Blockade of interleukin-6 signalling with siltuximab enhances melphalan cytotoxicity in preclinical models of multiple myeloma

Signalling through the interleukin (IL)-6 pathway induces proliferation and drug resistance of multiple myeloma cells. We therefore sought to determine whether the IL-6-neutralizing monoclonal antibody siltuximab, formerly CNTO 328, could enhance the activity of melphalan, and to examine some of the mechanisms underlying this interaction. Siltuximab increased the cytotoxicity of melphalan in KAS-6/1, INA-6, ANBL-6, and RPMI 8226 human myeloma cell lines (HMCLs) in an additive-to-synergistic manner, and sensitized resistant RPMI 8226.LR5 cells to melphalan. These anti-proliferative effects were accompanied by enhanced activation of drug-specific apoptosis in HMCLs grown in suspension, and in HMCLs co-cultured with a human-derived stromal cell line. Siltuximab with melphalan enhanced activation of caspase-8, caspase-9, and the downstream effector caspase-3 compared with either of the single agents. This increased induction of cell death occurred in association with enhanced Bak activation. Neutralization of IL-6 also suppressed signalling through the phosphoinositide 3-kinase/Akt pathway, as evidenced by decreased phosphorylation of Akt, p70 S6 kinase and 4E-BP1. Importantly, the siltuximab/melphalan regimen demonstrated enhanced anti-proliferative effects against primary plasma cells derived from patients with myeloma, monoclonal gammopathy of undetermined significance, and amyloidosis. These studies provide a rationale for translation of siltuximab into the clinic in combination with melphalan-based therapies

Novel treatment paradigm for elderly patients with multiple myeloma

The treatment of multiple myeloma has undergone important changes in the last few years. The use of novel agents, such as the immunomodulatory drugs thalidomide and lenalidomide, and the proteasome inhibitor bortezomib, has increased the treatment options available and significantly improved the outcome of this rare disease. Several trials have shown the advantages linked to the use of novel agents both in young patients, who are considered eligible for transplantation, and elderly patients, who are considered transplant ineligible. In the non-transplant setting, novel agent-containing regimens have replaced the traditional melphalan-prednisone approach. Preliminary data also support the role of consolidation and maintenance therapy to further improve outcomes. An appropriate management of side effects is fundamental for the success of the treatment, and outcome should always be balanced against the toxicity profile associated with the regimen used. This review provides an overview of the latest strategies including novel agents used to treat elderly patients with multiple myeloma