Adaptive therapy is a novel up-and-coming cancer treatment strategy to minimize chemoresistance in cells to improve patient prognosis. The standard of care cancer treatment has a fixed linear approach known as Maximum Tolerated Dose (MTD) which promotes an exponential growth of resistant cancer cell populations in the tumor. Through this treatment procedure, a population of chemoresistant cells resurges, decreasing the survival in patients, and narrowing potential treatment options (Gatenby). An assortment of chemotherapeutic drugs and dosing schedules were tested on ER+ endocrine-resistant MCF7 breast cancer cells in an immunodeficient mouse model. After the cessation of treatment, some mouse models’ tumors remained stable or began to shrink. Several immunodeficient mouse models have indicated unexpectedly high levels of neutrophils stemming from an unknown origin. We aim to understand if neutrophils' innate immunity may affect tumor size post-chemotherapy treatment and if it has therapeutic implications along with adaptive therapy. MCF7 breast cancer tumors were extracted from the mice, embedded in wax, and sliced, and immunofluorescence was performed to detect neutrophils and nuclear components. Currently, the protocol is in its third round of optimization.