To maintain or not to maintain: treatment forever in myeloma?
Achieving a first complete remission in myeloma has become feasible with novel agent-based combination therapies followed by autologous stem cell transplantation (ASCT), leading to CR rates of 40%. But continuously occurring relapses in these patients have led to the revival of maintenance (MT) concepts aiming to eliminate or control minimal residual disease when myeloma burden is low and not too many clonal tidings have been induced. On the other side, the clinical effectiveness of MT has to be balanced against its considerable cost, toxicity and effects on quality of life. Owing to low effectiveness and side effects of chemotherapy, steroids as monotherapy and α-interferon are obsolete options for maintenance concepts, while low-dose thalidomide should be considered in low-risk patients that do not achieve at least very good partial remission after ASCT, when other MT options are not available. There is limited data on the effectiveness of Bortezomib (BTZ) MT in high-risk patients with respect to both progression-free survival (PFS) and overall survival (OS). Lenalidomide (LEN) MT after ASCT shows a clear PFS benefit, but data on OS and the influence on the outcome of subsequent therapies are conflicting. Toxicity includes haematotoxicity, venous thromboembolism and the induction of secondary primary malignancies. LEN-MT cannot be considered a standard approach after ASCT yet, but should be discussed on a case by case basis with every patient, as well as BTZ-MT in t(4;14) positive myelomas. In non-transplant eligible patients keeping patients on prolonged therapies has been shown to be beneficial and the distinction to MT is often purely semantic.