Discordant response or progression in patients with myeloma treated with thalidomide-based regimens.

Thalidomide-based regimens (TBR) are now widely used for the treatment of refractory multiple myeloma and have shown significant activity in newly diagnosed patients. In some patients with secretory disease, we observed discrepancies between the reduction of the monoclonal protein levels and the plasma cell infiltration in the bone marrow and/or extramedullary sites of relapse after treatment with TBR. The purpose of this study was to assess the incidence and analysis of this phenomenon in all myeloma patients treated with TBR in our Institution. Patients and methods: We studied all patients who received TBRs and had a follow up time of at least 6 months. Partial response (PR) was defined as at least 50% reduction of serum myeloma protein and soft tissue plasmacytomas and/or > 90% reduction of Bence Jones protein excretion and minor response as a > 25% reduction of the serum myeloma protein or > 50% reduction of the Bence Jones myeloma protein. Results: Between July 1999 and July 2002 we treated 94 patien...