Rituximab: a benchmark in the development of chemotherapy-free treatment strategies for follicular lymphomas.

Background: With the introduction of the anti-CD20 antibody rituximab, the outcome of patients with follicular lymphoma (FL) has greatly improved over the last two decades. First-line prolonged rituximab monotherapy is effective, achieving long-term remission and prolonged failure-free survival in some patients. Additionally, rituximab has been shown to synergize with chemotherapeutic and novel targeted agents alike with measurable gains in duration of response. As such, rituximab has made its mark in the treatment of FL and remains a valid agent despite the availability of newer monoclonal antibodies. This review summarizes the evolving role of rituximab as the first available anti-CD20 monoclonal antibody, emphasizing its clear activity as a single agent and in combination with chemotherapy or molecular targeted agents, and setting the standard for the development of new anti-CD20 monoclonal antibodies. Conclusion: We provide data that support the ongoing use of rituximab as a therapeutic partner for novel agents in future clinical trials exploring chemotherapy-free alternatives.

The role of body mass index in survival outcome for lymphoma patients: US intergroup experience.

BACKGROUND: The role of body mass index (BMI) in survival outcomes is controversial among lymphoma patients. We evaluated the association between BMI at study entry and failure-free survival (FFS) and overall survival (OS) in three phase III clinical trials, among patients with diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL) and Hodgkin's lymphoma (HL). PATIENTS AND METHODS: A total of 537, 730 and 282 patients with DLBCL, HL and FL were included in the analysis. Baseline patient and clinical characteristics, treatment received and clinical outcomes were compared across BMI categories. RESULTS: Among patients with DLBCL, HL and FL, the median age was 70, 33 and 56; 29%, 29% and 37% were obese and 38%, 27% and 37% were overweight, respectively. Age was significantly different among BMI groups in all three studies. Higher BMI groups tended to have more favorable prognosis factors at study entry among DLBCL and HL patients. BMI was not associated with clinical outcome with P-values of 0.89, 0.30 and 0.40 for FFS, and 0.64, 0.67 and 0.09 for OS, for patients with DLBCL, HL and FL, respectively. The association remains non-significant after adjusting for other clinical factors in the Cox model. A subset analysis of males with DLBCL treated on R-CHOP revealed no differences in FFS (P = 0.48) or OS (P = 0.58). CONCLUSION: BMI was not significantly associated with clinical outcomes among patients with DLBCL, HD or FL, in three prospective phase III clinical trials. The findings contradict some previous reports of similar investigations. Further work is required to understand the observed discrepancies.

Primary CNS posttransplant lymphoproliferative disease (PTLD): an international report of 84 cases in the modern era.

We performed a multicenter, International analysis of solid organ transplant (SOT)-related primary central nervous system (PCNS) posttransplant lymphoproliferative disease (PTLD). Among 84 PCNS PTLD patients, median time of SOT-to-PTLD was 54 months, 79% had kidney SOT, histology was monomorphic in 83% and tumor was EBV+ in 94%. Further, 33% had deep brain involvement, 10% had CSF involvement, while none had ocular disease. Immunosuppression was reduced in 93%; additional first-line therapy included high-dose methotrexate (48%), high-dose cytarabine (33%), brain radiation (24%) and/or rituximab (44%). The overall response rate was 60%, while treatment-related mortality was 13%. With 42-month median follow-up, three-year progression-free survival (PFS) and overall survival (OS) were 32% and 43%, respectively. There was a trend on univariable analysis for improved PFS for patients who received rituximab and/or high-dose cytarabine. On multivariable Cox regression, poor performance status predicted inferior PFS (HR 2.61, 95% CI 1.32-5.17, p = 0.006), while increased LDH portended inferior OS (HR 4.16, 95% CI 1.29-13.46, p = 0.02). Moreover, lack of response to first-line therapy was the most dominant prognostic factor on multivariable analysis (HR 8.70, 95% CI 2.56-29.57, p = 0.0005). Altogether, PCNS PTLD appears to represent a distinct clinicopathologic entity within the PTLD spectrum that is associated with renal SOT, occurs late, is monomorphic and retains EBV positivity.

