Relapsed B-cell Acute Lymphoblastic Leukemia Research Articles

Donor-derived CD19-targeted T cell infusion induces minimal residual disease-negative remission in relapsed B-cell acute lymphoblastic leukaemia with no response to donor lymphocyte infusions after haploidentical haematopoietic stem cell transplantation.

Relapse is a common cause of failure in patients with B-cell acute lymphoblastic leukaemia (B-ALL) after haploidentical haematopoietic stem cell transplantation (haplo-HSCT), and non-responders to donor lymphoblastic infusion after HSCT have a very poor prognosis. Although donor-derived CD19-directed chimeric antigen receptor-modified (CAR) T cells can potentially cure leukaemia, their effectiveness and safety have not been confirmed in relapsed B-ALL cases after haplo-HSCT. Between January 2015 and January 2017, two and four patients each received one and two infusions of CAR T cells from haplo-HSCT donors. Five (83·33%) achieved minimal residual disease (MRD)-negative remission; one patient was discharged automatically without evaluation after developing severe thrombotic microangiopathies. Four of five responsive patients relapsed after 2-7months, and one died of sepsis following MRD-negative remission after a second infusion. None of the other second infusion recipients achieved a second complete remission. Five patients (83·33%) experienced eight courses of grade 1-3 cytokine release syndrome; two were treated with tocilizumab. Two (33·3%) and one patient developed grade 2 and 3 acute graft-versus-host disease (aGVHD), respectively; the former was controlled with glucocorticoids. Donor-derived CAR T-cell infusion seems be effective and safe for relapsed B-ALL after haplo-HSCT, although larger clinical studies are needed.

Targeting the vulnerability to NAD+ depletion in B-cell acute lymphoblastic leukemia.

Although substantial progress has been made in the treatment of B-cell acute lymphoblastic leukemia (B-ALL), the prognosis of patients with either refractory or relapsed B-ALL remains dismal. Novel therapeutic strategies are needed to improve the outcome of these patients. KPT-9274 is a novel dual inhibitor of p21-activated kinase 4 (PAK4) and nicotinamide phosphoribosyltransferase (NAMPT). PAK4 is a serine/threonine kinase that regulates a variety of fundamental cellular processes. NAMPT is a rate-limiting enzyme in the salvage biosynthesis pathway of nicotinamide adenine dinucleotide (NAD) that plays a vital role in energy metabolism. Here, we show that KPT-9274 strongly inhibits B-ALL cell growth regardless of cytogenetic abnormalities. We also demonstrate the potent in vivo efficacy and tolerability of KPT-9274 in a patient-derived xenograft murine model of B-ALL. Interestingly, although KPT-9274 is a dual PAK4/NAMPT inhibitor, B-ALL cell growth inhibition by KPT-9274 was largely abolished with nicotinic acid supplementation, indicating that the inhibitory effects on B-ALL cells are mainly exerted by NAD+ depletion through NAMPT inhibition. Moreover, we have found that the extreme susceptibility of B-ALL cells to NAMPT inhibition is related to the reduced cellular NAD+ reserve. NAD+ depletion may be a promising alternative approach to treating patients with B-ALL.

Toll-like receptor 2 costimulation potentiates the antitumor efficacy of CAR T Cells.

Chimeric antigen receptor (CAR) T-cell immunotherapies have shown unprecedented success in treating leukemia but limited clinical efficacy in solid tumors. Here, we generated 1928zT2 and m28zT2, targeting CD19 and mesothelin, respectively, by introducing the Toll/interleukin-1 receptor domain of Toll-like receptor 2 (TLR2) to 1928z and m28z. T cells expressing 1928zT2 or m28zT2 showed improved expansion, persistency and effector function against CD19+ leukemia or mesothelin+ solid tumors respectively in vitro and in vivo. In a patient with relapsed B-cell acute lymphoblastic leukemia, a single dose of 5 × 104/kg 1928zT2 T cells resulted in robust expansion and leukemia eradication and led to complete remission. Hence, our results demonstrate that TLR2 signaling can contribute to the efficacy of CAR T cells. Further clinical trials are warranted to establish the safety and efficacy of this approach.

Abstract CT078: Impact of disease burden and transplant on long-term survival after CD19 CAR therapy in adults with relapsed B-cell acute lymphoblastic leukemia

