Nonmyeloablative allogeneic transplantation with or without ⁹⁰yttrium ibritumomab tiuxetan is potentially curative for relapsed follicular lymphoma: 12-year results

In 2008, we reported favorable 5-year outcomes of nonmyeloablative allogeneic stem cell transplantation after fludarabine, cyclophosphamide, rituximab (FCR) conditioning for relapsed and chemosensitive follicular lymphoma. However, innovative strategies were still needed to treat patients with chemorefractory disease. We therefore subsequently performed a trial in which ⁹⁰Y-ibritumomab tiuxetan (0.4 mCi/kg) was added to the fludarabine, cyclophosphamide conditioning regimen (⁹⁰YFC). Here, we report updated results of the FCR trial and outcomes after ⁹⁰YFC. For the FCR group (N = 47), since the last update, one patient developed recurrent disease. With a median follow-up of 107 months (range, 72-142 months), the 11-year overall survival and progression-free survival rates were 78%, and 72%, respectively. For the ⁹⁰YFC group (N = 26), more patients had chemorefractory disease than did those in the FCR group (38% and 0%, P < .001). With a median follow-up of 33 months (range,17-94 months), the 3-year progression-free survival rates for patients with chemorefractory and chemosensitive disease were 80% and 87%, respectively (P = .7). The low frequency of relapse observed after a long follow-up interval of 9 years in the FCR group suggests that these patients are cured of their disease. The addition of ⁹⁰Y to the conditioning regimen appears to be effective in patients with chemorefractory disease. This trial was registered at www.clinicaltrials.gov as NCT00048737.