Immunotherapy in leukaemia.

Leukaemia is the common name for a group of malignant diseases of the haematopoietic system with complex classifications and characteristics. Remarkable progress has been made in basic research and preclinical studies for acute leukaemia compared to that of the many other types/subtypes of leukaemia, especially the exploration of the biological basis and application of immunotherapy in acute myeloid leukaemia (AML) and B-cell acute lymphoblastic leukaemia (B-ALL). In this review, we summarize the basic approaches to immunotherapy for leukaemia and focus on the research progress made in immunotherapy development for AML and ALL. Importantly, despite the advances made to date, big challenges still exist in the effectiveness of leukaemia immunotherapy, especially in AML. Therefore, we use AML as an example and summarize the mechanisms of tumour cell immune evasion, describe recently reported data and known therapeutic targets, and discuss the obstacles in finding suitable treatment targets and the results obtained in recent clinical trials for several types of single and combination immunotherapies, such as bispecific antibodies, cell therapies (CAR-T-cell treatment), and checkpoint blockade. Finally, we summarize novel immunotherapy strategies for treating lymphocytic leukaemia and clinical trial results.

Blinatumomab Added to Chemotherapy in Infant Lymphoblastic Leukemia.

BACKGROUND: KMT2A-rearranged acute lymphoblastic leukemia (ALL) in infants is an aggressive disease with 3-year event-free survival below 40%. Most relapses occur during treatment, with two thirds occurring within 1 year and 90% within 2 years after diagnosis. Outcomes have not improved in recent decades despite intensification of chemotherapy. METHODS: We studied the safety and efficacy of blinatumomab, a bispecific T-cell engager molecule targeting CD19, in infants with KMT2A-rearranged ALL. Thirty patients younger than 1 year of age with newly diagnosed KMT2A-rearranged ALL were given the chemotherapy used in the Interfant-06 trial with the addition of one postinduction course of blinatumomab (15 µg per square meter of body-surface area per day; 28-day continuous infusion). The primary end point was clinically relevant toxic effects, defined as any toxic effect that was possibly or definitely attributable to blinatumomab and resulted in permanent discontinuation of blinatumomab or death. Minimal residual disease (MRD) was measured by polymerase chain reaction. Data on adverse events were collected. Outcome data were compared with historical control data from the Interfant-06 trial. RESULTS: The median follow-up was 26.3 months (range, 3.9 to 48.2). All 30 patients received the full course of blinatumomab. No toxic effects meeting the definition of the primary end point occurred. Ten serious adverse events were reported (fever [4 events], infection [4], hypertension [1], and vomiting [1]). The toxic-effects profile was consistent with that reported in older patients. A total of 28 patients (93%) either were MRD-negative (16 patients) or had low levels of MRD (<5×10-4 [i.e., <5 leukemic cells per 10,000 normal cells], 12 patients) after the blinatumomab infusion. All the patients who continued chemotherapy became MRD-negative during further treatment. Two-year disease-free survival was 81.6% in our study (95% confidence interval [CI], 60.8 to 92.0), as compared with 49.4% (95% CI, 42.5 to 56.0) in the Interfant-06 trial; the corresponding values for overall survival were 93.3% (95% CI, 75.9 to 98.3) and 65.8% (95% CI, 58.9 to 71.8). CONCLUSIONS: Blinatumomab added to Interfant-06 chemotherapy appeared to be safe and had a high level of efficacy in infants with newly diagnosed KMT2A-rearranged ALL as compared with historical controls from the Interfant-06 trial. (Funded by the Princess Máxima Center Foundation and others; EudraCT number, 2016-004674-17.).

Enhancing CD19 Chimeric Antigen Receptor T Cells Through Memory-Enriched T Cells.

Chimeric antigen receptor T (CAR-T) cells directed against CD19 have transformed the therapy of relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL). A recent study reports promising activity and safety of CD19 CAR-T cells generated from naïve, stem, and central memory T cells in adults with R/R B-ALL. See related article by Aldoss et al., p. 742.

Clinically Applicable Assessment of Tisagenlecleucel CAR T Cell Treatment by Digital Droplet PCR for Copy Number Variant Assessment.

