CAR-T and monoclonal antibodies in treatment of refractory precursor B-cell acute lymphoblastic leukemia in children: a single-center retrospective analysis

Abstract

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is the most common childhood cancer. Currently, the possibility
of achieving 5-year remission exceeds 90%. However, the prognosis for children with relapsed or refractory
leukemia remains poor. New treatment methods have been developed for BCP-ALL, such as monoclonal or bispecific
antibodies and T cells expressing chimeric antigen receptor T cell therapy (CAR-T).
Objective: This study was a single-center analysis of pediatric patients with relapsed or refractory BCP-ALL CD19(+)
who received CAR-T therapy after prior administration of anti-CD 22 monoclonal antibodies or bispecific anti-CD19/
/CD3 antibodies in some patients.

Material and methods: This retrospective single-center analysis covers the years 2020–2023 when eight cases of relapsed
ALL were diagnosed. Six patients with BCP-ALL CD19(+) were qualified for the CAR-T procedure (age 5.5–14.5
years, five boys, one girl).

Results: In 1/6 pts, the qualification to CAR-T was relapse after allo-HSCT in first line therapy. 2/6 pts, due to resistant
first relapse (high PCR MRD at day 28 of second line therapy), were qualified to CAR-T without prior allo-HSCT. 3/6
patients after HSCT for the treatment of first relapse had a second relapse and were qualified for CAR-T. All patients
were in disease remission before CAR-T, in some cases due to the use of antibodies. All patients remained in disease
remission after CAR-T (follow-up 16–46 months).

Conclusions: 1. The prognosis in children with relapsed BCP-ALL, including relapses after bone marrow transplantation,
is still very poor.
2. CAR-T has shown promising results in CD19(+) BCP-ALL patients with a particularly poor prognosis.
3. Further studies on immunotherapy in leukemia are required.