Comparison of Two Post-Transplant Predictive Indexes: Day 100 is a Better Time-Point for Response Evaluation after Autologous Stem Cell Transplantation in Multiple Myeloma: Ass Retrospective Study

In Multiple Myeloma (MM), response to High-Dose Chemotherapy (HDC) and Autologous Stem Cell Transplant (ASCT) has important prognostic and therapeutic implications. Best timing for response evaluation after ASCT is not well studied. Our study evaluated the correlation between response on day 30 and day 100 after ASCT with Progression Free Survival (PFS) and Overall Survival (OS) in 119 MM patients. Median follow-up was 39.8 months. Complete Response (CR) was achieved in 53.8% and 55.5% of patients on D 30 and D 100, respectively. On D30, there was no significant difference in PFS or OS in CR vs. no CR group (35.4 vs. 22.1 months, p: 0.058) and (92.6 months vs. not reached p: 0.96) respectively nor in responders (R) vs. Non-Responders (NR) group (97.8 vs. 47.1 months p: 0.08) and (30.2 vs. 18.9 months, p: 0.09) respectively. While on D100, PFS was significantly better in CR vs. no CR group (33.8 vs. 18.1 months, p: 0.0047) as well as in R vs. NR (30.6 vs. 16.9 months p: 0.015). However, OS was not better in either (92.6 vs. 52.1 months p: 0.46) and (92.6 months vs. not reached p: 0, 88) respectively. In conclusion, after HDC and ASCT for MM, we recommend doing response evaluation on D100 rather than D30 as it better correlates with PFS. Further studies are required to confirm this finding in the era of consolidation and maintenance treatment.