Safety and Efficacy of Chimeric Antigen Receptor T-Cell Therapy in Children With Central Nervous System Leukemia

CAR T-cell-associated neurotoxicity in central nervous system hematologic disease: Is it still a concern?

Chimeric antigen receptor (CAR) T-cell systemic immunotherapy has revolutionized how clinicians treat several refractory and relapsed hematologic malignancies. Due to its peculiar mechanism of action, CAR T-cell-based therapy has enlarged the spectrum of neurological toxicities. CAR T-cell-associated neurotoxicity-initially defined as CAR T-cell-related encephalopathy syndrome (CRES) and currently coined within the acronym ICANS (immune effector cell-associated neurotoxicity syndrome)-is perhaps the most concerning toxicity of CAR T-cell therapy. Importantly, hematologic malignancies (especially lymphoid malignancies) may originate in or spread to the central nervous system (CNS) in the form of parenchymal and/or meningeal disease. Due to the emergence of deadly and neurological adverse events, such as fatal brain edema in some patients included in early CAR T-cell trials, safety concerns for those with CNS primary or secondary infiltration arose and contributed to the routine exclusion of individuals with pre-existing or active CNS involvement from pivotal trials. However, based primarily on the lack of evidence, it remains unknown whether CNS involvement increases the risk and/or severity of CAR T-cell-related neurotoxicity. Given the limited treatment options available for patients once they relapse with CNS involvement, it is of high interest to explore the role of novel clinical strategies including CAR T cells to treat leukemias/lymphomas and myeloma with CNS involvement. The purpose of this review was to summarize currently available neurological safety data of CAR T-cell-based immunotherapy from the clinical trials and real-world experiences in adult patients with CNS disease due to lymphoma, leukemia, or myeloma. Increasing evidence supports that CNS involvement in hematologic disease should no longer be considered per se as an absolute contraindication to CAR T-cell-based therapy. While the incidence may be high, severity does not appear to be impacted significantly by pre-existing CNS status. Close monitoring by trained neurologists is recommended.

Humanized CD19-directed CAR-T Cell Therapy in Pediatric Relapsed/Refractory Acute Lymphoblastic Leukemia With CNSL or Neurological Comorbidity

Chimeric antigen receptor T cell (CAR-T) therapy has breakthrough potential for relapsed/refractory (R/R) acute lymphoblastic leukemia (ALL). However, because of the risk for neurotoxicity, trials usually exclude patients with central nervous system leukemia (CNSL) or active neurological comorbidities (NC). Here, we evaluated the efficacy and neurotoxicity of humanized CD19-directed CAR-T therapy for R/R ALL with CNSL or NC. Of 12 enrolled patients, 4 had CNSL with bone marrow (BM) or testicular recurrence, 3 had BM relapses with NC, and 5 had BM relapse without NC. Bridging chemotherapy was performed for high tumor burden before CAR-T therapy. Patients with CNSL or BM relapse with NC or without NC experienced 100% complete remission. Tumor burden reduction did not occur in 1 patient with NC, who developed grade 5 neurotoxicity before BM assessment, and one patient with CNSL developed leukoencephalopathy. Severe cytokine release syndrome and neurotoxicity developed in 0% with CNSL, 33.3% with BM relapse and NC, and 0% without NC. CAR-T cells expanded in the cerebrospinal fluid (CSF) of all patients with no difference among CNSL, BM with NC, or no NC (respective median percentages among lymphocyte: 33.7%, 48.2% and 34.5%, P =0.899; respective median concentrations: 0.82, 2.21, and 0.46/μL, P =0.719). Median CSF CAR-T cell duration was 5.5 (3-9) months with CNSL and 3 (2-3) months without CNSL ( P =0.031). CAR-T can be given safely and effectively to pediatric patients with R/R ALL with CNSL or NC who have near-normal neurological status. High tumor burden may confer increased risk for severe neurotoxicity.

BCMA CAR-T Therapy Is Safe and Effective for Refractory/Relapsed Multiple Myeloma With Central Nervous System Involvement

Central nervous system (CNS) involvement is a rare complication of multiple myeloma (MM) that portends an extremely poor prognosis. Although chimeric antigen receptor (CAR)-T cell therapy is considered a promising strategy for patients with MM, the role of CAR-T cell therapy in MM involving the CNS has not been fully elucidated. In this study, we retrospectively analyzed 4 cases of B-cell maturation antigen CAR-T cell therapy for patients with relapsed/refractory MM involving the CNS. Patients received a range of 2-7 lines of prior therapy, including 1 autologous hematopoietic stem cell transplant. The most common adverse event was cytokine release syndrome, which was observed in all 4 patients, including 2 with grade 1 and 2 with grade 2. No patient was complicated with immune effector cell-associated neurotoxicity syndrome. Within the follow-up (median: 257 d, range: 116-392 d), 3 of 4 patients reached complete remission (CR), and 1 patient reached partial response. At the data cutoff, 1 patient continued to remain in CR at day 220, and the patient with partial response died at day 116. The other 2 patients relapsed at 317 and 111 days with CR durations of 287 and 81 days, respectively. Our results show promising effectiveness and acceptable safety of CAR-T cell therapy for heavily pretreated patients with CNS MM.

Recent Advances in Pediatric Cancer Research

Over the past few years, the field of pediatric cancer has experienced a shift in momentum, and this has led to new and exciting findings that have relevance beyond pediatric malignancies. Here we present the current status of key aspects of pediatric cancer research. We have focused on genetic and epigenetic drivers of disease, cellular origins of different pediatric cancers, disease models, the tumor microenvironment, and cellular immunotherapies.