CD19/CD22 targeting with cotransduced CAR T cells to prevent antigen-negative relapse after CAR T-cell therapy for B-cell ALL.

ABSTRACT: CD19-negative relapse is a leading cause of treatment failure after chimeric antigen receptor (CAR) T-cell therapy for acute lymphoblastic leukemia. We investigated a CAR T-cell product targeting CD19 and CD22 generated by lentiviral cotransduction with vectors encoding our previously described fast-off rate CD19 CAR (AUTO1) combined with a novel CD22 CAR capable of effective signaling at low antigen density. Twelve patients with advanced B-cell acute lymphoblastic leukemia were treated (CARPALL [Immunotherapy with CD19/22 CAR Redirected T Cells for High Risk/Relapsed Paediatric CD19+ and/or CD22+ Acute Lymphoblastic Leukaemia] study, NCT02443831), a third of whom had failed prior licensed CAR therapy. Toxicity was similar to that of AUTO1 alone, with no cases of severe cytokine release syndrome. Of 12 patients, 10 (83%) achieved a measurable residual disease (MRD)-negative complete remission at 2 months after infusion. Of 10 responding patients, 5 had emergence of MRD (n = 2) or relapse (n = 3) with CD19- and CD22-expressing disease associated with loss of CAR T-cell persistence. With a median follow-up of 8.7 months, there were no cases of relapse due to antigen-negative escape. Overall survival was 75% (95% confidence interval [CI], 41%-91%) at 6 and 12 months. The 6- and 12-month event-free survival rates were 75% (95% CI, 41%-91%) and 60% (95% CI, 23%-84%), respectively. These data suggest dual targeting with cotransduction may prevent antigen-negative relapse after CAR T-cell therapy.

Immunotherapy with CD25/CD71-allodepleted T cells to improve T-cell reconstitution after matched unrelated donor hematopoietic stem cell transplant: a randomized trial.

BACKGROUND AIMS: Delayed immune reconstitution is a major challenge after matched unrelated donor (MUD) stem cell transplant (SCT). In this randomized phase 2 multi-center trial, Adoptive Immunotherapy with CD25/71 allodepleted donor T cells to improve immunity after unrelated donor stem cell transplant (NCT01827579), the authors tested whether allodepleted donor T cells (ADTs) can safely be used to improve immune reconstitution after alemtuzumab-based MUD SCT for hematological malignancies. METHODS: Patients received standard of care or up to three escalating doses of ADTs generated through CD25+/CD71+ immunomagnetic depletion. The primary endpoint of the study was circulating CD3+ T-cell count at 4 months post-SCT. Twenty-one patients were treated, 13 in the ADT arm and eight in the control arm. RESULTS: The authors observed a trend toward improved CD3+ T-cell count at 4 months in the ADT arm versus the control arm (230/µL versus 145/µL, P = 0.18), and three ADT patients achieved normal CD3+ T-cell count at 4 months (>700/µL). The rates of significant graft-versus-host disease (GVHD) were comparable in both cohorts, with grade ≥2 acute GVHD in seven of 13 and four of eight patients and chronic GVHD in three of 13 and three of eight patients in the ADT and control arms, respectively. CONCLUSIONS: These data suggest that adoptive transfer of ADTs is safe, but that in the MUD setting the benefit in terms of T-cell reconstitution is limited. This approach may be of more use in the context of more rigorous T-cell depletion.

Results of a trial of PET-directed therapy for early-stage Hodgkin's lymphoma.

