Eculizumab is a humanized monoclonal antibody that binds to human complement (C5 protein) thereby inhibiting the completion of the terminal complement pathway and development of the membrane attack complex involved in bacterial destruction. It is recommended for treatment of complement-mediated microangiopathies. However, as is usually the case when one interferes with Mother Nature or the natural course of a disease process by using a drug like this, a price is extracted. In this case, it is an increase incidence of invasive meningococcal disease.
A group of physicians from England led by Dr. Sydel Parikh (10.1542/peds.2016-2452) working in the public health arena, report a case of meningococcal group B vaccine (4CMenB) failure in a young adult receiving eculizumab for atypical hemolytic uremic syndrome. The failure of the vaccine to work in this patient who was receiving eculizumab, which is actually a failure to activate the complement system, led to infection in this young adult from a normally vaccine preventable meningococcal strain. The infecting organism, a meningococcal B strain, was penicillin resistant, effectively thwarting the penicillin prophylaxis the patient was receiving. The development of monoclonal antibodies with the ability to right untoward responses of a flawed immune system has added a powerful tool to the clinicians armamentarium, but as Peter Parker aka Spiderman learned from his uncle Ben Parker, “with great power comes great responsibility”.