A BCR/ABL1 Monitoring Test is a quantitative in vitro diagnostic device used to monitor the BCR/ABL1 to ABL1 ratio by reverse-transcriptase quantitative polymerase chain reaction (RQ-PCR) on whole blood or bone marrow of diagnosed Philadelphia chromosome positive (Ph+) chronic myeloid leukemia (CML) patients expressing BCR-ABL1 fusion transcripts such as e13a2 and/or e14a2. It is intended for use during monitoring of treatment response by reporting results on the international scale (%IS) and as log molecular reduction (MR) value.