What signals are generated by anti-CD20 antibody therapy?

Effects of CD20 antibodies and kinase inhibitors on B-cell receptor signalling and survival of chronic lymphocytic leukaemia cells

Recently, clinical trial results have established inhibitors of B-cell receptor (BCR)-associated kinase (BAKi), with or without CD20 moniclonal antibodies (mAbs), as the preferred first-line treatment for most chronic lymphocytic leukaemia (CLL) patients. Using phosphospecific flow cytometry, we showed that in leukaemic cells from CLL patients the CD20 therapeutic antibodies - rituximab, ofatumumab, and obinutuzumab - inhibited BCR signalling pathways targeting preferentially pBTK^Y551 - but not BTK^Y223 - and pAKT. On the contrary, ibrutinib and idelalisib reduced pBTK^Y223 to a higher extent than pBTK^Y551 . The strong reduction of pAKT induced by idelalisib was enhanced by its combination with rituximab or ofatumumab. Moreover, CD20 mAbs and BAKi induced the death of leukaemia cells that was significantly potentiated by their combination. Analysis of the enhancement of cell death in these combinations revealed an approximately additive enhancement induced by rituximab or obinutuzumab combined with ibrutinib or idelalisib. Taken together, our data identified negative regulatory effects of CD20 mAbs and their combinations with BAKi on BCR signalling and cell survival in CLL. In conclusion, this study advances our understanding of mechanisms of action of CD20 mAbs as single agents or in combination with BAKi and could inform on the potential of combined therapies in ongoing and future clinical trials in patients with CLL.

Targeting CD20: teaching an old dog new tricks

Rituximab was the first monoclonal antibody used for the treatment of a malignancy. In the 22 years since initial approval, it has become a vital component of therapy for a multitude of B-cell malignancies. Within the last several years, however, there has been a robust development of novel agents targeting CD20, including second generation anti-CD20 antibodies, biosimilar antibodies, and subcutaneous formulations that have been approved. The era of passive immunotherapy is now yielding to therapeutic approaches that actively engage the immune system. Emerging approaches leverage immunomodulatory drugs or novel checkpoint inhibitors to enhance CD20 therapy. Recent data sets on bispecific CD3/CD20 antibodies demonstrate exciting early findings, and CD20-directed chimeric antigen receptor T-cell therapies are now entering clinical trials. Anti-CD20 therapies are a vital component of the treatment of B-cell malignancies, and there is a dynamic therapeutic environment with multiple new data sets reviewed here.

Advances in therapies for non-Hodgkin lymphoma in children

Pediatric patients with newly diagnosed, non-Hodgkin Lymphoma (NHL) have an excellent overall survival. However, therapy regimens are associated with acute toxicity and late effects. Furthermore, patients with relapsed or refractory disease have relatively few options with proven clinical benefit. Both histologic and molecular differences exist between adult and pediatric NHL preventing simple translation of adult NHL successes into improvements in pediatric NHL treatment. This review summarizes the introduction of targeted therapies into frontline treatments for patients with anaplastic large-cell lymphoma and CD20–positive tumors, with the goal of improving overall survival while limiting both short- and long-term toxicities. In addition, newer approaches that have limited data in children but may have a significant role in how we treat pediatric NHL in the future are reviewed, which include CD19 directed therapy, Notch inhibition, the tri-functional antibody, FBTA05, and EZH2 inhibition.

Advances in therapies for non-Hodgkin lymphoma in children

Pediatric patients with newly diagnosed, non-Hodgkin Lymphoma (NHL) have an excellent overall survival. However, therapy regimens are associated with acute toxicity and late effects. Furthermore, patients with relapsed or refractory disease have relatively few options with proven clinical benefit. Both histologic and molecular differences exist between adult and pediatric NHL preventing simple translation of adult NHL successes into improvements in pediatric NHL treatment. This review summarizes the introduction of targeted therapies into frontline treatments for patients with anaplastic large-cell lymphoma and CD20–positive tumors, with the goal of improving overall survival while limiting both short- and long-term toxicities. In addition, newer approaches that have limited data in children but may have a significant role in how we treat pediatric NHL in the future are reviewed, which include CD19 directed therapy, Notch inhibition, the tri-functional antibody, FBTA05, and EZH2 inhibition.

A molecular perspective on rituximab: A monoclonal antibody for B cell non Hodgkin lymphoma and other affections

Rituximab (a chimeric anti-CD20 monoclonal antibody) is the first Food and Drug Administration approved anti-tumor antibody. Immunotherapy by rituximab, especially in combination-therapy, is a mainstay for a vast variety of B-cell malignancies therapy. Its therapeutic value is unquestionable, yet the mechanisms of action responsible for anti-tumor activity of rituximab and rituximab resistance mechanisms are not completely understood. Investigation of the mechanisms of action that contribute to the rituximab activity have eventually directed to a suite of novel combinations and novel treatment schedules, and also have resulted new generations of antibodies with more desired effects. Although, further investigations are needed to define the mechanisms of rituximab resistance and prominent effector activity of the altered next generation anti-CD20 to improve their efficacies and develop new anti-CD20 monoclonal antibodies in NHL treatment. This article focuses on the properties of CD20 which led scientists to select it as an effective therapeutic target and the molecular details of mechanisms of rituximab action and resistance. We also discuss about the impact of rituximab in monotherapy and in combination with chemotherapy regimens. Finally, we comparatively summarize the next generations of anti CD20 monoclonal antibodies to highlight their advantages relative to their ancestor: Rituximab.

Can rituximab induce long-term disease remission in patients with intra-ocular non-infectious inflammation?

Treatment of non-infectious uveitis is based primarily on the use of systemic corticosteroids and second-line immunosuppressive drugs. However, their extensive side effect profile, particularly for steroids, has led to the increased use of other immunosuppressive drugs, as sparing capacity agents. Rituximab is an anti-CD20 chimeric antibody, often given as a single course of 2 infusions, resulting in complete depletion of peripheral mature B cells. While it is licensed to treat refractory systemic lymphoma patients, it has also shown promising results in systemic auto-immune diseases, where a single course of treatment is able to achieve long-term clinical remission. Treatment with rituximab has been reported for various ocular conditions, suggesting it may be effective in inducing long-term disease control and other systemic immunosuppressive agents can be reduced or discontinued. When disease relapse occurs, a further course or courses can be given with good results. This review summarizes the current evidence regarding the role of rituximab in treating non-infectious uveitis.