A multicenter phase II study incorporating high-dose rituximab and liposomal doxorubicin into the CODOX-M/IVAC regimen for untreated Burkitt's lymphoma.

BACKGROUND: Despite improvement with intensive multi-agent chemotherapy, 2-year progression-free survival (PFS) rates for adults with high-risk Burkitt's lymphoma (BL) remains <55%. PATIENTS AND METHODS: We conducted a phase II trial for newly diagnosed classic BL utilizing liposomal doxorubicin (Adriamycin) in lieu of doxorubicin and incorporating intravenous rituximab (at 500 mg/m(2) twice/cycle) into the CODOX-M/IVAC regimen. Correlative analyses included paired serum and cerebrospinal fluid (CSF) rituximab levels and close examination of cardiac function. RESULTS: Among 25 BL patients, the median age was 44 years (23-70) and 4 patients were HIV positive. There were 20 high-risk and 5 low-risk patients. At baseline, 40% of high-risk patients had bone marrow involvement, 35% had bulky disease and 15% had central nervous system involvement. The overall response rate was 100% (complete remission 92%). At 34-month median follow-up, the 2-year PFS and overall survival (OS) rates for all patients were 80% and 84%, respectively (low-risk: both 100%; high-risk: 76% and 81%, respectively). Furthermore, the 2-year PFS, OS, and disease-specific survival (DSS) rates for high-risk, HIV-negative patients were 84%, 89% and 100%, respectively. Adverse events (AEs) appeared to be consistent with prior CODOX-M/IVAC data, although there were several grade 3 cardiac events noted (all declined ejection fraction without clinical symptoms). The mean serum rituximab levels at 24 h after cycles 1 and 3 for patients without relapse were 258 and 306 µg/ml, respectively, versus 131 and 193 µg/ml, respectively, for patients with early progression (P = 0.002 and 0.002, respectively). The mean CSF rituximab levels for all patients were 0.11 and 0.24 µg/ml, respectively, at cycle 1 (24/72 h), which equated to serum:CSF ratios of 0.05% and 0.20%, respectively. CONCLUSIONS: The integration of rituximab into CODOX-M/IVAC for adult BL was feasible and tolerable, while changes in cardiac function warrant continued examination. This regimen was associated with excellent survival rates for HIV-negative BL. Further investigation of the predictive value of serum rituximab is needed. Clinicaltrials.gov NCT00392990.

Carbon dioxide partial pressure in the columbia river.

Columbia River water is supersaturated with respect to atmospheric carbon dioxide by 200 to 870 parts per million. An equilibrium exists between the carbon dioxide partial pressure and pH, and Henry's law is obeyed in this natural water. The carbon dioxide pressure can be calculated by a determination of the pH, total carbon dioxide, and temperature.

Submarine thermal sprirngs on the galapagos rift.

The submarine hydrothermal activity on and near the Galápagos Rift has been explored with the aid of the deep submersible Alvin. Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new oceanic lithosphere at the Galápagos Rift in the first million years may be vented from thermal springs, predominantly along the axial ridge within the rift valley. The vent areas are populated by animal communities. They appear to utilize chemosynthesis by sulfur-oxidizing bacteria to derive their entire energy supply from reactions between the seawater and the rocks at high temperatures, rather than photosynthesis.

Modulation of neutrophil function by lysozyme. Potential negative feedback system of inflammation.

