Prognostic impact of early‐versus‐late responses to different induction regimens in patients with myeloma undergoing autologous hematopoietic cell transplantation: results from the CALM study by the CMWP of the EBMT

Background In autologous stem cell transplant (ASCT)-eligible myeloma patients, prolonged induction does not necessarily improve the depth of response. Method We analysed 1,222 ASCT patients who were classified based on (1) the interval between induction and stem cell collection, (2) the type of induction regimen: BID (Bortezomib, IMiDs and Dexamethasone), Bortezomib-based, or CTD (Cyclophosphamide, Thalidomide and Dexamethasone), and (3) the time to best response (Early i.e. best response within 4 or 5 months, depending on the regimen vs Late; Good i.e. VGPR or better vs Poor) RESULTS: The length of induction treatment required to achieve a Good response did not affect PFS (p=0.65) or OS (p=0.61) post-ASCT. The three types of regimen resulted in similar outcomes: median PFS 31, 27.7 and 30.8 months (p=0.31), and median OS 81.7, 92.7, and 77.4 months, respectively (p=0.83). On multivariate analysis, neither the type nor the duration of the induction regimen affected OS and PFS, except for Early Good Responders who had a better PFS compared to Early Poor Responders (HR = 1.21, p value = 0.02). However, achieving a Good response at induction was associated with a better response (≥ VGPR) post-transplant CONCLUSION: The kinetics of response did not affect outcomes.