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Plasma cell P170 expression and response to treatment in multiple myeloma
F Patriarca1, C Melli, D Damiani
1Department of Clinical and Morphological Research, Udine University Hospital, Italy.
Background:
Vincristine and anthracyclines are first-line agents for the treatment of multiple myeloma (MM). P170-related multidrug resistance (MDR) may influence the response to these drugs.
Materials And Methods:
P170 expression of bone marrow plasma cells was assayed by immunocytochemistry (alkaline phosphatase anti-alkaline phosphatase technique) with the MRK-16 monoclonal antibody. A case was considered positive if one per cent or more of plasma cells stained as strongly as positive controls.
Results:
Six of 17 (35%) cases in relapse and 18/72 (25%) at diagnosis were MDR positive. MDR positivity was not found in micromolecular MM and was significantly associated with the serum beta 2-microglobulin level. Response to treatments including dexamethasone, vincristine and doxorubicin, or idarubicin, or mitoxantrone was independent of MDR positivity (50% in positive cases vs. 56% in negative ones).
Conclusions:
The detection of P170 in bone marrow plasma cells with the currently available methodology is not likely to predict response to treatments that include vincristine, anthracyclines or mitoxantrone. Further studies are required to evaluate the relevance of P170-related MDR to the development of MM therapy.
Insights
P-glycoprotein (P170) multidrug resistance (MDR) in multiple myeloma (MM) plasma cells does not predict treatment response. Current methods for detecting P170-MDR are insufficient for guiding therapy decisions in MM patients.
Area of Science:
- Hematology
- Oncology
- Molecular Biology
Background:
- Vincristine and anthracyclines are standard treatments for multiple myeloma (MM).
- P-glycoprotein (P170)-related multidrug resistance (MDR) can impact treatment efficacy in MM.
Purpose of the Study:
- To investigate the association between P170 expression in bone marrow plasma cells and treatment response in multiple myeloma patients.
- To evaluate the clinical utility of P170 detection for predicting therapeutic outcomes in MM.
Main Methods:
- Immunocytochemistry using the MRK-16 monoclonal antibody was employed to detect P170 expression in bone marrow plasma cells.
- A threshold of 1% or more strongly stained plasma cells was used to define P170 positivity.
Main Results:
- MDR positivity was observed in 35% of relapsed and 25% of newly diagnosed MM cases.
- P170 positivity was not detected in micromolecular MM and correlated with serum beta 2-microglobulin levels.
- Treatment response rates were similar between MDR-positive (50%) and MDR-negative (56%) patients, indicating independence from P170 status.
Conclusions:
- Current methods for detecting P170 in bone marrow plasma cells are unlikely to predict response to treatments involving vincristine, anthracyclines, or mitoxantrone.
- Further research is necessary to determine the relevance of P170-related MDR in the context of multiple myeloma treatment development.