Interim Maintenance is the third phase of treatment for ALL. It’s primary focus is to destroy any remaining leukemia cells in the body over a period of approximately 8 weeks. Typically, IM consists of four rounds, lasting two weeks each.
Each round consists of an inpatient stay for an average of 4 days, followed by 10 days outpatient. While inpatient, the patient receives a slow HD-MTX IV over 24 hours due to its toxicity, and then remain inpatient for at least several days as the body clears the methotrexate. The MTX clearing must be carefully monitored to ensure the body is properly and safely recovered before the patient can go home.
It is common during IM to develop mucositis and other MTX side-effects that may prolong the inpatient stay. It’s not unusual for each of the four rounds to be more difficult than the previous one.