Cellular Therapy in Chronic Lymphocytic Leukemia: Have We Advanced in the Last Decade?

BACKGROUND: Chronic lymphocytic leukemia (CLL) is a heterogeneous B-cell malignancy, affecting mainly older adults. Despite the recent introduction of multiple targeted agents, CLL remains an incurable disease. Cellular therapy is a promptly evolving area that has developed over the last decades from such standard of care as hematopoietic cell transplantation (HCT) to the novel treatment modalities employing genetically engineered immune cells. SUMMARY: Tailoring the proper treatment for each patient is warranted and should take into account the disease biology, patient characteristics, and the available treatment modalities. Nowadays, the most broadly applied cellular therapies for CLL management are HCT and chimeric antigen receptor-T (CAR-T) cells. However, CAR-T cell therapy is currently not yet approved in CLL, and the appropriate sequencing for the administration of these agents remains to be clarified. KEY MESSAGES: The current review will discuss various available cellular treatment options, their advances and limitations, as well as the optimal timing for the employment of such therapies in CLL patients.

Eosinophilic Pleocytosis in the Cerebrospinal Fluid following CAR-T Cell Therapy for Central Nervous System Lymphoma: A Case for Warning?

INTRODUCTION: Chimeric antigen receptor T (CAR-T) cell therapy, emerging as an efficient treatment option for patients with secondary central nervous system (CNS) lymphoma, is frequently complicated with immune effector cell-associated neurotoxicity syndrome (ICANS). CASE PRESENTATION: We report a case of a 64-year-old woman with transformed follicular lymphoma, developing high-grade ICANS with eosinophilic pleocytosis following third-line therapy with CAR-T cells (tisagenlecleucel). During bridging therapy, she declined neurologically and was diagnosed with secondary CNS lymphoma. She received methotrexate-cytarabine-thiotepa-rituximab regimen with clinical and radiological improvement. Post-CAR-T cell infusion she developed cytokine release syndrome grade II and ICANS grade III. Given the lack of response to steroids, anakinra was initiated with complete ICANS resolution. Cerebrospinal fluid (CSF) analysis, performed only on day +10 due to thrombocytopenia, revealed eosinophils, while infections were excluded. CONCLUSION: This report emphasizes the importance of CSF analysis in individuals with CAR-T-related neurotoxicity for elucidating the role of specific immune cells in such complications.

[CHIMERIC ANTIGEN RECEPTOR T CELLS (CAR-T CELLS) THERAPY FOR B-CELL HEMATOLOGICAL MALIGNANCIES - FROM THE ISRAELI SOCIETY OF HEMATOLOGY AND TRANSFUSION MEDICINE].

INTRODUCTION: Using immunotherapy to fight cancer, and specifically, the use of engineered T-cells expressing a chimeric receptor against an antigen found on malignant cells (chimeric antigen receptor, CAR-T cells) constitutes a significant breakthrough in the treatment of the disease. In recent years, several CAR-T therapies have been approved in Europe and the USA, and some are already approved and funded through the national health basket in Israel, for the indications of diffuse large B-cell lymphoma, mantle cell lymphoma and B-cell acute lymphoblastic leukemia, after the failure of at least two lines of treatment. The treatment with CAR-T cells achieves prolonged remissions and even long-term cure of patients who had a very poor prognosis. However, the treatment involves significant side effects, and requires specific expertise in the management of patients both during the period of preparation for cell transplantation, and following the treatment. During the immediate post-infusion period, the most common adverse reactions are cytokine release syndrome (CRS) which stems from the activation of the immune system, and neurological toxicity that can accompany CRS. These effects require close monitoring, grading their severity, and providing anti-cytokine therapy or steroid therapy until control of symptoms is achieved. Later effects can be persistent cytopenias, immune over-activation, and prolonged immune deficiency. Treatments for additional indications and new CAR-T constructs are being developed and will allow more effective and safer treatment. This article summarizes the principles for CAR-T administration that, as currently provided in Israel, include the short- and long-term follow-up of the patients.

