Improved Outcome and Decreased Morbidity and Mortality Rates of B-Cell Malignancies with Less Intensive Chemotherapy Induction: Experience in a Single Institution

Background: High-Dose chemotherapy is necessary one of the most important tools for improving response rates and for decreasing relapse rate in childhood B-cell malignancies. However, deaths during induction or in Complete Remission (CR) in children with higher disease burden had adversely influenced pEFS in our setting, and for this reason an accomplished clinical support is mandatory for achieving these better results.

Objective: Our aim was to diminish morbidity and mortality of patients with B-cell malignancies with the administration of a reduced intensity BFM-based induction phase, plus the addition of rituximab in a pilot study. We also retrospectively analyzed the outcome of this group of patients.

Methods: This is a prospective study, single arm, non-randomized local trial for treatment of B-cell malignancies. Between December-2008 and March-2016, 81 pts consecutive (<16 years/old) (52:M/29:F) were enrolled in a protocol HPG-09, and 70 of them resulted evaluable.

Patients were stratified according stage and DHL level in Risk-1, Risk-2, Risk-3 and Risk-4. Risk-4 included patients with stage IV and stage III with DHL levels higher than 1,000 U/dl.

The pathology, flow-cytometry and cytogenetic findings disclosed 60 cases of Burkitt Lymphoma, 11 diffuse large B cell Lymphomas, 9 mature-B acute lymphoblastic leukemia, and 1 Precursor-B ALL with with t(8;14).

The treatment locally-none BFM-counterpart included 4 doses of Rituximab administered to Risk-4 cases during early phases of treatment and intensified chemotherapy with HDMTX (24 hr) 5 g/m2, plus reduced intensity induction with pre-phase followed by A1 block (MTX 1 g/m2 4 hr infusion), in order to decrease morbidity and early mortality rates.

Results: Distribution of patient according to risk-groups was: Risk-1 (n=2) 2%, Risk-2 (n=9) 11%, Risk-3: (n=13) 16% and Risk-4 (n=46) 57% of cases. Median DHL= 3,642 (range: 396-33,673) UI/dl, CNS+ cases was observed in 6 cases. Complete remission (CR) was achieved in 95.1% of the cases and 4.9% of patients died in early phases of treatment. From patient who achieve CR, 6 adverse events were observed (all of them in Risk-4 group): 2 relapses and 4 death in CR (1 Steven´s-Johnson Syndrome, 2 tumor lysis syndrome plus CID and 1 patient died after extensive initial surgery) The pEFS for R1, R2, and R3 was 100%. With a median follow-up of 48 (range:6-61) months, the pEFS (SE) for all risks groups was 91 (4)% and for Risk-4 85 (6)%.

Conclusions: Risk-4 group accounted for 66% of the total population of patients, defining a more aggressive disease prevalence in our setting. Locally-adapted strategy based on BFM experience was successfully implemented, reducing induction intensity and with the incorporation of 4 doses of Rituximab. The outcome of this group of patients was very good. Reduction of induction intensity and addition of Rituximab resulted in low mortality rate and excellent survival outcome.