Chimeric antigen receptor (CAR) T cell therapy is an innovative immunotherapy for treating cancers in both children and adults with proven utility in numerous clinical trials. Significantly, some CAR T cell therapies have now been approved by relevant national regulatory bodies across numerous countries for clinical therapeutic use outside of clinical trials. One such recently licensed product is tisagenlecleucel, a CAR T therapy approved for the treatment of B-cell acute lymphoblastic leukemia (B-ALL) using autologous T cells from the patient. The genetically engineered T cells target a protein called CD19, common to B cells, through a CAR incorporating a 4-1BB costimulatory domain to improve response. Since tisagenlecleucel is now a standard of care treatment for B-ALL, it is clinically essential to be able to accurately monitor these CAR T cells in patients. Assessment of the copy number variant (CNV) of the CAR T cell products allows this within a clinically acceptable timeframe for optimal patient benefit. However, no standardized method with high reproducibility and efficiency has been described within a routine clinical laboratory setting. Here, we demonstrated a novel digital droplet PCR (ddPCR)-based methodology for the study of CNV (ddPCR-CNV) in 4-1BB CD19-specific CAR T cells with universal applicability across clinical diagnostic laboratories.

One-Step Next-Generation Sequencing of Immunoglobulin and T-Cell Receptor Gene Recombinations for MRD Marker Identification in Acute Lymphoblastic Leukemia.

Within the EuroClonality-NGS group, immune repertoire analysis for target identification in lymphoid malignancies was initially developed using two-stage amplicon approaches, essentially as a progressive modification of preceding methods developed for Sanger sequencing. This approach has, however, limitations with respect to sample handling, adaptation to automation, and risk of contamination by amplicon products. We therefore developed one-step PCR amplicon methods with individual barcoding for batched analysis for IGH, IGK, TRD, TRG, and TRB rearrangements, followed by Vidjil-based data analysis.

Construction of three-gene-based prognostic signature and analysis of immune cells infiltration in children and young adults with B-acute lymphoblastic leukemia.

BACKGROUND: Although B-acute lymphoblastic leukemia (B-ALL) patients' survival has been improved dramatically, some cases still relapse. This study aimed to explore the prognosis-related novel differentially expressed genes (DEGs) for predicting the overall survival (OS) of children and young adults (CAYAs) with B-ALL and analyze the immune-related factors contributing to poor prognosis. METHODS: GSE48558 and GSE79533 from Gene Expression Omnibus (GEO) and clinical sample information and mRNA-seq from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database were retrieved. Prognosis-related key genes were enrolled to build a Cox proportional model using multivariate Cox regression. Five-year OS of patients, clinical characteristic relevance and clinical independence were assessed based on the model. The mRNA levels of prognosis-related genes were validated in our samples and the difference of immune cells composition between high-risk and low-risk patients were compared. RESULTS: One hundred and twelve DEGs between normal B cells and B-ALL cells were identified based on GSE datasets. They were mainly participated in protein binding and HIF-1 signaling pathway. One hundred and eighty-nine clinical samples were enrolled in the study, both Kaplan-Meier (KM) analysis and univariate Cox regression analysis showed that CYBB, BCL2A1, IFI30, and EFNB1 were associated with prognosis, CYBB, BCL2A1, and EFNB1 were used to construct prognostic risk model. Moreover, compared to clinical indicators, the three-gene signature was an independent prognostic factor for CAYAs with B-ALL. Finally, the mRNA levels of CYBB, BCL2A1, and EFNB1 were significantly lower in B-ALL group as compared to controls. The high-risk group had a significantly higher percentage of infiltrated immune cells. CONCLUSION: We constructed a novel three-gene signature with independent prognostic factor for predicting 5-year OS of CAYAs with B-ALL. Additionally, we discovered the difference of immune cells composition between high-risk and low-risk groups. This study may help to customize individual treatment and improve prognosis of CAYAs with B-ALL.

ERAP2 Inhibition Induces Cell-Surface Presentation by MOLT-4 Leukemia Cancer Cells of Many Novel and Potentially Antigenic Peptides.

Recent studies have linked the activity of ER aminopeptidase 2 (ERAP2) to increased efficacy of immune-checkpoint inhibitor cancer immunotherapy, suggesting that pharmacological inhibition of ERAP2 could have important therapeutic implications. To explore the effects of ERAP2 inhibition on the immunopeptidome of cancer cells, we treated MOLT-4 T lymphoblast leukemia cells with a recently developed selective ERAP2 inhibitor, isolated Major Histocompatibility class I molecules (MHCI), and sequenced bound peptides by liquid chromatography tandem mass spectrometry. Inhibitor treatment induced significant shifts on the immunopeptidome so that more than 20% of detected peptides were either novel or significantly upregulated. Most of the inhibitor-induced peptides were 9mers and had sequence motifs and predicted affinity consistent with being optimal ligands for at least one of the MHCI alleles carried by MOLT-4 cells. Such inhibitor-induced peptides could serve as triggers for novel cytotoxic responses against cancer cells and synergize with the therapeutic effect of immune-checkpoint inhibitors.

