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Blood Oct 2009Interferon-alpha (IFN-alpha) has direct inhibitory effects on some tumors and is a potent stimulator of both the innate and adaptive immune systems. A tumor-targeting...
Interferon-alpha (IFN-alpha) has direct inhibitory effects on some tumors and is a potent stimulator of both the innate and adaptive immune systems. A tumor-targeting antibody-IFN-alpha conjugate (mAb-IFN-alpha) could kill by direct actions of the monoclonal antibody (mAb) and IFN-alpha on tumor cells and also potentiate a tumor-directed immune response. The modular Dock-and-Lock method (DNL) was used to generate 20-2b, the first immunocytokine having 4 cytokine (IFN-alpha2b) groups that are fused to the humanized anti-CD20 mAb, veltuzumab. Additional mAb-IFN-alpha constructs, each retaining potent IFN-alpha2b biologic activity, also were produced by DNL. The 20-2b shows enhanced antibody-dependent cellular cytotoxicity compared with veltuzumab but lacks complement-dependent cytotoxicity. The 20-2b inhibits in vitro proliferation of lymphoma cells and depletes them from whole human blood more potently than the combination of veltuzumab and a nontargeting, irrelevant, mAb-IFN-alpha. The 20-2b demonstrated superior therapeutic efficacy compared with veltuzumab or nontargeting mAb-IFN-alpha in 3 human lymphoma xenograft models, even though mouse immune cells respond poorly to human IFN-alpha2b. Targeting IFN-alpha with an anti-CD20 mAb makes the immunocytokine more potent than either agent alone. These findings suggest that 20-2b merits clinical evaluation as a new candidate antilymphoma therapeutic.
Topics: Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Humans; Interferon alpha-2; Interferon-alpha; Lymphoma, B-Cell; Male; Mice; Recombinant Fusion Proteins; Recombinant Proteins; Xenograft Model Antitumor Assays
PubMed: 19710501
DOI: 10.1182/blood-2009-06-228890 -
Leukemia & Lymphoma Aug 2009Monoclonal antibodies (mAbs) are increasingly used in treatment protocols for chronic lymphocytic leukemia (CLL). Here we determined (i) the extent of antibody-dependent... (Comparative Study)
Comparative Study
Monoclonal antibodies (mAbs) are increasingly used in treatment protocols for chronic lymphocytic leukemia (CLL). Here we determined (i) the extent of antibody-dependent cellular cytotoxicity (ADCC) of four different mAbs against primary CLL cells, (ii) whether ADCC correlates with antigen density on CLL cells, and (iii) whether allogeneic natural killer (NK) cells display superior ADCC than autologous. Effector cells for ADCC were (i) NK-92 cells not expressing FcR, (ii) NK-92 cells transfected with a high-affinity Fc receptor, (iii) autologous NK cells from patients with CLL, (iv) allogeneic NK cells. Results suggest that ADCC contributes to killing of CLL cells by anti-CD20 antibodies (rituximab and veltuzumab), whereas mAbs against CD22 (epratuzumab) and CD23 (lumiliximab) showed minimal ADCC. The magnitude of anti-CD20 mediated ADCC did not correlate with antigen density of CD20. ADCC was not influenced by the FcR genotype expressed by autologous NK cells. Allogeneic NK cells were superior to autologous NK cells in killing primary CLL cells.
Topics: Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antibodies, Monoclonal, Murine-Derived; Antibody-Dependent Cell Cytotoxicity; Antigens, CD; Antigens, CD20; Antigens, Neoplasm; Antineoplastic Agents; CD52 Antigen; Cell Line, Tumor; Genotype; Glycoproteins; Humans; In Vitro Techniques; Killer Cells, Natural; Leukemia, Lymphocytic, Chronic, B-Cell; Middle Aged; Receptors, IgG; Recombinant Fusion Proteins; Rituximab; Sialic Acid Binding Ig-like Lectin 2; Transfection
PubMed: 19562616
DOI: 10.1080/10428190903026500 -
Zeitschrift Fur Rheumatologie Jul 2009The clinical success of B-cell depletion using the anti-CD20 antibody rituximab has sparked a new era in the therapy of rheumatic diseases. A large variety of novel... (Review)
Review
The clinical success of B-cell depletion using the anti-CD20 antibody rituximab has sparked a new era in the therapy of rheumatic diseases. A large variety of novel B-cell directed biologic agents has been developed recently. The new strategies not only aim at depleting B-cells (ocrelizumab, veltuzumab, ofatumumab, TRU-015) but also target essential survival and proliferation factors such as BAFF (belimumab, atacicept, briobacept), and are directed at modulating B-cell function via CD22 (epratuzumab), inhibition of costimulation (abatacept) and induction of tolerance (abetimus). Thus far, clinical trials indicate high efficacy comparable to rituximab as well as a good safety profile. This review summarizes the therapeutic mechanisms of the novel B-cell directed agents and the current status of clinical trials in rheumatic diseases.
