Background: Cancer stem cells are the cancer cells that have abilities to self-renew, differentiate into defined progenies, and initiate and maintain tumor growth. Among the reported makers of the cancer stem cells, CD133 is the most well-known marker for isolating and studying cancer stem cells in different types of cancer. The CD133high population of cancer cells are not only capable of self-renewal, proliferation, but also highly metastatic and resistant to therapy.
Aim and Objectives: To know about PROM-1 (CD 133) overexpression in adult acute lymphoblastic leukemia Egyptian patients and relation to outcome.
Subjects and Methods:This is a Prospective study, was conducted at Ain Shams university hospitals. Internal medicine department, Clinical hematology and stem cell transplantation unit, on 47 adult patients with Acute Lymphocytic Leukemia, over aperiod of Six months.
Result: according to outcome there were 22 (68.75%) with Complete remission, 8 (25%) with Resistant and 2 (6.25%) died.  There were 26 (81.2%) with fever, 10 (31.2%) with Bleeding tendency, 26 (81.2%) with Lymph node, 17 (53.1%) with Hepatosplenomegaly, 9 (28.1%) with Mediastinal mass and 17 (53.1%) with Bone pain.
Conclusion: Prominin 1 positive expression is a helpful prognostic marker in patients with ALL. Prominin 1 should be routinely assessed at diagnosis in ALL patients for better prognostic assessment and should be taken in consideration in designing future therapeutic strategies based on patient specific risk factors.