A BAFF ligand-based CAR-T cell targeting three receptors and multiple B cell cancers.

B cell-activating factor (BAFF) binds the three receptors BAFF-R, BCMA, and TACI, predominantly expressed on mature B cells. Almost all B cell cancers are reported to express at least one of these receptors. Here we develop a BAFF ligand-based chimeric antigen receptor (CAR) and generate BAFF CAR-T cells using a non-viral gene delivery method. We show that BAFF CAR-T cells bind specifically to each of the three BAFF receptors and are effective at killing multiple B cell cancers, including mantle cell lymphoma (MCL), multiple myeloma (MM), and acute lymphoblastic leukemia (ALL), in vitro and in vivo using different xenograft models. Co-culture of BAFF CAR-T cells with these tumor cells results in induction of activation marker CD69, degranulation marker CD107a, and multiple proinflammatory cytokines. In summary, we report a ligand-based BAFF CAR-T capable of binding three different receptors, minimizing the potential for antigen escape in the treatment of B cell cancers.

Immunophenotype of acute lymphoblastic leukemia in minorities- analysis from the SEER database.

Acute Lymphocytic Leukemia (ALL) is a malignancy that originates from immature lymphoid cells and is clinically established with flow cytometry through disease-specific markers. Variation between ethnic groups is an epidemiological aspect of ALL. Higher incidence rates have been observed in Latin American patients and ALL in Latinos carries a dismal prognosis. The cell of origin in ALL is derived from immature cells of either the B or T lineage. Most reported data among Latinos either exclusively looks at B cell precursor ALL or do not distinguish between subtypes. We used the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) database to delineate the differences in incidence rates of B-ALL and T-ALL across ethnic groups in the United States. Data from SEER-18 was used to compare incidence rates of T-ALL and B-ALL. Due to the utilization of cytogenetics and subsequent changes in ICD coding over the years examined the most recent data reported from 2002 to 2017. We compared rates in Non-Hispanic Whites (NHWs), Latinos, Blacks and Asian-Pacific Islanders (API). Age-adjusted incidence rates per 100,000 person-years were calculated. The incidence rate of B-ALL in the Latino population was consistently higher than other race/ethnicities throughout the years, ranging from 1.0 per 100,000 in 2002 to 2.5 per 100,000 in 2017. Blacks had the lowest age adjusted incidence rate (AAIR) of B-ALL overall, with rates approximately one third of those found in Latinos and the highest AAIR of T-ALL with an AAIR of 0.5 per 100,000.

Response to blinatumomab or inotuzumab ozogamicin for isolated extramedullary relapse of adult acute lymphoblastic leukemia after allogeneic hematopoietic cell transplantation: a case study.

Isolated extramedullary relapse (EMR) without bone marrow relapse (BMR) after allogeneic hematopoietic cell transplantation (allo-HCT) is a rare condition in patients with acute lymphoblastic leukemia (ALL), and the role of immunotherapeutic agents for these patients remains unclear. We analyzed treatment outcomes of blinatumomab or inotuzumab ozogamicin (INO) as first- or second-line salvage therapy in nine patients with Philadelphia chromosome-negative B-cell precursor ALL presenting with isolated EMR after previous allo-HCT. In seven patients receiving blinatumomab as first-line salvage therapy, 4 (57.1%) achieved complete remission (CR). Among the three patients without remission after blinatumomab, two switched to INO and subsequently showed responses {one CR and one partial response [PR]}, and one switched to multiagent chemotherapy that led to CR. In the two patients receiving first-line salvage therapy with INO, one showed PR and the other achieved CR. Overall, 6 (66.7%) of nine patients achieved CR, and five of them proceeded to allo-HCT in CR. The median overall survival after relapse was 27.8 months. In conclusion, both blinatumomab and INO showed good response rates and a safe bridging role to second allo-HCT in patients with isolated EMR. However, clinical differences between isolated EMR and EMR with BMR remain to be elucidated.

Relapsed ALL: CAR T vs transplant vs novel therapies.

Chimeric antigen receptor T-cell therapy targeting CD19 (CART19) has expanded the treatment options for patients with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (ALL). The approval of tisagenlecleucel for pediatric and young adult patients with r/r ALL has allowed broader access for some patients, but the treatment of older adults is available (at the time of this writing) only within a clinical trial. High remission rates have been consistently observed with varied CART19 products and treatment platforms, but durability of remissions and thus the potential role of a consolidative allogeneic stem cell transplant (SCT) is more uncertain and likely to vary by product and population treated. The immunologic characteristics of CARTs that confer high response rates also account for the life-threatening toxicities of cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, the severity of which also varies by patient and disease characteristics and product. Further considerations informing a decision to treat include feasibility of leukapheresis and timeline of manufacture, alternative treatment options available, and the appropriateness of a potential consolidative allogeneic SCT. Advances in the field are under way to improve rate and duration of responses and to mitigate toxicity.