Topics: Antibodies, Monoclonal; B-Lymphocytes; Humans; Rheumatic Diseases
PubMed: 19513729
DOI: 10.1007/s00393-009-0438-2 -
Journal of Clinical Oncology : Official... Jul 2009This is a multicenter phase I/II dose-finding study in relapsed/refractory B-cell non-Hodgkin's lymphoma (NHL) evaluating veltuzumab, a humanized anti-CD20 antibody with...
PURPOSE
This is a multicenter phase I/II dose-finding study in relapsed/refractory B-cell non-Hodgkin's lymphoma (NHL) evaluating veltuzumab, a humanized anti-CD20 antibody with structure-function differences from chimeric rituximab.
PATIENTS AND METHODS
Eighty-two patients (median age, 64 years; 79% stage III/IV, one to nine prior treatments) received four once-weekly doses of 80 to 750 mg/m(2) of veltuzumab and were assessed for safety, efficacy, pharmacodynamics, pharmacokinetics, and immunogenicity.
RESULTS
Veltuzumab was well tolerated, with no grade 3 to 4 drug-related adverse events despite short infusion times (typically 2 hours initially, 1 hour subsequently at doses < 375 mg/m(2)). In follicular lymphoma, 24 (44%) of 55 patients had objective responses (OR), with 15 (27%) complete responses (CRs) or CRs unconfirmed (CRus) by International Working Group criteria, and with some responses occurring despite two to five prior rituximab-containing regimens, less favorable prognosis (elevated lactate dehydrogenase, tumors > 5 cm, and Follicular Lymphoma International Prognostic Index > or = 2), and at all dose levels. The CRs/CRus were durable (median duration, 19.7 months), with five patients still ongoing (15.9 to 37.6 months duration). In marginal zone lymphoma, five (83%) of six patients had ORs, with two CRs/CRus (33%), and in diffuse large B-cell lymphoma, three (43%) of seven patients achieved partial responses. At all dose levels studied, B cells were depleted after the first infusion, veltuzumab serum half-lives were similar after the fourth infusion, and mean antibody serum levels exceeded values considered important for anti-CD20 therapy (ie, 25 microg/mL).
CONCLUSION
Veltuzumab appeared safe and active at all tested doses, encouraging further study, including dose levels less than those typically used with rituximab.
Topics: Adult; Aged; Aged, 80 and over; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; B-Lymphocytes; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Fatigue; Female; Fever; Headache; Humans; Kaplan-Meier Estimate; Lymphoma, B-Cell; Lymphoma, Non-Hodgkin; Male; Middle Aged; Pruritus; Recurrence; Treatment Outcome
PubMed: 19451441
DOI: 10.1200/JCO.2008.19.9117 -
Blood Jun 2009The dock and lock (DNL) method is a new technology for generating multivalent antibodies. Here, we report in vitro and in vivo characterizations of 20-22 and 22-20, a...
