Anti-CLL1-based CAR T-cells with 4-1-BB or CD28/CD27 stimulatory domains in treating childhood refractory/relapsed acute myeloid leukemia.

BACKGROUND: Though the efficacy of anti C-type lectin-like molecule-1 (CLL1) CAR T-cells in refractory/relapsed acute myeloid leukemia (R/R-AML) have been occasionally reported, the influence of co-stimulatory domain CAR T-cells is not investigated so far. METHOD: Seven R/R-AML children treated with anti-CLL1 CAR T-cells were enrolled onto this preliminary comparison study. Among these seven patients, four received CD28/CD27-based CAR T-cells therapy, and three received 4-1BB-based CAR T-cells therapy. RESULT: The overall response rates were 75% and 66.7% in CD28/CD27 and 4-1BB group respectively. All patients experienced grade 1 to 2 cytokine release syndrome, with only one patient experiencing grade 2 immune effector cell-associated neurotoxicity syndrome. The maximum CAR T-cells durations were 156 and 274 days for CD28/CD27 group and 4-1BB group respectively. The 1-yr overall survival rate was 57.1%. CONCLUSIONS: A preliminary similar efficacy/safety index was observed in anti-CLL1-based CAR T-cells with 4-1BB or CD28/CD27 co-stimulatory elements in treating pediatric R/R-AML.

Observation of Alectinib- and Crizotinib- included chemotherapy in children with ALK-positive anaplastic large cell lymphoma: A single institutional experience.

Approximately one-third children with anaplastic large cell lymphoma (ALCL) relapse after completion of chemotherapy, particularly for those high-risk patients. The introduction of novel therapeutic modalities is much needed for these sub-group patients. Two groups (n = 3, n = 4) of ALCL patients were treated with crizotinib- and alectinib-included ALCL-99 therapy, respectively, achieving complete remission rates of 66.7% and 100%. Two patients of crizotinib group relapsed, while none relapsed among the alectinib-treated patients. Adding alectinib instead of crizotinib sufficiently suppressed and maintained the deep NPM-ALK molecular response. ALK inhibitors were well tolerated with only grade 1 adverse events in both groups. Though a relatively small case number, this study raised the possibility that alectinib-included therapeutic regimens may benefit the early response, in-depth molecular remission, and persistent remission to some extent. Further studies are warranted to validate our preliminary findings.

Characteristics of anti-CLL1 based CAR-T therapy for children with relapsed or refractory acute myeloid leukemia: the multi-center efficacy and safety interim analysis.

C-type lectin-like molecule-1 (CLL1) is preferentially expressed on acute myeloid leukemia (AML) stem cells and AML blasts, which can be considered as AML-associated antigen. Anti-CLL1-based CAR-T cells exhibited effective tumor-killing capacity in vitro and in AML-bearing mouse model. In this report, eight children with relapsed or refractory AML (R/R-AML) were recruited for a phase 1/2 clinical trial of autologous anti-CLL1 CAR-T cell immunotherapy. The objectives of this clinical trial were to evaluate the safety and the preliminary efficacy of anti-CLL1 CAR-T cell treatment. Patients received one dose of autologous anti-CLL1 CAR-T cells after lymphodepletion conditioning. After CAR-T treatment, patients developed grade 1-2 cytokine release syndrome (CRS) but without any lethal events. 4 out of 8 patients achieved morphologic leukemia-free state (MLFS) and minimal residual disease (MRD) negativity, 1 patient with MLFS and MRD positivity, 1 patient achieved complete remission with incomplete hematologic recovery (CRi) but MRD positivity, 1 patient with partial remission (PR), and 1 patient remained at stable disease (SD) status but had CLL1-positive AML blast clearance. These results suggested that anti-CLL1-based CAR-T cell immunotherapy can be considered as a well-tolerated and effective option for treating children with R/R-AML.

Effects of NRAS Mutations on Leukemogenesis and Targeting of Children With Acute Lymphoblastic Leukemia.

Through the advancements in recent decades, childhood acute lymphoblastic leukemia (ALL) is gradually becoming a highly curable disease. However, the truth is there remaining relapse in ∼15% of ALL cases with dismal outcomes. RAS mutations, in particular NRAS mutations, were predominant mutations affecting relapse susceptibility. KRAS mutations targeting has been successfully exploited, while NRAS mutation targeting remains to be explored due to its complicated and compensatory mechanisms. Using targeted sequencing, we profiled RAS mutations in 333 primary and 18 relapsed ALL patients and examined their impact on ALL leukemogenesis, therapeutic potential, and treatment outcome. Cumulative analysis showed that RAS mutations were associated with a higher relapse incidence in children with ALL. In vitro cellular assays revealed that about one-third of the NRAS mutations significantly transformed Ba/F3 cells as measured by IL3-independent growth. Meanwhile, we applied a high-throughput drug screening method to characterize variable mutation-related candidate targeted agents and uncovered that leukemogenic-NRAS mutations might respond to MEK, autophagy, Akt, EGFR signaling, Polo-like Kinase, Src signaling, and TGF-ß receptor inhibition depending on the mutation profile.