Up-Front Thalidomide-Dexamethasone (THAL) and Double Autologous Transplantation (Double TX) for Multiple Myeloma: Comparison with Double TX without Added Thalidomide and Prognostic Implications of Chromosome 13 Deletion and Translocation t(4;14).

Aim of the present sudy was to evaluate the benefit of novel agents combined with conventional therapies in multiple myeloma (MM), with particular emphasis on patients (pts) carrying adverse cytogenetic abnormalities. For this purpose, we analyzed a series of 142 pts who received thalidomide-dexamethasone (thal-dex) and double autologous transplantation (double Tx). By study design, thal-dex was administered from the outset until the second autologous Tx. On an intent-to-treat basis, stringently defined (immumofixation negative) complete remission (CR) rate following double Tx and thal-dex was 54%. This value was significantly higher (P=0.0009) compared to the 33% observed in a comparable series of 129 pts who received double Tx without thal-dex. In comparison with these latter patients, addition of thal-dex to double Tx significantly prolonged PFS (median: 31 vs 42 months; P=0.04) and did not adversely affect survival after post-transplant relapse (P=0.7). All 142 pts included in the study were investigated at baseline for the presence of chromosome 13 deletion [del(13)] by FISH analysis and of t(4;14) using a RT-PCR assay. An analysis on an intent-to-treat basis performed according to the presence or absence of these cytogenetic abnormalities revealed that the probability to respond (more than 90% reduction in M protein concentration) to primary therapy with thal-dex for 94 pts who carried both del(13) and t(4;14) was significantly lower compared to that of 69 pts with del(13) alone (12% vs 41%, respectively; P=0.012) and of 18 pts with t(4;14) alone (12% vs 50%, respectively; P=0.006). The lower probability of response to first-line thal-dex therapy conferred by the presence of both del(13) and t(4;14) was completely offset by subsequent application of double Tx and thal-dex. Indeed, on an intent-to-treat basis, the probability to attain a very good partial response or CR for pts with both del(13) and t(4;14) positivity was 68% compared to 80% for pts with both del(13) and t(4;14) negativity (P=0.1). With a median follow-up of 24 months, the 3-year projected probabilities of OS and PFS were 80% and 59%, respectively (intent-to-treat). The presence or absence of t(4;14) had no significant impact on the 3-year projected probability of OS (80.12% vs 80.42%, respectively; P=0.3). Furthermore, an analysis of pts who actually received thal-dex and double Tx showed that curves of OS and EFS were almost superimposable among pts who carried or lacked both del(13) and t(4;14). Indeed, the 3-year projected probability of OS for pts with both these cytogenetic abnormalities was 92% compared to 88% for pts who were negative for both del(13) and t(4;14); (P=0.7); the corresponding figures for EFS were 70% vs 77%, respectively (P=0.9). These results suggest that thal-dex combined with double Tx may overcome the unfavourable prognosis conferred by del(13) and t(4;14). A longer follow-up is required before definite conclusions can be drawn.