Multiple site place-of-care manufactured anti-CD19 CAR-T cells induce high remission rates in B-cell malignancy patients.

Chimeric antigen receptor (CAR) T cells targeting the CD19 antigen are effective in treating adults and children with B-cell malignancies. Place-of-care manufacturing may improve performance and accessibility by obviating the need to cryopreserve and transport cells to centralized facilities. Here we develop an anti-CD19 CAR (CAR19) comprised of the 4-1BB co-stimulatory and TNFRSF19 transmembrane domains, showing anti-tumor efficacy in an in vivo xenograft lymphoma model. CAR19 T cells are manufactured under current good manufacturing practices (cGMP) at two disparate clinical sites, Moscow (Russia) and Cleveland (USA). The CAR19 T-cells is used to treat patients with relapsed/refractory pediatric B-cell Acute Lymphocytic Leukemia (ALL; n = 31) or adult B-cell Lymphoma (NHL; n = 23) in two independently conducted phase I clinical trials with safety as the primary outcome (NCT03467256 and NCT03434769, respectively). Probability of measurable residual disease-negative remission was also a primary outcome in the ALL study. Secondary outcomes include complete remission (CR) rates, overall survival and median duration of response. CR rates are 89% (ALL) and 73% (NHL). After a median follow-up of 17 months, one-year survival rate of ALL complete responders is 79.2% (95%CI 64.5‒97.2%) and median duration of response is 10.2 months. For NHL complete responders one-year survival is 92.9%, and median duration of response has not been reached. Place-of-care manufacturing produces consistent CAR-T cell products at multiple sites that are effective for the treatment of patients with B-cell malignancies.

Identification of immune subtypes of Ph-neg B-ALL with ferroptosis related genes and the potential implementation of Sorafenib.

BACKGROUND: The clinical outcome of Philadelphia chromosome-negative B cell acute lymphoblastic leukemia (Ph-neg B-ALL) varies considerably from one person to another after clinical treatment due to lack of targeted therapies and leukemia's heterogeneity. Ferroptosis is a recently discovered programmed cell death strongly correlated with cancers. Nevertheless, few related studies have reported its significance in acute lymphoblastic leukemia. METHODS: Herein, we collected clinical data of 80 Ph-neg B-ALL patients diagnosed in our center and performed RNA-seq with their initial bone marrow fluid samples. Throughout unsupervised machine learning K-means clustering with 24 ferroptosis related genes (FRGs), the clustered patients were parted into three variant risk groups and were performed with bioinformatics analysis. RESULTS: As a result, we discovered significant heterogeneity of both immune microenvironment and genomic variance. Furthermore, the immune check point inhibitors response and potential implementation of Sorafenib in Ph-neg B-ALL was also analyzed in our cohort. Lastly, one prognostic model based on 8 FRGs was developed to evaluate the risk of Ph-neg B-ALL patients. CONCLUSION: Jointly, our study proved the crucial role of ferroptosis in Ph-neg B-ALL and Sorafenib is likely to improve the survival of high-risk Ph-neg B-ALL patients.

[Bispecific antibodies in onco-hematology: Applications and perspectives]. / Anticorps bispecifiques en oncohématologie : applications et perspectives.

Bispecific antibodies are novel approaches of immunotherapy engaging immune cells to destroy tumor cells. Their structure is variable and underlies their pharmacocinetic properties. These coumpounds are now being evaluated across multiple hematological malignancies. The anti-CD3/CD19 antibody blinatumomab is the first in class and have been approved for the treatment of patients with Ph-negative B-cell acute lymphoblastic leukemia. Other emerging applications are lymphoma, multiple myeloma and acute myeloid leukemia. The safety profile of bispecific antibodies is acceptable while limited by neurotoxicity and cytokine-release syndrome. The present review aims to depict the landscape of emerging bispecific antibodies currently in development for hematological malignancies.

CAR T-cells in acute lymphoblastic leukemia: Current results.

