Relapse Pattern After Bortezomib Based Salvage Therapy in Patients with Multiple Myeloma

More intensive and novel therapy options in multiple myeloma (MM) improve the treatment outcome. However, disease evolution, induced with long disease duration and extensive pretreatment, has resulted in changes in the biological behavior of MM and unusual relapse emergence. Therefore, we studied the relapse pattern after bortezomib based salvage treatment in patients with MM and also we analyzed the prognostic significance according to relapse pattern.

We have retrospectively analyzed the relapse pattern. Eligibility criteria included primary refractory or relapsed MM patients who must have received previous chemotherapy and they also received at least 2 cycles of bortezomib based salvage treatment. Immunoglobulin M type of MM, primary amyloidosis and plasma cell leukemia were excluded in this study. For evaluation of disease response, International Myeloma Working Group (IMWG) uniform response criteria were used.

Between November 2004 and August 2011, 132 patients received bortezomib based salvage chemotherapy. In 132 patients, 91 (68.9%) patients showed the disease relapse. The pattern of relapse after bortezomib salvage treatment was heterogeneous, the 14/91 (15.4%) patients relapsed as a novel manifestation comparison with the initiation of bortezomib (plasmacytoma: 7 patients, light chain escape pattern: 4 patients and, plasma cell leukemia: 2 patients). There was no statistical difference in the duration from diagnosis to bortezomib treatment according to novel (group A) vs isoform (group B) relapse. In the group B, the median overall survival after relapse was 16.1 months (95% CI: 11.4–20.8) and the group A was 2.5 months (95% CI: 0.0–5.7)(p=0.000). The 27 out of 132 patients received the retreatment of bortezomib and 23 out of 27 patients showed the disease progression. The 4/24 (16.7%) patients relapsed as a novel manifestation (plasmacytoma: 2 patients, light chain escape pattern: 1 patients and intact immunoglobulin secretion from plasmacytoma type: 1 patient). In patients received retreatment of bortezomib, novel relapsed group showed the trend of poor survival without statistical significance (2.2 months vs 10.0 months) (p=0.30).

Our report suggests that bortezomib treatment contribute as a selective pressure and it has culminated in novel relapse manifestation. The relapsed patients as novel pattern after bortezomib treatment show the extreme poor prognosis. These findings suggest that these patients may be worth consideration for intensive treatment or early clinical trials.

No relevant conflicts of interest to declare.