Abstract Objectives: CD19-specific chimeric antigen receptor (CAR) T cells have demonstrated high initial responses in patients with relapsed B-cell acute lymphoblastic leukemia (B-ALL). However, clinical characteristics associated with the durability of response remain undefined. Herein, we report the results from analysis of our phase I clinical trial of 19-28z CAR T cells in adult patients with relapsed B-ALL with a focus on impact of pre-treatment disease burden and post-CAR T cell allogeneic transplant on long-term clinical outcome. Methods: Adults with relapsed B-ALL were infused with autologous T cells expressing the 19-28z CAR. Disease burden was assessed by bone marrow biopsy immediately prior to T cell infusion. We grouped patients into 2 cohorts based on disease burden upon T cell infusion: minimal residual disease (MRD) with <5% blasts in bone marrow and morphologic disease (≥5% blasts). Median follow-up duration was 18 months (range, 0.2-57.3). Results: 51 adults received 19-28z CAR T cells; 20 in the MRD and 31 in the morphologic cohort. Complete remission (CR) rates were comparable (95% and 77%, respectively). However, median event-free and overall survivals widely diverged among the 42 patients who achieved MRD-negative CR: not reached (NR) (95% confidence interval [CI]: 4.2-NR) vs. 6.3 months (95% CI, 4.8-9.0) (p=0.0005), and NR (95% CI, 15.3-NR) vs. 17 months (95% CI, 8.5 - 36.2) (p=0.0189), in the MRD and morphologic cohorts, respectively. Subsequent allogeneic HSCT in either cohort did not improve survival (p=0.8). MRD cohort patients developed substantially less severe cytokine release syndrome (CRS) and neurotoxicity, both correlating with peak CAR T cell expansion (p=0.0326 and p=0.0001, respectively). Conclusion: Despite comparable initial CR rates between the two cohorts, durability of 19-28z CAR T cell mediated remissions and survival in adult patients with relapsed B-ALL positively correlated to a low disease burden and do not appear to be enhanced by allogeneic transplant. Our findings strongly support the early incorporation of CD19 CAR therapy before morphologic relapse in B-ALL. Citation Format: Jae H. Park, Isabelle Rivere, Xiuyan Wang, Brigitte Senechal, Kevin Curran, Craig Sauter, Yongzeng Wang, Bianca Santomasso, Daniel Li, Renier Brentjens, Michel Sadelain. Impact of disease burden and transplant on long-term survival after CD19 CAR therapy in adults with relapsed B-cell acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT078. doi:10.1158/1538-7445.AM2017-CT078

Retrospective chart review of hospitalizations and costs associated with the treatment of adults with Philadelphia-negative B-cell relapsed or refractory acute lymphoblastic leukemia in Belgium

Objectives: To quantify hospitalizations and costs among adults with Philadelphia-negative relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (ALL) who received current salvage chemotherapies in Belgium.Methods: A retrospective chart review identified patients aged ≥18 years and hospitalized between 2005 and 2015 for Ph-negative R/R B-cell ALL. Data were collected from the index date (first diagnosis of R/R ALL) until death or loss to follow-up. The salvage chemotherapy period was defined as the first chemotherapy hospitalization after the index date to the earliest of death, loss to follow-up, last chemotherapy dose plus 30 days, or initiation of hematological stem cell transplantation (HSCT). The primary endpoint was the percent of time in the hospital during the salvage chemotherapy period. Hospitalization costs were reported from the public health care payer perspective.Results: Nineteen patients were included, with median age of 37 years. The average proportion of time patients spent in the hospital during the salvage chemotherapy period was 50.5%. From the index date to death, patients received a mean of 1.8 lines of chemotherapy, most commonly hyper-CVAD (31%). There was a mean of 5.5 inpatient hospitalizations and 40.1 outpatient visits with 40.8 outpatient lab tests. Mean costs per patient were €79,973 for hospitalization (excluding HSCT), €26,337 for HSCT, €21,007 for chemotherapy drugs, and €6,341 for outpatient management, resulting in a total cost from the payer’s perspective of €133,965 per patient.Conclusion: Adults with Ph-negative R/R ALL spend half the time receiving salvage chemotherapy in the hospital. Their treatment is associated with large reimbursement costs in Belgium.

Inotuzumab ozogamicin in relapsed B-cell acute lymphoblastic leukemia.

Despite an improved understanding of disease biology and the use of multi-agent chemotherapy, the long-term survival of adults with B-cell acute lymphoblastic leukemia (B-ALL) ranges from 35% to 50%. Management of patients with relapsed B-ALL, a group characterized by dismal outcomes, poses a clinical challenge. To address this unmet need, novel therapeutics are being investigated in the setting of relapsed B-ALL with encouraging results. CD22 is an important B-cell antigen expressed in 80-90% of B-ALL cases. CD22 undergoes constitutive endocytosis with antibody ligation, making it an attractive biologic target for immunoconjugates. Inotuzumab ozogamicin (IO), a CD22-targeted antibody-drug conjugate demonstrated impressive single agent activity even among heavily pretreated relapsed B-ALL patients. A recent randomized phase III clinical trial demonstrates superiority of IO over standard of care chemotherapy as first- or second-line salvage therapy for relapsed B-ALL. In this review, we summarize the preclinical and clinical data available to date using IO in relapsed B-ALL.

The mechanism of B cell acute lymphoblastic leukemia development

B cell acute lymphoblastic leukemia (B-ALL) is a common malignant disease in children. Gene mutations in transcriptional factors and signal transduction molecules result in differentiation block and abnormal proliferation of B lymphoid progenitor cells. Children with B-ALL generally have a good prognosis, but about 20% of the pediatric patients and 60% adult patients still suffer from the high risk of relapse. Better understanding of the mechanism of leukemogenesis leads to significant improvement in treatment of ALL patients. Gene expression analysis and whole genome sequencing technologies have identified a number of novel gene mutations, but the roles of those mutations in leukemogenesisis remain unclear. This review mainly summarizes the so far identified cooperating gene mutations related to cell development and differentiation, epigenetic regulation, cell cycle and apoptosis, signal pathway, non-coding RNA, and leukemia clone evolution, some of which may be tightly associated with the relapse of B-ALL. In addition, we also review mouse models of B-ALL which may be useful for study of pathogenesis, risk classification, and design of future therapy.

