Investigational treatment options in phase I and phase II trials for relapsed or refractory acute lymphoblastic leukemia in pediatric patients

Treatment for a B-cell acute lymphoblastic leukemia patient carrying a rare TP53 c.C275T mutation: A case report

TP53 mutations are associated with poor prognosis in the vast majority of cancers. In this study, we present a pediatric B-cell acute lymphoblastic leukemia (B-ALL) patient carrying a rare TP53 c.C275T mutation. This extremely rare mutation affects an amino acid residue located between the TAD domain and the DNA-binding domain of p53. The patient was resistant to most conventional chemotherapy regimens and remained minimal residual disease (MRD)-positive after five rounds of such regimens. We tested the sensitivity of the patient's leukemic cells to 21 anti-cancer drugs by performing in vitro drug sensitivity assays. The results showed that bortezomib had a very strong killing effect on the patient's leukemic cells. Therefore, we subsequently treated the patient with bortezomib combined with vindesine, cytarabine, and fludarabine. After one course of treatment, the patient became MRD-negative, and there was no recurrence during a 9-month follow-up. In conclusion, our report suggests that the TP53 c.C275T mutation is associated with poor prognosis in B-ALL. Fortunately, bortezomib combined with chemotherapy could achieve a better therapeutic effect than conventional regimens in this type of ALL.

Outcome of chimeric antigen receptor T-cell therapy following treatment with inotuzumab ozogamicin in children with relapsed or refractory acute lymphoblastic leukemia

Chimeric antigen receptor T cells targeting CD19 (CART-19) have shown remarkable efficacy for relapsed/refractory (R/R) B-cell precursor acute lymphoblastic leukemia (BCP-ALL). We investigated whether prior use of inotuzumab ozogamicin (InO), an anti-CD22 antibody conjugated to calicheamicin, may impact CAR T-cell manufacturing or efficacy via pre-CART-19 depletion of the B-cell compartment. In this international, retrospective analysis, 39 children and young adults receiving InO before (n = 12) and/or after (n = 27) T-cell apheresis as bridging therapy to CART-19 treatment were analyzed. Median age at infusion was 13 years (range 1.4-23 years). Thirty-four out of 39 patients (87.2%) obtained complete remission. With a median follow-up of 18.2 months after CART-19 infusion, 12-month event-free survival (EFS) was 53.3% (95% confidence interval (CI): 38.7-73.4) and overall survival (OS) was 77.8% (95% CI: 64.5-93.9). Seventeen patients (44%) relapsed with a median of 159 days (range 28-655) after CART-19 infusion. No difference in day 28 minimal residual disease negative complete response rate, 12-month OS/EFS, or incidence of CD19-positive or -negative relapses was observed among patients receiving InO before or after apheresis. Compared to published data for patients treated with CART-19 therapy without prior InO exposure, response and OS/EFS for patients treated with InO prior to CART-19 are similar.

Antibody and Cellular-Based Therapies for Pediatric Acute Lymphoblastic Leukemia: Mechanisms and Prospects

BACKGROUND

Acute lymphoblastic leukemia (ALL) is one of the most commonly diagnosed cancers in children. Despite enormous efforts to treat ALL over the past decade, the intensity of conventional chemotherapeutic strategies has reached the tolerance limit. Among various recently developed therapeutic approaches, antibody and cellular-based therapies showed less toxicity and better curative effect.

SUMMARY

Due to advanced mechanistic actions, these innovative therapies have provided durable responses and long-term survival in eradicating pediatric ALL, especially patients with refractory/relapsed ALL. Owing to these aspects, herein, we emphasize the mechanisms of action and application status of antibodies targeting tumor antigens, antibody-drug conjugates, bispecific antibodies, and chimeric antigen receptor T cells.

KEY MESSAGES

The significant prospects and challenges are discussed, highlighting the innovative immunotherapies to deal with ALL. Together, this review will summarize the progress of antibody and cellular-based therapies for pediatric ALL, which may promote further research on antibody-based biopharmaceutics.