The dock and lock (DNL) method is a new technology for generating multivalent antibodies. Here, we report in vitro and in vivo characterizations of 20-22 and 22-20, a pair of humanized hexavalent anti-CD20/22 bispecific antibodies (bsAbs) derived from veltuzumab (v-mab) and epratuzumab (e-mab). The 22-20 was made by site-specific conjugation of e-mab to 4 Fabs of v-mab; 20-22 is of the opposite configuration, composing v-mab and 4 Fabs of e-mab. Each bsAb translocates both CD22 and CD20 into lipid rafts, induces apoptosis and growth inhibition without second-antibody crosslinking, and is significantly more potent in killing lymphoma cells in vitro than their parental antibodies. Although both bsAbs triggered antibody-dependent cellular toxicity, neither displayed complement-dependent cytotoxicity. Intriguingly, 22-20 and 20-22 killed human lymphoma cells in preference to normal B cells ex vivo, whereas the parental v-mab depleted malignant and normal B cells equally. In vivo studies in Daudi tumors revealed 20-22, despite having a shorter serum half-life, had antitumor efficacy comparable with equimolar v-mab; 22-20 was less potent than 20-22 but more effective than e-mab and control bsAbs. These results indicate multiple advantages of hexavalent anti-CD20/22 bsAbs over the individual parental antibodies and suggest that these may represent a new class of cancer therapeutics.
Topics: Animals; Antibodies, Bispecific; Antibodies, Monoclonal; Antibody-Dependent Cell Cytotoxicity; Antigens, CD20; Apoptosis; Calcium; Caspases; Cell Proliferation; Cytotoxicity, Immunologic; Female; Humans; Immunotherapy; Lymphoma, B-Cell; Mice; Mice, SCID; Sialic Acid Binding Ig-like Lectin 2; Survival Rate
PubMed: 19372261
DOI: 10.1182/blood-2008-10-187138 -
Current Opinion in Molecular... Apr 2009Veltuzumab is a humanized, second-generation anti-CD20 mAb currently under development by Immunomedics Inc for the potential treatment of B-cell non-Hodgkin's lymphoma...
Veltuzumab is a humanized, second-generation anti-CD20 mAb currently under development by Immunomedics Inc for the potential treatment of B-cell non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukemia (CLL). Licensee Nycomed is developing veltuzumab for the potential treatment of rheumatoid arthritis and immune thrombocytopenic purpura (ITP). Veltuzumab contains 90 to 95% human antibody sequences with identical antigen framework regions to epratuzumab (a humanized anti-CD22 mAb) and similar antigen-binding determinants to rituximab (chimeric, anti-CD20 mAb and the first-line treatment of aggressive and indolent NHL). In vitro studies have demonstrated that veltuzumab has enhanced binding avidities and a stronger effect on complement-dependent cytotoxicity compared with rituximab in selected cell lines. In dose-finding phase I/II clinical trials in patients with low-grade NHL, intravenous veltuzumab demonstrated a substantial rate of complete responses in concurrence with shorter and more tolerable infusions compared with rituximab. Currently there has been no evidence of an immune response to repeated administrations, and no serious adverse events related to veltuzumab treatment in patients with NHL. Veltuzumab is undergoing clinical trials using a low-dose subcutaneous formulation in patients with NHL, CLL and ITP. Prospective, randomized clinical trials are needed to clarify the role veltuzumab will play in a market where the therapy of B-cell lymphoproliferative disorders is dominated by rituximab.
Topics: Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Cell Line; Clinical Trials as Topic; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Lymphoma, Non-Hodgkin; Purpura, Thrombocytopenic, Idiopathic
PubMed: 19330725
DOI: No ID Found -
Journal of Nuclear Medicine : Official... Mar 2009We determined whether therapeutic responses using a bispecific antibody that pretargeted (90)Y-hapten-peptide radioimmunotherapy or a directly radiolabeled, humanized,... (Comparative Study)
Comparative Study
UNLABELLED
We determined whether therapeutic responses using a bispecific antibody that pretargeted (90)Y-hapten-peptide radioimmunotherapy or a directly radiolabeled, humanized, (90)Y-anti-CD20 IgG (veltuzumab) could be improved by combining these treatments with unlabeled humanized antibodies against CD22 (epratuzumab), CD74 (milatuzumab), or veltuzumab.
METHODS
Nude mice bearing established subcutaneous Ramos human Burkitt lymphoma were treated with antibodies alone or in combination with pretargeted radioimmunotherapy (PT-RAIT) or radioimmunotherapy, and tumor growth was monitored. Biodistribution studies examined the effect that predosing with unlabeled veltuzumab had on radioimmunotherapy and PT-RAIT targeting.
