Feasibility and Efficacy of a Planned Second Transplant (“auto” or “mini-allo”) Intensification in 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.

It has been shown in non-randomized studies that tandem transplant results in an increased CR rate. A 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 a survival benefit from a second transplant. The aim of our study was to investigate the feasibility and efficacy in terms of response up-grading and survival from a second transplant intensification in patients with chemosensitive disease who failed to achieve CR or near-CR with a first transplant. Patients diagnosed with MM from Oct 1999 to Dec 2003 younger than 70 years received 6 courses of VBMCP/VBAD chemotherapy 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 (either a second auto with CVB - cyclophosphamide, etoposide and BCNU - intensification or a dose-reduced intensity “allo” with Fludarabine/MEL-140 conditioning, depending on sibling donor availability). It is of note that 99 (55%) did not receive the second HDT procedure because patient refusal -28 pts-, lack of CD34–17 pts-, progressive disease - 16 pts-, poor PS -15 pts-, physician decision -14 pts-, others -8 pts-. Patients who did not proceed with the second transplant were significantly older (58 vs. 55 yrs, p= 0.001) and had higher serum beta2-microglobulin levels (4.7 vs. 3.5, p=0.02). Fifty nine patients received a second autologous transplant while 23 underwent a “mini-allo”. Twenty-eight percent of the patients given a second autologous transplant achieved an up-graded response (CR or near-CR: 7%, PR: 10% and MR 12%) while 61% showed “no change”, progressive disease or early death. A response up-grade was observed in 43% of patients undergoing a “mini-allo” procedure (CR: 26%, PR: 4%, MR: 3%). The CR rate was significantly higher with the allogeneic procedure (26 vs. 5%, p=0.01). However, there was a trend towards a higher TRM with the “miniallo” procedure (5% vs. 17% (p=0.09). The survival from the second high-dose procedure was not significantly different between the two transplant modalities (2nd auto vs “mini-allo”).

Conclusions.

1. in about one-half of the patients in whom a tandem transplant is planned the second high-dose procedure is not performed,

2. a dose-reduced intensity allogeneic transplant after an autologous procedure results in a significantly higher CR rate than a tandem autologous transplant,

3. with the current follow-up we found no significant differences in survival between the two transplant modalities.