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Recent advances in multiple myeloma include numerous approvals of novel therapies with unprecedented efficacy, a rapid and sustained tempo of new drug development, and further refinements to prognostication to include minimal residual disease (MRD) testing and improved risk stratification. The upfront use of immunomodulatory drug and proteasome inhibitor combinations followed by maintenance has resulted in transformative clinical benefit. Four-drug regimens incorporating monoclonal antibodies are reporting unprecedented rates of complete response and MRD negativity in the absence of intensification. In the context of these advances, the added value of high-dose melphalan with autologous stem-cell transplant (HDM-ASCT) is a key question. From a safety standpoint, HDM-ASCT is associated with both acute toxicities that reduce quality of life and long-term toxicities that may limit life expectancy for some patients. The present review discusses the recent advances in induction therapy, the impact of these advances on HDM-ASCT, the evolving role of MRD testing and the short- and long-term risks of HDM-ASCT. Recognising that prospective data remains limited, we suggest that HDM-ASCT not be considered mandatory for eligible newly diagnosed patients who are treated with highly efficacious regimens and achieve deep responses, but rather be held in reserve without early exposure to the clinical and genomic toxicity inherent to this approach., (© 2020 British Society for Haematology and John Wiley & Sons Ltd.)

Multiple myeloma (MM) is a cancer of terminally differentiated plasma cells. MM remains incurable, but overall survival of patients has progressively increased over the past two decades largely due to novel agents such as proteasome inhibitors (PI) and the immunomodulatory agents. While these therapies are highly effective, MM patients can be de novo resistant and acquired resistance with prolonged treatment is inevitable. There is growing interest in early, accurate identification of responsive versus non-responsive patients; however, limited sample availability and need for rapid assays are limiting factors. Here, we test dry mass and volume as label-free biomarkers to monitor early response of MM cells to treatment with bortezomib, doxorubicin, and ultraviolet light. For the dry mass measurement, we use two types of phase-sensitive optical microscopy techniques: digital holographic tomography and computationally enhanced quantitative phase microscopy. We show that human MM cell lines (RPMI8226, MM.1S, KMS20, and AMO1) increase dry mass upon bortezomib treatment. This dry mass increase after bortezomib treatment occurs as early as 1 h for sensitive cells and 4 h for all tested cells. We further confirm this observation using primary multiple myeloma cells derived from patients and show that a correlation exists between increase in dry mass and sensitivity to bortezomib, supporting the use of dry mass as a biomarker. The volume measurement using Coulter counter shows a more complex behavior; RPMI8226 cells increase the volume at an early stage of apoptosis, but MM.1S cells show the volume decrease typically observed with apoptotic cells. Altogether, this cell study presents complex kinetics of dry mass and volume at an early stage of apoptosis, which may serve as a basis for the detection and treatment of MM cells.