RESUMEN
Quantitative immuneprecipitation mass-spectrometry (QIP-MS) allows the identification of the M-protein in patients with multiple myeloma (MM) otherwise in complete response, and could be considered suitable for measurable residual disease (MRD) evaluation in peripheral blood. In the context of the GEM2012MENOS65 and GEM2014MAIN trials, we compared the performance of QIP-MS in serum with next-generation flow (NGF) cytometry in bone marrow to assess MRD in paired samples obtained post-induction, transplant, consolidation and after 24 cycles of maintenance. At each time point, both NGF and QIP-MS were able to segregate two groups of patients with significantly different progression-free survival (PFS); when the evolution of the results obtained with either method was considered, maintaining or converting to MRD negativity was associated with longer survival, significantly better when compared to sustaining or converting to MRD positivity. Of note, reemergence of MRD by QIP-MS was associated with high risk of imminent clinical progression. In conclusion, MRD evaluation by NGF and MS achieve similar prognostic value based in single time point assessments and kinetics. Thus, the minimally-invasive nature of MRD monitoring by MS represents a breakthrough in high-sensitive response assessment in MM. GEM2012MENOS65: #NCT01916252 and EudraCT as #2012-005683-10. GEM2014MAIN: #NCT02406144 and at EudraCT as 2014-00055410.
RESUMEN
Multiple myeloma is an incurable plasma cell malignancy. Most patients end up relapsing and developing resistance to antineoplastic drugs, like bortezomib. Antibiotic tigecycline has activity against myeloma. This study analyzed tigecycline and bortezomib combination on cell lines and plasma cells from myeloma patients. Apoptosis, autophagic vesicles, mitochondrial mass, mitochondrial superoxide, cell cycle, and hydrogen peroxide were studied by flow cytometry. In addition, mitochondrial antioxidants and electron transport chain complexes were quantified by reverse transcription real-time PCR (RT-qPCR) or western blot. Cell metabolism and mitochondrial activity were characterized by Seahorse and RT-qPCR. We found that the addition of tigecycline to bortezomib reduces apoptosis in proportion to tigecycline concentration. Supporting this, the combination of both drugs counteracts bortezomib in vitro individual effects on the cell cycle, reduces autophagy and mitophagy markers, and reverts bortezomib-induced increase in mitochondrial superoxide. Changes in mitochondrial homeostasis and MYC upregulation may account for some of these findings. These data not only advise to avoid considering tigecycline and bortezomib combination for treating myeloma, but caution on the potential adverse impact of treating infections with this antibiotic in myeloma patients under bortezomib treatment.