ThaDD plus high dose therapy and autologous stem cell transplantation does not appear superior to ThaDD plus maintenance in elderly patients with de novo multiple myeloma

Objectives: With the aim to address the issue whether high‐dose therapy (HDT) is required after new drugs combinations to improve outcome of elderly newly diagnosed multiple myeloma (MM) patients, we compared the toxicity and the outcome of ThaDD plus maintenance to those of ThaDD plus HDT‐autologous stem cell transplantation (ASCT). Methods: Sixty‐two patients not eligible for HDT receiving six courses of ThaDD regimen plus maintenance with thalidomide were compared to 26 patients eligible for HDT treated with four courses of ThaDD followed by melphalan 100–200 mg/m² and ASCT. The two groups were matched for the main characteristics except for age favouring the HDT group. Results and conclusions: Complete remission (CR) obtained with ThaDD plus maintenance was 24% whereas it was 57% after ThaDD plus HDT‐ASCT (P = 0.0232). However, after a median follow‐up of 36 months, median time to progression (TTP) and progression free survival (PFS) of the group of patients undergone HDT were not significantly different to those of patients receiving ThaDD plus maintenance (32 vs. 31 months: P = 0.962; 32 vs. 29 months: P = 0.726, respectively). Five‐year overall survival (OS) was 49% in the first group and 46% in the latter one (P = 0.404). As expected, a significantly higher incidence of grade 3–4 neutropenia, thrombocytopenia, infections, mucositis and alopecia were observed in the ThaDD plus HDT group. Our results suggest that in elderly MM patients ThaDD plus HDT, albeit significantly increases CR rate, seems to be equivalent to ThaDD plus maintenance in terms of TTP, PFS and OS. These results challenge the requirement for HDT consolidation in this subset of patients.