Rituximab added to an intensified salvage chemotherapy program followed by autologous stem cell transplantation improved the outcome in relapsed and refractory aggressive non-Hodgkin lymphoma.

We investigated the addition of rituximab to an intensified salvage program followed by a myeloablative course with autologous stem cell transplantation (ASCT) in patients with relapsed or refractory aggressive non-Hodgkin lymphoma (NHL). Patients with relapsed or progressive aggressive NHL were treated with two cycles of conventional salvage chemotherapy (DHAP) followed by high-dose sequential chemotherapy (cyclophosphamide, methotrexate with vincristine and etoposide) and a final myeloablative course (BEAM) with ASCT. Rituximab (375 mg/m(2)) was administered at each treatment cycle. This cohort was compared with a historical control group of patients treated with the same chemotherapy but without rituximab. Patients from both groups were matched by duration of first remission and lactate dehydrogenase serum levels. Forty-five patients were treated with chemotherapy and 22 with immunochemotherapy. The overall response rates (ORR) at the final evaluation were 63% for the immunochemotherapy group and 42% for the chemotherapy group (p = 0.330). In the historical controlled analysis freedom from second failure (FF2F) at 2 years in the immunochemotherapy group was 57% and overall survival (OS) was 77%. FF2F in the chemotherapy group was 18% (p = 0.0051) and OS was 37% (p = 0.0051). In the matched-pair analysis, FF2F was 58% in the immunochemotherapy group compared to 16% in the chemotherapy group (p = 0.0517); OS was 74 vs 33%, respectively (p = 0.0424). The toxicity was tolerable and comparable in both groups. The addition of rituximab to an intensified salvage chemotherapy regimen seems to improve the prognosis. However, only prospective randomized trial can offer sufficient data of the value of rituximab in relapsed and refractory aggressive NHL.

A Phase I study with an anti-CD30 ricin A-chain immunotoxin (Ki-4.dgA) in patients with refractory CD30+ Hodgkin's and non-Hodgkin's lymphoma.

Ki-4.dgA is an anti-CD30 immunotoxin (IT) constructed by coupling the monoclonal antibody Ki-4 via a sterically hindered disulfide linker to deglycosylated ricin A-chain. This IT was efficacious in vitro and in SCID mice with disseminated human Hodgkin's lymphoma. Accordingly, a Phase I trial in patients (pts) with Hodgkin's lymphoma was designed. The objectives of this Phase I trial were to determine the maximum tolerated dose, the dose-limiting toxicities, pharmacokinetics, and antitumor activity. Seventeen pts with relapsed CD30+ lymphoma were treated with escalating doses (5, 7.5, or 10 mg/m(2)/cycle) of the IT as four bolus infusions on days 1, 3, 5, and 7 for one to three cycles. All of the pts had progressive disease and were heavily pretreated. Nine had primary progressive disease and 14 had advanced disease with massive tumor burdens. The mean age was 35 years (24-52 years). Peak serum concentrations of the intact IT varied from 0.23 to 1.1 microg/ml. Side effects and dose-limiting toxicities were related to vascular leak syndrome, i.e., decreases in serum albumin, edema, weight gain, hypotension, tachycardia, myalgia, and weakness. The maximum tolerated dose was 5 mg/m(2). Seven of 17 (40%) pts made human antiricin antibodies (> or =1.0 microg/ml), and 1 pt developed human antimouse antibodies (> or =1.0 microg/ml). Clinical response in the 15 evaluable pts included 1 partial remission, 1 minor response, and 2 stable diseases. In conclusion, the IT was less well tolerated than other ITs of this type. This might be because of the low number of CD30+ peripheral blood mononuclear cells, and in part because of binding of the IT to soluble CD30 antigen and the resulting circulation of IT/sCD30 complexes.

Imaging of central nervous system lymphomas with iodine-123 labeled rituximab.

Most patients with primary central nervous system (CNS) lymphoma (PCNSL) relapse after initial response to chemotherapy or the combination of chemotherapy and irradiation. Thus, novel treatment regimens for relapsed PCNSL are needed. As the majority of PCNSL are B-cell neoplasms expressing the CD20 antigen, treatment with the chimeric monoclonal antibody (MAb) rituximab might be reasonable. Nevertheless, the potential efficacy of intravenous rituximab in PCNSL seems to be limited as MAbs are high molecular weight proteins, which might be unable to pass the blood brain barrier. Thus, we performed dosimetric measurements with iodine-123 (123I)-rituximab to evaluate rituximab uptake in PCNSL after systemic intravenous administration. We analyzed four patients with PCNSL receiving a preinfusion of 250 mg/m2 rituximab followed by 200-500 MBq of the gamma-emitter 123I-rituximab. Single photon emission computed tomography (SPECT) was performed 1, 24 and 48 h after administration of the radio-immunoconstruct. Only one patient showed a very weak or questionable uptake of 123I-rituximab into tumor tissue which was ninefold lower compared with the blood-pool accumulation. These data suggest that systemic MAb-based radio-immunotherapy is not feasible in patients with PCNSL because a sufficient activity in the tumor will be associated with severe hematotoxicity. If an uptake of therapeutic rituximab doses into PCNSL can be achieved remains questionable.

The human anti-CD30 antibody 5F11 shows in vitro and in vivo activity against malignant lymphoma.

CD30 is a promising target for antibody-based immunotherapy of Hodgkin lymphoma (HL) and anaplastic large cell lymphoma. To overcome the limitations from currently available murine anti-CD30 monoclonal antibodies (mAbs), a new fully human anti-CD30 antibody was generated. Binding properties were evaluated by recombinant CD30 capture enzyme-linked immunosorbent assay (ELISA) and fluorescence-activated cell-sorter (FACS) flow cytometry. Activity of this new mAb was assessed in vitro using growth inhibition and antibody-dependent cellular cytotoxicity (ADCC) assays on several cell lines. In vivo activity was determined in a solid as well as in a disseminated xenografted model of HL in severe combined immunodeficiency (SCID) mice. The mAb 5F11 showed specific binding to CD30 (cluster A). The ADCC assays indicated dose-dependent lysis of L540 cells when 5F11 was combined with human effector cells. Upon cross-linking in vitro, 5F11 inhibited the growth of CD30-expressing cell lines. In vivo, treatment with 5F11 induced a marked growth delay or even a complete regression of established xenografted HL in SCID mice. In the disseminated HL model, a high proportion of 5F11-treated mice experienced long-term survival. The new human anti-CD30 monoclonal antibody 5F11 shows promise as a means of CD30-targeted immunotherapy of malignant lymphomas. Based on these results, a clinical phase 1 study in patients with refractory CD30+ lymphoma has been initiated.