Tandem Autologous Transplant Versus Reduced Intensity Conditioned Allogeneic Transplant (Allo-RIC) as Second Intensification in Chemosensitive Patients with Multiple Myeloma (MM) Not Achieving Complete Remission (CR) or Near-CR with a First Autologous Transplant. Results from a Spanish PETHEMA/GEM Study.

One randomized trial showed that tandem transplant resulted in a significantly longer EFS and OS in patients failing to achieve CR or near-CR with a single transplant. However, other studies failed to show benefit from a second transplant. The aim of our study was to investigate the efficacy in terms of response improvement and survival from a second transplant intensification in patients with chemosensitive disease who failed to achieve CR or near-CR with a first high-dose procedure. Patients diagnosed with MM from Oct 1999 to Dec 2004 younger than 70 years received 6 courses of VBMCP/VBAD and responding patients were intensified with busulphan/melphalan or MEL-200 followed by stem cell support. Patients not achieving CR or near-CR were planned to undergo a second transplant (second auto with CVB - cyclophosphamide, etoposide and BCNU - or MEL-200 intensification or an allo-RIC with Fludarabine/MEL-140 conditioning, if sibling donor available). Eighty-eight patients received a second autologous transplant while 26 underwent an allo-RIC. Thirty-seven percent of the patients given a second autologous transplant improved their response status (CR 11%, near-CR: 6%, PR: 9% and MR 11%) while 63% showed “no change”, progressive disease or early death. A response was observed in 45% of patients undergoing the allo-RIC (CR: 33%, PR: 4%, MR: 8%). The CR rate was significantly higher with allo-RIC (33% vs. 11%, p= 0.02). There was a trend towards a higher TRM with the allo-RIC (5% vs. 16%, p=0.09). Although the median EFS (26 vs 19 m) and OS (57 m vs not reached in allo-RIC) from the second high-dose procedure were not significantly different, there is a plateau in the “allo-RIC” group beyond 3 years of the second procedure not observed in the autologous arm.

Conclusions:

1. an allo-RIC transplant after an autologous procedure results in a significantly higher CR rate than a second autologous transplant, and

2. despite the lack of significant differences in survival between the two transplant modalities, there is a plateau in the allogeneic group not observed in the autologous arm.