Anti-CD 19 and Anti- CD 20 Chimeric Antigen Receptor-Modified T Cells for B-Cell Malignancies: A Systematic Review and Meta-Analysis

Background:Chimeric antigen receptor (CAR) modified T cells targeting CD19 and CD20 have shown activity in Phase I, II trials of patients with hematological malignancies. CD19 and CD20 targeted CAR constructs from several different institutions have demonstrated consistently high anti-tumor efficacy in children and adults with relapsed B-cell acute lymphoblastic leukemia (B-ALL), chronic lymphocytic leukemia (CLL) and B-cell non-Hodgkin lymphoma (B-NHL). We conducted a systematic review and meta-analysis of all published clinical trials studying the role of efficacy as well as safety of CD-19 and CD-20 CAR-T therapy for B-cell hematologic malignancies.Methods:Literature search was performed using MEDLINE (Ovid SP and PubMed), EMBASE, The Cochrane Library, Scopus and Web of Science. We conducted meta-analysis using random effects model using Comprehensive Metaanalysis 3.0. Heterogeneity was assessed using Q-statistic and it was quantified using I2statistic.Results:After a comprehensive literature search 4476 studies were identified and finally 15 eligible studies involving 121 patients were included in the final systematic review. The infused CAR T-cell dose was in the range of 0.76 x 106 to 3 x 107 cells/kg in seven trials and in the range of 0.8 x 107 cells to 3.3 x 109 cells/m2in 6 trials. Among 106 patients, the overall response to treatment after CAR T-cell infusion were 33% complete remission (CR), 30 % partial remission (PR), 21% stable disease (SD), and 8% progressive disease (PD). Three studies described response to immunotherapy as minimal residual disease negative (MRD-) and as no evidence of disease (NED) and after including it, the overall CR was 38%. Major adverse events included fever (38%), hypotension (23%), chills (29%), rigor (28%), fatigue 17% and dyspnea 10%. One patient died from cytokine release syndrome, which is potentially serious complication. Neurological symptoms require prompt recognition and management.Conclusion:CAR T cell therapy is a promising treatment for refractory and relapsed hematological malignancies. The durable responses of CAR T cell therapy help integrate it in standard treatment protocols. Patients who are refractory to standard salvage chemotherapy or relapse after allo - HSCT have overall poor prognosis and can potentially achieve remission again with CAR T cell therapy. DisclosuresMcBride:Sanofi: Research Funding. Anwer:Seattle Genetics: Other: Advisory Board Participant; Incyte: Speakers Bureau.

Prolonged Response in Patient With Multiply Relapsed B-cell Acute Lymphoblastic Leukemia and Monosomy-7 to Bortezomib, Lenalidomide, and Dexamethasone

Isolated monosomy-7, a rare cytogenetic abnormality in patients with pediatric acute lymphoblastic leukemia (ALL), portends a worse prognosis. Despite improvements in treatment, outcomes for patients with relapsed ALL remain poor. Novel treatments adopted from the B-cell malignancy multiple myeloma may have a role in treatment of ALL. Bortezomib is one such agent currently in phase III trials for B and T ALL. This study presents a patient with B-cell ALL and monosomy-7 who relapsed off therapy. The combination of bortezomib, lenalidomide, and dexamethasone was used to attain remission before bone marrow transplant after conventional relapse therapy failed. A recurrence after bone marrow transplant was controlled for a prolonged period with the same therapy. The case supports the hypothesis that bortezomib, lenalidomide, and dexamethasone should be further explored in the treatment of B-cell ALL with monosomy-7.

Aberrant Notch Signaling in the Bone Marrow Microenvironment of Acute Lymphoid Leukemia Suppresses Osteoblast-Mediated Support of Hematopoietic Niche Function.

More than half of T-cell acute lymphoblastic leukemia (T-ALL) patients harbor gain-of-function mutations in the intracellular domain of Notch1. Diffuse infiltration of the bone marrow commonly occurs in T-ALL and relapsed B-cell acute lymphoblastic leukemia patients, and is associated with worse prognosis. However, the mechanism of leukemia outgrowth in the marrow and the resulting biologic impact on hematopoiesis are poorly understood. Here, we investigated targetable cellular and molecular abnormalities in leukemia marrow stroma responsible for the suppression of normal hematopoiesis using a T-ALL mouse model and human T-ALL xenografts. We found that actively proliferating leukemia cells inhibited normal hematopoietic stem and progenitor cell (HSPC) proliferation and homing to the perivascular region. In addition, leukemia development was accompanied by the suppression of the endosteum-lining osteoblast population. We further demonstrated that aberrant Notch activation in the stroma plays an important role in negatively regulating the expression of CXLC12 on osteoblasts and their differentiation. Notch blockade reversed attenuated HSPC cycling, leukemia-associated abnormal blood lineage distribution, and thrombocytopenia as well as recovered osteoblast and HSPC abundance and improved the hematopoietic-supportive functions of osteoblasts. Finally, we confirmed that reduced osteoblast frequency and enhanced Notch signaling were also features of the marrow stroma of human ALL tissues. Collectively, our findings suggest that therapeutically targeting the leukemia-infiltrated hematopoietic niche may restore HSPC homeostasis and improve the outcome of ALL patients.

