A Bortezomib-Based Protocol Induces a High Rate of Complete Remission with Minor Toxicity in Adult Patients with Relapsed/Refractory Acute Lymphoblastic Leukemia

The treatment of relapsed/refractory acute lymphoblastic leukemia (RR-ALL) presents a true clinical challenge. In 2012, a protocol combining bortezomib, dexamethasone, asparaginase, doxorubicin, and vincristine administered to children with RR-ALL was published with encouraging results. Over the past 5 years, we have implemented this protocol in the adult RR-ALL population (> 18 years) and addressed its feasibility in terms of remission rate and toxicity. Here, we present the results of our experience in 9 patients, all of whom received multiple previous chemotherapy protocols, two of them relapsing after an allogeneic bone marrow transplantation. All of the five B-ALL patients, and two of the four T-ALL achieved complete remission. Of the seven patients achieving complete remission, two patients were referred for allogeneic bone marrow transplantation, two patients were subsequently given blinatumomab, and one patient subsequently received donor lymphocyte infusion followed by blinatumomab. Thus, five out of nine patients treated (55%) were able to proceed to best available therapy in a complete remission. We observed minimal adverse effects, mainly hematological toxicity. We conclude that the bortezomib-based protocol should be evaluated as an effective and well-tolerated treatment option for adult patients either unfit for or failing standard salvage chemotherapy, as a bridge to immunotherapy or allogeneic bone marrow transplantation.