Molecular remission after allogeneic or autologous transplantation of hematopoietic stem cells for multiple myeloma

Purpose: To assess the clinical relevance of minimal residual disease (MRD) in patients with multiple myeloma (MM), 50 patients were monitored while t hey were in complete clinical remission (CCR) after autologous or allogenei c stem-cell transplantation. Patients and Methods: Stringent molecular monitoring using clonal markers b ased on rearranged immunoglobulin heavy-chain genes was performed in 44 of 50 MM patients in CCR, Molecular clinical remission (MCR) wets defined as m ore than one consecutive negative polymerase chain reaction (PCR) test resu lt. Results: Twelve (27%) of 44 molecularly monitored patients achieved MCR; fo ur of the 12 became PCR-positive, and one of these four relapsed. In compar ison with patients who did not achieve MCR, patients who achieved MCR had a significantly lower relapse rate (41% v 16%; P < .05) and longer relapse-f ree survival (35 v 110 months; P < .005). Fourteen of 26 patients in CCR wh o had received allografts were evaluated on a molecular basis: seven (50%) of the 14 achieved MCR and did not relapse; one of the seven remaining pati ents relapsed. Thirty of 47 patients in CCR who received autografts were ev aluated on a molecular basis: five (16%) of the 30 achieved MCR; two of the se five became PCR-negative, and one of these two relapsed. Ten of the 25 r emaining patients later relapsed. For these nonrandomised groups, the highe r MCR rate after allograft procedures was statistically significant (P < .0 1; Fisher's exact test). Conclusion: MCR can be obtained in a relatively high proportion of MM patie nts who have achieved CCR alter undergoing allograft procedures and in a sm ellier fraction of patients after undergoing autograft procedures. In appro ximately one fourth of MM patients who achieve CCR after transplantation, i t may be possible to keep the disease burden constantly below the PCR thres hold. Because MCR was associated with prolonged relapse-free survival, thes e patients could have a relatively favorable clinical outcome. J Clin Oncol 18:2273-2281. (C) 2000 by American Society of Clinical Oncology.