Recent advances in antigen-targeted therapy in non-Hodgkin's lymphoma

Generation of a highly stable, internalizing anti-CD22 single-chain Fv fragment for targeting non-Hodgkin's lymphoma

The generation of a single chain Fv (scFv) fragment derived from the anti-CD22 monoclonal antibody LL2 resulted in a molecule with good antigen binding but very poor stability properties, thus hampering its clinical applicability. Here we report on the construction of an engineered LL2 scFv fragment by rational mutagenesis. The contribution of uncommon wild-type sequence residues for providing stability to the conserved common core structure of immunoglobulins was examined. Aided by computer homology modeling, 3 destabilizing residues within the core of the wild-type VH domain were identified. Owing to the conserved nature of the buried core structure, mutagenesis of these sites to respective consensus residues markedly stabilized the molecule but did not influence its antigen binding properties: the engineered scFv MJ-7 exhibited exceptional biophysical stability with a half-life not reached after 6 days of incubation in human serum at 37 degrees C, while fully retaining the epitope specificity of the monoclonal antibody, and antigen binding affinity of the wild-type scFv. Furthermore, both the monoclonal antibody LL2 and the engineered scFv fragment became fully internalized after only 30 min of incubation at 37 degrees C with CD22+ tumor cells. These properties predict scFv MJ-7 could become a novel powerful tool to selectively deliver cytotoxic agents to malignant CD22+ cells.

Rituximab in combination with vinorelbine/gemcitabine chemotherapy in patients with primary refractory or early relapsed T cell rich B cell lymphoma. A pilot study

Rituximab is a chimeric monoclonal antibody that binds specifically to the CD20 antigen expressed in most B cell lymphomas. As single agent or in combination with chemotherapy rituximab has shown significant activity in patients with relapsing or refractory aggressive lymphomas. Because T cell rich B cell lymphomas (TCRBCL) also express the CD20 antigen, we decided to evaluate the efficacy and tolerability of the anti-CD20 monoclonal antibody rituximab combined with chemotherapy in four patients with either primary refractory or early relapsed TCRBCL. The chemotherapy regiment consisted of vinorelbin and gemcitabine, a combination with known efficacy in patients with refractory aggressive lymphomas. The patients received 6 cycles of rituximab at the dose of 375 mg/m(2), combined with vinorelbine 25 mg/m(2) and gemcitabine 800 mg/m(2) at 3-week intervals. Three complete responses and one partial response were observed among our four patients with refractory or early relapsed TCRBCL without significant adverse effects, indicating considerable efficacy of this combination. Therefore, rituximab should be tested in combination with chemotherapy in the front line treatment of patients with TCRBCL.

Efficacy and safety of 90Y ibritumomab tiuxetan (zevalin) radioimmunotherapy for non-Hodgkin’s lymphoma

Radioimmunotherapy, an emerging treatment option for certain patients with non-Hodgkin's lymphoma (NHL), enables the targeting of cytotoxic radiation to tumor cells with minimal irradiation of normal cells. Yttrium 90 ibritumomab tiuxetan (Zevalin; Biogen Idec Inc, Cambridge, MA) was approved in February 2002 for the treatment of patients with relapsed or refractory low-grade, follicular, or transformed B-cell NHL, including patients with rituximab-refractory NHL. Yttrium 90 ibritumomab tiuxetan is an effective treatment with a consistent overall response rate of 73% to 83%. It has a good safety profile and is generally well tolerated in the indicated population. The results of clinical trials show that (90)Y ibritumomab tiuxetan can be used effectively and safely in many patients with NHL, including those with mild thrombocytopenia and those with disease that is refractory to rituximab, without the adverse events associated with conventional chemotherapy and external beam radiation therapy. The use of (90)Y ibritumomab tiuxetan does not preclude subsequent therapy with other conventional treatment options.

In vitro and in vivo purging of B lymphoma cells from stem-cell products using anti-CD20 Abs

BACKGROUND

Autologous stem-cell transplantation has proved curative therapy for relapsed NHL. However, recurrence of underlying disease remains the major cause of treatment failure in this setting.

