Potent anti‐leukemia activities of humanized CD19‐targeted Chimeric antigen receptor T (CAR‐T) cells in patients with relapsed/refractory acute lymphoblastic leukemia

Chimeric antigen receptor T (CAR‐T) cell therapy has shown promising results for relapsed/refractory (R/R) acute lymphoblastic leukemia (ALL). The immune response induced by murine single‐chain variable fragment (scFv) of the CAR may limit CAR‐T cell persistence and thus increases the risk of leukemia relapse. In this study, we developed a novel humanized scFv from the murine FMC63 antibody. A total of 18 R/R ALL patients with or without prior murine CD19 CAR‐T therapy were treated with humanized CD19‐targeted CAR‐T cells (hCART19s). After lymphodepletion chemotherapy with cyclophosphamide and fludarabine, the patients received a single dose (1 × 10⁶/kg) of autologous hCART19s infusion. Among the 14 patients without previous CAR‐T therapy, 13 (92.9%) achieved complete remission (CR) or CR with incomplete count recovery (CRi) on day 30, whereas 1 of the 3 patients who failed a second murine CAR‐T infusion achieved CR after hCART19s infusion. At day 180, the overall and leukemia‐free survival rates were 65.8% and 71.4%, respectively. The cumulative incidence of relapse was 22.6%, and the nonrelapse mortality rate was 7.1%. During treatment, 13 patients developed grade 1‐2 cytokine release syndrome (CRS), 4 patients developed grade 3‐5 CRS, and 1 patient experienced reversible neurotoxicity. These results indicated that hCART19s could induce remission in patients with R/R B‐ALL, especially in patients who received a reinfusion of murine CAR‐T.     

How I treat refractory/relapsed diffuse large B-cell lymphomas with CD19-directed chimeric antigen receptor T cells

Chimeric antigen receptor (CAR) T cells targeting CD19 represent a promising salvage immunotherapy for relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL), offering ~40% of long-term responses. In everyday clinical practice, haematologists involved in CAR T cell treatment of patients with R/R DLBCL have to deal with diagnostically complex cases and difficult therapeutic choices. The availability of novel immunotherapeutic agents for R/R DLBCL and recent advances in understanding CAR T-cell failure mechanisms demand a rational approach to identify the best choice for bridging therapy and managing post-CAR T-cell therapy relapses. Moreover, positron emission tomography/computerised tomography may result in false-positive interpretation, highlighting the importance of post-treatment biopsy. In this review, we discuss all above issues, presenting four instructive cases, with the aim to provide criteria and new perspectives for CAR T-cell treatment of DLBCL.     

Chimeric antigen receptor T cells for acute lymphoblastic leukemia

Chimeric antigen receptor (CAR) modified T cells targeted to CD19 have resulted in unprecedented remission rates for adult and pediatric patients with relapsed and refractory B cell acute lymphoblastic leukemia (ALL). With regulatory approval for tisagenlecleucel and many other agents under active investigation, the use of CAR T cells for ALL continues to expand. While some remissions from anti-CD19 CAR T cells are durable without a consolidative allogeneic stem cell transplantation, CD19 positive and negative relapses remain a significant concern fueling investigations into the biology of CAR T cell persistence and the development of CARTs that target more than 1 antigen. The treatment related toxicities of cytokine release syndrome and neurologic events are potentially life threatening but recent advances have improved understanding and management strategies. This review summarizes outcomes for patients with ALL treated with CD19-CAR T cells while exploring the field's challenges and future directions.     

Impact of reinduction regimens for relapsed and refractory acute lymphoblastic leukemia in adults

The clinical outlook for adults with acute lymphoblastic leukemia (ALL) has Improved with the use of intensive chemotherapy. Complete remissions (CR) are achieved in 80% of adults but the majority relapse on maintenance chemotherapy and a few exhibit primary resistance to induction therapy. This report compares the various salvage treatments and provides guidance in selecting a regimen with the optimum clinical outcome. Regimens using high-dose ara-C (HDAC) in combination with mltoxantrone, amsacrine, or idarublcin are superior to HDAC alone or with L-asparaginase. The sequential administration of methotrexate and L-asparaginase Is equally effective. The duration of second CR is short for all chemotherapeutic regimens. © 1994 Wiley-Liss, Inc.     

