Safety and efficacy of subcutaneous blinatumomab in adult patients with R/R B-ALL: phase Ib trial

Novel immunotherapies have improved long-term survival in patients with B-cell acute lymphocytic leukemia (B-ALL). However, outcomes for adult patients with relapsed/refractory (R/R) B-ALL remain poor, and better treatments are warranted. Continuous intravenous infusion of blinatumomab is a standard treatment used in R/R B-ALL. Recently, subcutaneous (SC) delivery of blinatumomab has been developed to further improve efficacy and allow ease of administration for patients.

Here, we summarize results from the dose-expansion phase of a global, single-arm, multicenter phase Ib trial (NCT04521231) investigating the efficacy and safety of single-agent SC blinatumomab in heavily pretreated adult patients with R/R ALL, published by Jabbour et al.¹ in American Journal of Hematology.

Study design¹

• This study included adult patients with R/R ALL who had ≥5% blasts in the bone marrow, and an Eastern Cooperative Oncology Group Performance Status of ≤2.
• Patients received up to five cycles of SC blinatumomab at two doses:
  • 250 μg once daily/500 μg three times weekly; or
  • 500 μg once daily/1000 μg three time weekly.
• The primary endpoint was complete remission/complete remission with partial hematologic recovery (CR/CRh) within the first two cycles.

Key findings¹

• At the data cut off of September 15, 2023, a total of 27 patients with a median age of 52 years (range, 19–78 years) were treated with SC blinatumomab.

Efficacy

• The CR/CRh and measurable residual disease negativity rates at 250 μg/500 μg and 500 μg/1000 μg doses after two cycles are reported in Figure 1.
• Overall, nine patients who achieved measurable residual disease negative CR/CRh after SC blinatumomab underwent allogeneic HSCT
• At the 500 μg/1000 μg dose, one patient developed CD19-negative relapse.

Figure 1. Best hematologic responses within the first two cycles of treatment* 

CR, complete remission; CRh, complete remission with partial hematologic recovery; MRD, measurable residual disease
*Data from Jabbour, et al.¹

Safety

The adverse events reported at the 250 μg/500 μg and 500 μg/1000 μg dose are summarized in Table 1. No Grade 4 treatment-related CRS or neurological events were reported.

Table 1. AEs*