Reduced Intensity Conditioning Regimen for Allografting Following Autografting Is Feasible and Has a Strong Anti Multiple Myeloma Activity.

The development of reduced intensity conditioning regimens (RICT) has renewed interest in allografting for patients with multiple myeloma (MM). Taking advantage of this new approach, we firstly postulated that combining maximal tumor reduction achieved with autografting and the benefits of RICT, we could achieve more cures of multiple myeloma (MM) with acceptable toxicity. Sixteen patients, 51 years of age (range, 36–63) with previously treated stage III MM were given melphalan 140 mg/m² and autologous peripheral blood progenitor cells (PBPC) reinfusion. The regimen-related toxicities were moderate with a median of 8 and 11 days of neutropenia and thrombocitopenia, respectively. Forty-six to 156 days later (median, 79 days), the patients received fludarabine 30 mg/m²/d x 3 days plus 2 Gy TBI and HLA-identical donor mobilized PBPC. Postgrafting immunosuppression consisted of cyclosporine and mycophenolate mofetil. Donor lymphocyte infusions were given to eight patients with stable mixed chimerism or progressive disease who did not show signs of aGVHD. Engraftment occurred in 14 patients (87%). Ten patients (62%) are alive with 9 of them in continuous complete remission 11–36 months (median, 30 months) after transplants. All remitters patients achieved full chimerism and developed GVHD. Grade II–III acute GVHD occurred in 7 patients (43%) but no patient died of aGVHD. Three patients (18%) developed extensive chronic GVHD requiring intensive therapy. Six patients died; five of them of progressive disease and one of progressive disease combined with extensive cGVHD and interstitial pneumonitis. In conclusion, this 2-step approach is feasible and demonstrated to have a strong antimyeloma activity with reduced deaths due to acute toxicities.