Superior efficacy of rituximab-based chemoimmunotherapy as an initial therapy in newly diagnosed patients with B cell indolent lymphomas: long-term results from a single center in China.

BACKGROUND: Rituximab has been confirmed to improve the survival of patients with B cell indolent non-Hodgkin lymphomas (B-iNHLs) in Western world as previously reported, however, it is rarely reported in Chinese cohort. This study is to investigate the efficacy and safety of rituximab-based chemoimmunotherapy and select subpopulations most sensitive to the regimen in Chinese B-iNHL patients.

METHODS: 334 B-iNHL patients from our center were retrospectively assessed.

RESULTS: Patients received R-based chemoimmunotherapy showed significantly higher rates of overall response (OR) (93.0% vs. 53.4%, P < 0.001) and complete response (CR) (63.3% vs. 16.0%, P < 0.001) compared with the patients received other therapies. Survival analysis showed that rituximab-based chemoimmunotherapy could obviously improve the progression-free survival (PFS) (110 vs. 49 months, P = 0.001) and overall survival (OS) (120 vs. 72 months, P < 0.001) in patients with B-iNHLs. Interestingly, in chronic lymphocytic leukemia (CLL) patients, we found that the patients with β2-microglobulin (β2-MG) < 3.5 mg/L, lactate dehydrogenase (LDH) < 220 U/L, zeta-chain-associated protein kinase 70 (ZAP-70) negative, and non high-risk genetic abnormality could achieve more benefits from R-based regimens with higher CR rate (P = 0.003, 0.029, 0.013 and 0.038, respectively). Meanwhile, more CLL patients achieved minimal residual disease (MRD) negative after rituximab-based treatment (46.5% vs. 10.3%, P < 0.001). Moreover, CLL patients with MRD < 1%, LDH < 220 U/L, complete remission (CR) or partial remission (PR), β2-MG < 3.5 mg/L and non high-risk cytogenetic abnormality showed superior outcome compared to the controls (P = 0.001, 0.000, 0.000, 0.001 and 0.013, respectively). No other side-effects increased in chemoimmunotherapy group except the elevation of grade 3-4 neutropenia.

CONCLUSIONS: Our results demonstrate the superior efficacy of rituximab-based chemoimmunotherapy as an initial therapy in Chinese cohort with newly diagnosed B-iNHLs and further identify subpopulations that are more sensitive to R-based chemoimmunotherapy in CLL group.