Study of Oral Navitoclax Tablet In Combination With Oral Ruxolitinib Tablet When Compared With Oral Ruxolitinib Tablet To Assess Change In Spleen Volume In Adult Participants With Myelofibrosis ~36 mi. (Kragujevac, Serbia, +165 more cities) University Clinical Center Kragujevac /ID# 230855 del(11)(q10), +27 more biomarkers Myelofibrosis navitoclax, +1 more drug targeted therapy