Drug General Information (ID: DDIUA198T5)
Drug Name			Tositumomab		Drug Info		Regorafenib		Drug Info
Drug Type		Monoclonal antibody				Small molecule
Therapeutic Class		Antineoplastics				Vegf/Vegfr Inhibitors

Mechanism of Tositumomab-Regorafenib Interaction (Severity Level: Major)
Increased risk of bleeding Click to Show/Hide Mechanism Graph
Drug Name		Tositumomab				Regorafenib
Mechanism		Risk of bleeding Antiplatelet effects				Risk of bleeding Antiplatelet/anticoagulant effects
Key Mechanism Factor 1
		Factor Name		Bleeding
		Factor Description		Patients may be at risk for bleeding when the outcome of a disease or disease treatment confounds the standard mechanisms for maintaining hemostasis. Signs or symptoms of abnormal bleeding include: bleeding that takes a long time to stop (including nosebleeds, bleeding gums, bleeding from cuts and abrasions, and menstrual bleeding); severe unexplained bruising, or bruising that becomes larger; blood in the urine or stool, etc.
Mechanism Description		Increased risk of bleeding by the combination of Tositumomab and Regorafenib

Recommended Action
Management		Concomitant use of other medications that interfere with platelet function or coagulation should be considered cautiously in patients treated with regorafenib. Close clinical and laboratory observation for bleeding complications is recommended during therapy. The INR should be monitored more frequently during coadministration of warfarin.

References
1	Cerner Multum, Inc. "UK Summary of Product Characteristics.".
2	EMEA. European Medicines Agency "EPARs. European Union Public Assessment Reports.".
3	Product Information. Stivarga (regorafenib). Bayer Pharmaceutical Inc, West Haven, CT.