An objective assessment in newly diagnosed multiple myeloma to avoid treatment complications and strengthen therapy adherence.

In heterogeneous multiple myeloma (MM) patients treatment decisions are challenging. The hypothesis was that adaptation of treatment intensity (dose reduction [DR] vs. none) according to an objective risk score (revised-myeloma comorbidity index [R-MCI]) rather than physician judgement alone may improve therapy efficacy and avoid toxicities. We performed this study in 250 consecutive MM patients who underwent a prospective fitness assessment at our center, after having received induction protocols based on physicians' judgement. DR, serious adverse events (SAE), response, progression-free survival (PFS) and overall survival (OS) were compared in fitness (fit, intermediate-fit, frail), age (<60, ≥70 years [y]) and therapy intensity subgroups at baseline and follow-up. Fit and <60 y patients were mostly treated with full intensity, whereas frail and ≥70 y patients usually received DR. Hematological and non-hematological SAE were more frequently seen in frail versus ≥70 y patients. Dose adaptations were mainly necessary in frail patients. OS and PFS were similar in fit and intermediate-fit but significantly worse in frail patients (P=0.0245/P<0.0001), whereas in age-based subgroups, OS and PFS differences did not reach significance (P=0.1362/P=0.0569). Non-hematological SAE were another negative predictor for impaired OS and PFS (P=0.0054/P=0.0021). In the follow-up performed at a median of 11 months after the first fitness assessment, the R-MCI improved or remained stable in 90% versus deteriorated in only 10% of patients. In conclusion, separation by R-MCI/frailty-defined subgroups was superior to age-based subgroups and can be used to improve tailored treatment. Fitter patients benefit from intensive therapies, whereas frail patients bear a need for initial DR.