The combined use of an immunotoxin and a radioimmunoconjugate to treat disseminated human B-cell lymphoma in immunodeficient mice.

Immunoconjugates (ICs) consist of a targeting moiety and a toxic moiety and have the specificity that traditional cancer therapy lacks. At appropriate doses, ICs are safe and effective in treating various cancers in experimental animals and in humans. However, because cures are rarely achieved using single agents, regimens involving combinations of agents with different mechanisms of action must be evaluated. In this study, we explored the efficacy and toxicity of a combination of two IC therapies, radioimmunotherapy (RIT) and immunotoxin (IT) therapy, to treat advanced, disseminated human lymphoma in immunodeficient mice. We proposed to use the bystander effect of RIT to reduce large tumor burdens, followed by an IT to eliminate residual tumor cells. Our results indicate that, when used alone, both RIT and IT therapy were safe and effective, but not curative. When the two therapies were combined, efficacy and toxicity became dependent on the temporal order of administration. Thus, with the doses used in this study, when RIT was administered after IT therapy, the regimen was curative. In contrast, when RIT was administered before IT therapy, the combination was highly toxic or even lethal. Both RIT and IT therapy induced pulmonary vascular leak, but with different kinetics. When RIT was given prior to IT therapy, the pulmonary vascular leak became life-threatening but not when the two agents were administered in the reverse order.     

Therapy of human T-cell acute lymphoblastic leukaemia in severe combined immunodeficient mice with two different anti-CD7-saporin immunotoxins containing hindered or non-hindered disulphide cross-linkers

A SCID mouse model of human T-ALL has been used to determine the in vivo therapeutic efficacy of two anti-CD7-saporin immunotoxins constructed with either a hindered (HB2-SMPT-Sap) or non-hindered (HB2-SPDP-Sap) disulphide bond between antibody and saporin. Groups of 10 SCID mice were injected intravenously (i.v.) with 2 × 10⁶ human T-ALL HSB-2 cells followed seven days later by i.v. injection with either a single dose or with 3 doses of HB2-SPDP-Sap or HB2-SMPT-Sap given on alternate days. Control groups received equivalent sham injections of PBS or molar equivalent amounts of unconjugated HB2 antibody + saporin. Animals receiving a single dose of HB2-SMPT-Sap showed better survival than animals receiving a single dose of HB2-SPDP-Sap but the difference was not shown to be significant by log-rank analysis. When given as a triple dose both immunotoxins performed similarly. Comparison of single-dose with triple-dose IT therapy revealed that the therapeutic effect of a triple dose of HB2-SPDP-Sap was significantly better than that of single dose, but this was not the case with HB2-SMPT-Sap. Pharmacokinetic studies of HB2-SPDP-Sap and HB2-SMPT-Sap in normal and HSB-2 leukaemia bearing SCID mice failed to reveal any difference in clearance rates for these two IT's. We conclude from these studies that there is no therapeutic advantage to be gained from constructing the HB2-Sap IT with a hindered disulphide bond in this particular model of human T-ALL.     

Phase I study of radioimmunotherapy with an anti-CD20 murine radioimmunoconjugate ((90)Y-ibritumomab tiuxetan) in relapsed or refractory indolent B-cell lymphoma