Impact of mTOR expression on clinical outcome in paediatric patients with B-cell acute lymphoblastic leukaemia - preliminary report.

Aim of the studyTo characterise expression of mTOR (mammalian target of rapamycin) in childhood B-cell acute lymphoblastic leukaemia (ALL), and to evaluate a possible link between mTOR and clinical characteristics.Material and methodsThe examined group consisted of 21 consecutive patients, aged 1–18 years, diagnosed with B-cell ALL in 2010, and 10 relapsed B-cell ALL patients diagnosed for the first time between 2009 and 2011, who developed relapse before 2014. All subjects were treated in the Department of Paediatric Haematology and Oncology of the Medical University of Warsaw according to the ALL-IC BFM 2002 Protocol. We evaluated mTOR and phospho-mTOR expression by immunohistochemistry using rabbit monoclonal antibodies.ResultsmTOR expression was found to be significantly associated with the risk of relapse and was more frequent in ALL recurrence. No significant relationship was detected between mTOR expression and other features of high-risk disease in paediatric ALL.ConclusionsmTOR activity could be considered a high-risk feature in paediatric B-cell ALL. Expression of mTOR kinase is observed remarkably more frequently in disease recurrence than at first diagnosis, indicating higher proliferative and survival potential of leukaemic cells in relapse. Routine analysis of mTOR activity could be performed to select patients that may potentially benefit from mTOR inhibitors (MTI) treatment.

FDG-PET/CT for detecting relapse in patients with acute lymphoblastic leukemia.

A 16-year-old girl was presented with a mass in the medial side of the left eye with normal visual inspection. She was diagnosed as having precursor b-cell acute lymphoblastic leukemia (B-ALL) 9 years ago by bone marrow biopsy and her treatment was planned as allogeneic transplantation over chemotherapy. Complete remission was achieved by allogeneic bone marrow transplant from her sister. FDG PET/CT imaging was performed for determining extramedullary relapse and a slightly hyperdense, oval shaped 16 × 18 × 16 mmmass (red arrows) was located in the soft tissue between the left eyeball and the left nasal process of the maxilla on unenhanced axial CT image (Fig. 1). Corresponding axial (Fig. 2) PET and fused (Fig. 3) images showed high FDG uptake (SUVmax = 7.70) (red arrows) in the mass. Maximum intensity projection PET images with anterior view (Fig. 4) showed that there was no additional site of relapse. The extramedullary B-ALL relapse was confirmed by an incisional biopsy. The patient underwent bone marrow biopsy and there was no relapse in the bone marrow, compatible with FDG PET/CT findings. Figure 1.

Relapse in Teenage and Young Adult (TYA) Patients Treated on a Pediatric Minimal Residual Disease (MRD) Stratified Protocol Is Associated with a Poor Outcome: Results from UKALL2003

