Infectious Risks and Complications in Adult Leukemic Patients Receiving Blinatumomab

BACKGROUND: Blinatumomab is an anti-CD19 immunotherapy approved for relapsed/refractory B-cell acute lymphoblastic leukemia (ALL) with significantly increased survival rate. While blinatumomab showed lower rates of infection, neutropenia and mucosal barrier injury versus chemotherapy, its infection risks are not well described. METHODS: All patients who received blinatumomab for ≥ seven days at an academic cancer center from May 2015 to April 2017 were included. Patient characteristics pertinent to infectious risks and complications were examined. RESULTS: Twenty patients with refractory (25%), relapsed (70%), or remitted (5%) B-ALL who received a total of 35 cycles were included. Ten of the 35 cycles were interrupted, none of which were due to infections. Twenty-six infections (n) were observed with lower respiratory (9), gastrointestinal (6) and bacteremia (5) being most common. Compared to patients without nodular, possible mold pneumonia (n=16), patients with nodular pneumonia (n=4) had significantly lower baseline absolute neutrophil count (ANC) (2319 v. 208/μL, p=0.011). There were no differences in baseline characteristics including ANC between bacteremic and non-bacteremic patients. One patient was discharged with no antibacterial prophylaxis since ANC recovered to >500cells/μL, but developed Pseudomonal bacteremia within a week with ANC ~100cells/μL. CONCLUSION: Despite blinatumomab’s relatively modest myelosuppression and the lack of mucotoxicity, host factors (e.g., duration and degree of neutropenia/lymphopenia) play a key role and should be considered when choosing anti-microbial prophylaxis. In relapsed/refractory disease, the ANC should be monitored closely post blinatumomab since neutropenia can unexpectedly develop after treatment which may be compounded by the underlying disease and recent chemotherapy effects.