Legal Name

Jurisdiction of Organization

TESARO Securities Corporation*

Massachusetts

TESARO UK Limited*

United Kingdom

TESARO Development, Ltd.*

Bermuda

TESARO Bio GmbH*

Switzerland

TESARO Bio Germany GmbH*

Germany

TESARO Bio Italy S.r.l.*

Italy

TESARO Bio France SAS*

France

TESARO Bio Spain, S.L.*

Spain

TESARO Bio Netherlands B.V.*

Netherlands

TESARO Bio Sweden AB*

Sweden

TESARO Bio Austria GmbH*

Austria