The superior outcomes of teenage and young adult (TYA) patients with acute lymphoblastic leukemia (ALL) treated on contemporary pediatric minimal residual disease (MRD) directed chemotherapy regimens compared to adult ALL protocols are well established. However, there are limited data on the outcome of relapse following such regimens and consequently no consensus on optimal salvage strategies.UKALL 2003 was a prospective, randomised controlled trial investigating treatment modification according to MRD status at the end of induction in consecutively diagnosed children and young people with ALL recruited from the UK and Republic of Ireland between October 2003 and June 2011. The trial was initially open to children up to the age of 18 years but the upper age limit was increased to 20th birthday in 2006 and 25th birthday in 2007. Here we report the relapse outcomes of 16 - 24 year old TYA patients recruited to the trial.All TYA patients recruited to UKALL 2003 who subsequently relapsed were identified using the trial database, which also provided data regarding prognostic factors at presentation, MRD risk group, treatment allocation, site of and time to relapse and overall outcome. Individual centers were then contacted for follow up information including salvage chemotherapy, disease response, use of transplantation, subsequent outcome and cause of death.Of a total of 229 TYA patients recruited, 42 (18.3%) relapsed. The immunophenotype in those who subsequently relapsed was precursor B cell (B-ALL) in 30 patients and T cell (T-ALL) in 12. The median white cell count at diagnosis was 22x109/l and 1 patient had central nervous system (CNS) involvement. In B-ALL, 4 had good risk cytogenetics (all high hyperdiploid), 13 had intermediate risk, 6 had high risk (3 with MLL rearrangements), and 7 had unknown cytogenetics. End of induction MRD risk group was low risk in 2, intermediate risk in 11 and high risk in 29.The median time from diagnosis to relapse was 17 months (17.5 months for B-ALL and 14 months for T-ALL, p=0.1). The site of relapse was isolated bone marrow (BM) in 30 patients, combined BM and CNS in 4, combined BM and testicular in 1, and isolated CNS in 6 (T-ALL; 8 BM, 3 BM+CNS, 1 isolated CNS) (B-ALL; 23 BM, 1 BM+CNS, 1 BM + testicular, 5 isolated CNS).36 of the 42 relapsed patients were given salvage chemotherapy, using a variety of regimens including R3 (n=9), Fludarabine/Cytarabine/Idarubicin based (n=16), and Clofarabine based (n=4). One patient received Blinatumamab and one entered the MARALL study (a Phase I/II study of the combination of Veltuzumab (anti-CD20) and Epratuzumab (anti-CD22) with intensive chemotherapy in patients with relapsed B-cell ALL). A second complete remission rate was achieved in 22 patients (61%) and a further 2 had an empty marrow without count recovery. 23 patients proceeded to an allogeneic hemopoietic stem cell transplant.The median overall survival (OS) from relapse was 213 days (actuarial 5 year OS of 18%). 9 patients remain alive; 8 in remission (1 unconfirmed) and 1 undergoing active treatment. The cause of death in the 33 patients who died was relapsed/refractory disease in 20, complications of re-induction treatment in 4, transplant related complications in 6 and unknown in 2. 1 further patient died of sepsis post transplant in the context of pancytopenia and suspected (though unproven) relapse.Those relapsing earlier than the median of 17 months had a shorter median survival and 5 year OS from relapse compared to those relapsing at >17 months (median 113.5 v 400 days, and OS 10% v 37%, p=0.0075). When this analysis was restricted to only the B-ALL cohort the effect was even more marked (median 151 v 595 days, OS 0% v 45%). No patient with B-ALL relapsing ≤24 months was salvageable. There were no differences in salvage approach between the early and late relapsing cohorts, nor differences in MRD risk. The late relapsing cohort did have more patients with good risk cytogenetics, and fewer with high risk cytogenetics.TYA patients with ALL who relapse despite intensive, contemporary MRD directed chemotherapy have an extremely poor outcome. Patients with B-ALL relapsing at 24 months from diagnosis or earlier are unsalvageable. Improving the outcomes of TYA ALL patients will depend on a) more accurate early identification of those destined to relapse and b) use of innovative therapies in those at high risk of relapse or with overt relapse. DisclosuresNo relevant conflicts of interest to declare.

FDA Approval: Blinatumomab.

On December 3, 2014, the FDA granted accelerated approval of blinatumomab (Blincyto; Amgen, Inc.) for treatment of Philadelphia chromosome-negative relapsed or refractory precursor B-cell acute lymphoblastic leukemia (R/R ALL). Blinatumomab is a recombinant murine protein that acts as a bispecific CD19-directed CD3 T-cell engager. The basis for the approval was a single-arm trial with 185 evaluable adults with R/R ALL. The complete remission (CR) rate was 32% [95% confidence interval (CI), 26%-40%], and the median duration of response was 6.7 months. A minimal residual disease response was achieved by 31% (95% CI, 25%-39%) of all patients. Cytokine release syndrome and neurologic events were serious toxicities that occurred. Other common (>20%) adverse reactions were pyrexia, headache, edema, febrile neutropenia, nausea, tremor, and rash. Neutropenia, thrombocytopenia, and elevated transaminases were the most common (>10%) laboratory abnormalities related to blinatumomab. A randomized trial is required in order to confirm clinical benefit.

ADAM28 overexpression regulated via the PI3K/Akt pathway is associated with relapse in de novo adult B-cell acute lymphoblastic leukemia

B-cell acute lymphoblastic leukemia (B-ALL) in adults is a very challenging disease. Relapse following remission after induction chemotherapy remains the major barrier to patient survival. ADAM28 is overexpressed in several human tumors and is related to cell proliferation and lymph node metastasis. To date, no information has been available on the prognostic role of ADAM28 in B-ALL. Fifty consecutive patients with de novo B-ALL and 22 healthy donors were enrolled in this study and were followed for 2.8 years. Our data suggested that ADAM28 expression in B-ALL patients was significantly increased (P<0.0001). Patients experiencing disease relapse exhibited significantly increased ADAM28 expression, compared with those with favorable outcomes (P=0.0094). Notably, ADAM28 overexpression was associated with lower probabilities of relapse-free survival (RFS) and event-free survival (EFS) (P<0.001) and was a significant prognostic factor (P<0.001). In vitro, the PI3K/Akt pathway inhibitor, as well as arsenic trioxide (ATO), down-regulated ADAM28 expression. Our results were the first to indicate that ADAM28 overexpression in B-ALL patients is correlated with relapse. ADAM28 overexpression is potentially regulated by the PI3K/Akt pathway. These data demonstrate that ADAM28 might serve as a novel biomarker for evaluating relapse in B-ALL and as a potential therapeutic target in B-ALL patients.

