Extramedullary relapse of acute lymphoblastic leukemia after allogeneic hematopoietic stem cell transplantation treated by CAR T-cell therapy: a case report

Characterization of Extramedullary Disease in B-ALL and Response to CAR T-cell Therapy

A substantial fraction of patients with relapsed/refractory B-ALL will have non-CNS EMD.

CAR T cells may have limited efficacy in multifocal non-CNS EMD, and serial imaging is needed to identify and monitor EMD.

Chimeric antigen receptor (CAR) T cells effectively eradicate medullary B-cell acute lymphoblastic leukemia (B-ALL) and can traffic to and clear central nervous system (CNS) involvement. CAR T-cell activity in non-CNS extramedullary disease (EMD) has not been well characterized. We systematically evaluated CAR T-cell kinetics, associated toxicities, and efficacy in B-ALL non-CNS EMD. We conducted a retrospective review of B-ALL patients with non-CNS EMD who were screened for/enrolled on one of three CAR trials (CD19, CD22, and CD19/22) at our institution. Non-CNS EMD was identified according to histology or radiographic imaging at extramedullary sites excluding the cerebrospinal fluid and CNS parenchyma. Of ∼180 patients with relapsed/refractory B-ALL screened across multiple early-phase trials over an 8-year period, 38 (21.1%) presented with isolated non-CNS EMD (n = 5) or combined medullary/non-CNS EMD (n = 33) on 18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging. A subset receiving CAR T cells (18 infusions) obtained FDG PET/CT scans preinfusion and postinfusion to monitor response. At best response, 72.2% (13 of 18) of patients showed a medullary minimal residual disease–negative complete remission and complete (n = 7) or partial (n = 6) non-CNS EMD response. Non-CNS EMD responses to CAR T cells were delayed (n = 3), and residual non-CNS EMD was substantial; rarely, discrepant outcomes (marrow response without EMD response) were observed (n = 2). Unique CAR-associated toxicities at non-CNS EMD sites were seen in select patients. CAR T cells are active in B-ALL non-CNS EMD. Still, non-CNS EMD response to CAR T cells may be delayed and suboptimal, particularly with multifocal disease. Serial FDG PET/CT scans are necessary for identifying and monitoring non-CNS EMD.

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

BACKGROUND

chimeric antigen receptor-modified T cell (CAR-T) therapy is an effective and promising treatment for refractory and multiply relapsed B-cell acute lymphoblastic leukemia (B-ALL). Because of its side effects and poor responses such as neurotoxicity and cytokine release syndrome, patients with central nervous system leukemia were excluded in most previous clinical trials of CAR-T treatment.

PATIENTS AND METHODS

We enrolled 3 B-ALL patients with central nervous system leukemia relapse. They were infused with CD19-specific CAR-Ts, and their clinical responses were evaluated by bone marrow smear, flow cytometry, and cytogenetic alterations detected by quantitative PCR, interleukin-6, and the expansion and persistence of circulating CAR-Ts in peripheral blood and cerebrospinal fluid.

RESULTS

After CAR-T infusion, 2 of the 3 patients experienced bone marrow minimal residual disease-negative complete remission, and all patients tested negative for residual leukemia cells in cerebrospinal fluid tested by flow cytometry. These 3 patients experienced grade 2 or 3 cytokine release syndrome, which resolved completely after symptomatic treatment. None experienced neurotoxicity or needed further intensive care.

CONCLUSION

CAR-T infusion is a potentially effective treatment for relapsed/refractory B-ALL patients with central nervous system involvement.

Chimeric Antigen Receptor (CAR) T Cell Therapy for B-Acute Lymphoblastic Leukemia (B-ALL)

With the exploitation of adoptive immunotherapies, the outcomes of patients with relapsed and refractory B cell hematologic malignancies have seen drastic improvements. To this end, a paradigm shift away from toxic and ineffective chemotherapies has been visible with the FDA approval of genetically modified autologous T cell products designed to express chimeric antigen receptors able to specifically recognize the CD19 cell surface marker. To date, CAR-T cells have two FDA-approved indications including relapsed or refractory acute lymphoblastic leukemia in children and young adults as well as large B cell lymphoma that is relapsed and/or refractory to two prior therapies. This chapter will discuss the utility of this therapy in B-ALL, common toxicities and their management, relationship to other therapies such as stem cell transplantation, and future directions.