Host responses to infectious organisms should be modulated so that tissue-damaging products of inflammatory cells do not produce excessive destruction of normal tissue. Lysozyme, which is continuously secreted by monocytes, which, in turn, migrate relatively late to inflammatory areas, was found to significantly dampen several responses of neutrophils to inflammatory stimulants. Thus, human lysozyme obtained and purified from the urine of patients with monocytic leukemia (but not its structurally similar and comparably cationic analogue, eggwhite lysozyme) depresses chemotaxis of normal neutrophils to activated complement, bacterial supernate, and N-formylmethionyl-phenylalanine. In addition, human (but not eggwhite) lysozyme depresses oxidative metabolism (hexose monophosphate shunt activity) and superoxide generation of neutrophils. The specificity of the suppressive effects was indicated by inhibition studies with rabbit antihuman lysozyme antibody, and with the trisaccharide of N-acetylglucosamine, a specific inhibitor of lysozyme. The results suggest that lysozyme, a product of inflammatory cells themselves, may function in a negative feedback system to modulate the inflammatory response.

Ideal rather than actual body weight should be used to calculate cell dose in allogeneic hematopoietic stem cell transplantation.

Whether the CD34+ and CD3+ cell doses in allogeneic HSCT should be estimated using actual (ABW) or ideal (IBW) body weight has never been definitively determined. We have shown that CD34+ cell doses based upon IBW are better predictive of engraftment after autologous and allogeneic HSCT. Sixty-three patients undergoing reduced-intensity HSCT after a uniform preparative regimen were evaluated to determine the effect of cell dose. ABW and IBW were 45-147 kg (median 79) and 52-85 kg (median 67) respectively. The ABW-IBW difference was -24% to +133% (median +16%); nine patients were >5% underweight and 41 were >5% overweight. The CD34+ cell dose (10(6)/kg) was 1.4-11.8 (median 5) by IBW and 1.2-9.3 (median 4.5) by ABW. The CD3+ cell dose (10(8)/kg) was 0.9-14.9 (median 3) by IBW and 0.7-19.7 (median 2.7) by ABW. While CD34+ and CD3+ cell doses based upon IBW were found to affect transplant-related mortality, and disease-free and overall survival significantly, those based on ABW were either not predictive of outcome or the differences were of borderline significance. We suggest using IBW rather than ABW to calculate cell doses for HSCT; for statistical analyses and for clinical practice if a specific cell dose is being targeted.

Does younger donor age affect the outcome of reduced-intensity allogeneic hematopoietic stem cell transplantation for hematologic malignancies beneficially?

Sixty three patients aged 27-66 years (median 52) were allografted from HLA-matched sibling (n=47), 10 of 10 allele-matched unrelated (n=19), or one-antigen/allele-mismatched (n=7) donors aged 24-69 years (median 46) after a conditioning regimen comprising 100 mg/m(2) melphalan. Cyclophosphamide (50 mg/kg) was also administered to patients who had not been autografted previously. Cyclosporine or tacrolimus, and mycophenolate mofetil were administered to prevent graft-versus-host disease (GVHD). The 2-year cumulative incidences of relapse and TRM were 55 and 24% respectively, and 2-year probabilities of overall survival (OS) and disease-free survival (DFS) were 36 and 21%, respectively. Poor performance status, donor age >45 years and elevated lactate dehydrogenase (LDH) increased the risk of treatment-related mortality (TRM), refractory disease and donor age >45 years increased the risk of relapse, and OS and DFS were adversely influenced by refractory disease, poor performance status, increased LDH, and donor age >45 years. Our data suggest that younger donor age is associated with better outcome after sub-myeloablative allogeneic hematopoietic stem cell transplantation (HSCT) for hematologic malignancies due to lower TRM and relapse. This finding raises the question of whether a young 10-allele-matched unrelated donor is superior to an older matched sibling donor in patients where the clinical situation permits a choice between such donors.

Separation of clonogenic tumor cells from small cell lung cancer bone marrow and small cell lung cancer cell lines.

