Associations of ofatumumab exposure and treatment outcomes in patients with untreated CLL receiving chemoimmunotherapy

Ocrelizumab and ofatumumab, but not rituximab, trigger complement induction in vitro

The clinical and adverse effects of the therapeutic monoclonal antibodies (mAb) ocrelizumab, ofatumumab and rituximab in multiple sclerosis (MS) are presently subject to extensive study. While the two former are approved for MS, the older and less costly rituximab is used off label, and adverse effect profiles are important in their evaluation. The three mAbs all induce B cell depletion, with complement-dependent cytotoxicity (CDC) as one of several mechanisms of action. Complement activation is also postulated to underlie adverse reactions related to infusion/injection. Such administration-related reactions are associated with all three mAbs, but comparisons have so far been indirect, resting on incidence reports from separate clinical trials. The objective of this study was to perform head-to-head comparison of complement activation by ofatumumab, ocrelizumab and rituximab. In vitro experiments were performed in whole blood from healthy donors. The complement-activating potential of the three mAbs was analyzed after 30 min of exposure to 0.3 mg/mL or 0.9 mg/mL of each drug, and compared with those of the well-known TNF inhibitory mAbs adalimumab and infliximab, the latter with recognized potential for infusion reactions. Ofatumumab, ocrelizumab, and infliximab, but not rituximab and adalimumab, triggered statistically significant complement activation measured as increased levels of terminal C5b-9 complement complex (TCC), a sensitive marker of such activation. While results demand careful interpretation, they provide an indication of distinct complement-inducing potential among anti-CD20 mAbs currently used to treat MS.

Monoclonal Antibodies, Bispecific Antibodies and Antibody-Drug Conjugates in Oncohematology

Background:

The therapeutic outcomes and the prognosis of patients with various hematologic malignancies are not always ideal with the current standard of care.

Objective:

The aim of this study is to analyze the results of the use of monoclonal antibodies, bispecific antibodies and antibody-drug conjugates for the therapy of malignant hemopathies.

Methods:

A mini-review was achieved using the articles published in Web of Science and PubMed between January 2017 and January 2020 and the new patents were made in this field.

Results:

Naked monoclonal antibodies have improved the therapeutic results obtained with standard of care, but they also have side effects and the use of some of them can lead to the loss of the target antigen through trogocytosis, which explains the resistance that occurs during therapy. The results obtained with naked monoclonal antibodies have been improved by a better monoclonal antibody preparation, the use of bispecific antibodies (against two antigens on the target cell surface or by binding both surface antigen on target cells and T-cell receptor complex, followed by cytotoxic T-lymphocytes activation and subsequent cytolysis of the target cell), the use of monoclonal or bispecific constructs in frontline regimens, combining immunotherapy with chemotherapy, including through the use of antibody-drug conjugates (which provides a targeted release of a chemotherapeutic agent).

Conclusion:

Immunotherapy and immuno-chemotherapy have improved the outcome of the patients with malignant hemopathies through a targeted, personalized therapy, with reduced systemic toxicity, which in some cases can even induce deep complete remissions, including minimal residual disease negativity.