Post-transplant leukemia relapse in organs: biology. and behavior in 585 reports

Resistance of extramedullary leukemia growth post-transplant prevents cure. Review of its behavior detailed in 585 published cases should lead to better treatment. Leukemic tumors were found up to 13 years after transplant, most in sites inaccessible to physical exam. In 83%, marrow was not in morphologic relapse; next relapse was most often extramedullary. Induction protocols alone produced few durable responses in acute leukemias and fatal marrow aplasia in 17 %. Overall, 120 patients survived over 2 years, 43 relapse-free up to 18 years, the majority after combined tumor-directed and systemic therapy. Overall median survival was 9 months. This review highlights how results can improve: by defining extent of leukemia involvement with scans before transplant, and emergently when leukemic tumor is found after, ablating tumor directly to abort metastasis, and determining dosing of systemic chemotherapy that protects, without ablating, donor marrow. Monitoring total body remission with body scans should increase transplant cures.

Treatment and outcome of Philadelphia chromosome-positive acute lymphoblastic leukemia in adults after relapse

INTRODUCTION

Despite the significant progress that has been made over the last years in the front-line treatment of Philadelphia (Ph) chromosome-positive acute lymphoblastic leukemia (ALL), relapses are frequent and their treatment remains a challenge, especially among patients with resistant BCR-ABL1 mutations.

AREAS COVERED

This manuscript reviews available data for the treatment of adult patients with relapsed/refractory Ph-positive ALL, with a focus on the role of tyrosine kinase inhibitors (TKIs), monoclonal antibodies, and immunotherapy.

EXPERT OPINION

Although a majority of patients with first relapsed Ph-positive ALL respond to subsequent salvage chemotherapy plus TKI combination, their outcomes remain poor. The main predictor of survival is the achievement of major molecular response anytime during the morphological response. More treatment strategies to improve survival are under investigation. Monoclonal antibodies and bispecific antibody constructs hold considerable promise in improving the outcomes of patients with relapsed ALL including Ph-positive ALL.

Chimeric Antigen Receptor T Cell Therapy in Patients with Multiply Relapsed or Refractory Extramedullary Leukemia

Autologous CD19-directed chimeric antigen receptor T lymphocyte (CAR-T) therapy is an approved and effective treatment for the management of patients with refractory and multiply relapsed B cell precursor acute lymphoblastic leukemia (B-ALL). Experience using this therapy in pediatric patients with extramedullary (EM) disease is limited, in part because these patients have frequently been excluded from clinical trials owing to concerns for an increased risk of immune effector cell-associated neurotoxicity syndrome (ICANS). We infused 7 patients with refractory or multiply relapsed B-ALL who presented with isolated EM relapse with tisagenlecleucel. Six patients had isolated central nervous system (CNS) leukemia, and 1 patient had an isolated testicular relapse. An initial complete response was seen in all patients, with 5 patients remaining in CAR-T-induced remission at a median of 18 months from first infusion. Reversible ICANS was seen in 1 patient with CNS leukemia. Durable B cell aplasia occurred in 3 patients, with a median time to B cell recovery of 6.5 months in the other patients. These data suggest that CAR-T therapy has promising safety and efficacy in treating EM leukemia, although definitive conclusions are limited by the small size of the cohort and limited follow-up period.

CAR-T cells: the Chinese experience

INTRODUCTION

Chimeric antigen receptor T (CAR-T) cells are harnessed to identify and lyse malignant cells specifically, efficiently, and independently of the major histocompatibility complex (MHC). As a result, prognoses of relapsed or refractory (R/R) B cell hematological malignancies as well as limited types of solid tumors, have been ameliorated to a great extent. In China, a rising number of clinical trials that contribute to the development of novel CAR-T therapeutic strategies have been conducted on an extensive scale.

AREAS COVERED

We summarize registered clinical trials related to CAR-T therapy conducted in China by evaluating various parameters such as distribution, study phase, CAR structure, target antigen, and disease. The efficacy, toxicity, and, more importantly, the new strategies for optimization of CAR-T therapy of Chinese studies and clinical trials are elaborated in detail.