We conducted a phase I study to evaluate the safety and efficacy of radioimmunotherapy with yttrium-90-ibritumomab tiuxetan (Y2B8) in Japanese patients with relapsed or refractory indolent B-cell lymphoma. Indium-111-labeled ibritumomab tiuxetan (In2B8; 3.5 or 5 mCi [129.5 or 185 MBq]) was administered on day 1, followed by serial gamma-camera imaging to investigate the distribution of In2B8 in the whole body of patients and to judge the feasibility of Y2B8 administration. Y2B8 with a dose of 0.3 mCi/kg (11.1 MBq/kg) or 0.4 mCi/kg (14.8 MBq/kg) was administered on day 8. Grade 4 neutropenia and grade 3 thrombocytopenia were observed in three of nine of the patients evaluated for safety. Critical toxicities (prolonged thrombocytopenia or severe non-hematological toxicities) were observed in two of six patients in the 0.4 mCi/kg (14.8 MBq/kg) dose group but were not seen in any of the three patients in the 0.3 mCi/kg (11.1 MBq/kg) dose group. The non-hematological toxicities of the nine patients were of grade 2 or less, except in two patients who had been heavily treated previously. They experienced critical toxicities such as infection, diarrhea, hyponatremia and prolonged thrombocytopenia, as well as other frequent grade 2 non-hematological toxicities. Although the pharmacokinetic profiles were similar to those in the US study, one of the two patients was clarified retrospectively as showing abnormal biodistribution of In2B8 in the bone marrow, as judged by an independent third party panel of radiologists. Five of the 10 participants achieved complete responses or unconfirmed complete responses and two partial responses. In conclusion, the recommended dose of Y2B8 for the subsequent phase II study for Japanese patients is 0.4 mCi/kg (14.8 MBq/kg). This dose of radioimmunotherapy was feasible when patients with altered biodistribution of In2B8 were excluded, and it was highly effective. (Cancer Sci 2005; 96: 903-910).     

Effectiveness of HB2 (anti-CD7)--saporin immunotoxin in an in vivo model of human T-cell leukaemia developed in severe combined immunodeficient mice.

The transplantation of the human T-cell acute lymphoblastic leukaemia (T-ALL) cell line HSB-2 into severe combined immunodeficient (SCID) mice was found to produce a disseminated pattern of leukaemia similar to that seen in man. The intravenous injection of 10(7) HSB-2 cells was associated with a universally fatal leukaemia. Histopathological examination of animals revealed the spread of leukaemia initially from bone marrow to involve all major organs including the meninges. An immunotoxin (HB2-Sap) was constructed by conjugating the anti-CD7 MAb HB2 to the ribosome-inactivating protein saporin. An in vitro protein synthesis inhibition assay revealed specific delivery of HB2-Sap immunotoxin (IT) to CD7+ HSB-2 target cells with an IC50 of 4.5 pM. When SCID mice were injected with 10(6) HSB-2 cells and then treated 8 days later with a single intravenous dose of 10 micrograms of immunotoxin there was a significant therapeutic effect evidenced by the numbers of animals surviving in the therapy group compared with untreated controls (chi 2 = 5.348, P = 0.021). These results demonstrate the useful application of human leukaemia xenografts in SCID mice and the potential therapeutic effect of an anti-CD7 immunotoxin in human T-ALL.     

Therapy of advanced B-lymphoma xenografts with a combination of 90Y-anti-CD22 IgG (epratuzumab) and unlabeled anti-CD20 IgG (veltuzumab)

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.     

Complete regression of human B-cell lymphoma xenografts in mice treated with recombinant anti-CD22 immunotoxin RFB4(dsFv)-PE38 at doses tolerated by cynomolgus monkeys

RFB4(dsFv)-PE38 is a recombinant immunotoxin in which the variable light domain (V(L)) is disulfide bonded via cysteine residues to the variable heavy domain (V(H)), which in turn is fused to PE38, a mutant form of Pseudomonas exotoxin A. RFB4 binds to CD22, which is a differentiation antigen expressed on the majority of B-cell leukemias and lymphomas. To examine the potential efficacy of RFB4(dsFv)-PE38 when administered at a dose schedule appropriate for phase I testing, mice bearing CA46 human CD22+ Burkitt's lymphoma xenografts were treated on alternate days i.v. for 3 doses (QOD x 3). Complete regressions were observed in 80% and 100% of mice treated with 200 and 275 microg/kg QOD x 3, respectively. The higher dose was 27% of the LD50 and 34% of the LD10 in mice. Because RFB4(dsFv)-PE38 is stable at 37 degrees C, it could also be given by continuous infusion using pumps placed in the peritoneal cavity; complete regressions also resulted from this mode of administration. To study toxicology, a pilot toxicology study of RFB4(dsFv)-PE38 was undertaken in cynomolgus monkeys, which like humans but unlike mice have CD22, which binds RFB4. Doses of 100 and 500 microg/kg i.v. QOD x 3 were well tolerated, indicating that a dose that cured tumors in mice was tolerated by primates. Based on these preclinical results, RFB4(dsFv)-PE38 is being developed for the treatment of patients with CD22-positive leukemias and lymphomas.     

