099 15


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