Drug Interaction Report

MONITOR: The administration of inactivated, killed, or otherwise noninfectious vaccines to patients receiving B-cell depletion therapy with ublituximab has not been studied but may be associated with diminished or suboptimal immunologic response. Ublituximab use causes a depletion of B-cells and can be expected to similarly increase the risk of a decreased or suboptimal immunologic vaccine response if immunization occurs before B-cells counts have recovered. Pharmacodynamic data has shown the median time to B-cell repletion following discontinuation of ublituximab is 70.3 weeks (range 0.1 to 75.1 weeks). For infants of mothers who have been exposed to ublituximab during pregnancy, there is a potential for depletion of B cells in their infants.

MANAGEMENT: Ublituximab therapy may interfere with the effectiveness of non-live vaccines. Immunization status should be assessed prior to initiating ublituximab and recommended immunizations with non- live vaccines should be completed whenever possible at least 2 weeks prior to ublituximab initiation. For infants of mothers exposed to ublituximab during pregnancy, non-live vaccines may be administered as indicated, however, adequacy of vaccine response should be assessed; this may include a consultation with a qualified specialist or measurement of vaccine-induced response titers to verify that a protective immune response has been mounted. Local vaccination guidelines and prescribing information for individual vaccines should be consulted for further guidance.