Inhibition of human B-cell lymphoma by an anti-CD20 antibody and its chimeric F(ab')2 fragment via induction of apoptosis

Monoclonal antibodies (mAb) directed against CD20, either unmodified or in radiolabeled forms, have been successfully used in clinic as effective therapeutic agents in the management of non-Hodgkin's B-cell lymphoma. Despite all clinical success the exact mechanisms of action of various anti-CD20 antibodies remains mostly unclear. Several mechanisms have been proposed to be responsible for the therapeutic activity of anti-CD20 antibodies, including antibody-dependent cell-mediated cytotoxicity, complement-mediated cytotoxicity, and direct inhibition of tumor growth via induction of apoptosis. We previously produced an anti-CD20 mAb, HI47, and showed that the antibody effectively blocked human B-cell proliferation in vitro and inhibited xenografted B-cell lymphoma in nude mice. In this study, we engineered the chimeric versions of both the Fab and F(ab)'2 fragments of HI47 and produced the fragments in E. coli. Both fragments competed efficiently with HI47 for binding to CD20+ B cells, and inhibited proliferation of B-lymphoma cells in a dose-dependent manner. Mechanistic studies revealed that both antibody fragments induced significant degree of B-cell apoptosis that is independent of any cross-linking agents. Further, both the F(ab)'2 and Fab fragments when administered in vivo significantly inhibited the growth of human B-cell lymphoma xenografts in nude mice. The bivalent F(ab)'2 fragment showed consistently better efficacy compared to its monovalent Fab counterpart in inducing apoptosis and inhibiting B-cell lymphoma growth both in vitro and in vivo. Taken together, these observations suggest that HI47 and its fragments most likely exert their antitumor activity through induction of cell apoptosis, and cross-linking/dimerization of CD20 molecules on B- cell surface is an important, but not essential, process for therapeutic efficacy of HI47 and its fragments.     

Feasibility and pharmacokinetic study of a chimeric anti-CD20 monoclonal antibody (IDEC-C2B8, rituximab) in relapsed B-cell lymphoma

Background: In clinical trials in the USA, IDEC-C2B8 (a mouse-humanchimeric anti-CD20 monoclonal antibody) has demonstrated high response rateswith only mild toxic effects in relapsed B-cell lymphoma at a dose of fourweekly 375 mg/m² infusions. The aim of the present trial wasto determine whether or not this dose is practically applicable to Japanesepatients with relapsed B-cell lymphoma with respect to safety,pharmacokinetics and efficacy.Patients and methods: Patients with relapsed CD20+ B-cell lymphomareceived intravenous infusions of IDEC-C2B8 once a week for four weeks. Atotal of 12 patients (four at 250 mg/m² and eight at 375mg/m²) were enrolled.Results: All 11 eligible patients treated with either dose leveltolerated IDEC-C2B8 well. Commonly observed adverse drug reactions weregrades 1 or 2 non-hematologic toxicities during the infusion, consistingmostly of flu-like symptoms and skin reactions. All of the observedhematologic toxicities were of grade 3 or less, and transient. A rapid andsustained B-cell decrease in peripheral blood was observed, but noinfectious episodes were encountered. Human anti-mouse and anti-chimericantibodies were not detected. Of the 11 eligible patients (eight withfollicular, two with diffuse large-cell and one with mantle cell lymphoma),two showed a complete response and five showed a partial response, and allof the seven responders had lymphoma with follicular histology. Apharmacokinetic analysis showed that the elimination half-life (T1/2) ofIDEC-C2B8 was 445 ± 361 hours, and that the serum antibody levelsincreased in parallel with the course of infusions, and in most patients wasstill measurable at three months.Conclusions: The dose of four weekly 375 mg/m² infusionsof IDEC-C2B8 is safe and effective in Japanese patients with relapsed B-celllymphoma. Further studies evaluating IDEC-C2B8 are warranted.     

European phase II study of rituximab (chimeric anti-CD20 monoclonal antibody) for patients with newly diagnosed mantle-cell lymphoma and previously treated mantle-cell lymphoma, immunocytoma, and small B-cell lymphocytic lymphoma.