BACKGROUND: It is unclear whether patients with early-stage Hodgkin's lymphoma and negative findings on positron-emission tomography (PET) after three cycles of chemotherapy with doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) require radiotherapy. METHODS: Patients with newly diagnosed stage IA or stage IIA Hodgkin's lymphoma received three cycles of ABVD and then underwent PET scanning. Patients with negative PET findings were randomly assigned to receive involved-field radiotherapy or no further treatment; patients with positive PET findings received a fourth cycle of ABVD and radiotherapy. This trial assessing the noninferiority of no further treatment was designed to exclude a difference in the 3-year progression-free survival rate of 7 or more percentage points from the assumed 95% progression-free survival rate in the radiotherapy group. RESULTS: A total of 602 patients (53.3% male; median age, 34 years) were recruited, and 571 patients underwent PET scanning. The PET findings were negative in 426 of these patients (74.6%), 420 of whom were randomly assigned to a study group (209 to the radiotherapy group and 211 to no further therapy). At a median of 60 months of follow-up, there had been 8 instances of disease progression in the radiotherapy group, and 8 patients had died (3 with disease progression, 1 of whom died from Hodgkin's lymphoma); there had been 20 instances of disease progression in the group with no further therapy, and 4 patients had died (2 with disease progression and none from Hodgkin's lymphoma). In the radiotherapy group, 5 of the deaths occurred in patients who received no radiotherapy. The 3-year progression-free survival rate was 94.6% (95% confidence interval [CI], 91.5 to 97.7) in the radiotherapy group and 90.8% (95% CI, 86.9 to 94.8) in the group that received no further therapy, with an absolute risk difference of -3.8 percentage points (95% CI, -8.8 to 1.3). CONCLUSIONS: The results of this study did not show the noninferiority of the strategy of no further treatment after chemotherapy with regard to progression-free survival. Nevertheless, patients in this study with early-stage Hodgkin's lymphoma and negative PET findings after three cycles of ABVD had a very good prognosis either with or without consolidation radiotherapy. (Funded by Leukaemia and Lymphoma Research and others; RAPID ClinicalTrials.gov number, NCT00943423.).

4 Gy versus 24 Gy radiotherapy for patients with indolent lymphoma (FORT): a randomised phase 3 non-inferiority trial.

BACKGROUND: Follicular lymphoma has been shown to be highly radiosensitive with responses to doses as low as 4 Gy in two fractions. This trial was designed to explore the dose response for follicular lymphoma comparing 4 Gy in two fractions with 24 Gy in 12 fractions METHODS: FORT is a prospective randomised, unblinded, phase 3 non-inferiority study comparing radiotherapy given as 4 Gy in two fractions with a standard dose of 24 Gy in 12 fractions. Entry criteria included all patients aged over 18 years, having local radiotherapy for radical or palliative local control, with follicular lymphoma or marginal zone lymphoma, who had received no previous treatment for at least 1 month before. The primary outcome was time to local progression analysed on an intention-to-treat basis. Randomisation was centralised through the Cancer Research UK and University College London Cancer Trials Centre. Radiotherapy target sites were randomised (1:1) with minimisation stratified by histology (follicular lymphoma vs marginal zone lymphoma), treatment intent (palliative or curative) and centre. This trial is registered with ClinicalTrials.gov number, NCT00310167. FINDINGS: 299 sites were randomly assigned to 24 Gy and 315 sites to 4 Gy between April 7, 2006, and June 8, 2011, at 43 centres in the UK. After a median follow-up of 26 months (range 0·39-75·4), 91 local progressions had been recorded (21 in the 24 Gy group and 70 in the 4 Gy group). Time to local progression with 4 Gy was not non-inferior to 24 Gy (hazard ratio 3·42, 95% CI 2·09-5·55, p<0·0001). Eight (3%) of 282 patients in the 24 Gy group and four (1%) of 300 in the 4 Gy group had acute grade 3-4 toxic effects. Four (1%) patients in the 24 Gy group and four (1%) patients in the 4 Gy group had late toxic effects. Mucositis was the most common event in the 24 Gy group (two patients with acute mucositis and two with late mucositis; all grade 3) and was not reported in the 4 Gy group. The most common acute effect was pain at the site of irradiation (two patients in the 4 Gy group, one patient in the 24 Gy group; all grade 3), and the most common late effect was fatigue (two patients in the 4 Gy group, one patient in the 24 Gy group; all grade 3). INTERPRETATION: 24 Gy in 12 fractions is the more effective radiation schedule for indolent lymphoma and should be regarded as the standard of care. However, 4 Gy remains a useful alternative for palliative treatment. FUNDING: Cancer Research UK.

Long-term outcomes by bone marrow B-cell depletion from the R2W trial of bortezomib with cyclophosphamide and rituximab in Waldenstrom macroglobulinaemia.

