Melanoma complicating treatment with natalizumab for multiple sclerosis: A report from the Southern Network on Adverse Reactions (SONAR)

A 43‐year‐old female with multiple sclerosis developed urethral melanoma. The only potential risk factor was treatment with natalizumab, a humanized monoclonal antibody against α4 integrins. To investigate the risk‐exposure relationship, we reviewed this case, all other published cases, and cases of natalizumab‐associated melanoma reported to regulatory agencies. Data sources included the Food and Drug Administration's (FDA) Adverse Event Reporting System (FAERS) (2004–2014), a FDA Advisory Committee Meeting Report, and peer‐reviewed publications. In the United States, the manufacturer maintains an FDA‐mandated Tysabri Safety Surveillance Program (part of the Tysabri Outcomes Unified Commitment to Health (TOUCH)) of natalizumab‐treated patients. We statistically compared reporting completeness for natalizumab‐associated melanoma cases in FAERs for which information was obtained entirely from the TOUCH program versus cases where FAERS information was supplemented by TOUCH program information. FAERS included 137 natalizumab‐associated melanoma reports in patients with multiple sclerosis. Median age at melanoma diagnosis was 45 years (range: 21–74 years). Changes in preexisting nevi occurred in 16%, history of cutaneous nevi occurred in 22%, diagnosis within 2 years of beginning natalizumab occurred in 34%, and 74% had primary surgical treatment. Among seven natalizumab‐treated MS patients who developed biopsy‐confirmed melanoma on treatment and reported in the literature, median age at diagnosis was 41 years (range: 38–48 years); and the melanoma diagnosis occurred following a median of 12 natalizumab doses (range: 1–77 doses). A history of mole or nevi was noted in four patients and a history of prior melanoma was noted in one patient. Completeness scores for reports were significantly lower for FAERS cases reported from the TOUCH program versus FAERS cases supplemented by TOUCH information (median score of 2 vs. 4 items out of 8‐possible items, P