PURPOSE: Mantle-cell lymphoma (MCL), immunocytoma (IMC), and small B-cell lymphocytic lymphoma (SLL) are B-cell malignancies that express CD20 and are incurable with standard therapy. A multicenter phase II study was conducted to assess the toxicity and the overall response rates (RR) and complete response (CR) rates to rituximab (chimeric anti-CD20 monoclonal antibody). PATIENTS AND METHODS: Between January 1997 and January 1998, 131 patients with newly diagnosed MCL (MCL1; n = 34) and previously treated MCL (MCL2; n = 40), IMC (n = 28), and SLL (n = 29) received rituximab 375 mg/m(2)/wk for 4 weeks via intravenous infusion. Restaging studies were performed 1 and 2 months after treatment. An analysis of the duration of response was conducted in December 1998. RESULTS: Eleven patients were unassessable, including one who died of splenic rupture after the first infusion. The RR among the 120 assessable patients was 30% (36 of 120 patients). The RR by histology was as follows: MCL1, 38%; MCL2, 37%; IMC, 28%; and SLL, 14%. Ten patients, all with MCL, achieved CR. The median duration of response in MCL was 1.2 years. Immediate side effects were common and usually responded to adjustments in the infusion rate. There were 31 episodes of infection after treatment; most cases were mild. Cardiac arrhythmia and ophthalmologic side effects occurred in 10 and nine patients, respectively, including one case of severe loss of visual acuity. CONCLUSION: Single-agent rituximab has moderate activity in MCL and IMC but only limited activity in SLL. The duration of response in MCL was similar to that previously reported in follicular lymphoma. Its use in combination with cytotoxic chemotherapy to increase the CR rate is warranted in MCL and IMC.     

Establishment of a human t(4;11) leukemia in severe combined immunodeficient mice and successful treatment using anti-CD19 (B43)-pokeweed antiviral protein immunotoxin.

Human acute leukemia, with a chromosomal translocation involving chromosomes 4 and 11, t(4;11)(q21;q23), is the most common form of leukemia in infants and responds very poorly to conventional therapy. A human CD19+ mixed-lineage leukemia cell line with a t(4;11)(q21;q23) translocation, RS4;11, disseminated and proliferated in the hematopoietic tissues and other organs of mice with severe combined immunodeficiency in a manner similar to that observed in humans and killed 100% of the animals. The anti-CD19(B43)-pokeweed antiviral protein immunotoxin selectively inhibited clonogenic RS4;11 cells in vitro, markedly reduced the burden of disseminated leukemia of severe combined immunodeficient mice, and, most importantly, resulted in the long-term survival of treated animals. This severe combined immunodeficient mouse model should be useful for the design of more effective treatment strategies for refractory human leukemias.     

A phase I/II study of galiximab (an anti-CD80 monoclonal antibody) in combination with rituximab for relapsed or refractory, follicular lymphoma.

BACKGROUND: Galiximab is a monoclonal antibody that targets CD80, a costimulatory molecule constitutively expressed on follicular and other lymphomas. Modest single-agent clinical activity and tolerability were demonstrated in a phase I study in relapsed or refractory, follicular non-Hodgkin's lymphoma (NHL). A phase I/II study was conducted to evaluate galiximab in combination with a standard course of rituximab. Safety, pharmacokinetics, and efficacy were evaluated. PATIENTS AND METHODS: Patients with follicular NHL who had relapsed or failed primary therapy were enrolled. Rituximab-refractory patients (no response or a response with time to progression <6 months) were excluded. Patients received 4 weekly i.v. infusions of galiximab (125, 250, 375, or 500 mg/m(2)) and rituximab (375 mg/m(2)). International Workshop Response Criteria (IWRC) were used to evaluate response. RESULTS: Seventy-three patients received treatment. All had received at least one prior lymphoma therapy; 40% were rituximab naive. Infusions were delivered in an outpatient setting and were well tolerated. The most common study-related adverse events (AE) were lymphopenia, leukopenia, neutropenia, fatigue, and chills. The overall response rate at the recommended phase II dose of galiximab (500 mg/m(2)) was 66%: 19% complete response, 14% unconfirmed complete response, and 33% partial response. The median progression free survival was 12.1 months. Combination therapy did not appear to alter pharmacokinetics. CONCLUSION: These results indicate that galiximab can be safely combined with a standard course of rituximab. This doublet biologic approach offers the potential to avoid or delay chemotherapy or to integrate with other lymphoma therapies. A phase III, randomized study evaluating clinical benefit of rituximab versus the combination has been initiated.     