In vitro cellular drug resistance in children with relapsed/refractory acute lymphoblastic leukemia

Cellular drug resistance is thought to be an important cause of the poor prognosis for children with relapsed or refractory acute lymphoblastic leukemia (ALL), but it is unknown when, to which drugs, and to what extent resistance is present. We determined in vitro resistance to 13 drugs with the MTT assay. Compared with 141 children with initial ALL, cells from 137 children with relapsed ALL were significantly more resistant to glucocorticoids, L-asparaginase, anthracyclines, and thiopurines, but not to vinca-alkaloids, cytarabine, ifosfamide, and epipodophyllotoxins. Relapsed ALL cells expressed the highest level of resistance to glucocorticoids, with a median level 357- and >24-fold more resistant to prednisolone and dexamethasone, respectively, than initial ALL cells, whereas the resistance ratios for the other drugs differed from 0.8- to 1.9-fold, intraindividual comparisons between initial and relapsed samples from 16 children with ALL showed that both de novo and acquired drug resistance were involved. Specific in vitro drug-resistance profiles were associated with high-risk relapsed ALL groups. In vitro drug resistance was also related to the clinical response to chemotherapy in relapsed/refractory childhood ALL. We conclude that drug resistance may explain the poor prognosis for children with relapsed/refractory ALL. These day may be helpful to design alternative treatment regimens for relapsed childhood ALL.     

Rituximab plus chemotherapy in children with relapsed or refractory CD20-positive B-cell precursor acute lymphoblastic leukemia

We treated three children with relapsed or refractory CD20 positive B-cell precursor acute lymphoblastic leukemia with rituximab in combination with chemotherapy, which produced a decreasing or persistent low positive minimal residual disease load. Two children subsequently underwent allogeneic stem cell transplantation and remain in complete remission at days +399 and +332.     

CD19 chimeric antigen receptor T cell therapy for haematological malignancies

T cells can be redirected to recognize tumour antigens by genetic modification to express a chimeric antigen receptor (CAR). These consist of antibody‐derived antigen‐binding regions linked to T cell signalling elements. CD19 is an ideal target because it is expressed on most B cell malignancies as well as normal B cells but not on other cell types, restricting any ‘on target, off tumour’ toxicity to B cell depletion. Recent clinical studies involving CD19 CAR‐directed T cells have shown unprecedented responses in a range of B cell malignancies, even in patients with chemorefractory relapse. Durable responses have been achieved, although the persistence of modified T cells may be limited. This therapy is not without toxicity, however. Cytokine release syndrome and neurotoxicity appear to be frequent but are treatable and reversible. CAR T cell therapy holds the promise of a tailored cellular therapy, which can form memory and be adapted to the tumour microenvironment. This review will provide a perspective on the currently available data, as well as on future developments in the field.     

Anti-CD19 chimeric antigen receptor-modified T-cell therapy bridging to allogeneic hematopoietic stem cell transplantation for relapsed/refractory B-cell acute lymphoblastic leukemia: An open-label pragmatic clinical trial

Chimeric antigen receptor-modified T-cell (CAR-T) therapy is effective and safe for patients with relapsed/refractory B-cell acute lymphoblastic leukemia (r/r B-ALL), but its value has been limited in terms of long-term leukemia-free survival. New strategies that can help CAR-T therapy achieve lasting effect are urgently warranted. This non-randomized interventional pragmatic clinical trial had a particular aim. It explored whether consolidative allogeneic hematopoietic stem cell transplantation (allo-HSCT) could improve the long-term prognosis of the minimal residual disease-negative complete remission (MRD⁻ CR) patients after CAR-T therapy. In the first stage, 58 r/r B-ALL patients received split doses of CAR-T cells after lymphodepleting chemotherapy, and 51 (87.9%) achieved CR. In the second stage, 21/47 MRD⁻ CR patients without previous allo-HSCT and contraindications or other restrictions, on their own accord, received consolidative allo-HSCT within three months after CAR-T therapy. There was no difference in overall survival (OS) between the MRD⁻ CR patients who received allo-HSCT and those who did not. However, event-free survival (EFS) and relapse-free survival (RFS) were significantly prolonged by allo-HSCT in the subgroups. This was with either high (≥5%) pre-infusion bone marrow MRD assessed by flow cytometry (BM-FCM-MRD) or poor prognostic markers (P < .05). However, no difference was found in EFS and RFS for patients with pre-infusion BM-FCM-MRD <5% and without poor prognostic markers (P > .05). To conclude, CAR-T therapy bridging to allo-HSCT is a safe and effective therapeutic strategy for r/r B-ALL patients, and may prolong their EFS and RFS, especially when they have high pre-infusion BM-FCM-MRD or poor prognostic markers.     