One of the major obstacles to successful autologous bone marrow transplantation is tumor contamination of the marrow. We attempted to separate tumor cells from the marrow of patients with small cell lung cancer by layering bone marrow on a discontinuous albumin gradient and then assessing hematopoietic potential (CFUc) and clonogenic tumor cells (TCFUc) by standard techniques. In the six of seven patients whose bone marrow grew tumor colonies, 75 to 80% of CFUc could be found in Fraction 3 of the gradient; while 80 to 90% of TCFUc could be found in light-density Fraction 1 + 2. Furthermore, we observed tumor colony growth in Fraction 1 + 2 in some patients whose unfractionated bone marrow failed to grow tumor colonies. In separate experiments, we layered five cell lines established in patients with small cell lung cancer on the gradient and found that cells from four of the five lines also migrated to Fraction 1 + 2, and TCFUc from these lines were observed in Fractions 1 + 2 in three of four lines tested. We conclude that gradient fractionation may be one way of removing clonogenic tumor cells from the bone marrow of small cell lung cancer patients prior to autologous transplantation.

Phase I study of fludarabine plus cyclophosphamide in patients with previously untreated low-grade lymphoma: results and and long-term follow-up--a report from the Eastern Cooperative Oncology Group.

PURPOSE: To determine the toxicity and recommended phase II doses of the combination of fludarabine plus cyclophosphamide in chemotherapy-naive patients with low-grade lymphoma. PATIENTS AND METHODS: Previously untreated patients with low-grade lymphoma were entered onto dosing cohorts of four patients each. The cyclophosphamide dose, given on day 1, was increased from 600 to 1, 000 mg/m(2). Fludarabine 20 mg/m(2) was administered on days 1 through 5. The first eight patients were treated every 21 days; later patients were treated every 28 days. Prophylactic antibiotics were required. RESULTS: Prolonged cytopenia and pulmonary toxicity each occurred in three of eight patients treated every 3 weeks. The 19 patients treated every 28 days, who were given granulocyte colony-stimulating factor as indicated, did not have undue nonhematologic toxicity. Dose-limiting toxicity was hematologic. At the recommended phase II/III dose (cyclophosphamide 1,000 mg/m(2)), grade 4 neutropenia was observed in 17% of all cycles and 31% of first cycles. Grade 3 or 4 thrombocytopenia was seen in only 1% of all cycles. The median number of cycles per patient was six (range, two to 11) for all patients enrolled. The response rate was 100% of 27 patients entered; 89% achieved a complete and 11% a partial response. Nineteen of 22 patients with bone marrow involvement had clearing of the marrow. Median duration of follow-up was more than 5 years; median overall and disease-free survival times have not been reached. Kaplan-Meier estimated 5-year overall survival and disease-free survival rates were 66% and 53%, respectively. CONCLUSION: The recommended dosing for this combination in patients with previously untreated low-grade lymphoma is cyclophosphamide 1, 000 mg/m(2) day 1 and fludarabine 20 mg/m(2) days 1 through 5. The regimen has a high level of activity, with prolonged complete remissions providing 5-year overall and disease-free survival rates as high as those reported for other therapeutic approaches in untreated patients.

2-Chlorodeoxyadenosine is an active salvage therapy in advanced indolent non-Hodgkin's lymphoma.

PURPOSE: To determine the response rate to 2-chlorodeoxyadenosine (2-CdA; cladribine) in patients with advanced indolent non-Hodgkin's lymphoma (NHL) who fail to respond to or progress after a response to standard chemotherapy drugs. PATIENTS AND METHODS: Twenty-one patients were treated with at least one cycle of 2-CdA 0.1 mg/kg/d by continuous infusion for 5 or 7 days. RESULTS: The overall response rate (complete response [CR] and partial response [PR]) was nine of 21 patients (43%; 95% confidence interval, 22% to 64%). Unmaintained durable responses (longest follow-up, 29+ months) have been observed. The treatment was well tolerated by all patients. The major toxicity was related to myelosuppression (predominantly neutropenia) and immunosuppression with infection. CONCLUSION: The purine analog 2-CdA is an active salvage therapy in pretreated patients with indolent NHL, and deserves further assessment in untreated patients and in combination with other chemotherapy agents.

