The period after treatment when a WM patient has experienced either stabilization of disease, an improvement in laboratory values and in physical signs and symptoms, or perhaps disease progression is called a “response.” While an improvement is sometimes commonly referred to as a “remission," the preferred scientific terminology is “response.”
Response to treatment and duration of response varies widely. Currently, there is no way to accurately predict how good or how long a response will be for an individual patient. One of the goals of WM researchers is to better determine how patients will respond to a particular treatment based on the variations in each person’s disease biology and unique genetic makeup.
The Third International Workshop on Waldenstrom’s Macroglobulinemia established the following definitions of response to treatment:
- Progressive disease occurs when there is an increase in serum monoclonal IgM of greater than 25% (confirmed by a second measurement), progression of clinically significant disease findings including cytopenias (reduction in number of blood cells), bulky lymph nodes or enlarged organs, or significant symptoms and conditions (fever, night sweats, weight loss, hyperviscosity, neuropathy, symptomatic cryoglobulinemia, symptomatic cold agglutinin disease, amyloidosis).
- Stable disease is categorized by a reduction in serum monoclonal IgM of less than 25% or an increase of less than 25%, without progression of lymph node or organ enlargement, cytopenias, or clinically significant disease symptoms.
- Minor response is a reduction in serum monoclonal IgM equal to or greater than 25%, but less than 50%, and no new symptoms or signs of active disease.
- Partial response is a reduction in serum monoclonal IgM equal to or greater than 50%, a 50% decrease in lymph node or organ enlargement on physical examination or on CT scan, and no new symptoms or signs of active disease.
- Very good partial response is a reduction in serum monoclonal IgM of 90%.
- Complete response is categorized by a disappearance of serum and urine monoclonal IgM, absence of malignant cells in the bone marrow, resolution of enlarged lymph nodes or organs confirmed by CT scan, and no signs or symptoms of disease. Reconfirmation is required six weeks later.
- Not evaluable or delayed response occurs in cases where there is insufficient time or data for a determination of response to treatment. This may occur after purine analog or monoclonal antibody therapy; therefore, patients should be followed for at least three months after treatment initiation to be considered unresponsive to therapy.
- Objective response is a statistical term combining the number of complete and partial responses.