Chimeric antigen receptor T-cell therapy as a bridge to haematopoietic stem cell transplantation for refractory/relapsed B-cell acute lymphoblastic leukemia

Although chimeric antigen receptor T cells (CAR-T) targeted at CD19 or CD22 have achieved high complete remission (CR) in refractory/relapsed B-cell acute lymphoblastic leukaemia (B-ALL), it is uncertain if allogeneic haematopoietic stem cell transplantation (allo-HSCT) should be performed after CAR-T therapy to accomplish a sustainable remission. Fifty-two cases with relapsed/refractory B-ALL who underwent allo-HSCT after CR by CD19 or CD22 CAR-T were enrolled. The median time from CAR-T infusion to allo-HSCT was 50 (34–98) days. Myeloablative reduced-intensity conditioning (RIC) with total body irradiation/fludarabine-based or busulfan/fludarabine-based regimens was used. Incidences of grade II–IV acute graft-versus-host disease (aGVHD) and severe aGVHD were 23·1% and 5·8% respectively. Of 48 evaluable cases, 16 developed chronic GVHD (cGVHD) and in three of them the pattern was extensive. With a median follow-up of 334 (41–479) days, one-year overall survival and event-free survival (EFS) were 87·7% and 73·0%. One-year relapse rate and transplant-related mortality (TRM) were 24·7% and 2·2% respectively. With quick bridge to allo-HSCT after CAR-T therapy, high EFS for refractory/relapsed B-ALL has been achieved in this relatively large cohort. Our myeloablative RIC regimens have resulted in low incidences of aGVHD, cGVHD, viral reactivation and very low TRM even majority of transplants from haploidentical donors. Long-term follow-up is warranted.     

Amsacrine with high-dose cytarabine is highly effective therapy for refractory and relapsed acute lymphoblastic leukemia in adults

Thirty-six patients with relapsed acute lymphoblastic leukemia (ALL) and four with primary refractory ALL were treated with a regimen that included amsacrine, 200 mg/m2, intravenously daily for three days with cytarabine, 3 gm/m2, by infusion over three hours daily for five days. There were 27 remissions in the 36 relapsed patients and two in the four patients with primary refractory disease. Seventeen of the 23 patients with common ALL, four of the six with T-cell ALL, one of the three with B-cell ALL, and seven of eight whose cells were not characterized responded. Toxicity of this regimen was comparable to other reinduction regimens for ALL, but the side effects characteristic of high-dose cytarabine therapy were absent. Since these results compare favorably with conventional induction regimens, its use in the primary treatment of adults and children with high-risk ALL is proposed.     

Comparison of single infusion of anti-BC-MA versus combined infusion of anti-CD19 chimeric antigen receptor T cells for immune reconstruction in relapsed/refractory multiple myeloma

<正>Objective We observed and compared the differences in immune reconstruction between single-infusion anti-B-cell maturation antigen( BCMA),chimeric antigen receptor T cells( CAR-T),and combined infusion of anti-CD19 CAR-T cells in the treatment of recurrent/refractory multiple myeloma( RRMM).     

Outcome of patients with relapsed/refractory acute lymphoblastic leukemia after blinatumomab failure: No change in the level of CD19 expression

Blinatumomab, a bi‐specific T‐cell engaging CD3‐CD19 antibody construct, has shown significant activity in patients with relapsed/refractory (R/R) B‐cell acute lymphoblastic leukemia (ALL). Despite this improvement, most patients relapse. Here, we describe the outcome of 68 patients with R/R ALL after failure of blinatumomab therapy: 38 (56%) blinatumomab refractory; 30 (44%) relapsing after initial response. After a median follow‐up of 49 months, 9 (13%) patients remained alive. The median overall survival after blinatumomab failure was 5.2 months. At the time of failure, among 61 patients evaluated for immunophenotype, 56 (92%) had CD19‐positive blasts; only five (8%) had ALL recurrence with CD19‐negative disease. Two patients progressed with lower CD19 expression. In summary, the outcome of patients with R/R ALL after blinatumomab failure is poor and treatment of these patients remains an unmet medical need. Our findings indicate that blinatumomab therapy would not exclude a significant number of patients from the potential benefit of subsequent CD19‐directed therapies such as chimeric antigen receptor T‐cell therapy.     

