new york u.s. house representatives committee launch probe drugmaker allergan plc agn.n deal transfer patent native american tribe shield review bipartisan group four representatives house oversight government committee include republican chairman trey gowdy top democrat elijah cummings send letter company tuesday say arrangement could impair competition across pharmaceutical industry allergan say last month transfer patent dry eye medication restasis new york saint regis mohawk tribe agree exclusively license back company exchange ongoing payments representatives ask allergan provide document agreements tribe financial detail drug cover patent document whether drugmaker consider similar arrangements drug allergan say plan cooperate committee request company share close 1.18 0.6 percent 209.80 tuesday allergan argue legal maneuver aim remove administrative patent challenge inter part review ipr u.s. patent trial appeal board challenge federal court drugmaker say believe patent subject ipr process tribe sovereign immunity company still face challenge patent federal court say plan invoke tribe immunity federal court still legal experts say maneuver could also use protect patent challenge federal court well early tuesday allergan chief executive brent saunders defend transactions proper way shield patent flaw break ipr process saunders send letter republican senator charles grassley democratic senator dianne feinstein chairman rank member senate judiciary committee four democratic u.s. senators ask launch committee investigation deal last week allergan competitor mylan nv myl.n challenge patent ipr process call allergan deal tribe sham transaction say tribe allow invoke immunity patent board previously recognize immunity state entities public universities tribal immunity consider even strong shield u.s. house committee launch probe allergan patent deal