CD19-redirected chimeric antigen receptor-modified T cells: a promising immunotherapy for children and adults with B-cell acute lymphoblastic leukemia (ALL).

Relapsed and chemotherapy-refractory B-cell acute lymphoblastic leukemia (B-ALL) remain significant causes of cancer-associated morbidity and mortality for children and adults. Development of new molecularly targeted treatment strategies for patients with high-risk B-ALL is thus a major preclinical and clinical priority. Adoptive cellular therapy with patient-derived human T cells genetically engineered to express CD19 redirected chimeric antigen receptors (CD19 CAR T cells) is one immunotherapeutic modality that has recently demonstrated remarkable efficacy in re-inducing remission in patients with multiply relapsed B-ALL. Investigative teams at several major cancer centers are currently conducting phase I clinical trials in children and/or adults with relapsed/refractory B-ALL to assess the safety and to identify the maximally tolerated dose of each group's CD19 CAR T-cell product. All groups have reported major clinical toxicities associated with CD19 CAR T-cell treatment, including cytokine release syndrome (CRS) and macrophage activation syndrome, neurologic dysfunction and aplasia of normal B lymphocytes, while CD19 CAR T cells persist in vivo. Toxicities have generally been transient or manageable with supportive care measures. Some patients with life-threatening CD19 CAR T-cell induced sequelae have received anti-cytokine receptor antibody treatment to diminish CRS symptoms and/or corticosteroids to terminate CAR T-cell proliferation. Remarkably, 67-90% of children and adults with B-ALL treated with CD19 CAR T cells in these trials have achieved morphologic leukemia remission with many patients also in molecular remission. The duration of CD19 CAR T cell persistence in vivo has varied appreciably among treated patients and likely reflects differences in the CD19 CAR constructs utilized at each institution. CD19-positive and CD19-negative B-ALL relapses after CD19 CAR T-cell treatment have occurred in some patients. Phase II trials to assess the efficacy of CD19 CAR T-cell immunotherapy in larger cohorts of patients with relapsed/refractory B-ALL are ongoing or planned.

90Y-labelled anti-CD22 epratuzumab tetraxetan in adults with refractory or relapsed CD22-positive B-cell acute lymphoblastic leukaemia: a phase 1 dose-escalation study

Prognosis of patients with relapsed or refractory acute lymphoblastic leukaemia is poor and new treatments are needed. We aimed to assess the feasibility, tolerability, dosimetry, and efficacy of yttrium-90-labelled anti-CD22 epratuzumab tetraxetan ((90)Y-DOTA-epratuzumab) radioimmunotherapy in refractory or relapsed CD22-positive B-cell acute lymphoblastic leukaemia in a standard 3 + 3 phase 1 study. Adults (≥18 years) with relapsed or refractory B-cell acute lymphoblastic leukaemia (with CD22 expression on at least 70% of blast cells) were enrolled at six centres in France. Patients received one cycle of (90)Y-DOTA-epratuzumab on days 1 and 8 (give or take 2 days) successively at one of four dose levels: 2·5 mCi/m(2) (92·5 MBq/m(2); level 1), 5·0 mCi/m(2) (185 MBq/m(2); level 2), 7·5 mCi/m(2) (277·5 MBq/m(2); level 3), and 10·0 mCi/m(2) (370 MBq/m(2); level 4). The primary objective was to identify the maximum tolerated dose of (90)Y-DOTA-epratuzumab. We assessed safety during infusions and regularly after radioimmunotherapy over a 6-month period. Analyses included only patients who received radioimmunotherapy. The trial is closed to inclusion and is registered at ClinicalTrials.gov, NCT01354457. Between Aug 25, 2011, and June 11, 2014, 17 patients (median age 62 years; range 27-77) were treated (five at level 1, three at level 2, three at level 3, and six at level 4). Radioimmunotherapy infusion was overall well tolerated. One dose-limiting toxic effect (aplasia lasting 8 weeks) occurred at level 4, but the maximum tolerated dose was not reached. The most common grade 3-4 adverse events were pancytopenia (one patient at level 2, one at level 3, and six at level 4) and infections (three at level 1, one at level 2, and five at level 4). (90)Y-DOTA-epratuzumab radioimmunotherapy is well tolerated. We recommend the dose of 2 × 10·0 mCi/m(2) 1 week apart per cycle for phase 2 studies. Immunomedics and Direction de la Recherche Clinique of Nantes.

Are all chimeric antigen receptors created equal?