There remains a lack of consensus as to the most appropriate primary therapy in Waldenstrom macroglobulinemia (WM). We evaluated a novel bortezomib-based combination and developed a sensitive WM-specific flow cytometry assay (limit of detection 0.004% of leucocytes) to assess bone marrow (BM) response. Sixty treatment-naïve WM patients were enroled into this phase II trial and randomised (2:1) to receive cyclophosphamide and rituximab with either bortezomib (BRC) or fludarabine (FCR). The primary objective was to assess the overall response rate (ORR) in eligible patients receiving BRC (N = 41). An ORR of 97.6% (95%CI:87.1-99.9) was observed; 27 (65.9%) patients remain alive without progression after 62.6 months median follow-up, with 2-, 3- and 5-year progression-free survival (PFS) rates of 92.7% (95%CI:79.0-97.6), 80.5% (95%CI:64.8-89.7) and 65.5% (95%CI:48.8-77.9). Persistent WM B-cells were demonstrable in 19/38 patients at the end of treatment (median 0.24%, range 0.02-11.2%). PFS was markedly longer in patients with BM B-cell depletion (<0.004%) compared to those who had persistent BM B-cells detectable at end of treatment (HR = 0.06, 95%CI:0.01-0.47, p < 0.001), and remained independently associated after adjusting for baseline risk stratification or investigator-assessed response. BRC is a tolerable, highly efficacious regimen for treatment-naïve WM patients. BM B-cell depletion is independently associated with patient outcomes.

Transcriptional signatures associated with persisting CD19 CAR-T cells in children with leukemia.

In the context of relapsed and refractory childhood pre-B cell acute lymphoblastic leukemia (R/R B-ALL), CD19-targeting chimeric antigen receptor (CAR)-T cells often induce durable remissions, which requires the persistence of CAR-T cells. In this study, we systematically analyzed CD19 CAR-T cells of 10 children with R/R B-ALL enrolled in the CARPALL trial via high-throughput single-cell gene expression and T cell receptor sequencing of infusion products and serial blood and bone marrow samples up to 5 years after infusion. We show that long-lived CAR-T cells developed a CD4/CD8 double-negative phenotype with an exhausted-like memory state and distinct transcriptional signature. This persistence signature was dominant among circulating CAR-T cells in all children with a long-lived treatment response for which sequencing data were sufficient (4/4, 100%). The signature was also present across T cell subsets and clonotypes, indicating that persisting CAR-T cells converge transcriptionally. This persistence signature was also detected in two adult patients with chronic lymphocytic leukemia with decade-long remissions who received a different CD19 CAR-T cell product. Examination of single T cell transcriptomes from a wide range of healthy and diseased tissues across children and adults indicated that the persistence signature may be specific to long-lived CAR-T cells. These findings raise the possibility that a universal transcriptional signature of clinically effective, persistent CD19 CAR-T cells exists.

Clonal expansion of T memory stem cells determines early anti-leukemic responses and long-term CAR T cell persistence in patients.

Low-affinity CD19 chimeric antigen receptor (CAR) T cells display enhanced expansion and persistence, enabling fate tracking through integration site analysis. Here we show that integration sites from early (1 month) and late (>3yr) timepoints cluster separately, suggesting different clonal contribution to early responses and prolonged anti-leukemic surveillance. CAR T central and effector memory cells in patients with long-term persistence remained highly polyclonal, whereas diversity dropped rapidly in patients with limited CAR T persistence. Analysis of shared integrants between the CAR T cell product and post-infusion demonstrated that, despite their low frequency, T memory stem cell clones in the product contributed substantially to the circulating CAR T cell pools, during both early expansion and long-term persistence. Our data may help identify patients at risk of early loss of CAR T cells and highlight the critical role of T memory stem cells both in mediating early anti-leukemic responses and in long-term surveillance by CAR T cells.

Predicted Risks of Cardiovascular Disease Following Chemotherapy and Radiotherapy in the UK NCRI RAPID Trial of Positron Emission Tomography-Directed Therapy for Early-Stage Hodgkin Lymphoma.

