Bone Marrow Effects

A mean decrease compared to baseline in white blood cell (WBC) count of approximately 15% (mainly neutrophils and lymphocytes) and in platelet count of approximately 10% was observed in placebo- controlled trials in adult patients with 7 mg and 14 mg of teriflunomide tablets. The decrease in mean WBC count occurred during the first 6 weeks and WBC count remained low during treatment. In placebo-controlled studies in adult patients, neutrophil count <1.5 × 109/L was observed in 12% and 16% of patients receiving teriflunomide tablets 7 mg and 14 mg, respectively, compared with 7% of patients receiving placebo; lymphocyte count <0.8 × 109/L was observed in 10% and 12% of patients receiving teriflunomide tablets 7 mg and 14 mg, respectively, compared with 6% of patients receiving placebo. No cases of serious pancytopenia were reported in premarketing clinical trials of teriflunomide but rare cases of pancytopenia and agranulocytosis have been reported in the postmarketing setting with leflunomide. A similar risk would be expected for teriflunomide [see  Clinical Pharmacology (12.3)]. Cases of thrombocytopenia with teriflunomide, including rare cases with platelet counts less than 50,000/mm3, have been reported in the postmarketing setting. Obtain a complete blood cell count (CBC) within 6 months before the initiation of treatment with teriflunomide. Further monitoring should be based on signs and symptoms suggestive of bone marrow suppression. 

Risk of Infection/Tuberculosis Screening

Patients with active acute or chronic infections should not start treatment until the infection(s) is resolved. If a patient develops a serious infection consider suspending treatment with teriflunomide tablets and using an accelerated elimination procedure. Reassess the benefits and risks prior to resumption of therapy. Instruct patients receiving teriflunomide tablets to report symptoms of infections to a physician.

Teriflunomide tablets are not recommended for patients with severe immunodeficiency, bone marrow disease, or severe, uncontrolled infections. Medications like teriflunomide tablets that have immunosuppression potential may cause patients to be more susceptible to infections, including opportunistic infections. 

In placebo-controlled studies of teriflunomide in adult patients, no overall increase in the risk of serious infections was observed with teriflunomide tablets 7 mg (2.2%) or 14 mg (2.7%) compared to placebo (2.2%). 

However, one fatal case of klebsiella pneumonia sepsis occurred in a patient taking teriflunomide tablets 14 mg for 1.7 years. Fatal infections have been reported in the postmarketing setting in patients receiving leflunomide, especially Pneumocystis jirovecii pneumonia and aspergillosis. Most of the reports were confounded by concomitant immunosuppressant therapy and/or comorbid illness which, in addition to rheumatoid disease, may predispose patients to infection. 

In clinical studies with teriflunomide, cytomegalovirus hepatitis reactivation has been observed. In clinical studies with teriflunomide in adult patients, cases of tuberculosis have been observed. Prior to initiating teriflunomide tablets, screen patients for latent tuberculosis infection with a tuberculin skin test or with a blood test for mycobacterium tuberculosis infection. Teriflunomide has not been studied in patients with a positive tuberculosis screen, and the safety of teriflunomide in individuals with latent tuberculosis infection is unknown. For patients testing positive in tuberculosis screening, treat by standard medical practice prior to therapy with teriflunomide.

Vaccination

No clinical data are available on the efficacy and safety of live vaccinations in patients taking teriflunomide. Vaccination with live vaccines is not recommended. The long half-life of teriflunomide should be considered when contemplating administration of a live vaccine after stopping teriflunomide tablets.

Malignancy

The risk of malignancy, particularly lymphoproliferative disorders, is increased with the use of some immunosuppressive medications. There is a potential for immunosuppression with teriflunomide. No apparent increase in the incidence of malignancies and lymphoproliferative disorders was reported in the teriflunomide clinical trials, but larger and longer-term studies would be needed to determine whether there is an increased risk of malignancy or lymphoproliferative disorders with teriflunomide.