New advances in leukaemia immunotherapy by the use of Chimeric Artificial Antigen Receptors (CARs): state of the art and perspectives for the near future

Generation and characterization of ErbB2-CAR-engineered cytokine-induced killer cells for the treatment of high-risk soft tissue sarcoma in children

Pediatric patients with recurrent, refractory or advanced soft tissue sarcoma (STS) who are simultaneously showing signs of cumulative treatment toxicity are in need of novel therapies. In this preclinical analysis, we identified ErbB2 as a targetable antigen on STS cells and used cytokine-induced killer (CIK) cells transduced with the lentiviral 2^nd-generation chimeric antigen receptor (CAR) vector pS-5.28.z-IEW to target ErbB2-positive tumors. Solely CIK cell subsets with the CD3⁺ T cell phenotype showed up to 85% cell surface expression of the respective CAR. A comparison of wildtype (WT), mock-vector and ErbB2-CAR-CIK cells showed, that engineered cells exhibited diminished in vitro expansion, retained WT CIK cell phenotype with higher percentages of differentiated effector memory/effector cells. Activating natural killer (NK) cell receptor NKG2D-restricted target cell recognition and killing of WT and ErbB2-CAR-CIK cells was maintained against ErbB2-negative tumors, while ErbB2-CAR-CIK cells demonstrated significantly increased cytotoxicity against ErbB2-positive targets, including primary tumors. ErbB2-CAR- but not WT CIK cells proliferated, infiltrated and efficiently lysed tumor cell monolayers as well as 3D tumor spheroids.

Here, we demonstrate a potential cell therapeutic approach using ErbB2-CAR-CIK cells for the recognition and elimination of tumor cells expressing ErbB2, which we identified as a targetable antigen on high-risk STS cells.

Cytokine-induced killer cells engineered with exogenous T-cell receptors directed against melanoma antigens: enhanced efficacy of effector cells endowed with a double mechanism of tumor recognition

Cytokine-induced killer (CIK) cells consist of a heterogeneous population of polyclonal T lymphocytes displaying NK phenotype and HLA-unrestricted cytotoxic activity against a broad range of tumors. We sought to determine whether transduction of CIK cells with T cell receptor (TCR) genes specific for tumor-associated antigens could generate effector cells endowed with a double mechanism of tumor recognition. HLA-A2-restricted TCR-transduced (TD) CIK directed against the melanoma antigens Mart1 and NY-ESO1 were generated by lentiviral transduction and successfully expanded over a 3-4-week period. TD-CIK cells were both CD3(+)/CD56(-) and CD3(+)/CD56(+) (31±8% and 59±9%, respectively), indicating that both major histocompatibility complex (MHC)-restricted T cells and MHC-unrestricted CIK could be targeted by lentiviral transduction. At the end of the culture, the majority of both unmodified and TD-CIK displayed an effector memory phenotype, without considerable expression of replicative senescence and exhaustion markers. Functionally, TD-CIK specifically recognized tumor cells expressing the relevant antigen as well as maintained their MHC-unrestricted tumor activity. The cytotoxic activity of TD-CIK against HLA-A2(+) melanoma cell lines was significantly higher than the untransduced counterparts at a low effector:target ratio (cytotoxic activity of TD-CIK was from 1.9- to 4.3-fold higher than untransduced counterparts). TD-CIK were highly proficient in releasing high amount of IFN-γ upon antigen-specific stimulation and were able to recognize primary melanoma targets. In conclusion, we showed that (1) the reproducibility and simplicity of CIK transduction and expansion might solve the problem of obtaining adequate numbers of potent antitumor effector cells for adoptive immunotherapy; (2) the presence of both terminal effectors as well as of less differentiated progenitors might confer them long survival in vivo; and (3) the addition of an MHC-restricted antigen recognition allows not only targeting tumor surface antigens but also a wider range of cytoplasmic or nuclear antigens, involved in tumor proliferation and survival. TD-CIK cells with a double mechanism of tumor recognition are an attractive and alternative tool for the development of efficient cell therapeutic strategies.

Chimeric antigen receptors against CD33/CD123 antigens efficiently target primary acute myeloid leukemia cells in vivo

As significant numbers of acute myeloid leukemia (AML) patients are still refractory to conventional therapies or experience relapse, immunotherapy using T cells expressing chimeric antigen receptors (CARs) might represent a valid treatment option. AML cells frequently overexpress the myeloid antigens CD33 and CD123, for which specific CARs can be generated. However, CD33 is also expressed on normal hematopoietic stem/progenitor cells (HSPCs), and its targeting could potentially impair normal hematopoiesis. In contrast, CD123 is widely expressed by AML, while low expression is detected on HSPCs, making it a much more attractive target. In this study we describe the in vivo efficacy and safety of using cytokine-induced killer (CIK) cells genetically modified to express anti-CD33 or anti-CD123 CAR to target AML. We show that both these modified T cells are very efficient in reducing leukemia burden in vivo, but only the anti-CD123 CAR has limited killing on normal HSPCs, thus making it a very attractive immunotherapeutic tool for AML treatment.