METHODS

Development of effective MAb therapy directed against the B cell surface antigen CD20 has added a valuable tool of clearing contaminating lymphoma cells from stem-cell products by either in vitro or in vivo application.

RESULTS

Transplantation of successfully in vitro purged bone marrow using Mabs has been correlated with prolonged survival in large Phase-II study. So far, no randomized trial could demonstrate a therapeutic benefit for in vitro purging. The anti-CD20 Mab rituximab has been used for in vivo purging at the time of stem cell collection or peritransplantation. This method has been shown to be safe and feasible. In the majority of patients the combination of rituximab with anti-lymphoma chemotherapy meant the collected stem cell products were free of molecularly-detectable lymphoma cells.

DISCUSSION

The increasing ability to kill all lymphoma cells in vivo by regimens including myeloablative therapy renders contaminating lymphoma cells of the autologous stem cell product the main source for disease recurrence. Clearing of these cells remains a prerequisite for curative stem-cell transplantation. Establishment of safe and effective therapeutic schedules using Mabs will enhance the chance for collection of lymphoma-free hematopoietic stems cells.

The role of surgery in the treatment of pediatric B-cell non-Hodgkin's lymphoma

BACKGROUND

Within the last 20 years, the role of surgery in the management of pediatric B-cell non-Hodgkin's lymphoma (B-NHL) has changed substantially. Along with the assignment of risk-adjusted therapy and specific treatment protocols, surgical procedures have been restricted to defined situations including abdominal emergencies, diagnostic biopsy, total tumor extirpation and second-look operations.

METHODS

The authors retrospectively analyzed the effect of initial surgery and second-look operation on event-free survival (EFS) in 79 patients with B-NHL (abdominal primary, n = 57; head or neck tumor, n = 22). Furthermore, the prognostic significance of the stage of disease for the patients analyzed was evaluated.

RESULTS

Therapy results showed that the extent of resection did not have a significant influence on EFS and that stage of disease was of prognostic relevance only for patients with head and neck tumors. The number of patients who had a second-look operation (n = 12) was too small for statistical interpretation.

CONCLUSIONS

Because tumor resectability is determined by the stage of disease, which is the superimposed predictor of prognosis, the influence of the extent of resection on EFS cannot be interpreted independently. Nevertheless, the following conclusions can be drawn: in patients with proven localized disease, total resections should be attempted, if not mutilating, to avoid intensified chemotherapy. However, if only partial resections seem feasible, surgical interventions should be restricted to the least necessary procedures for treating life-threatening local tumor effects and establishing a definite diagnosis.

Using unconjugated antibodies as an immunotherapeutic approach to treatment of B-cell neoplasms

B-cell neoplasms have the sixth highest mortality incidence and one of the largest rates of increase of all malignancies. Frequent relapse and the development of refractory disease in this patient group have stimulated research to find alternative treatments. The use of unconjugated antibodies offers a new approach to the treatment of non-Hodgkin's lymphoma and chronic lymphocytic leukemia. This article will explore the pharmacology, dosage, and administration guidelines as well as side effect management of the available drugs in this classification. Expectations for future approaches to the treatment of B-cell neoplasms will be discussed.

Radioimmunotherapy for non-Hodgkin's lymphoma with yttrium 90 ibritumomab tiuxetan

The increasing incidence of non-Hodgkin's lymphoma (NHL), coupled with the lack of optimal treatment options, has prompted the development of novel treatments. Of these, radioimmunotherapy is one of the most promising. Two of the radiolabeled monoclonal antibody therapies being studied in the treatment of NHL are yttrium 90 (90Y) ibritumomab tiuxetan and iodine 131 (131I) tositumomab. The radionuclides 90Y and 131I emit beta radiation; 131I also emits gamma radiation, thus requiring more elaborate precautionary measures to limit radiation exposure. The monoclonal antibody portions of the drugs target the CD20 surface antigen that is present on the majority of B-cell lymphomas, resulting in direct radiation to the targeted cells, as well as indirect targeting of adjacent cells (known as the crossfire effect). Clinical trials of 90Y ibritumomab tiuxetan in patients with NHL have produced promising results. The safe and effective use of radioimmunotherapy requires a multidisciplinary team approach in which nurses play a central role.