PURPOSE: The contemporary management of early-stage Hodgkin lymphoma (ES-HL) involves balancing the risk of late adverse effects of radiotherapy against the increased risk of relapse if radiotherapy is omitted. This study provides information on the risk of radiation-related cardiovascular disease to help personalize the delivery of radiotherapy in ES-HL. METHODS: We predicted 30-year absolute cardiovascular risk from chemotherapy and involved field radiotherapy in patients who were positron emission tomography (PET)-negative following three cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine chemotherapy within a UK randomized trial of PET-directed therapy for ES-HL. Cardiac and carotid radiation doses and chemotherapy exposure were combined with established dose-response relationships and population-based mortality and incidence rates. RESULTS: Average mean heart dose was 4.0 Gy (range 0.1-24.0 Gy) and average bilateral common carotid artery dose was 21.5 Gy (range 0.6-38.1 Gy), based on individualized cardiovascular dosimetry for 144 PET-negative patients receiving involved field radiotherapy. The average predicted 30-year radiation-related absolute excess overall cardiovascular mortality was 0.56% (range 0.01%-6.79%; < 0.5% in 67% of patients and > 1% in 15%), whereas average predicted 30-year excess incidence was 6.24% (range 0.31%-31.09%; < 5% in 58% of patients and > 10% in 24%). For cardiac disease, the average predicted 30-year radiation-related absolute excess mortality was 0.42% (0.79% with mediastinal involvement and 0.05% without) and for stroke, it was 0.14%. CONCLUSION: Predicted excess cardiovascular risk is small for most patients, so radiotherapy may provide net benefit. However, for a minority of patients receiving high doses of radiation to cardiovascular structures, it may be preferable to consider advanced radiotherapy techniques to reduce doses or to omit radiotherapy and accept the increased relapse risk. Individual assessment of cardiovascular and other risks before treatment would allow personalized decision making about radiotherapy in ES-HL.

Durable Responses and Low Toxicity After Fast Off-Rate CD19 Chimeric Antigen Receptor-T Therapy in Adults With Relapsed or Refractory B-Cell Acute Lymphoblastic Leukemia.

PURPOSE: Prognosis for adult B-cell acute lymphoblastic leukemia (B-ALL) is poor, and there are currently no licensed CD19 chimeric antigen receptor (CAR) therapeutics. We developed a novel second-generation CD19-CAR (CAT19-41BB-Z) with a fast off rate, designed for more physiologic T-cell activation to reduce toxicity and improve engraftment. We describe the multicenter phase I ALLCAR19 (NCT02935257) study of autologous CAT19-41BB-Z CAR T cells (AUTO1) in relapsed or refractory (r/r) adult B-ALL. METHODS: Patients age ≥ 16 years with r/r B-ALL were eligible. Primary outcomes were toxicity and manufacturing feasibility. Secondary outcomes were depth of response at 1 and 3 months, persistence of CAR-T, incidence and duration of hypogammaglobulinemia and B-cell aplasia, and event-free survival and overall survival at 1 and 2 years. RESULTS: Twenty-five patients were leukapheresed, 24 products were manufactured, and 20 patients were infused with AUTO1. The median age was 41.5 years; 25% had prior blinatumomab, 50% prior inotuzumab ozogamicin, and 65% prior allogeneic stem-cell transplantation. At the time of preconditioning, 45% had ≥ 50% bone marrow blasts. No patients experienced ≥ grade 3 cytokine release syndrome; 3 of 20 (15%) experienced grade 3 neurotoxicity that resolved to ≤ grade 1 within 72 hours with steroids. Seventeen of 20 (85%) achieved minimal residual disease-negative complete response at month 1, and 3 of 17 underwent allogeneic stem-cell transplantation while in remission. The event-free survival at 6 and 12 months was 68.3% (42.4%-84.4%) and 48.3% (23.1%-69.7%), respectively. High-level expansion (Cmax 127,152 copies/µg genomic DNA) and durable CAR-T persistence were observed with B-cell aplasia ongoing in 15 of 20 patients at last follow-up. CONCLUSION: AUTO1 demonstrates a tolerable safety profile, high remission rates, and excellent persistence in r/r adult B-ALL. Preliminary data support further development of AUTO1 as a stand-alone treatment for r/r adult B-ALL.

Positron Emission Tomography Score Has Greater Prognostic Significance Than Pretreatment Risk Stratification in Early-Stage Hodgkin Lymphoma in the UK RAPID Study.