The marketing authorization of tisagenlecleucel, a 2nd generation of CD19-directed CAR T-cells, containing the 4-1 BB co-stimulatory domain, in 2017 in USA and in 2018 in EU, has revolutionized the therapeutic strategy in advanced B-cell acute lymphoblastic leukemia (B-ALL) in children, adolescents and young adults (AYAs) with relapsed or refractory disease. This innovative treatment, based on a "living drug", has shown very impressive short-term responses. However, safety profile and complex logistics require high expertise centers and tight collaborations between addressing and treating centers. Current research is exploring the possibility to move to first line ALL with high-risk features and/or first high-risk relapse. More efficient CAR T-cells products, are still lacking to counteract the escape mechanisms already described. Moreover, to define the bridge-to-CAR time for each patient remains a challenge to obtain optimal disease burden allowing expansion and persistence of CAR T-cells. Also difficult is to identify patients who will benefit from further therapy after infusion, such as allogeneic HSCT or may be immuno-modulatory treatment. Finally, CAR T-cells directed against T-ALL are only in their beginning but require more complex engineering process to avoid T- cell immune-deficiency or fratricide.

Cytokine Release Syndrome after Treatment of Anti-CD19 CAR-T Therapy with IL-6 Knocking Down in Patients with Central Nervous System B-cell Acute Lymphocytic Leukemia.

OBJECTIVE: To investigate the cytokine release syndrome (CRS) condition for central nervous system B-cell acute lymphocytic leukemia (CNS B-ALL) patients after CAR-Ts targeting CD19 with short hairpin RNA (shRNA)-IL-6 gene silencing technology (ssCART-19s) infusion. METHODS: This prospective observational research included a total of 12 cases of patients with CNS B-ALL from March 2017 to February 2020. ssCART-19 infusions (5×106 cells/kg) were given to patients for 3 consecutive days. After infusion, the temperature of all patients was detected constantly and the CRS was carefully monitored within 1 month after treatment. The serum levels of IL-2, IL-4, IL-6, IL-10, IFN-γ, TNF-α, CRP and IL-17A were tested by enzyme-linked immunosorbent assay (ELISA) within 10 days after infusion. RESULTS: All 12 CNS B-ALL patients showed CRS with 100% incidence rate, with 3 cases (25.00%) of CRS stage I and 9 cases (75.00%) with CRS stage II. No CRS stage III~V was observed. The overall response rate was 91.67% (11/12), with 10 patients (83.33%) showed CR and 1 case (8.33%) of PR. In 9 patients with CRS stage II, the temperature increased persistently, ranging from 4 days to 14 days after infusion, and decreased gradually after 14 days of nursing treatment. The hyperthermia condition started from 1 day after infusion and returned to baseline at the following 2-10 days of nursing treatment. The levels of the inflammatory factors increased markedly after ssCAR-T19s infusion for 2-3 days compared to the baseline, and gradually returned to the baseline after treatment. After 10 days of infusion, all inflammatory factors returned to normal levels. CONCLUSION: ssCART-19s infusion induced short-term slight CRS with increased temperature and inflammatory factors, and no severe CRS was observed.

Mechanisms of Immunosuppressive Tumor Evasion: Focus on Acute Lymphoblastic Leukemia.

Acute lymphoblastic leukemia (ALL) is a malignancy with high heterogeneity in its biological features and treatments. Although the overall survival (OS) of patients with ALL has recently improved considerably, owing to the application of conventional chemo-therapeutic agents, approximately 20% of the pediatric cases and 40-50% of the adult patients relapse during and after the treatment period. The potential mechanisms that cause relapse involve clonal evolution, innate and acquired chemoresistance, and the ability of ALL cells to escape the immune-suppressive tumor response. Currently, immunotherapy in combination with conventional treatment is used to enhance the immune response against tumor cells, thereby significantly improving the OS in patients with ALL. Therefore, understanding the mechanisms of immune evasion by leukemia cells could be useful for developing novel therapeutic strategies.

CD19-CAR T cells undergo exhaustion DNA methylation programming in patients with acute lymphoblastic leukemia.

CD19-CAR T cell therapy has evolved into the standard of care for relapsed/refractory B cell acute lymphoblastic leukemia (ALL); however, limited persistence of the CAR T cells enables tumor relapse for many patients. To gain a deeper understanding of the molecular characteristics associated with CAR T cell differentiation, we performed longitudinal genome-wide DNA methylation profiling of CD8+ CD19-CAR T cells post-infusion in ALL patients. We report that CAR T cells undergo a rapid and broad erasure of repressive DNA methylation reprograms at effector-associated genes. The CAR T cell post-infusion changes are further characterized by repression of genes (e.g., TCF7 and LEF1) associated with memory potential and a DNA methylation signature (e.g., demethylation at CX3CR1, BATF, and TOX) demarcating a transition toward exhaustion-progenitor T cells. Thus, CD19-CAR T cells undergo exhaustion-associated DNA methylation programming, indicating that efforts to prevent this process may be an attractive approach to improve CAR T cell efficacy.