Phase I trial of dose escalation with growth factor support in patients with previously untreated diffuse aggressive lymphomas: determination of the maximum-tolerated dose of ProMACE-CytaBOM.

PURPOSE: The aim of this study was to determine the maximum-tolerated dose (MTD) of cyclophosphamide, doxorubicin, etoposide, prednisone, bleomycin, cytarabine, methotrexate, and leucovorin (ProMACE-CytaBOM) when the myelotoxic drugs cyclophosphamide, doxorubicin, etoposide, and cytarabine are escalated. PATIENTS AND METHODS: Thirty-eight eligible patients with diffuse aggressive non-Hodgkin's lymphoma were treated on a phase I trial of dose escalation using the ProMACE-CytaBOM regimen and granulocyte-macrophage colony-stimulating factor (GM-CSF; Schering, Kenilworth, NJ). Patients were treated with recombinant (r)GM-CSF 10 microg/kg/d subcutaneously from day 9 to 19. Twenty-seven patients had stage IV disease, four had stage III, and seven had bulky stage II. Half of the patients had bone marrow involvement. The median age was 45 years. RESULTS: We found that the MTD was 200% for the escalated drugs in this regimen (although we never escalated above the MTD or defined by dose-limiting toxicity) and that the normalized dose-intensity (NDI; defined as the ratio of the received dose-intensity to the 100% dose-intensity of ProcMACE-CytaBOM) decreased with each cycle and was lower for the day-8 drug (cytarabine) than for the day-1 drugs. The complete response (CR) rate was 66%, and 92% of patients who achieved CR are alive without disease with a median follow-up time for survival of 3.6 years. CONCLUSION: The MTD of cyclophosphamide, doxorubicin, etoposide, and cytarabine in the ProMACE-CytaBOM regimen given with growth factor support is 200%, and this dose should be tested in larger phase II trials.

Human immunodeficiency virus-related lymphomas: a possible association between tumor proliferation, lack of ploidy anomalies, and immune deficiency.

In an attempt to identify a biologic basis for the aggressive clinical behavior of human immunodeficiency virus (HIV)-associated lymphomas (HAL), dual-parameter flow-cytometric analysis was performed on 22 paraffin-embedded biopsy specimens. Cases were analyzed for DNA ploidy, the percentage of cells in S-phase (proliferative activity), and content of a recently identified proliferation-associated nuclear antigen, p105. The DNA-content analysis of 22 HALs was compared with that of 109 cases of intermediate-grade non-Hodgkin's lymphoma (NHL) unrelated to the acquired immune deficiency syndrome (AIDS) studied previously in our laboratory and 125 cases of high-grade NHL reported in the literature. The proliferative activity was higher in intermediate-grade HAL relative to non-AIDS NHL (24.0% v 10.4%; P = .03), and in high-grade HAL in comparison with NHLs of similar histology unassociated with HIV infection (24.8% v 19%), although the latter did not reach statistical significance. The number of mitoses per 10 high-power fields was found to correlate with the percentage of cells in S-phase (r = .68; P = .0004). Although p105 content tended to be higher in HAL than in an AIDS-related complex (ARC)-associated hyperplastic lymph node control, no statistically significant associations were found between p105 content and proliferative activity or the number of mitoses per 10 high-power fields. When compared with non-AIDS NHLs of comparable grade, there was a trend toward a lower incidence of DNA aneuploidy in both intermediate- (25% v 56%) and high-grade (38.5% v 60%) HALs. The higher proliferative activity and lower incidence of DNA aneuploidy found in HAL relative to non-AIDS NHL of comparable histologic grade may represent differences in pathogenesis and may underlie the poor prognosis of HIV-associated NHL.

Radioimmunodetection and radioimmunotherapy of cutaneous T cell lymphomas using an 131I-labeled monoclonal antibody: an Illinois Cancer Council Study.