PURPOSE: Accurate stratification of patients is an important goal in Hodgkin lymphoma (HL), but the role of pretreatment clinical risk stratification in the context of positron emission tomography (PET) -adapted treatment is unclear. We performed a subsidiary analysis of the RAPID trial to assess the prognostic value of pretreatment risk factors and PET score in determining outcomes. PATIENTS AND METHODS: Patients with stage IA to IIA HL and no mediastinal bulk underwent PET assessment after three cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine; 143 PET-positive patients (PET score, 3 to 5) received a fourth doxorubicin, bleomycin, vinblastine, and dacarbazine cycle and involved-field radiotherapy, and 419 patients in complete metabolic remission were randomly assigned to receive involved-field radiotherapy (n = 208) or no additional treatment (n = 211). Cox regression was used to investigate the association between PET score and pretreatment risk factors with HL-specific event-free survival (EFS). RESULTS: High PET score was associated with inferior EFS, before (P < .001) and after adjustment (P = .01) for baseline risk stratification. Only patients with a postchemotherapy PET score of 5 (uptake ≥ three times maximum liver uptake) had an increased risk of progression or HL-related death (hazard ratio, 9.4 v score of 3; 95% CI, 2.8 to 31.3 and hazard ratio, 6.7 v score of 4; 95% CI, 1.4 to 31.7). Patients with a PET score of 5 also had inferior progression-free and overall survival. There was no association between European Organisation for Research and Treatment of Cancer or German Hodgkin Study Group risk group and EFS, before or after adjusting for PET score (all P > .4). CONCLUSION: In RAPID, a positive PET scan did not carry uniform prognostic weight; only a PET score of 5 was associated with inferior outcomes. This suggests that in future trials involving patients without B symptoms or mediastinal bulk, a score of 5 rather than a positive PET result should be used to guide treatment escalation in early-stage HL.

Enhanced CAR T cell expansion and prolonged persistence in pediatric patients with ALL treated with a low-affinity CD19 CAR.

Chimeric antigen receptor (CAR)-modified T cells targeting CD19 demonstrate unparalleled responses in relapsed/refractory acute lymphoblastic leukemia (ALL)1-5, but toxicity, including cytokine-release syndrome (CRS) and neurotoxicity, limits broader application. Moreover, 40-60% of patients relapse owing to poor CAR T cell persistence or emergence of CD19- clones. Some factors, including the choice of single-chain spacer6 and extracellular7 and costimulatory domains8, have a profound effect on CAR T cell function and persistence. However, little is known about the impact of CAR binding affinity. There is evidence of a ceiling above which increased immunoreceptor affinity may adversely affect T cell responses9-11. We generated a novel CD19 CAR (CAT) with a lower affinity than FMC63, the high-affinity binder used in many clinical studies1-4. CAT CAR T cells showed increased proliferation and cytotoxicity in vitro and had enhanced proliferative and in vivo antitumor activity compared with FMC63 CAR T cells. In a clinical study (CARPALL, NCT02443831 ), 12/14 patients with relapsed/refractory pediatric B cell acute lymphoblastic leukemia treated with CAT CAR T cells achieved molecular remission. Persistence was demonstrated in 11 of 14 patients at last follow-up, with enhanced CAR T cell expansion compared with published data. Toxicity was low, with no severe CRS. One-year overall and event-free survival were 63% and 46%, respectively.

Histone H3 lysine 9 methylation occurs rapidly at the onset of random X chromosome inactivation.

In female mammals, a single X chromosome is stably and heritably silenced early in embryogenesis. The inactive X is characterized by asynchronous DNA replication and epigenetic chromatin modifications, including DNA methylation, histone H3/H4 hypoacetylation, and incorporation of a variant histone macroH2A. X inactivation is initiated by a cis-acting RNA molecule, the X-inactive specific transcript (Xist), which coats the chromosome. However, the mechanism by which Xist induces chromosome silencing is poorly understood. An important approach towards answering this question has been to determine the temporal order of epigenetic chromatin modifications in an in vitro model system, differentiating XX embryonic stem (ES) cells, and thereby to identify candidate targets for Xist RNA. To date, these studies have demonstrated that, following accumulation of Xist RNA, the transition to late replication of the X chromosome is the earliest detectable event. H4 hypoacetylation, macroH2A1.2 incorporation, and DNA methylation all occur subsequently. Recently, it has been shown that chromatin of the inactive X is also characterized by methylation of histone H3 at lysine 9 (H3-K9). Here we show that H3-K9 methylation is a very early event in the process of X inactivation, which closely parallels the onset of Xist RNA accumulation.

