CD56 as Prognostic Factor in Patients with Multiple Myeloma Treated by High-Dose Chemotherapy and Autologous Stem Cell Transplantation.

Neuronal cell adhesion molecule (NCAM, CD56) is expressed by approximately 75% of multiple myeloma (MM) clones. The lack of CD56 expression on MM cells is described to be associated with a higher frequency of extramedullary involvement (Pellat-Deceunynck et al. 1998) and a lower overall survival in patients treated by conventional chemotherapy (Sahara et al. 2002). We analyzed the CD56 expression of myeloma cells by flowcytometry in 52 newly diagnosed patients to determine its prognostic and clinical relevance. Seventeen of 52 patients were NCAM-negative and 35 patients NCAM positive. The CD56 expression did not correlate with elevated beta2-microglobulin levels or deletions of chromosome 13q14 as investigated by interphase FISH. All patients were scheduled for treatment according to the GMMG-HD3 protocol and received 3 cycles of VAD or TAD induction chemotherapy, followed by CAD chemotherapy, stem cell collection and high dose chemotherapy with melphalan and autologous stem cell transplantation (ASCT). We analyzed the response rate (EBMT/IBMTR criteria) 3 months after the first ASCT and the event free survival (EFS) (median 479 days, range 29–911 days). Three months after the first ASCT, 6/17 of the CD56 negative patients were in CR, 7/17 in PR, 1/17 in MR and 3/17 had PD. Of the CD56 positive patients evaluated for clinical outcome 5/35 showed CR, 20/35 a PR and 10/35 a PD. In an intention-to-treat analysis, EFS showed no significant difference between these two groups. With only 13 events out of 52 cases, a longer follow up in terms of EFS and OS is required. We conclude that in patients treated by high-dose melphalan and autologous stem cell transplantation, the lack of CD56 did not correlate with a poor response rate 3 month after transplantation. Our preliminary results indicate that high-dose therapy followed by ABSCT is able to overcome the poor prognosis of CD56 negative patients treated with conventional chemotherapy.