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Functional P-gp expression in multiple myeloma patients at primary diagnosis and relapse or progressive disease
V Nuessler1, F Gieseler, E Gullis
1Klinikum Grosshadern, Medizinische Klinik und Poliklinik III, Munich, Germany.
Abstract:
In this study, 25 multiple myeloma (MM) patients at primary diagnosis and 18 MM patients at relapse or progressive disease (PD) were examined in order to investigate the incidence of P-glycoprotein (P-gp) expression at initial diagnosis and relapse or PD. Furthermore, P-gp expression in relation to VAD regimen response was determined. P-gp expression in the myeloma cells was determined using monoclonal antibody 4E3.16 and the rhodamine 123 functional test. The percentage of patients with P-gp overexpression at primary diagnosis ranged between 0 and 41% in the literature vs 32% in our study. The percentage of P-gp positive patients at relapse or PD ranged between 29 and 59% in the literature vs 33% in this analysis. All P-gp positive patients had a functional P-gp, ie a pumping P-gp. A significant difference concerning response (50 vs 58.3%) to VAD treatment and median survival (10 vs 12.5 months) between P-gp positive and P-gp negative patients could not be determined. Six of 12 P-gp negative MM patients at relapse or PD developed after VAD therapy a relapse combined with P-gp overexpression. These results do not confirm the suggestions that P-gp overexpression influences response to VAD treatment. However, the results described in the literature and our own emphasize the need for careful accompanying research programmes aimed at detecting the complexity of chemotherapy resistance in the light of developing a risk-adapting therapy for MM patients.
Insights
This study investigated P-glycoprotein (P-gp) expression in multiple myeloma (MM) patients. P-gp overexpression did not significantly impact response to VAD therapy, but further research is needed for risk-adapting MM treatment.
Area of Science:
- Oncology
- Hematology
- Pharmacology
Background:
- Multiple myeloma (MM) is a hematologic malignancy characterized by uncontrolled plasma cell proliferation.
- Chemotherapy resistance, particularly P-glycoprotein (P-gp) overexpression, is a significant challenge in MM treatment.
- Understanding P-gp expression dynamics is crucial for optimizing therapeutic strategies.
Purpose of the Study:
- To determine the incidence of P-glycoprotein (P-gp) expression in multiple myeloma (MM) patients at initial diagnosis and relapse.
- To evaluate the relationship between P-gp expression and response to the VAD (vincristine, doxorubicin, dexamethasone) regimen.
- To explore the development of P-gp overexpression following VAD therapy in relapsed/progressive MM patients.
Main Methods:
- Analysis of P-gp expression in 25 newly diagnosed and 18 relapsed/progressive MM patients.
- Utilized monoclonal antibody 4E3.16 and rhodamine 123 functional assay to assess P-gp expression.
- Correlated P-gp status with VAD treatment response and median survival.
Main Results:
- P-gp overexpression incidence was 32% at primary diagnosis and 33% at relapse/progressive disease.
- All P-gp positive patients exhibited functional P-gp activity.
- No significant differences in VAD response (50% vs 58.3%) or median survival (10 vs 12.5 months) were observed between P-gp positive and negative patients.
- Six of 12 P-gp negative patients developed P-gp overexpression after VAD therapy.
Conclusions:
- P-gp overexpression does not appear to significantly influence response to VAD treatment in MM patients.
- The emergence of P-gp overexpression post-therapy suggests complex resistance mechanisms.
- Further research is essential to understand chemotherapy resistance and develop risk-adapting therapies for MM.