Impact of the time interval between end of induction and autologous hematopoietic transplantation in newly diagnosed patients with multiple myeloma.

Multiple Myeloma patients eligible for autologous hematopoietic transplantation (AHT) typically receive 3-6 cycles of induction therapy before transplant. The last induction cycle is completed 2-4 weeks prior to mobilization. We evaluated the impact of the time interval between end of induction and AHT on progression-free survival (PFS) and overall survival (OS). A total of 1055 patients who underwent AHT were identified. The median time to transplant (TTT) was 33 days (27-42 quartile range). Patients with less than 33 days of TTT had significantly prolonged PFS (35.6 vs. 32.1 months, p < 0.03) but non-significant OS differences compared to those with more than 33 days. Quartile comparisons showed that patients in the 1st quartile (less than 27 days) had significantly prolonged PFS (36.7 vs. 30.9 months, p < 0.01) compared to the 4th quartile group (more than 42 days). In a subgroup analysis of patients with partial or worse biochemical response prior to transplant, patients in the 1st quartile had significantly prolonged PFS (37.7 vs. 28.7 months, p < 0.04) compared to the 4th quartile group. In conclusion, we showed that a prolonged TTT is associated with inferior outcomes compared to tighter chemotherapy schedules. This finding was especially prevalent in patients with partial response at induction.