FLAG-IDA in the treatment of refractory/relapsed adult acute lymphoblastic leukemia

Relapsed or refractory adult acute lymphoblastic leukemias (ALL) have poor prognosis. The strategy for treating these patients is through reinduction chemotherapy followed by allogeneic stem cell transplantation, provided that the toxicity of the salvage regimen is acceptable. Twenty three patients with relapsed/refractory adult ALL were treated with fludarabine, cytarabine, granulocyte colony-stimulating factor, and idarubicin (FLAG-IDA). Five patients had primary refractory disease, and 18 were in first relapse. Nine (39.1%) patients achieved complete remission (CR) following salvage therapy, whereas 13 (56.5%) patients were refractory, and one patient died in aplasia due to infection. In patients achieving remission, the median time to reach absolute neutrophil count (ANC) more than 0.5×10⁹/l and 1×10⁹/l was 20 (range 16–25) and 24 (range 20–28) days from the start of chemotherapy, respectively. Platelet levels of more than 20×10⁹/l and 100×10⁹/l were achieved in a median time of 23 (range 19–25) and 33 (range 28–39) days, respectively. Fever more than 38.5°C was observed in 18 of 23 patients (78.2%), 13 had fever of unknown origin, and 5 had documented infections. Nonhematological side effects, consisting mainly of mucositis (18/23 or 78.2%) and transient liver toxicity increase (10/23 or 43.4%), were generally tolerated. All nine patients who achieved CR received a second course with FLAG-IDA, and seven patients underwent allogeneic stem cell transplantation (four from a matched donor, one from a mismatched donor, and two from an unrelated donor), while two did not reach that stage due to early relapse from CR. The median overall survival (OS) for all 23 patients was 4.5 (range 1–38) months; for the nine responders, the disease-free survival (DFS) and the OS were 6 (range 3–38) and 9 (7–38) months, respectively; the seven patients who received allogeneic stem cell transplantation had a DFS of 10 (range 7–38) months. In our experience, FLAG-IDA is a well-tolerated regimen in relapsed/refractory ALL patients; the toxicity is acceptable, enabling patients who have achieved CR to receive allogeneic transplantation.     

Clofarabine-based chemotherapy for relapsed/refractory adult acute lymphoblastic leukemia and lymphoblastic lymphoma. The Spanish experience

The present study reports the Spanish PETHEMA group experience in 31 heavily pretreated relapsed/refractory acute lymphoblastic leukemia (ALL) and lymphoma (LL) patients treated with clofarabine-based regimens. The complete remission (CR) rate was 31% (median CR duration of 3 months [range 2–28]) and the overall survival probability at 1 year was 10% (95%CI 4–16%). Responses were seen in B and T lineage diseases and in patients with adverse cytogenetics. Hematological and infectious grade >3 toxicities were found in 100 and 67% of the patients, respectively, with 7 (23%) treatment-related deaths. Other organ toxicities were infrequent. Clofarabine-based chemotherapy regimens might induce CRs in ALL and LL patients, but hematological toxicity and infections may limit their use in heavily pretreated patients.     

Correlates of resistance and relapse during blinatumomab therapy for relapsed/refractory acute lymphoblastic leukemia

We retrospectively analyzed 65 patients with refractory/relapsed (r/r) ALL who were treated with blinatumomab for predictors of leukemia response as well as clinical patterns of relapse and resistance with particular focus on downregulation of CD19 expression and extramedullary disease (EM‐ALL). The complete remission (CR) rate was 51%, and 15 (45%) responders underwent allogeneic hematopoietic cell transplantation (HCT) in CR. High leukemia burden (bone marrow blasts >50%) (P = .02), history of prior EM‐ALL (P = .005), and active EM‐ALL at the time of initiating blinatumomab (P = .05) predicted lower CR rate. Among refractory cases, 13 (41%) had evidence of EM‐ALL progression, and CD19 expression was negative or dim in 18% and 23%, respectively. Among responders, 20 (61%) subsequently relapsed among whom EM‐ALL relapse occurred in 8 (40%) patients, and CD19 expression was negative or dim in 35 and 6% of evaluable cases, respectively. Pretreatment moderate/strong CD19 expression (P = .01) and history of prior EM‐ALL during ALL course (P = .04) were risk factors for developing EM‐ALL at progression/relapse. However, no pretreatment factors predicted progression/relapse with CD19‐negative ALL. Overall‐survival (OS) and even‐free survival were improved for patients underwent allogeneic HCT compared to responders who did not. Furthermore, OS was superior for patients responded to blinatumomab compared to those who did not. Extramedullary and CD19‐negative disease are common during blinatumomab failure in r/r ALL. In addition to high leukemia burden, concurrent or prior history EM‐ALL were associated with lower response to blinatumomab. Higher CD19 expression as well as prior history of EM‐ALL were associated with EM‐ALL at the time of blinatumomab failure.