Targeting of acute myeloid leukaemia by cytokine-induced killer cells redirected with a novel CD123-specific chimeric antigen receptor

Current therapeutic regimens for acute myeloid leukaemia (AML) are still associated with high rates of relapse. Immunotherapy with T-cells genetically modified to express chimeric antigen receptors (CARs) represents an innovative approach. Here we investigated the targeting of the interleukin three receptor alpha (IL3RA; CD123) molecule, which is overexpressed on AML bulk population, CD34(+) leukaemia progenitors, and leukaemia stem cells (LSC) compared to normal haematopoietic stem/progenitor cells (HSPCs), and whose overexpression is associated with poor prognosis. Cytokine-induced killer (CIK) cells were transduced with SFG-retroviral-vector encoding an anti-CD123 CAR. Transduced cells were able to strongly kill CD123(+) cell lines, as well as primary AML blasts. Interestingly, secondary colony experiments demonstrated that anti-CD123.CAR preserved in vitro HSPCs, in contrast to a previously generated anti-CD33.CAR, while keeping an identical cytotoxicity profile towards AML. Furthermore, limited killing of normal monocytes and CD123-low-expressing endothelial cells was noted, thus indicating a low toxicity profile of the anti-CD123.CAR. Taken together, our results indicate that CD123-specific CARs strongly enhance anti-AML CIK functions, while sparing HSPCs and normal low-expressing antigen cells, paving the way to develop novel immunotherapy approaches for AML treatment.

Progress in pediatrics in 2011. Choices in endocrinology, gastroenterology, hemato-oncology, infectious diseases, otolaryngology, pharmacotherapy and respiratory tract illnesses

Main progresses in endocrinology, gastroenterology, hemato-oncology, infectious diseases, otolaryngology, pharmacotherapy, and respiratory tract illnesses selected from articles published in The Italian Journal of Pediatrics in 2011 were reviewed. Risk factors for gastroenteritis and appendicitis in developing countries may be useful in improving our understanding of these diseases. Childhood hearing impairment is a world-wide problem which continues to have an high prevalence in newborns. Among the mechanisms of diseases, obese children often have asthma and high hepcidin levels that may reduce serum iron concentrations. In cystic fibrosis, 18q distal deletion has been described as a novel mutation. Hypothyroidism in children with central nervous system infections may increase mortality rates. Infrared tympanic thermometer (IRTT) in oral mode for the measurement of body temperature may be useful in fever screening in a busy setup. In newborns, the transmission of CMV infection through breast milk may be prevented through freezing or pasteurization. Recent advances in treatment of constipation, urinary tract infections, leukemia, pain in children with cancer, neonates with sepsis or difficult weaning from mechanical ventilation will likely contribute towards optimizing management of these common disorders. The work of the Family Pediatricians Medicines for Children Research Network aims to develop competence, infrastructure, networking and education for pediatric clinical trials.

The future is now: chimeric antigen receptors as new targeted therapies for childhood cancer

Improved outcomes for children with cancer hinge on the development of new targeted therapies with acceptable short-term and long-term toxicity. Progress in basic, preclinical, and clinical arenas spanning cellular immunology, gene therapy, and cell-processing technologies have paved the way for clinical applications of chimeric antigen receptor-based therapies. This is a new form of targeted immunotherapy that merges the exquisite targeting specificity of monoclonal antibodies with the potent cytotoxicity, potential for expansion, and long-term persistence provided by cytotoxic T cells. Although this field is still in its infancy, clinical trials have already shown clinically significant antitumor activity in neuroblastoma, chronic lymphocytic leukemia, and B-cell lymphoma, and trials targeting a variety of other adult and pediatric malignancies are under way. Ongoing work is focused on identifying optimal tumor targets and elucidating and manipulating both cell- and host-associated factors to support expansion and persistence of the genetically engineered cells in vivo. In pediatric oncology, CD19 and GD2 are compelling antigens that have already been identified for targeting pre-B acute lymphoblastic leukemia and neuroblastoma, respectively, with this approach, but it is likely that other antigens expressed in a variety of childhood cancers will also soon be targeted using this therapy. The potential to target essentially any tumor-associated cell-surface antigen for which a monoclonal antibody can be made opens up an entirely new arena for targeted therapy of childhood cancer.