A radiolabeled murine monoclonal antibody (T101) was used for imaging and therapy of six patients with cutaneous T cell lymphoma (CTCL). Radioimmunodetection was performed with a 5.6 to 13.1 mCi 131I-T101 preparation (9.6 to 10.5 mg). A therapeutic dose of 100.5 to 150.1 mCi 131I on 9.9 to 16.9 mg of antibody was administered to five patients, with subsequent retreatment following plasmapheresis in three patients at the time of disease progression. All patients responded to their initial therapy and two patients responded to retreatment. Regression of skin lesions and peripheral adenopathy was witnessed. All patients reported resolution of their chronic pruritus. The duration of response ranged from 3 weeks to 3 months. Acute toxicity included fevers, pruritus, and mild dyspnea in two instances. Myelosuppression was seen in patients receiving the 144.7 mCi, 145.0 mCi, and 150.1 mCi 131I-T101 doses. Radioimmunodiagnostic and therapy studies included gamma scintigraphy, plasma, urinary, and wholebody antibody clearances, and biodistribution determined from skin, bone marrow, and liver biopsies. Immunologic studies included immunoperoxidase staining of target tissues, immunofluorescent flow cytometric analysis on peripheral blood and bone marrow, assays for serum blocking factors, determination of a human antimouse antibody (HAMA) response, and quantitation of circulating T101 levels. These preliminary data suggest that 131I-T101 has therapeutic potential in CTCL and that myelosuppression will be the limiting toxicity.

Phase I/II trial of IDEC-Y2B8 radioimmunotherapy for treatment of relapsed or refractory CD20(+) B-cell non-Hodgkin's lymphoma.

PURPOSE: Yttrium-90 ibritumomab tiuxetan (IDEC-Y2B8) is a murine immunoglobulin G1 kappa monoclonal antibody that covalently binds MX-DTPA (tiuxetan), which chelates the radioisotope yttrium-90. The antibody targets CD20, a B-lymphocyte antigen. A multicenter phase I/II trial was conducted to compare two doses of unlabeled rituximab given before radiolabeled antibody, to determine the maximum-tolerated single dose of IDEC-Y2B8 that could be administered without stem-cell support, and to evaluate safety and efficacy. PATIENTS AND METHODS: Eligible patients had relapsed or refractory (two prior regimens or anthracycline if low-grade disease) CD20(+) B-cell low-grade, intermediate-grade, or mantle-cell non-Hodgkin's lymphoma (NHL). There was no limit on bulky disease, and 59% had at least one mass > or = 5 cm. RESULTS: The maximum-tolerated dose was 0.4 mCi/kg IDEC-Y2B8 (0.3 mCi/kg for patients with baseline platelet counts 100 to 149,000/microL). The overall response rate for the intent-to-treat population (n = 51) was 67% (26% complete response [CR]; 41% partial response [PR]); for low-grade disease (n = 34), 82% (26% CR; 56% PR); for intermediate-grade disease (n = 14), 43%; and for mantle-cell disease (n = 3), 0%. Responses occurred in patients with bulky disease (> or = 7 cm; 41%) and splenomegaly (50%). Kaplan-Meier estimate of time to disease progression in responders and duration of response is 12.9+ months and 11.7+ months, respectively. Adverse events were primarily hematologic and correlated with baseline extent of marrow involvement with NHL and baseline platelet count. One patient (2%) developed an anti-antibody response (human antichimeric antibody/human antimouse antibody). CONCLUSION: These phase I/II data demonstrate that IDEC-Y2B8 radioimmunotherapy is a safe and effective alternative for outpatient therapy of patients with relapsed or refractory NHL. A phase III study is ongoing.

Use of total leukocyte and platelet counts to guide stem cell apheresis in healthy allogeneic donors treated with G-CSF.