Phase I study of LY2469298, an Fc-engineered humanized anti-CD20 antibody, in patients with relapsed or refractory follicular lymphoma

Patients with follicular lymphoma (FL), where position 158 of FcγR-IIIa is heterozygous valine/phenylalanine or homozygous phenylalanine (F-carriers), have natural killer cells with lower binding affinity to IgG than valine homozygote patients. In addition, F-carriers show less efficacy with rituximab treatment than patients homozygous for valine. LY2469298 is a humanized IgG1 monoclonal antibody targeting CD20, with human germline framework regions, and specific amino acid substitutions engineered into the Fc region to increase effector function in antibody-dependent cell-mediated cytotoxicity. This dose-escalation, phase I study was conducted to assess the safety, pharmacokinetics and preliminary efficacy of LY2469298 in Japanese patients with previously treated, CD20-positive FL who had not relapsed or progressed within 120 days of prior rituximab. LY2469298 was administered by intravenous infusion at 100 or 375 mg/m(2) weekly for 4 weeks. Ten patients were enrolled (median age, 60 years); all had previously been treated with rituximab. Nine patients were F-carriers while one was homozygous for valine at position 158 of FcγRIIIa. No patients developed dose-limiting toxicities, and the most frequent adverse events were lymphopenia, pyrexia, leukopenia, chills and neutropenia. Five (50%) of the ten patients responded to LY2469298 treatment (three complete responses, one unconfirmed complete response and one partial response). Serum LY2469298 was eliminated in a biphasic manner and the pharmacokinetic profiles were not different from those in a preceding study in the United States. In conclusion, LY2469298 was well tolerated and clinical activity was observed in FL patients pretreated with rituximab, mostly consisting of F-carriers. Further investigation of FL is warranted.     

Reduction of tumor burden and stabilization of disease by systemic therapy with anti-CD20 antibody (rituximab) in patients with primary cutaneous B-cell lymphoma

BACKGROUND: Primary cutaneous B-cell lymphoma (CBCL) is characterized by restriction to the skin, a high incidence of recurrence after various treatment modalities, and a variable but mostly favorable prognosis. METHODS: Ten patients with long standing primary CBCL (3 with follicular CBCL, 5 with cutaneous, large B-cell lymphoma, 1 with diffuse large cell lymphoma, and 1 with extranodal large cell lymphoma) were treated by intravenous application of a chimeric antibody against the CD20 transmembrane antigen that is present on malignant and normal B-cells. In 6 of 10 patients, several treatment attempts either had failed or could not be used due to severe side effects or underlying disease. RESULTS: The treatment regimen resulted in two complete regressions, five partial responses, and one mixed response, and two patients did not respond to the treatment. No severe side effects occurred, except for slight pain in the nodules after infusion and an urticarial reaction at the tumor sites. A prolonged, complete disappearance of B-cells from the peripheral blood was observed. The immunoglobulin serum levels and inflammatory markers were unchanged. Histologic examination of biopsies from two regressing tumor nodes showed necrotic tumor cells and infiltration with CD8 positive cells. CONCLUSIONS: Intravenous therapy with the anti-CD20 antibody rituximab is a nontoxic and effective treatment for patients with primary cutaneous B-cell lymphoma.     

