Antigen-induced chimeric antigen receptor multimerization amplifies on-tumor cytotoxicity

Ligand-induced receptor dimerization or oligomerization is a widespread mechanism for ensuring communication specificity,safeguarding receptor activation,and facilitating amplification of signal transduction across the cellular membrane.However,cell-surface antigeninduced multimerization(dubbed AIM herein)has not yet been consciously leveraged in chimeric antigen receptor(CAR)engineering for enriching T cell-based therapies.We co-developed ciltacabtagene autoleucel(cilta-cel),whose CAR incorporates two B-cell maturation antigen(BCMA)-targeted nanobodies in tandem,for treating multiple myeloma.Here we elucidated a structural and functional model in which BCMA-induced cilta-cel CAR multimerization amplifies myeloma-targeted T cell-mediated cytotoxicity.Crystallographic analysis of BCMA–nanobody complexes revealed atomic details of antigen–antibody hetero-multimerization whilst analytical ultracentrifugation and small-angle X-ray scattering characterized interdependent BCMA apposition and CAR juxtaposition in solution.BCMA-induced nanobody CAR multimerization enhanced cytotoxicity,alongside elevated immune synapse formation and cytotoxicity-mediating cytokine release,towards myeloma-derived cells.Our results provide a framework for contemplating the AIM approach in designing next-generation CARs.

Chidamide inhibits the NOTCH1-MYC signaling axis in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia(T-ALL)is one of the most dangerous hematological malignancies,with high tumor heterogeneity and poor prognosis.More than 60%of T-ALL patients carry NOTCH1 gene mutations,leading to abnormal expression of downstream target genes and aberrant activation of various signaling pathways.We found that chidamide,an HDAC inhibitor,exerts an antitumor effect on T-ALL cell lines and primary cells including an anti-NOTCH1 activity.In particular,chidamide inhibits the NOTCH1-MYC signaling axis by down-regulating the level of the intracellular form of NOTCH1(NICD1)as well as MYC,partly through their ubiquitination and degradation by the proteasome pathway.We also report here the preliminary results of our clinical trial supporting that a treatment by chidamide reduces minimal residual disease(MRD)in patients and is well tolerated.Our results highlight the effectiveness and safety of chidamide in the treatment of T-ALL patients,including those with NOTCH1 mutations and open the way to a new therapeutic strategy for these patients.

Using sound Clinical Paths and Diagnosis-related Groups(DRGs)-based payment reform to bring benefits to patientcare: A case study of leukemia therapy

China has been undertaking a profound reform on health care.Although more than 1.16 billion people have been covered by rural and urban medical insurance to date,the level of reimbursement from insurance is very limited,especially for critical diseases such as leukemia.This places heavy economic burdens on patients.Under these circumstances,systems innovation is imperative for the efficient utilization of limited funding.In this respect,certain valuable experience from other countries may prove helpful.The prospective payment system of Diagnosis-related Groups(DRGs),Clinical Paths,and the Comparative Effectiveness Analysis adopted by the National Institute of Health and Clinical Excellence(NICE,UK),can befine tools to reduce medical costs and improve quality of services.Treatments of acute promyelocytic leukemia at Rui-Jin Hospital,and childhood acute lymphoblastic leukemia at Shanghai Children’s Medical Center,can be taken as suitable models to illustrate the crucial role of Clinical Paths in guaranteeing clinical and cost effectiveness of medical services for critical diseases,and to satisfactorily justify the feasibility of DRGs in China.

Preclinical characterization and comparison between CD3/CD19 bispecific and novel CD3/CD19/CD20 trispecific antibodies against B-cell acute lymphoblastic leukemia:targeted immunotherapy for acute lymphoblastic leukemia

The CD19-targeting bispecific T-cell engager blinatumomab has shown remarkable efficacy in patients with relapsed/refractory B-cell precursor acute lymphoblastic leukemia.However,several studies showed that blinatumomab has a short plasma half-life due to its low molecular weight,and thus its clinical use is limited.Furthermore,multiple trials have shown that approximately 30%of blinatumomab-relapsed cases are characterized by CD19 negative leukemic cells.Here,we design and characterize two novel antibodies,A-319 and A-2019.Blinatumomab and A-319 are CD3/CD19 bispecific antibodies with different molecular sizes and structures,and A-2019 is a novel CD3/CD19/CD20 trispecific antibody with an additional anti-CD20 function.Our in vitro,ex vivo,and in vivo experiments demonstrated that A-319 and A-2019 are potent antitumor agents and capable of recruiting CD3 positive T cells,enhancing T-cell function,mediating B-cell depletion,and eventually inhibiting tumor growth in Raji xenograft models.The two molecules are complementary in terms of efficacy and specificity profile.The activity of A-319 demonstrated superior to that of A-2019,whereas A-2019 has an additional capability to target CD20 in cells missing CD19,suggesting its potential function against CD19 weak or negative CD20 positive leukemic cells.

IRF4 and IRF8 expression are associated with clinical phenotype and clinico-hematological response to hydroxyurea in essential thrombocythemia

The morbidity and mortality of myeloproliferative neoplasms(MPNs)are primarily caused by arterial and venous complications,progression to myelofibrosis,and transformation to acute leukemia.However,identifying molecular-based biomarkers for risk stratification of patients with MPNs remains a challenge.We have previously shown that interferon regulatory factor-8(IRF8)and IRF4 serve as tumor suppressors in myeloid cells.In this study,we evaluated the expression of IRF4 and IRF8 and the JAK2V617F mutant allele burden in patients with MPNs.Patients with decreased IRF4 expression were correlated with a more developed MPN phenotype in myelofibrosis(MF)and secondary AML(sAML)transformed from MPNs versus essential thrombocythemia(ET).Negative correlations between the JAK2V617F allele burden and the expression of IRF8(P<0.05)and IRF4(P<0.001)and between white blood cell(WBC)count and IRF4 expression(P<0.05)were found in ET patients.IRF8 expression was negatively correlated with the JAK2V617F allele burden(P<0.05)in polycythemia vera patients.Complete response(CR),partial response(PR),and no response(NR)were observed in 67.5%,10%,and 22.5%of ET patients treated with hydroxyurea(HU),respectively,in 12 months.At 3 months,patients in the CR group showed high IRF4 and IRF8 expression compared with patients in the PR and NR groups.In the 12-month therapy period,low IRF4 and IRF8 expression were independently associated with the unfavorable response to HU and high WBC count.Our data indicate that the expression of IRF4 and IRF8 was associated with the MPN phenotype,which may serve as biomarkers for the response to HU in ET.

CAR T-cell immunotherapy: a powerful weapon for fighting hematological B-cell malignancies

The current standard of care in hematological malignancies has brought considerable clinical benefits to patients.However,important bottlenecks still limit optimal achievements following a current medical practice.The genetic complexity of the diseases and the heterogeneity of tumor clones cause difficulty in ensuring long-term efficacy of conventional treatments for most hematological disorders.Consequently,new treatment strategies are necessary to improve clinical outcomes.Chimeric antigen receptor T-cell(CAR T)immunotherapy opens a new path for targeted therapy of hematological malignancies.In this review,through a representative case study,we summarize the current experience of CAR T-cell therapy,the management of common side effects,the causative mechanisms of therapy resistance,and new strategies to improve the efficacy of CAR T-cell therapy.