Response rates of extra-nodal diffuse large B cell lymphoma to anti-CD19-CAR T cells: A real word retrospective multicenter study.

Chimeric antigen receptor T-cells (CAR-T) are widely used for the treatment of relapsed/refractory diffuse large B cell lymphoma (DLBCL). The data for CAR-T cell therapy in patients with extra-nodal (EN) lymphoma is restricted. We included 126 consecutive patients with DLBCL treated with commercially available CAR-T cells (tisagenlecleucel, n = 100, 79.4% and axicabtagene ciloleucel, n = 26, 20.6%). At lymphodepletion, 72 of 126 (57%) patients had EN disease, 42 of 126 (33%) patients had nodal disease (ND)-only and 12 of 126 (10%) showed no disease assessed by PET-CT. There were no significant differences in CAR-T related toxicities and in the median Progression free survival (PFS) between EN patients and ND (10.76 [95% CI: 7.8-13.6] vs. 14.1 [95% CI: 10-18.1] months, p = .126). Similarly, median overall survival (OS) was not significantly different (15.36 [95% CI 12.5-18.2] vs. 18.4 [95% CI 14.8-22.1] months, p = .100). Subgroup analysis according to the number of EN involved sites showed that median PFS and OS were significantly higher in patients with <3 EN sites (12.3 months [95% CI 9-15.5] vs. 4.28 months [95% CI 0.6-7.9], p = .010) compared to patients with >2 EN sites, respectively (16.5 months [95% CI 13.4-19.6] vs. 8.7 months [95% CI 4.6-12.8], p = .05). In multivariate cox regression analysis, increased number sites of EN disease and high lactate dehydrogenase (LDH) at lymphodepletion negatively impacted PFS (p = .021 and <.001, respectively), while sex, type of product administered, age and performance status did not predict PFS and OS. Of note, all the patients with involvement of gastrointestinal tract (n = 9), urinary tract (n = 9), or pharynx (n = 3) at lymphodepletion, progressed or had an early relapse. In conclusions, patients with >2 EN sites at lymphodepletion have significantly worse clinical outcomes compared to patients with <3 EN sites. Patients with specific sites of EN disease may demonstrate grim prognosis.

Decreased Systemic Busulfan Exposure After Oral Dosing With Concomitant Levetiracetam Compared With Phenytoin.

BACKGROUND: Busulfan (Bu) conditioning used in hematopoietic stem cell transplantation may induce seizures, and prophylactic antiepileptic treatment is recommended. Following updated guidelines, in August 2019, the adult hematopoietic stem cell transplantation department of the Rambam Health Care Campus (Haifa, Israel) switched the antiepileptic prophylaxis protocol from phenytoin to oral levetiracetam during oral Bu conditioning. The aim of this study was to compare the pharmacokinetic parameters of Bu after oral dosing between patients receiving phenytoin and those receiving levetiracetam prophylaxis. METHODS: This study was a retrospective cohort study in adults undergoing myoablative conditioning with oral Bu between August 2018 and August 2020. Bu pharmacokinetic parameters (AUC0-6, C0, Cmax, and Tmax) were compared in patients treated with phenytoin comedication (during the year before the change in policy) and levetiracetam comedication (during the year after the change). Potential confounders were accounted for including age, azole comedication, and body weight. RESULTS: There were no significant differences in demographic and clinical parameters or weight-corrected Bu dose between the phenytoin group (n = 28) and the levetiracetam group (n = 25). There was no difference in the rate of voriconazole comedication, but fluconazole was more common in the phenytoin group (P = 0.026). The median AUC0-6 was significantly lower in the levetiracetam group (949 µM*min; IQR = 806 to 1101 µM*min) than in the phenytoin group (1208 µM*min; IQR = 1087 to 1389 µM*min; P < 0.001). This is a clinically significant difference of 258 µM*min (21%). Azole use was not associated with Bu exposure. CONCLUSIONS: The findings suggest that, after treatment with oral Bu, oral levetiracetam comedication is associated with reduced systemic exposure compared with phenytoin comedication, possibly because of decreased bioavailability.