Pharmacokinetics, biodistribution, and gamma camera imaging of 111In-KC-4G3 murine monoclonal antibody in athymic nude mice with or without human tumor xenografts

The pharmacokinetics and tissue distribution of the monoclonal antibody radioconjugate 111In-diethylenetriaminepentaacetic acid-KC-4G3, which is directed against a high molecular weight mucin(s) antigen expressed on the human milk fat globule and many epithelial cell membranes, were examined in BALB/c nude mice with and without xenografts of the human tumor lines ZR-75 (mammary adenocarcinoma, KC-4G3 antigen positive) and BALL-1 (B-cell lymphoma, KC-4G3 antigen negative). Plasma of ZR-75 and BALL-1 tumor-bearing nude mice inoculated with 111In-KC-4G3 had a higher initial volume of distribution (V1), steady state volume of distribution (Vss), and plasma clearance and a lower initial half-life (t1/2 alpha) than non-tumor-bearing nude mice. There were no significant differences in biological half-life (t1/2 beta) in tumor- and non-tumor-bearing nude mice. Urinary and fecal excretion of radioactivity by ZR-75 tumor-bearing mice was greater than that of BALL-1 and non-tumor-bearing mice. Localization of 111In-KC-4G3 in mice bearing xenografts of ZR-75 was significantly greater than in mice with BALL-1 tumors. Uptake of 111In-KC-4G3 by ZR-75 tumors averaged 14% of injected dose/g at 72 h after inoculation and was unaffected by antibody dose. Significantly, the radioconjugate concentration in ZR-75 tumors remained relatively constant from 72 to 336 h post-inoculation, while that in normal tissues declined considerably over this period. Nonspecific reticuloendothelial tissue uptake of 111In-KC-4G3 was only moderately affected by pretreatment with a large excess of unlabeled normal mouse immunoglobulin and was not changed by treatment with asialofetuin. Further enhancement of specific localization of 111In-KC-4G3 was obtained by subtraction of the blood pool identified by co-inoculation of 131I-labeled, isotype-identical, normal mouse immunoglobulin. Gamma camera images of 111In-KC-4G3-inoculated ZR-75 tumor-bearing mice showed enhanced tumor localization compared to mice with BALL-1 tumors. The results of this study suggest that 111In-KC-4G3 may prove useful for imaging and possibly therapy of human malignancies expressing the high molecular weight epithelial mucin(s).     

Bcl-2 antisense oligonucleotides are effective against systemic but not central nervous system disease in severe combined immunodeficient mice bearing human t(14;18) follicular lymphoma.

The t(14;18) is present in 85-90% of follicular lymphomas. It results in overexpression of the Bcl-2 protein, which inhibits apoptosis and plays a role in lymphomagenesis. Bcl-2 antisense oligonucleotides (ODNs) down-regulate Bcl-2 expression and inhibit growth of the follicular lymphoma cell line WSU-FSCCL. In this study, we have established a human lymphoma xenograft model in severe combined immunodeficient (SCID) mice using the WSU-FSCCL cell line. s.c., i.v., or i.p. injection of WSU-FSCCL cells into SCID mice results in the development of disseminated tumors, with the liver, spleen, bone marrow, and lymph nodes as major sites of disease. Tumors were fatal in 7-14 weeks, depending on cell inoculum and route of administration. Immunohistochemistry, flow cytometry, and cytogenetic analysis confirmed the human B-cell origin of tumor cells in the xenograft. Phosphorothioate ODNs against the translation initiation site of bcl-2 mRNA in the antisense and mismatched antisense sequences were administered i.v. or i.p. to the xenograft models three times a week for 2 weeks, starting on day 7 after tumor injections. Antisense-treated animals had significantly longer survival (mean, 11.6 weeks) compared with 7.6 weeks for the control group and 7.5 weeks for the mismatched antisense-treated animals (P = 0.002 and 0.004, respectively). More significantly, a pathological examination showed no tumor in the liver, spleen, or bone marrow of the antisense group. However, subsequent experiments showed that the central nervous system was involved, causing mice to die although other sites were disease free. We conclude that bcl-2 antisense ODN therapy is effective against systemic FSCCL disease in SCID mice xenografts; however, it does not prevent disease dissemination into the central nervous system causing animal death.     