RESULTS
None of the unconjugated antibodies was effective against established and rapidly growing xenografts, but PT-RAIT, at approximately 30% of its maximum tolerated dose, and radioimmunotherapy alone, at its maximum tolerated dose, were able to arrest growth and even entirely ablate tumors in some animals. Only combinations with veltuzumab improved therapeutic responses, most significantly when a veltuzumab regimen (weekly, 1.0 mg followed by 3 x 0.5 mg) was initiated 1 wk after PT-RAIT or (90)Y-veltuzumab. Biodistribution data indicated that when unlabeled veltuzumab (1.0 or 0.25 mg) was administered in advance of the radiolabeled veltuzumab or bispecific antibody injection, tumor uptake was significantly reduced ((111)In-veltuzumab, 47% and 25%, respectively; (111)In-hapten-peptide, 74% and 49%, respectively). Despite an approximately 50% decrease in radioactivity uptake in the tumor, antitumor responses were not diminished significantly for (90)Y-veltuzumab, and in the case of PT-RAIT responses were improved. However, higher amounts of predosed veltuzumab reduced the effects of PT-RAIT.
CONCLUSION
These studies suggest that administering unlabeled anti-CD20 IgG therapy after the radioactivity dose provides the best efficacy and that the amount of unlabeled anti-CD20 IgG administered as a predose to anti-CD20-targeted radionuclide therapy should be minimized.
Topics: Animals; Antibodies, Bispecific; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antigens, CD20; Antigens, Differentiation, B-Lymphocyte; Burkitt Lymphoma; Drug Therapy, Combination; Histocompatibility Antigens Class II; Humans; Indium Radioisotopes; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Transplantation; Radioimmunotherapy; Radiopharmaceuticals; Sialic Acid Binding Ig-like Lectin 2; Transplantation, Heterologous; Yttrium Radioisotopes
PubMed: 19223402
DOI: 10.2967/jnumed.108.058602 -
Blood Jan 2009Veltuzumab is a humanized anti-CD20 monoclonal antibody with complementarity-determining regions (CDRs) identical to rituximab, except for one residue at the 101st... (Comparative Study)
Comparative Study
Veltuzumab is a humanized anti-CD20 monoclonal antibody with complementarity-determining regions (CDRs) identical to rituximab, except for one residue at the 101st position (Kabat numbering) in CDR3 of the variable heavy chain (V(H)), having aspartic acid (Asp) instead of asparagine (Asn), with framework regions of epratuzumab, a humanized anti-CD22 antibody. When compared with rituximab, veltuzumab has significantly reduced off-rates in 3 human lymphoma cell lines tested, as well as increased complement-dependent cytotoxicity in 1 of 3 cell lines, but no other in vitro differences. Mutation studies confirmed that the differentiation of the off-rate between veltuzumab and rituximab is related to the single amino acid change in CDR3-V(H). Studies of intraperitoneal and subcutaneous doses in mouse models of human lymphoma and in normal cynomolgus monkeys disclosed that low doses of veltuzumab control tumor growth or deplete circulating or sessile B cells. Low- and high-dose veltuzumab were significantly more effective in vivo than rituximab in 3 lymphoma models. These findings are consistent with activity in patients with non-Hodgkin lymphoma given low intravenous or subcutaneous doses of veltuzumab. Thus, changing Asn(101) to Asp(101) in CDR3-V(H) of rituximab is responsible for veltuzumab's lower off-rate and apparent improved potency in preclinical models that could translate into advantages in patients.
Topics: Amino Acid Substitution; Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antibodies, Monoclonal, Murine-Derived; Antigens, CD20; Antineoplastic Agents; B-Lymphocytes; Cell Line, Tumor; Chlorocebus aethiops; Complement System Proteins; Complementarity Determining Regions; Disease Models, Animal; Drug Screening Assays, Antitumor; Humans; Lymphoma; Mice; Mutation, Missense; Rituximab; Structure-Activity Relationship
PubMed: 18941114
DOI: 10.1182/blood-2008-07-168146 -
Cancer Research Oct 2008Multivalent antibodies, either monospecific or bispecific, may improve the efficacy of current therapeutic interventions involving a single monoclonal antibody (mAb). We...