In the report accompanying this article, Kochenderfer et al discuss the efficacy of autologous T cells expressing a CD19-specific chimeric antigen receptor (CAR) in patients with relapsed diffuse large B-cell lymphoma. Although previous reports have demonstrated significant antitumor activity in low-grade B-cell malignancies and B-cell acute lymphoblastic leukemia (ALL), this is the first report to our knowledge to demonstrate the efficacy of CD19-targeted CAR T cells in patients with diffuse large B-cell lymphoma. A CAR is a recombinant receptor constructs composed of an extracellular single-chain variable fragment (scFv) derived from an antibody, linked to a transmembrane domain, which is further linked to one or more intracellular T-cell signaling domains (Fig 1). Because CARs combine the binding domain of an antibody and T-cell signaling moieties, they can redirect T-cell specificity to the tumor in an HLA-independent fashion and activate the CAR-modified T lymphocytes to lyse targeted tumor cells. Initial first-generation CARs were constructed through the fusion of an scFv-based antigen binding domain to an inert CD8 transmembrane domain, linked to a cytoplasmic signaling domain derived from the CD3or Fc receptor chains (Fig 1). Although T cells expressing first-generation CARs effectively engaged the target antigens, limited T-cell proliferation and diminished cytolytic activities were observed because of the lack of T-cell costimulation. For optimal activation and proliferation, T cells require both T-cell receptor engagement and signaling (termed signal 1), as well as costimulatory signaling through costimulatory receptors (ie, CD28, 4-1BB, OX-40) on T cells binding to cognate ligands (ie, CD80/86, 4-1BBL, OX-40L) expressed either by the targeted tumor cell or professional antigen-presenting cells (termed signal 2). To overcome the lack of T-cell costimulation (signal 2), firstgeneration CARs were further modified by incorporating the cytoplasmic signaling domains of T-cell costimulatory receptors. These second-generation CARs (Fig 1) enhanced signaling strength and persistence of the modified T cells, leading to superior antitumor activity. However, it remains unclear whether any particular second-generation CAR design is superior to the other. In one study by Carpenito et al, both CD28and 4-1BB–based CAR-modified T cells had the same antitumor activity, but the 4-1BB–based CAR enhanced in vivo persistence of T cells. In contrast, another study failed to demonstrate any significant difference between CD28and 4-1BB–based second-generation CARs with regard to proliferation, potency, antitumor efficacy, and persistence of the T cells. More recently, third-generation CARs containing tandem cytoplasmic signaling domains from two costimulatory receptors (Fig 1) were tested in certain mouse models, but clinical experience so far has been limited. Initial clinical results with first-generation CD19-targeted CAR-modified T cells were disappointing, but second-generation CAR-modified T cells displayed significantly enhanced expansion and persistence in patients with B-cell lymphoma. Using either CD28or 4-1BB–based second-generation CD19-specific CARs, investigators at Memorial Sloan Kettering Cancer Center (MSKCC), the University of Pennsylvania, and the National Cancer Institute published initial promising results of phase I clinical trials, reporting durable antitumor efficacy in patients with indolent B-cell malignancies, including chronic lymphocytic leukemia (CLL), and more recently reporting dramatic clinical responses in patients with relapsed B-cell ALL. These trials varied significantly with respect to infused T-cell product; CAR design, including scFv and costimulatory domains (CD28 v 4-1BB); means of gene transfer (retrovirus v lentivirus); ex vivo T-cell expansion; T-cell dose; intensity of conditioning chemotherapy; degree of tumor burden at the time of therapy; and age of the treated patient population. All of these variables make it difficult to compare results from one trial with those of another and the efficacy of one CAR T cell with that of another. Hinge First-generation CAR Second-generation CAR Third-generation CAR

Chimeric Antigen Receptor (CAR) T Cells Targeting the CD19 Antigen for the Treatment of Pediatric Relapsed B Cell ALL

T cells can be genetically modified to target tumor antigens through the expression of a chimeric antigen receptor (CAR). CAR T cells targeting the CD19 antigen is a novel therapeutic approach for patients with relapsed B cell acute lymphoblastic leukemia (B-ALL). We have previously demonstrated that CAR T cells have a significant clinical benefit in adult patients with relapsed B-ALL. The primary objective of this study (NCT01860937) is to extend the use and test the safety of CD19 specific CAR T cells in children with relapsed CD19+ B-ALL. To date, 11 pediatric patients with very high risk (VHR) or relapsed B-ALL have been enrolled on protocol with a median age of 13 years (range 2-23 years) at time of T cell collection. We have treated 4 pediatric patients with relapsed B-ALL (ages 13, 14, 19, and 22 years) using patient derived T cells expressing a CD19 specific CAR (19-28z). Complete response (complete remission or complete remission with incomplete count recovery) occurred in 2/4 (50%) patients. Severe cytokine release syndrome (sCRS) defined by fever for ≥3 consecutive days, elevated serum cytokine levels, and one clinical sign of toxicity (hypotension, hypoxia, neurologic disorder including altered mental status, obtundation, and/or seizure) occurred in both patients who responded to CAR T cells. Morphologic disease (≥5% bone marrow blasts) at time of treatment was present in three patients including both patients with sCRS. Systemic immunosuppressants (corticosteroids or anti-IL6 receptor antibody tocilizumab) abrogated clinical symptoms of sCRS. Elevated serum cytokines of IFN-g (>20 fold), fractalkine (>20 fold), Flt-3L (>55 fold), IL-5 (>15 fold), IL-6 (>100 fold), and IL-10 (>15 fold) were demonstrated in patients with sCRS. Monitoring of bone marrow demonstrated peak 19-28z CAR T-cell detection within 1-2 weeks following infusion with gradual contracture over 2-3 months. These early results demonstrate the feasibility and significant clinical impact of this approach in patients with relapsed B-ALL. To more rapidly generate statistically relevant data, demonstrate the “exportability” of this technology between academic institutions, and offer this therapeutic option to a broader number of pediatric patients with chemo-refractory B-ALL our trial will expand into a phase I multicenter clinical trial with a collaborating institution. Subsequent cohorts of patients will receive 19-28z CAR T cells and will be evaluated for toxicity, persistence of CAR T cells, and for anti-leukemic efficacy. DisclosuresOff Label Use: CAR T cells for relapsed B-ALL. Riviere:Juno Therapeutics: Consultancy, Scientific co-founder and Stock holder Other. Boulad:Genzyme Sanofi: Trials partially funded by Genzyme Sanofi Other. Sadelain:Juno Therapeutics: Consultancy, Scientific co-founder and Stock holder Other. Brentjens:Juno Therapeutics: Consultancy, Scientific co-founder and Stock holder Other.

