Hodgkin's disease. Future treatment strategies: fact or fiction?

The NADPH oxidase NOX5 protects against apoptosis in ALK-positive anaplastic large-cell lymphoma cell lines

Reactive oxygen species (ROS) are key modulators of apoptosis and carcinogenesis. One of the important sources of ROS is NADPH oxidases (NOXs). The isoform NOX5 is highly expressed in lymphoid tissues, but it has not been detected in any common Hodgkin or non-Hodgkin lymphoma cell lines. In diverse, nonlymphoid malignant cells NOX5 exerts an antiapoptotic effect. Apoptosis suppression is the hallmark feature of a rare type of lymphoma, termed anaplastic lymphoma kinase-positive (ALK(+)) anaplastic large-cell lymphoma (ALCL), and a major factor in the therapy resistance and relapse of ALK(+) ALCL tumors. We applied RT-PCR and Western blot analysis to detect NOX5 expression in three ALK(+) ALCL cell lines (Karpas-299, SR-786, SUP-M2). We investigated the role of NOX5 in apoptosis by small-interfering RNA (siRNA)-mediated gene silencing and chemical inhibition of NOX5 using FACS analysis and examining caspase 3 cleavage in Karpas-299 cells. We used immunohistochemistry to detect NOX5 in ALK(+) ALCL pediatric tumors. NOX5 mRNA was uniquely detected in ALK(+) ALCL cells, whereas cell lines of other lymphoma classes were devoid of NOX5. Transfection of NOX5-specific siRNA and chemical inhibition of NOX5 abrogated calcium-induced superoxide production and increased caspase 3-mediated apoptosis in Karpas-299 cells. Immunohistochemistry revealed focal NOX5 reactivity in pediatric ALK(+) ALCL tumor cells. These results indicate that NOX5-derived ROS contribute to apoptosis blockage in ALK(+) ALCL cell lines and suggest NOX5 as a potential pharmaceutical target to enhance apoptosis and thus to suppress tumor progression and prevent relapse in pediatric ALK(+) ALCL patients that resist classical therapeutic approaches.

Individualized target therapy of malignant lymphomas: an outlook

Hodgkin and non-Hodgkin lymphomas represent clonal malignant expansions of B or T cells that are at various stages of maturation. As our understanding of the immunophenotype, cytogenetics and molecular biology of the lymphomas broadened, treatment of these neoplasms is evolving to include targeted therapies directed against tumour-characteristic molecules and specific signalling pathways critical to lymphomagenesis.

New drugs in the treatment of Hodgkin's disease

In the treatment of Hodgkin's disease (HD) remission rates of 80% have been achieved with combination regimens such as COPP/ABVD; 30%-50% of these patients relapse, however, and less than 25% of those in first relapse can be cured. Although 90% of adults with advanced Hodgkin's disease (HD) achieve a complete remission with new polychemotherapy regimens such as BEACOPP, it is too early to assess how many patients ultimately can be cured. In addition, these regimens are associated with severe side effects including infertility, cardiomyopathy or second malignancies. Thus, alternative strategies for improving the outcome of patients with HD have been developed. These approaches include new cytostatic drugs and biological agents. Here, we review the most recent developments including the new vinca alkaloid vinorelbine, the anthracycline idarubicin, the nitrogen mustard bendamustine, the recently developed nucleoside analogue gemcitabine, and immunotoxins against Hodgkin/Reed-Sternberg cells. We conclude that current polychemotherapy regimens could possibly be improved by introducing new agents with a different mechanism of action such as gemcitabine. In addition, some of these new drugs including gemcitabine or vinorelbine could contribute to the reduction of toxic side effects, thus resulting in an improved quality of life for patients with HD.