The clinical role of the gut microbiome and fecal microbiota transplantation in allogeneic stem cell transplantation.

Outcomes of allogeneic hematopoietic stem cell transplantation (allo- HSCT) have improved in the recent decade; however, infections and graft-versus-host disease remain two leading complications significantly contributing to early transplant-related mortality. In past years, the human intestinal microbial composition (microbiota) has been found to be associated with various disease states, including cancer, response to cancer immunotherapy and to modulate the gut innate and adaptive immune response. In the setting of allo-HSCT, the intestinal microbiota diversity and composition appear to have an impact on infection risk, mortality and overall survival. Microbial metabolites have been shown to contribute to the health and integrity of intestinal epithelial cells during inflammation, thus mitigating graft-versus-host disease in animal models. While the cause-andeffect relationship between the intestinal microbiota and transplant-associated complications has not yet been fully elucidated, the above findings have already resulted in the implementation of various interventions aiming to restore the intestinal microbiota diversity and composition. Among others, these interventions include the administration of fecal microbiota transplantation. The present review, based on published data, is intended to define the role of the latter approach in the setting of allo-HSCT.

Midostaurin in combination with chemotherapy is most effective in patients with acute myeloid leukemia presenting with high FLT3-ITD allelic ratio who proceed to allogeneic stem cell transplantation while in first complete remission.

OBJECTIVES: Midostaurin, a multikinase and FLT3 inhibitor, is the first non-chemotherapy agent approved and widely adopted for the treatment of FLT3-ITD acute myeloid leukemia (AML). Yet, its role in improving survival of patients referred to allogeneic stem cell transplantation (allo-SCT) in first complete remission (CR1) needs to be defined. METHODS: This multicenter study retrospectively evaluated the outcome of 119 FLT3-ITD AML patients [59 (49.6%) males and 60 females] intensively treated between 2015 and 2019 at five Israeli centers. In our cohort, allo-SCT in CR1 was widely implemented (47%) and patient stratification was based on the current allelic ratio (AR) cutoff of 0.5. RESULTS: Ninety-eight patients (82.3%) achieved CR1/CR with incomplete count recovery (CRi). Death during induction was reported in 7 (5.9%) patients. In multivariate analysis, midostaurin use and allo-SCT in CR1 were the most significant factors affecting overall survival (OS). Midostaurin incorporation in chemotherapy regimens significantly improved CR + CRi rates (P = .002), reduced relapse rates (P = .02), and was remarkably advantageous for high-AR patients (2-year OS 82%). In low-AR patients, the midostaurin effect was much less prominent. CONCLUSIONS: Our results demonstrate benefits of midostaurin incorporation in intensive chemotherapy regimens, particularly for high-AR AML patients to whom it should be offered along with allo-SCT in CR1.

Pure Red Cell Aplasia following ABO-Mismatched Allogeneic Hematopoietic Stem Cell Transplantation: Resolution with Daratumumab Treatment.

Pure red cell aplasia (PRCA) can potentially occur after allogeneic hematopoietic stem cell transplantation (allo-HSCT) if recipient and donor ABO blood groups are mismatched, with the recipient having isoagglutinins against the donor blood group. Patient plasma cells that survive transplant conditioning produce anti-ABO isoagglutinins targeting donor erythroid precursors in the bone marrow and thus causing red cell aplasia. Therapeutic options include steroids, discontinuation of immunosuppression, plasmapheresis, donor lymphocyte infusion, rituximab, and bortezomib, all with limited benefit. Daratumumab utilized in the treatment of multiple myeloma is an anti-CD38 monoclonal antibody targeting plasma cells, which makes it a potentially efficient therapy for PRCA. The current case report presents a patient with post-allo-HSCT PRCA cured with daratumumab applied after failure of other therapies. Our findings demonstrate safety and high efficiency of daratumumab, suggesting its applicability as early treatment of post-allo-HSCT PRCA.

