Successful Treatment of Refractory and Relapsed CNS Acute Lymphoblastic Leukemia With CD-19 CAR-T Immunotherapy: A Case Report

Sequential autologous CAR-T and allogeneic CAR-T therapy successfully treats central nervous system involvement relapsed/refractory ALL: a case report and literature review

Background

The central nervous system (CNS) is the most common site of extramedullary invasion in acute lymphoblastic leukemia (ALL), and involvement of the CNS is often associated with relapse, refractory disease, and poor prognosis. Chimeric antigen receptor-T (CAR-T) cell therapy, a promising modality in cancer immunotherapy, has demonstrated significant advantages in the treatment of hematological malignancies. However, due to associated adverse reactions such as nervous system toxicity, the safety and efficacy of CAR-T cell therapy in treating CNSL remains controversial, with limited reports available.

Case report

Here, we present the case of a patient with confirmed B-ALL who experienced relapse in both bone marrow (BM) and cerebrospinal fluid (CSF) despite multiple cycles of chemotherapy and intrathecal injections. The infusion of autologous CD19 CAR-T cells resulted in complete remission (CR) in both BM and CSF for 40 days. However, the patient later experienced a relapse in the bone marrow. Subsequently, allogeneic CD19 CAR-T cells derived from her brother were infused, leading to another achievement of CR in BM. Significantly, only grade 1 cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) events were detected during the treatment period and showed improvement with symptomatic management. During subsequent follow-up, the patient achieved a disease-free survival of 5 months and was successfully bridged to hematopoietic stem cell transplantation.

Conclusion

Our study provides support for the argument that CNS involvement should not be deemed an absolute contraindication to CAR-T cell therapy. With the implementation of suitable management and treatment strategies, CAR-T therapy can proficiently target tumor cells within the CNS. This treatment option may be particularly beneficial for relapsed or refractory patients, as well as those with central nervous system involvement who have shown limited response to conventional therapies. Additionally, CAR-T cell therapy may serve as a valuable bridge to allogeneic hematopoietic stem cell transplantation (allo-HSCT) in these patients.

Central nervous system involvement in childhood acute lymphoblastic leukemia: challenges and solutions

Delivery of effective anti-leukemic agents to the central nervous system (CNS) is considered essential for cure of childhood acute lymphoblastic leukemia. Current CNS-directed therapy comprises systemic therapy with good CNS-penetration accompanied by repeated intrathecal treatments up to 26 times over 2-3 years. This approach prevents most CNS relapses, but is associated with significant short and long term neurotoxicity. Despite this burdensome therapy, there have been no new drugs licensed for CNS-leukemia since the 1960s, when very limited anti-leukemic agents were available and there was no mechanistic understanding of leukemia survival in the CNS. Another major barrier to improved treatment is that we cannot accurately identify children at risk of CNS relapse, or monitor response to treatment, due to a lack of sensitive biomarkers. A paradigm shift in treating the CNS is needed. The challenges are clear - we cannot measure CNS leukemic load, trials have been unable to establish the most effective CNS treatment regimens, and non-toxic approaches for relapsed, refractory, or intolerant patients are lacking. In this review we discuss these challenges and highlight research advances aiming to provide solutions. Unlocking the potential of risk-adapted non-toxic CNS-directed therapy requires; (1) discovery of robust diagnostic, prognostic and response biomarkers for CNS-leukemia, (2) identification of novel therapeutic targets combined with associated investment in drug development and early-phase trials and (3) engineering of immunotherapies to overcome the unique challenges of the CNS microenvironment. Fortunately, research into CNS-ALL is now making progress in addressing these unmet needs: biomarkers, such as CSF-flow cytometry, are now being tested in prospective trials, novel drugs are being tested in Phase I/II trials, and immunotherapies are increasingly available to patients with CNS relapses. The future is hopeful for improved management of the CNS over the next decade.

Immunotherapy and Allogeneic Bone Marrow Transplantation in B Acute Lymphoblastic Leukemia: How to Sequence?

Long-term disease control is achieved in 80–90% of patients with acute lymphoblastic leukemia of B origin (B-ALL). About half of adult and 10% of pediatric patients develop refractory or relapsed disease, whereas survival after relapse accounts about 10% in adults and 30–50% in children. Allogeneic bone marrow transplantation offers remarkable benefit in cases with unfavorable outcome. Nevertheless, novel immunotherapeutic options have been approved for patients with adverse prognosis. Immunotherapeutic agents, nowadays, are preferred over standard chemotherapy for patients with relapsed or refractory B-ALL The mode of action, efficacy and safety data of immunotherapeutic agents released, indications and sequence of those therapies over the course of treatment, are herein reviewed.

Novel Treatments for Pediatric Relapsed or Refractory Acute B-Cell Lineage Lymphoblastic Leukemia: Precision Medicine Era

With the markedly increased cure rate for children with newly diagnosed pediatric B-cell acute lymphoblastic leukemia (B-ALL), relapse and refractory B-ALL (R/R B-ALL) remain the primary cause of death worldwide due to the limitations of multidrug chemotherapy. As we now have a more profound understanding of R/R ALL, including the mechanism of recurrence and drug resistance, prognostic indicators, genotypic changes and so on, we can use newly emerging technologies to identify operational molecular targets and find sensitive drugs for individualized treatment. In addition, more promising and innovative immunotherapies and molecular targeted drugs that are expected to kill leukemic cells more effectively while maintaining low toxicity to achieve minimal residual disease (MRD) negativity and better bridge hematopoietic stem cell transplantation (HSCT) have also been widely developed. To date, the prognosis of pediatric patients with R/R B-ALL has been enhanced markedly thanks to the development of novel drugs. This article reviews the new advancements of several promising strategies for pediatric R/R B-ALL.