Blinatumomab For Relapsed/Refractory Acute Lymphocytic Leukemia: A Single Center Experience

Introduction: Patients with relapsed/refractory acute lymphoblastic leukemia (ALL) have a poor prognosis and limited treatment options. Blinatumomab was approved in 2014 for the treatment of relapsed/refractory Philadelphia chromosome-negative B-cell ALL. The largest published study of 189 patients with relapsed/refractory B-ALL showed a complete remission/complete remission without hematologic recovery of 43%. Here we report our single center experience in 7 patients with relapsed/refractory B-ALL treated with blinatumomab. Methods: We reviewed the charts of 7 adult patients with relapsed/refractory ALL. All patients were treated with blinatumomab 9 mcg daily as a continuous infusion on days 1-7, followed by 28 mcg daily as a continuous infusion on days 8 - 28 of a 6 week cycle. For cycle 2, 28 mcg daily as continuous infusion was given on days 1 - 28 of a 6 week cycle. Patients: The median age was 48 (range 23-70) and included 5 males/2 females. One patient had persistent disease after two cycles of induction (pt 4), 6 had relapsed B-ALL, and 4/6 had prior allogeneic stem cell transplant (SCT). Results: Two patients (28.6%) had complete remission and received allogeneic SCT in CR, 3 received additional therapy, 2 patient expired soon after blinatumomab. Three of 7 patients (42.9%) were unable to complete 2 cycles: patient 1 for progressive disease on cycle 1 day 13; patient 2 for trismus on cycle 2 day 17; patient 7 on cycle 2 day 8 for mental status changes which recurred after re-challenge. Other toxicities were relatively minor (rigors,headache). One patient (pt 7) developed a venous thromboembolism during the 2 week break period between cycles 1 and 2. Five patients are alive: three in CR post-SCT, one in CRi to other salvage therapy, and one on active therapy in a clinical trial. Conclusion: The observed response rates in our single center experience are not as high as reported in the clinical trials of blinatumomab in relapsed/refractory B-ALL. We saw responses in patients with MRD as well as one patient who had received 5 lines of prior therapy. It is not uncommon to see responses in clinical practice lower than those observed in a clinical trial. Studies are ongoing to determine the benefit of blinatumomab in other B-ALL settings. Our observed rates of CRS and neurologic toxicity were lower than those previously reported, and our experience suggests that it is relatively well-tolerated. Blinatumomab may be beneficial for some patients with B-ALL and provide a bridge to SCT for those who respond. Disclosures No relevant conflicts of interest to declare.