Third BNT162b2 mRNA SARS-CoV-2 Vaccine Dose Significantly Enhances Immunogenicity in Recipients of Allogeneic Hematopoietic Stem Cell Transplantation.

COVID-19-related mortality among hematopoietic stem cell transplantation (HSCT) recipients in the pre-vaccine era ranged between 22 and 33%. The Pfizer/BioNTech BNT162b2 vaccine demonstrated significant immunogenicity and efficacy in the healthy population; however, its long-term effects on allogeneic HSCT recipients remained unclear. Our study longitudinally evaluated humoral and cellular responses to the BNT162b2 vaccine in adult allogeneic HSCT patients. A positive response was defined as antibody titers ≥ 150 AU/mL post-second vaccination. Among 77 included patients, 51 (66.2%) responded to vaccination. Response-associated factors were female gender, recent anti-CD20 therapy, and a longer interval between transplant and vaccination. Response rates reached 83.7% in patients vaccinated >12 months post-transplant. At 6 months post-second vaccination, antibody titers dropped, but were significantly increased with the booster dose. Moreover, 43% (6/14) of non-responders to the second vaccination acquired sufficient antibody titers after booster administration, resulting in an overall response rate of 79.5% for the entire cohort. The BNT162b2 vaccine was effective in allogeneic transplant recipients. Although antibody titers decreased with time, the third vaccination led to their significant elevation, with 93% of third-dose responders maintaining titers above 150 AU/mL at 3 months post-administration.

Aberrant B cells, autoimmunity and the benefit of targeting B cells in chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) remains the main complication of allogeneic hematopoietic stem cell transplantation, limiting its chances for a successful outcome. The over-activity of CD4+ effector T cells and the excessive production of pro-inflammatory cytokines are followed by the development of immune-mediated inflammation and fibrosis of multiple organs. This is the reason for adopting T cell targeting therapies such as cyclosporine A, tacrolimus and mycophenolate mofetil. However, 40% of treated cGVHD patients remain unresponsive, which results in increased morbidity and mortality. Given the complexity of cGVHD pathogenesis, the involvement of B cells as an important player also needs to be explored. Function of aberrant B cells and secretion of relevant cytokines such as B cell activating factor (BAFF) have been found to correlate with cGVHD severity and have therefore become therapeutic targets. Better understanding of the role of B cells and their efficient targeting could improve the outcome of cGVHD.

Superior outcome of patients with favorable-risk acute myeloid leukemia using consolidation with autologous stem cell transplantation.

Autologous stem cell transplantation (ASCT), intensifying anti-leukemic effects without significant treatment-related mortality (TRM), is particularly appealing in AML with favorable genetic/molecular profile. This study retrospectively evaluated the outcomes of post-remission treatment in consecutive favorable-risk AML patients. Sixty-six patients were included: 32 had mutated NPM1/wild-type FLT-ITD, 16 had t(8:21) and 18 - inv(16). Forty patients received chemotherapy alone, 26 underwent ASCT upfront. In time-dependent analysis, the ASCT group demonstrated higher relapse-free (RFS) (p = .001) and overall survivals (OS) (p = .0007). The 1-year RFS and OS were 44.2% vs 88% and 71% vs 96% for chemotherapy and ASCT, respectively. The corresponding TRM was 4/40 (10.0%) and 0/26 (0%), with relapse rates of 70.0% and 19.2% (p = .0002). In multivariate analysis, ASCT was associated with superior OS and RFS. In conclusion, ASCT offers significantly superior RFS and OS in favorable-risk AML in first complete remission. These data support the recent resurgence of interest in ASCT for AML.