The Genomic Landscape of Relapsed B-Cell Acute Lymphoblastic Leukaemia (B-ALL) in Adolescents and Adults

Despite significant advancements in the treatment of paediatric B-cell acute lymphoblastic leukaemia (B-ALL), ALL remains one of the most challenging adult malignancies. Outcome of adult B-ALL is poor with only 40% 5-year event-free survival compared to >80% in children. B-ALL is characterised by the acquisition of chromosomal abnormalities and many are strong predictors of outcome. The difference in the prevalence of cytogenetic subtypes and specific genomic abnormalities observed between adult and childhood ALL suggests a difference in tumour biology that may contribute to the differences in patient outcome. Detailed analysis of the paediatric B-ALL genome have revealed a plethora of abnormalities targeting key pathways. Although specific alterations have been investigated in adult and adolescent B-ALL, studies of the genomic landscape remain scarce. In this study we set-out to define the genomic landscape of adolescent and adult relapsed B-ALL. Genomic backtracking analysis of sequential diagnostic and relapse samples revealed known and novel abnormalities that may play a role in chemoresistance and disease progression in these tumours.DNA was isolated from the diagnostic and relapse samples from 12 adolescents/adult patients (5 female and 7 male) diagnosed with B-ALL. Eight of the 12 patients had remission samples available. Known cytogenetic abnormalities were detected in 7 patients: high hyperdiploid, t(1;19), t(8;14) and t(4;11) rearrangements. Two cases were positive for the BCR-ABLfusion gene. The mean age at diagnosis was 36.8 years (range 16-59 years) of which 10 relapsed early, within 2 years of initial diagnosis. DNA for the 12 diagnostic, 12 relapse and 8 remission sample were hybridised to the Affymetrix SNP6.0 array to determine copy number abnormalities (CNAs). The mutational landscape was captured for 4 cases using the Agilent SureSelect Human All Exon V4+UTR kit and sequenced to depths of 200X.The incidences of the most prevalent abnormalities in paediatric B-ALL were determined in each adult/adolescent sample: CDKN2A/B 88% (21/24), IKZF1 20% (5/24), PAX5 8% (2/24), ETV6 0% (0/24), RB1 8% (2/24), BTG1 8% (2/24) and EBF1 17% (4/24). Deletions of CDKN2A/B were detected in all but one patient. In 9 cases the abnormality was seen at both diagnosis and relapse and one case had a de novo deletion at relapse. A further case had a sub-clone harbouring CDKN2A/B deletion at diagnosis that emerged as the dominant clone at relapse. Deletion of CDKN2A/Bhas been associated with poor overall survival and has been reported at high incidence in relapsed adult BCR-ABL1-ALL, but the association with prognosis and relapse in other subtypes has not been confirmed.Genomic backtracking analysis of the matched diagnostic and relapse samples identified, on average, 36 somatic mutations at relapse that were either not detected or were only detectable in a sub-clone at diagnosis. An average of 0.05 mutations per Mb were computationally predicted to be damaging to the function of the protein. Novel de novo mutations seen at relapse were identified in cancer-related genes: FAT4, CDCA7 and PVRL4. Sequencing at depth of >200X demonstrates the ability to detect mutations in the resistant clone which could be involved in disease progression. Mutations in the ATP-binding cassette transporter gene, ABCC9, were identified in a sub-clone at diagnosis at a variant frequency of 5% (13/268 reads) and at 43% (113/260) in the relapse sample. ABCC9is involved in drug resistance suggesting a potential role in chremoresistance in this patient.In conclusion, in-depth genomic analysis and whole-exome sequencing of matched diagnostic and relapse samples in adult/adolescent B-ALL has identified known and novel genomic abnormalities. Deletion of CDKN2A/B was prevalent in 11 of the 12 cases confirming the importance of this region in relapsed B-ALL. We have identified novel mutations in genes associated with chemoresistance and tumorigenesis: ABCC9, FAT4, CDCA7 and PVRL4. Our study provides the most comprehensive genetic portrait of adult relapsed B-ALL to date and is a significant step to defining the genetic causes of disease progression and chemoresistance. DisclosuresNo relevant conflicts of interest to declare.