Cell subsets and cytokine dynamics in cerebrospinal fluid after CAR-T cell therapy for B-cell acute lymphoblastic leukemia with central nervous system involvement

How I treat secondary CNS involvement by aggressive lymphomas

Secondary central nervous system (CNS) lymphoma (SCNSL) is a rare but clinically challenging scenario with historically disappointing outcomes. SCNSL refers to lymphoma that has spread into the CNS concurrently with systemic disease or CNS relapse during or after frontline immunochemotherapy, presenting with or without systemic lymphoma. Diffuse large B-cell lymphoma (DLBCL) denotes the most common entity, but an increased incidence is observed in other histologies, such as Burkitt lymphoma and mantle-cell lymphoma. The incidence, timing in disease course, location, evidence supporting the use of CNS prophylaxis, and treatment pathways vary according to histology. No randomized data exist to delineate the best treatment approaches with current recommendations based on retrospective and single-arm studies. However, a regimen comprising immunochemotherapy, incorporating agents that cross the blood-brain barrier, followed by thiotepa-containing conditioning and autologous stem-cell transplant outlined in the international MARIETTA study demonstrated improvement in outcomes, representing a major accomplishment in the care of patients with DLBCL with SCNSL. Anti-CD19 chimeric antigen receptor T cell denotes a paradigm shift in the treatment of patients with systemic aggressive lymphomas, with emerging data also demonstrating efficacy without higher neurotoxicity in those with SCNSL. In this manuscript we discuss 5 clinical scenarios and review the evidence supporting our recommendations.

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.

Efficacy and safety of CD19 CAR-T cell therapy for patients with B cell acute lymphoblastic leukemia involving extramedullary relapse

OBJECTIVE

To evaluate the efficacy and safety of CD19 chimeric antigen receptor (CAR) T cell therapy for patients with B cell acute lymphoblastic leukemia (B-ALL) involving extramedullary relapse.

METHODS

Fifteen patients with B-ALL involving extramedullary relapse who received CD19 CAR-T cell therapy in the First Affiliated Hospital, Zhejiang University School of Medicine from January 2016 to October 2021 were enrolled in this study. The overall survival and leukemia-free survival of patients were analyzed using Kaplan-Meier curves, and the response of extramedullary lesions in different locations following the CD19 CAR-T cell therapy was observed. Cytokine release syndrome (CRS), hematological toxicity, and immune effector cell-associated neurotoxicity syndrome (ICANS) during CD19 CAR-T cell therapy were analyzed.

RESULTS

The median follow-up time was 7 (3-71) months, and 11 cases (73.3%) achieved complete response, median duration of complete response was 6 (2-27) months; 3 cases (20.0%) achieved partial response; 1 case (6.7%) got progressive disease. The overall response rate was 93.3% (14/15), and the overall survival rate was 80.0% (12/15) at the end of follow-up. The cumulative incidence of relapse was 40.0% (6/15) and relapse mortality rate was 20.0% (3/15). Until last follow-up date, 9 cases (60.0%) were still in disease-free survival. Among the 15 patients, 13 cases (86.7%) developed cytokine release syndrome (CRS) after cell infusion, including 7 cases with grade 1-2 CRS, 6 cases with grade 3 CRS; 1 case suffered from reversible ICANS; 15 cases (100.0%) developed B cell dysplasia; 12 cases (80.0%) developed severe hematologic adverse reactions; 2 cases (13.3%) had abnormal liver function; 1 case (6.7%) had abnormal renal function; 4 cases (26.7%) developed infection. The adverse reactions mentioned above were well controlled.

CONCLUSION

CD19 CAR-T cell therapy shows explicit efficacy and controllable adverse reactions for B-ALL patients with extramedullary relapse.