Multivalent antibodies, either monospecific or bispecific, may improve the efficacy of current therapeutic interventions involving a single monoclonal antibody (mAb). We have applied the Dock-and-Lock (DNL) method, a new platform technology for the site-specific and covalent assembly of modular components into stably tethered complexes of defined composition, to prepare a hexavalent, anti-CD20 antibody, designated Hex-hA20, which comprises six Fabs with one Fc. We show that Hex-hA20 retains the binding activity of all six Fabs, associates with CD20 in lipid rafts, affects antibody-dependent cell-mediated cytotoxicity, but not complement-dependent cytotoxicity, and inhibits proliferation of Daudi, Raji, and Ramos cells in vitro at subnanomolar concentrations without the need for a cross-linking antibody. In addition, Hex-hA20 induces strong homotypical adhesion and is inefficient in stimulating calcium mobilization. Thus, Hex-hA20 exhibits biological properties attributable to both type I and type II anti-CD20 mAbs, as exemplified by rituximab and tositumomab, respectively. Although Hex-hA20 has a short serum half-life, it shows antitumor efficacy in tumor-bearing mice comparable with veltuzumab at equivalent doses. The versatile DNL method was also applied to generate two other multivalent anti-CD20 antibodies without the Fc region, Tri-hA20 and Tetra-hA20, comprising three and four Fabs of veltuzumab, respectively. Similar to Hex-hA20, these were purified to near homogeneity and shown to have potent antiproliferative activity in vitro, thus indicating the need for clustering three or more CD20 molecules on the cell surface to induce growth inhibition.
Topics: Animals; Antibodies, Monoclonal; Antigens, CD20; Apoptosis; Calcium; Caspases; Cell Line, Tumor; Cell Proliferation; Cytotoxicity, Immunologic; Female; Humans; Lymphoma; Mice; Neoplasm Transplantation; Transplantation, Heterologous
PubMed: 18922911
DOI: 10.1158/0008-5472.CAN-08-2033 -
Clinical Cancer Research : An Official... Oct 2008Antibodies are effective therapeutic agents in cancer, but cures are rarely if ever obtained. Combination therapies are likely to be more effective than a single agent....
PURPOSE
Antibodies are effective therapeutic agents in cancer, but cures are rarely if ever obtained. Combination therapies are likely to be more effective than a single agent. In this study, the combination of a new unconjugated humanized anti-CD20 IgG, veltuzumab, with a (90)Y-conjugated humanized antibody to CD22 (epratuzumab) was evaluated for the treatment of B-cell lymphoma in a nude mouse model system.
EXPERIMENTAL DESIGN
Nude mice were grafted with the Ramos human B-lymphoma and treatment initiated when tumors were >0.1 cm(3). In most experiments, mice were injected first with unconjugated anti-CD20, then with (90)Y-anti-CD22 1 day later. Additional weekly injections of the unconjugated veltuzumab were administered for 3 weeks. Controls included a single agent only and a nonreactive control radiolabeled antibody.
RESULTS
Unconjugated anti-CD20 veltuzumab alone did not have a significant therapeutic effect, even at a total dose of 2.5 mg per mouse. The (90)Y-anti-CD22 epratuzumab alone induced marked regressions of all tumors, but they regrew in a few weeks. The combination of these agents cured approximately 80% of the mice. A nonreactive control antibody labeled with (90)Y, used without veltuzumab, had no therapeutic effect. The therapeutic effect of (90)Y-epratuzumab required the maximum tolerated dose of radioactivity, which was 160 muCi per mouse.
CONCLUSIONS
These studies illustrate how combinations of unconjugated and radioconjugated antibodies against different B-cell markers can improve therapeutic outcome, and offer a new therapeutic paradigm for the treatment of B-cell lymphomas.
Topics: Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antigens, CD20; Cell Line, Tumor; Disease Models, Animal; Humans; Immunoglobulin G; Lymphoma, B-Cell; Male; Maximum Tolerated Dose; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Transplantation; Sialic Acid Binding Ig-like Lectin 2; Yttrium Radioisotopes
PubMed: 18829494
DOI: 10.1158/1078-0432.CCR-08-0404