R-GEMOX方案补救治疗复发或难治性弥漫大B细胞淋巴瘤

目的:观察利妥昔单抗联合盐酸吉西他滨和奥沙利铂(R-GEMOX)治疗复发或难治性弥漫大B细胞淋巴瘤的疗效和毒副反应。方法:利妥昔单抗375mg/m2化疗前1天静脉滴入,吉西他滨1000mg/m2,静脉滴入d1,d8,奥沙利铂130mg/m2,静脉滴入d2,以3周为1个化疗周期,3周期后评价临床疗效。结果:11例患者中,完全缓解(CR)3例,部分缓解(PR)4例。1例稳定(SD),3例进展(PD)。总缓解率为63.6%。化疗毒副反应主要为轻度的胃肠道反应,少数患者出现轻度的骨髓抑制,如白细胞及血小板减少。结论:利妥昔单抗联合盐酸吉西他滨和奥沙利铂(R-GEMOX)对复发或难治性进展型弥漫大B细胞淋巴瘤有较好的近期疗效,大部分患者可以承受其毒性,是一个值得进一步验证的补救性化疗方案。     

(90)Y ibritumomab tiuxetan (Zevalin) combined with BEAM (Z -BEAM) conditioning regimen plus autologous stem cell transplantation in relapsed or refractory low-grade CD20-positive B-cell lymphoma. A GELA phase II prospective study

BackgroundThis study was designed to evaluate the safety and efficacy of a conventional dose of yttrium-90 (⁹⁰Y) ibritumomab tiuxetan combined with the etoposide rabinoside acytarabine melphalan (BEAM) regimen before autologous stem cell transplantation (ASCT) in chemosensitive relapsed or refractory low-grade B-cell lymphomas.Patients and MethodsFrom March 2005 to August 2006, 77 prospective patients were included, 69 (90%) with follicular lymphomas.ResultsThe last salvage chemotherapy regimen included rituximab for 74 patients and ASCT for 75 patients. Before ASCT, rates of complete response/unconfirmed response (CR/CRu) and partial response were 77% and 23%, respectively. After zevaline-BEAM (Z-BEAM), time to >1 × 10⁹/L neutrophils was 12 days (range, 9-35 days), and time to >20 × 10⁹/L platelets was 12 days (range, 3-42 days). No other significant extrahematologic toxicity was observed. Three months after ASCT, 68 patients (88%) were in CR/CRu. After a median follow-up of 28 months, 2-year event-free survival (EFS) and overall survival were 63% and 97%, respectively, but EFS for first-relapsed patients was 72%. When using patients as their own controls, 2-year EFS was superior after ASCT and compared favorably with the duration of response of last chemotherapy (62% vs. 37%, P = .007) (Point 1.10).ConclusionZ-BEAM appears safe and needs to be further evaluated in a randomized trial.     

Consistent downregulation of human lactoferrin gene,in the common eliminated region 1 on 3p21.3, following tumor growth in severe combined immunodeficient (SCID) mice

Lactoferrin (LF) is one of 19 active genes in the common eliminated region 1 at 3p21.3 identified by us. LF was transfected into mouse fibrosarcoma A9. Fourteen severe combined immunodeficient (SCID) derived tumors from two PI based artificial chromosome (PAC)-transfectants containing the entire LF gene and two LF-cDNA transfectants were analyzed by real time polymerase chain reaction at the DNA and RNA level. Following SCID tumor passage, LF expression was decreased or eclipsed, in all tumors although DNA levels did not change considerably. Promoter methylation and/or rearrangement of the insertion site may be responsible for human LF downregulation in mouse fibrosarcoma derived tumors.     

Successful graft of HTLV-I-transformed human T-cells (MT-2) in severe combined immunodeficiency mice treated with anti-asialo GM-1 antibody.

To develop an experimental model of adult T-cell leukemia/lymphoma in small animals, severe combined immunodeficiency (SCID) mice treated with anti-asialo GM-1 antibody were inoculated with MT-2 cells, a cell line transformed by the human T-cell leukemia virus (HTLV-I). Three mice injected with 4 x 10(7) cells subcutaneously or intramuscularly developed tumors at or near inoculation sites. Immunofluorescent antibody (IFA) staining for HTLV-I structural protein, p19, revealed the specific antigen in the cytoplasm of most cells from tumors and the DNA signals of HTLV-I proviral DNA were also positive in cellular DNA by polymerase chain reaction assay with HTLV-I tax gene primers, SK43/SK44. The MT-2 cells did not invade in mouse organs.