EXPERT OPINION

In terms of the number of CAR-T clinical trials, China is second to the USA, registering approximately 33% of trials worldwide. China's extensive explorations and breakthroughs in the search of novel target antigens, optimization of CAR structure, cocktail CAR-T therapy, combination therapy, and extension of CAR-T cell applications, imply that we are currently on the verge of a revolution in CAR-T therapy.

Successful treatment of acute B lymphoblastic leukemia relapse in the skin and testicle by anti-CD19 CAR-T with IL-6 knocking down: a case report

Background

Extramedullary relapse is an important cause of treatment failure among patients with acute lymphoblastic leukemia (ALL). This type of relapse is commonly observed in the central nervous system, while it is rare in the testicles and skin. Chimeric antigen receptor-modified T cell (CAR-T) therapy targeting CD19 has shown to be a beneficial treatment approach for relapsed/refractory B cell acute lymphoblasticleukemia (r/r B-ALL). Yet, few studies have reported data regarding the treatment of extramedullary B-ALL relapse, especially both in skin and testicle, with CAR-T therapy.

Case presentation

Here we reported a single case of a patient with relapsed B-ALL in skin and testicle who was successfully treated by the shRNA-IL6-modified anti-CD19 CAR-T(ssCAR-T-19) therapy. A 29-year-old man with relapsed B-ALL in skin and testicle was enrolled in clinal trial involving the shRNA-IL6-modified anti-CD19 CAR-T(ssCAR-T-19) therapy (ClinicalTrials.gov number, NCT03919240). The patient had toxicity consistent with the grade 1 cytokine release syndrome.

Conclusions

ssCART-19 therapy may be used to effectively eliminate infiltrating leukemia cells in the skin and testicle with mild toxicity, which could be a much safer approach to bridge allo-HSCT, thus further improving the patient’s outcome.

Trial registration

ClinicalTrials.gov number, NCT03919240, Registered 18 April 2019, retrospectively registered.

A Bump in the Road: How the Hostile AML Microenvironment Affects CAR T Cell Therapy

Chimeric antigen receptor (CAR) T cells targeting CD19 have been successful treating patients with relapsed/refractory B cell acute lymphoblastic leukemia (ALL) and B cell lymphomas. However, relapse after CAR T cell therapy is still a challenge. In addition, preclinical and early clinical studies targeting acute myeloid leukemia (AML) have not been as successful. This can be attributed in part to the presence of an AML microenvironment that has a dampening effect on the antitumor activity of CAR T cells. The AML microenvironment includes cellular interactions, soluble environmental factors, and structural components. Suppressive immune cells including myeloid derived suppressor cells and regulatory T cells are known to inhibit T cell function. Environmental factors contributing to T cell exhaustion, including immune checkpoints, anti-inflammatory cytokines, chemokines, and metabolic alterations, impact T cell activity, persistence, and localization. Lastly, structural factors of the bone marrow niche, secondary lymphoid organs, and extramedullary sites provide opportunities for CAR T cell evasion by AML blasts, contributing to treatment resistance and relapse. In this review we discuss the effect of the AML microenvironment on CAR T cell function. We highlight opportunities to enhance CAR T cell efficacy for AML through manipulating, targeting, and evading the anti-inflammatory leukemic microenvironment.

Treatment Selection for Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia in the Era of Tyrosine Kinase Inhibitors

With the advent of tyrosine kinase inhibitors (TKIs), the treatment of Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) has entered a new era. The efficacy of TKIs compared with other ALL treatment options is emphasized by a rapid increase in the number of TKI clinical trials. Subsequently, the use of traditional approaches, such as combined chemotherapy and even allogeneic hematopoietic stem cell transplantation (allo-HSCT), for the treatment of ALL is being challenged in the clinic. In light of the increased use of TKIs in the clinic, several questions have been raised. First, is it necessary to use intensive chemotherapy during the induction course of therapy to achieve a minimal residual disease (MRD)-negative status? Must a patient reach a complete molecular response/major molecular response before receiving allo-HSCT? Does MRD status affect long-term survival after allo-HSCT? Is auto-HSCT an appropriate alternative for allo-HSCT in those Ph+ ALL patients who lack suitable donors? Here, we review the recent literature in an attempt to summarize the current status of TKI usage in the clinic, including several new therapeutic approaches, provide answers for the above questions, and speculate on the future direction of TKI utilization for the treatment of Ph+ ALL patients.