Q) How do you monitor for infection in patients with multiple sclerosis who take disease-modifying therapies?
The answer to this question is “it depends”—on several factors, including current and previous use of disease-modifying therapies (DMTs), concomitant medications, comorbidities, vaccination history, presence of John Cunningham virus (JCV) antibodies (in the case of natalizumab use), and prior or current use of immunosuppressive therapies.
There are many FDA-approved DMTs for multiple sclerosis (MS). Each has a different rate of infection occurring in clinical trials and varying requirements and/or recommendations for safety monitoring. The package inserts for each DMT offer some guidance for clinicians.
Injectable therapies. For two interferon therapies—interferon ß-1b SC and interferon ß-1a—it is recommended to order a complete blood count (CBC), blood chemistry, and liver function tests (LFTs) at baseline, then again at one, three, and six months, and then at clinician discretion thereafter.1,2 For peginterferon ß-1a, ordering a CBC, basic chemistry, and LFTs, at the clinician’s discretion, is advised.3 The package insert for interferon ß-1a IM does not offer specific recommendations for routine safety monitoring.4
The package insert for glatiramer acetate offers no recommendations for routine safety monitoring.5
In patients for whom two or more DMTs have failed to work, the monoclonal antibody daclizumab may be indicated. Compared to placebo and active comparator, this drug was associated with a higher risk for infection in clinical trials. The most commonly observed types were upper respiratory, urinary tract, and viral infections. There are no recommendations for CBC monitoring with daclizumab, but monthly LFTs are required due to increased risk for hepatic injury.6
Oral DMTs. Patients taking fingolimod, teriflunomide, and dimethyl fumarate have increased risk for infection; as a result, there are more safety monitoring recommendations for these medications.7-9
Prior to starting therapy with fingolimod, baseline CBC, blood chemistries, and varicella antibody testing should be done. During therapy, routine CBC testing and LFTs are advised at the clinician’s discretion or if the patient exhibits signs and symptoms of infection (see Table). In clinical trials, fingolimod use was interrupted if the lymphocyte count was sustained at < 200. In rare cases, progressive multifocal leukoencephalopathy (PML) has occurred—so the patient’s age, JCV antibody status, prior use of immunosuppressant therapy, and length of fingolimod treatment should be taken into consideration.7
Patients starting teriflunomide should have baseline LFTs and CBC and tuberculosis (TB) testing (either skin or serum), with subsequent monthly LFTs for the first six months on treatment. Some patients may experience neutropenia, thrombocytopenia, and lymphopenia. As a result, patients may have an increased risk for infection. Safety monitoring is at the clinician’s discretion.8
For patients initiating dimethyl fumarate, a baseline CBC is recommended, to be repeated every six to 12 months thereafter, and/or as clinically indicated. Since lymphopenia may occur, consider interruption of dimethyl fumarate in patients with lymphocyte counts < 0.5 persisting for more than six months. Rare cases of PML have also occurred; at the first suggestive sign or symptom, dimethyl fumarate should be withheld and appropriate diagnostic testing should be completed.9