Criteria of Adequate Response:
- Reduction of serum paraprotein to less than 50% of the pretreatment level and urine paraprotein to less than 10% of pretreatment level is required to be considered a partial remission.
- Improvement or stabilization of bone marrow function
- Improvement or stabilization of kidney function
- Normalization of serum calcium
- No new osseous or extra-osseous lesions
- Resolution of all symptoms
Criteria of Relapse or Progression:
- Progressive rise in level of paraproteinemia and/or paraproteinuria by more than 25%
- Development of hypercalcemia
- Appearance of new osseous or extra-osseous lesions
- Progressive bone marrow failure
Development of anemia, thrombocytopenia or neutropenia singly or in combination usually reflects one of two problems, drug toxicity or progressive disease. Concurrent assessment of bone marrow (aspiration + biopsy) and paraproteins (serum + urine) will usually resolve the question. If progressive disease, bone marrow examination shows heavy infiltration with abnormal plasma cells and rising paraprotein levels. If drug toxicity, bone marrow examination shows hypocellular marrow, usually with residual myeloma. Paraprotein levels are either falling or remaining stable. Pancytopenia developing unexpectedly in patients on long-term therapy with alkylating agents may be due to secondary leukemia or myelodysplasia.
The development of a falling paraprotein level and separate signs of progressive disease (such as new bone lesions) suggest that the myeloma is becoming non-secreting and the paraprotein may not be as useful to follow disease. For such patients, serum free light chain levels may be helpful to follow disease.