Prognostic value of early lymphocyte dynamics during blinatumomab therapy in relapsed or refractory B-cell precursor acute lymphoblastic leukemia: A real-world retrospective study.

BACKGROUND

Blinatumomab, a bispecific T-cell engager, mediates cytotoxicity through CD3+ T-cell activation and has shown efficacy in relapsed or refractory (R/R) B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Although T-cell expansion correlates with favorable outcomes, routine immunophenotyping is impractical in clinical settings.

OBJECTIVES

To determine whether early changes in absolute lymphocyte count (ALC), a readily available laboratory marker, can serve as a surrogate indicator of therapeutic response and long-term survival in patients receiving blinatumomab.

DESIGN

A retrospective cohort study of adult patients with R/R BCP-ALL treated with blinatumomab.

METHODS

We analyzed 162 adults with R/R BCP-ALL who received up to two cycles of blinatumomab. The primary outcome was complete remission (CR), and secondary outcomes included overall survival (OS). ALC change from day 1 to day 14 (ΔALC14) was calculated, and its association with outcomes was assessed using logistic and Cox regression models.

RESULTS

Of the 162 patients, 106 (65.4%) achieved CR. ΔALC14 was significantly greater in responders than in non-responders (median 0.344 vs. 0.146 × 109/L; P < 0.001). A high ΔALC14 (≥0.100× 109/L) was independently associated with higher response rates (OR: 2.96; P=0.004) and longer OS (median 15.3 vs. 7.0 months; P=0.007). Multivariate analysis confirmed high ΔALC14 as an independent predictor of response and favorable OS. Subgroup analyses suggested that the association between high ΔALC14 and response was more evident in first salvage than in later salvage (OR 8.40 vs. 1.82), whereas its association with OS was more evident in second or later salvage (median OS 14.5 vs. 4.3 months; P=0.005).

CONCLUSION

Early lymphocyte expansion during blinatumomab therapy, reflected by ΔALC14, is an independent predictor of treatment response. ALC monitoring may offer a simple, cost-effective tool for risk stratification.