Diagnostic and Response Criteria in Multiple Myeloma

Diagnostic criteria and treatment eligibility have been expanded to include patients with multiple myeloma who do not have abnormal levels of calcium, kidney problems, anemia, or bone disease, which were traditional triggers for requiring therapy, states Kenneth Anderson, MD. Patients who do not meet these criteria but have 60% plasma cells in the bone marrow, a kappa/lambda free light chain ratio abnormality, or multiple sites of bone disease, are also now eligible for treatment. This extends benefit of treatment to a broader group of patients, comments Anderson.

Response criteria are also being refined, says Anderson. Advancements in analytical techniques for detecting minimal residual disease (MRD), such as 8-color immunofluorescence and gene sequencing of the myeloma cell, can detect one myeloma cell per one million normal bone marrow cells, notes Anderson. Clinicians are also incorporating positron emission tomography scanning into response criteria. MRD information may also help determine whether individuals can stop maintenance therapy.

These developments in practice have also led to the inclusion of surrogate markers in clinical trial designs so that clinicians do not have to wait 8 to 10 years to define whether a treatment is useful, says Anderson. The leading surrogate endpoint for multiple myeloma trials is currently MRD, although questions still linger and standardization is needed. Findings have shown the MRD can predict progression-free survival and overall survival.