Age Subgroup Analysis of Health-Related Quality of Life of Blinatumomab Versus Standard-of-Care Chemotherapy in Patients with Relapsed or Refractory Philadelphia Chromosome-Negative B-Cell Precursor Acute Lymphoblastic Leukemia in a Randomized, Open-Label, Phase 3 Study (TOWER)

Background: Despite the availability of new therapies for acute lymphoblastic leukemia (ALL), older patients have historically poor responses to treatment and poor outcomes versus younger patients, with 5-year survival rates of approximately 20% or less. Blinatumomab is a bispecific T-cell engager (BiTE^®) antibody construct that redirects cytotoxic T cells to lyse CD19-positive B cells and is approved for the treatment of relapsed or refractory (r/r) B-cell precursor (BCP) ALL and for minimal residual disease-positive ALL in the US. In the phase 3 TOWER study in patients with r/r Philadelphia chromosome-negative (Ph-) BCP ALL who received blinatumomab compared with standard-of-care (SOC) chemotherapy, overall survival was improved (median, 7.7 vs 4.0 months; P=0.01; Kantarjian H, et al. N Engl J Med. 2017;376:836-847), and posttreatment health-related quality of life (HRQoL) across all EORTC QLQ-C30 scales was better (Topp MS, et al. Blood. 2018;131:2906-2914). TOWER efficacy results did not differ by age group. In this subgroup analysis of TOWER, we assessed the HRQoL of older patients versus younger patients who received blinatumomab or SOC chemotherapy.

Methods: Patients (N=405) with r/r Ph- BCP ALL were randomized 2:1 to receive 2 cycles of induction blinatumomab by continuous intravenous infusion (n=271) or SOC (n=134). Patients could receive transplant at any time following cycle 1. Those in remission could receive up to 3 consolidation cycles; 12 months of maintenance was allowed for those who received up to 3 consolidation cycles and had bone marrow response. HRQoL was assessed using the EORTC QLQ-C30 Questionnaire on days 1 (baseline), 8, and 15, on day 29 of cycle 1; day 1, 15, and 29 of each consolidation cycle; and at the safety follow-up. The questionnaire included 1 global health status scale, 5 functioning scales, 3 symptom scales, and 6 single-symptom items. For global health status and functioning scales, a higher score indicates better HRQoL; for symptom scales/items, a lower score indicates better HRQoL. A 10-point change was viewed as the minimum clinically important difference in EORTC QLQ-C30 (Zikos E, et al. EORTC. 2016). In this analysis, HRQoL in TOWER was assessed using two different age cutoffs: <35 versus ≥35 years (the randomization stratification in TOWER) and <55 versus ≥55 years (the stratification factor for INO-VATE, a phase 3 trial for another therapy in r/r ALL). Analyses included patients with baseline and ≥1 postbaseline result of any multi-item scale or single-item measure. Mean change from baseline in scores for each scale/item were summarized for cycle 1. Time to deterioration (TTD) analyses assessed the treatment effect based on timing from the initiation of treatment to a ≥10-point decrease for the functional scales and/or a ≥10-point increase for the symptom scales respectively.

Conclusions: Consistent with the efficacy results, compared with SOC, blinatumomab improved HRQoL and delayed the deterioration in HRQoL regardless of the age group in patients with r/r Ph- BCP ALL.

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