In this article, a mathematical model describing the growth orterminating myelogenous leukemia blood cancer's cells against naive T-celland eective T-cell population of body, presented by fractional dierentialequations. We use this model to analyze the stability of the dynamics, whichoccur in the local interaction of eector-immune cell and tumor cells. Wewill also investigate the optimal control of combined chemo-immunotherapy.We claim that our fractional dierential equations model is superior to itsordinary dierential equations counterpart in facilitating understanding of thenatural immune interactions to tumor and of the detrimental side eects whichchemotherapy may have on a patient's immune system.