Healthy stem cell donors start leukapheresis 4-5 days after starting G-CSF based on the peripheral blood CD34+ cell count (PBCD34). Data from 137 harvests (68 donors) were analyzed to determine correlation between pre-apheresis leukocytes (11.0-94.8x10(9)/l; median 38.8) and platelets (49-374x10(9)/l; median 180), and PBCD34 (3-276/microl; median 40). PBCD34 correlated positively with leukocytes (r=0.48; P<0.0001) and platelets (r=0.40; P<0.0001). When pre-apheresis leukocytes were >or=25 and platelets were >or=100, PBCD34 and CD34+ collection were 5-276/microl (median 57) and 0.5-27.6x10(6)/kg (median 4.7), respectively; significantly higher than PBCD34 of 3-74/microl (median 17) and CD34+ collection of 0.2-8.9 x 10(6)/kg (median 2.2) when leukocytes were <25 and/or platelets were <100. With leukocytes >or=25 and platelets >or=100, PBCD34 was low (<20/microl) 8% of the time, compared to 57% of the time with leukocytes <25 and/or platelets <100 (P<0.0001). Our data suggest that it is not always necessary to measure PBCD34 to guide leukapheresis in healthy donors because pre-apheresis leukocytes and platelets >or=25 and >or=100, respectively, are associated with excellent mobilization. When blood counts do not meet these criteria, PBCD34 should be determined prior to initiation of apheresis.

Radioimmunotherapy of relapsed non-Hodgkin's lymphoma with zevalin, a 90Y-labeled anti-CD20 monoclonal antibody.

Approximately 55,400 new cases of non-Hodgkin's lymphoma (NHL) are diagnosed each year, with the overall prevalence of the disease now estimated to be 243,000. Until recently, treatment alternatives for advanced disease included chemotherapy with or without external beam radiation. Based on the results of several clinical trials, the chimeric monoclonal antibody Rituximab has now been approved by the United States Food and Drug Administration as a treatment for patients with relapsed or refractory, low-grade or follicular, B-cell NHL. Several other monoclonal antibodies in conjugated and unconjugated forms have been evaluated in the treatment of NHL. Ibritumomab, the murine counterpart to Rituximab, radiolabeled with 90Y (Zevalin), is presently being evaluated in clinical trials. The success of radioimmunotherapy is dependent upon the appropriate choice of antibody, isotope, and chelator-linker. The Ibritumomab antibody targets the CD20 antigen. The antibody is covalently bound to the chelator-linker tiuxetan (MX-DTPA), which tightly chelates the isotope 90Y. To date, two Phase I/II Zevalin clinical trials have been completed in patients with low-grade, intermediate-grade, and mantle cell NHL. The overall response rate was 64% in the first trial and 67% in the later trial. Phase II and III trials are ongoing.

Autologous bone marrow transplantation in breast cancer: separation of clonogenic tumor cell colonies by gradient fractionation.

A major obstacle to successful autologous bone marrow transplantation in breast cancer is infiltration of the marrow by malignant cells. We layered bone marrow samples from seven breast cancer patients on a discontinuous bovine albumin gradient, then assessed hematopoietic potential (colony-forming units-culture [CFUc]) and clonogenic tumor cells (TCFUc) by standard techniques. We found that 78% of CFUc concentrated in fraction 3 of the gradient, which contained 10% of the total nucleated cell population. TCFUc were distributed across the gradient with 14% of colonies identified in this marrow fraction. We applied these techniques to two patients with metastatic breast cancer who were treated with high-dose mitomycin-C, doxorubicin, and cyclophosphamide before receiving 1.9 x 10(9) and 1.2 x 10(9) total cells, respectively, from CFUc-rich fraction 3. We observed tumor colony growth in three patients only in separated marrow fractions, suggesting that colony growth may be a function of the cell composition after fractionation or that growth factors may be separable. Ninety percent of clonogenic breast cancer cells can be separated from hematopoietic cells by discontinuous density gradient fractionation, a technique that is applicable to the large volumes necessary in bone marrow transplantation and that may be an important initial step in marrow purging for autologous transplantation.