Immunotherapy without or with low-intensity chemotherapy versus standard chemotherapy as first-line treatment for newly diagnosed b-ALL patients: A propensity score-matched study

Abstract Introduction： B-cell acute lymphoblastic leukemia(B-ALL) is a common malignant tumour of the blood system.With a high frequency of severe side effects and low tolerance to standard chemotherapy, some patients have a poor prognosis.Therefore,optimizing first-line treatment is critical to achieving deep remission and improving prognosis. In recent years, some data have indicated that integrating immunotherapy into first-line treatment improves remission rates, minimal residual disease(MRD) negativity rate and long-term prognosis. However, there is still a lack of relevant researches. This study aims to investigate the efficacy and safety of immunotherapy without or with low-intensity chemotherapy in patients newly diagnosed with B-ALL. Methods： This retrospective study included 133 patients newly diagnosed with B-ALL. Among them, 25 patients received immunotherapy(blinatumomab or inotuzumab ozogamicin) without or with low-intensity chemotherapy (immunotherapy group) while 108 patients received standard chemotherapy(chemotherapy group). After propensity score matching (1:1), each group consisted of 8 Philadelphia chromosome positive (Ph+) patients and 17 Philadelphia chromosome negative (Ph-) patients. All Ph+ patients received concurrent treatment with a tyrosine kinase inhibitor (TKI). Low-dose chemotherapy regimens included VP, CP or VDP, whereas standard chemotherapy regimens comprised VDLP, VDCP or VDCLP. Finally, remission rates and adverse event rates were compared between two groups. Results： The MRD negative rate was significantly greater in the immunotherapy group than in the chemotherapy group (88% vs. 48%, p=0.002).Compared to the chemotherapy group, the immunotherapy group had higher minimum platelet counts (30 vs. 8×10⁹/L, p = 0.006), shorter duration of platelet counts < 50×10⁹/L (6 vs. 17 d, p = 0.015) and higher minimum neutrophil counts (0.14 vs. 0.01×10⁹/L, p = 0.000). They experienced fewer pulmonary infection(56% vs. 84%, p=0.031). In addition, red blood cell transfusions (4 vs. 8u, p=0.030) and platelet transfusions(0 vs. 80u, p=0.000)were lower in the immunotherapy group. Conclusion: Our present study demonstrates that immunotherapy without or with low-intensity chemotherapy as first-line treatment improves clinical efficacy while reducing adverse events in newly diagnosed B-ALL patients compared to standard chemotherapy.