A recent study suggests that relapsed/refractory myeloma patients with abnormal plasma cells in the blood prior to therapy have a more aggressive form of multiple myeloma. Furthermore, the study authors speculated that if the number of abnormal plasma cells did not decrease following one cycle of therapy, it may be indicative of treatment resistance.

These findings were presented at the European Hematology Association (EHA) meeting in Barcelona, Spain, last month.

Multiple myeloma is a disease characterized by abnormal plasma cells. Plasma cells are typically located in the bone marrow, but they can be found in the blood as well. The number of abnormal plasma cells in the blood has been shown to go down with myeloma treatment.  However, the existence of abnormal plasma cells in the blood before treatment is associated with poorer outcome.

The study authors were interested in the prognostic significance of normal and abnormal plasma cells in the blood before treatment and after one cycle of treatment in relapsed or refractory myeloma patients.

Their study included 31 multiple myeloma patients who had relapsed or were resistant to at least one prior therapy. Patients were scheduled to receive a Velcade (bortezomib)-containing regimen or a combination treatment of vincristine (Oncovin), doxorubicin (Adriamycin), and dexamethasone (Decadron). 

Researchers measured normal and abnormal plasma cells in the blood immediately before therapy and then again after one cycle of treatment.

They found that patients with detectable abnormal plasma cells in the blood prior to treatment had a shorter time to progression (258 days) than patients with undetectable abnormal plasma cells in the blood (456 days). 

Following one cycle of therapy, patients with increased abnormal plasma cells in the blood had a shorter time to progression (57 days) than patients with decreasing (259 days) or undetectable abnormal plasma cells in the blood (not yet reached after the median observation period of more than 500 days). 

The overall survival time was also decreased for patients with increased abnormal plasma cells following one cycle of therapy (139 days) compared to patients with decreasing or undetectable abnormal plasma cells (not yet reached after the median observation period of more than 500 days).

Although the detection of normal plasma cells in the blood prior to therapy gave no indication of aggressive myeloma, patients with absent or decreasing normal plasma cells following one cycle of therapy had significantly shorter time to progression (217 days) than patients with increasing normal plasma cells (388 days).

Researchers believe that the detection of abnormal plasma cells in the blood prior to treatment may be a new way to identify patients with a more aggressive form of the disease.

Furthermore, it could also serve as a tool to identify treatment-resistant patients as early as the first cycle of therapy.

“If our findings are confirmed in larger studies,” stated the researchers, “these patients may be candidates for immediate switch to alternative therapy.”

For more information, see abstract 0954 on the EHA meeting website.