BCMA is not just a drug target anymore, for while the B-Cell Maturation Antigen (BCMA) --  a protein expressed on virtually all myeloma cells -- is the target of new CAR-T therapies, it is found in the blood also. Measuring its level of increase or decrease provides very fast feedback on whether a new treatment protocol is working or not.  This then correlates to time on treatment (TOT) for the particular drug protocol. The research is reported in abstract #4371 from the Institute for Myeloma & Bone Cancer Research, West Hollywood, CA. The principal author, Sean Bujarski, BA, describes their test for the level of BCMA in the blood at various intervals after beginning a new course of treatment in patients.  They began the tests at Cycle 1, Day 8  and compared changes in M-spike in the same patients at the same intervals as follows: Forty-nine myeloma patients receiving 83 treatment regimens were analyzed. Patients whose BCMA levels increased more than 25% by C1D8 had a shorter median time on treatment than all other regimens (1.73 months vs. 5.76 months). Patients who had a BCMA levels increase over 25% increase had a shorter median time on treatment than all other regimens (1.73 months vs. 5.76 months). Patients whose BCMA levels dropped by more than 25% had a longer time on treatment (6.91 months) when compared with all other regimens (2.89 months). In contrast, sM-protein levels did not show > 25% changes at these early time points. For those patients who achieved at least a minimal response, the time to achieve at least a 25% decrease in sBCMA was much shorter (median 7 days) than the time for sM‑protein (median 21 days). For those that progressed during the first cycle, the time to achieve at least a 25% increase in sBCMA was similarly much shorter (median 7 days) than the time for sM-protein (median 21 days). The bottom line is that tracking BCMA levels may be more important than tracking M-protein levels.

“Conclusions: We have shown that relative changes in sBCMA levels from baseline can much more rapidly determine changes in clinical status than the standard sM-protein biomarker among MM pts starting new treatments. By C1D8, sBCMA establishes changes in clinical status whereas sM-protein takes much longer to show the effect of treatment on response status. In addition, a > 25% increase or decrease in sBCMA levels at C1D8 indicates a much shorter or longer time on treatment, respectively for these patients. Thus, relative changes in sBCMA levels among myeloma patients on new therapies allows more rapid determination of changes in their clinical status, and these early changes predict the length of time on those treatments.”

As patients, waiting for results from our labs can be an ongoing source of stress and concern, as it always seems to take too long.  This new technique is simple and fast, and can give our oncologists early notice as to whether a new treatment should be continued or changed which is time we need as we fight this disease. Learn more about testing BCMA levels in this show on Myeloma Crowd Radio.