Randomized comparison of the stanford V regimen and ABVD in the treatment of advanced Hodgkin's Lymphoma: United Kingdom National Cancer Research Institute Lymphoma Group Study ISRCTN 64141244.

PURPOSE: This multicenter, prospective, randomized controlled trial compared the efficacy and toxicity of two chemotherapy regimens in advanced Hodgkin's lymphoma (HL): the weekly alternating Stanford V and the standard, twice-weekly regimen of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD). PATIENTS AND METHODS: Patients had stage IIB, III, or IV disease or had stages I to IIA disease with bulky disease or other adverse features. Radiotherapy was administered in both arms to sites of previous bulk (> 5 cm) and to splenic deposits, although this was omitted in the latter part of the trial for patients achieving complete remission (CR) in the ABVD arm. A total of 520 patients were randomly assigned and were assessed for the primary outcome measure of progression-free survival (PFS). Five hundred patients received protocol treatment, and radiotherapy was administered to 73% in the Stanford V arm and to 53% in the ABVD arm. RESULTS: The overall response rates after completion of all treatment were 91% for Stanford V and 92% for ABVD. During a median follow-up of 4.3 years, there was no evidence of a difference in projected 5-year PFS and overall survival (OS) rates (76% and 90%, respectively, for ABVD; 74% and 92%, respectively, for Stanford V). More pulmonary toxicity was reported for ABVD, whereas other toxicities were more frequent with Stanford V. CONCLUSION: In a large, randomized trial, the efficacies of Stanford V and ABVD were comparable when given in combination with appropriate radiotherapy.

Dicer regulates Xist promoter methylation in ES cells indirectly through transcriptional control of Dnmt3a.

BACKGROUND: X chromosome inactivation is the mechanism used in mammals to achieve dosage compensation of X-linked genes in XX females relative to XY males. Chromosome silencing is triggered in cis by expression of the non-coding RNA Xist. As such, correct regulation of the Xist gene promoter is required to establish appropriate X chromosome activity both in males and females. Studies to date have demonstrated co-transcription of an antisense RNA Tsix and low-level sense transcription prior to onset of X inactivation. The balance of sense and antisense RNA is important in determining the probability that a given Xist allele will be expressed, termed the X inactivation choice, when X inactivation commences. RESULTS: Here we investigate further the mechanism of Xist promoter regulation. We demonstrate that both sense and antisense transcription modulate Xist promoter DNA methylation in undifferentiated embryonic stem (ES) cells, suggesting a possible mechanistic basis for influencing X chromosome choice. Given the involvement of sense and antisense RNAs in promoter methylation, we investigate a possible role for the RNA interference (RNAi) pathway. We show that the Xist promoter is hypomethylated in ES cells deficient for the essential RNAi enzyme Dicer, but that this effect is probably a secondary consequence of reduced levels of de novo DNA methyltransferases in these cells. Consistent with this we find that Dicer-deficient XY and XX embryos show appropriate Xist expression patterns, indicating that Xist gene regulation has not been perturbed. CONCLUSION: We conclude that Xist promoter methylation prior to the onset of random X chromosome inactivation is influenced by relative levels of sense and antisense transcription but that this probably occurs independent of the RNAi pathway. We discuss the implications for this data in terms of understanding Xist gene regulation and X chromosome choice in random X chromosome inactivation.

Attenuated spread of X-inactivation in an X;autosome translocation.

X inactivation in female mammals involves transcriptional silencing of an entire chromosome in response to a cis-acting noncoding RNA, the X inactive-specific transcript (Xist). Xist can also inactivate autosomal sequences, for example, in X;autosome translocations; but here, silencing appears to be relatively inefficient. This variation has been attributed to either attenuated spreading of Xist RNA at the onset of X inactivation or inefficient maintenance of autosomal silencing. Evidence to date has favored the latter. Here, we demonstrate attenuated spreading of Xist RNA at the onset of X inactivation in the T(X;4)37H X;autosome translocation. Our findings provide direct evidence that underlying chromosome/chromatin features can disrupt spreading of the primary inactivating signal.