Recent clinical trials have shown that adoptive chimeric antigen receptor (CAR) T cell therapy is a very potent and possibly curative option in the treatment of B cell leukemias and lymphomas. However, targeting a single antigen may not be sufficient, and relapse due to the emergence of antigen negative leukemic cells may occur. A potential strategy to counter the outgrowth of antigen escape variants is to broaden the specificity of the CAR by incorporation of multiple antigen recognition domains in tandem. As a proof of concept, we here describe a bispecific CAR in which the single chain variable fragment (scFv) is replaced by a tandem of two single-antibody domains or nanobodies (nanoCAR). High membrane nanoCAR expression levels are observed in retrovirally transduced T cells. NanoCARs specific for CD20 and HER2 induce T cell activation, cytokine production and tumor lysis upon incubation with transgenic Jurkat cells expressing either antigen or both antigens simultaneously. The use of nanobody technology allows for the production of compact CARs with dual specificity and predefined affinity.

Chimeric antigen receptor (CAR)-T-cell therapy is an innovative form of adoptive cell therapy that has revolutionized the treatment of certain hematological malignancies, including B-cell non-Hodgkin lymphoma (NHL) and B-cell acute lymphoblastic leukemia (ALL). The treatment is currently also being studied in other B-cell neoplasms, including multiple myeloma (MM) and chronic lymphocytic leukemia (CLL). CD19 and B-cell maturation antigen (BCMA) have been the most popular target antigens for CAR-T-cell immunotherapy of these malignancies. This review will discuss the efficacy and toxicity data from the pivotal clinical studies of CD19- and BCMA-targeted CAR-T-cell therapies in relapsed/refractory B-cell malignancies (NHL, ALL, CLL) and MM, respectively.

Recent approval of chimeric antigen receptor (CAR) T cell therapy by the European Medicines Agency (EMA)/Federal and Drug Administration (FDA) and the remarkable results of CAR T clinical trials illustrate the curative potential of this therapy. While CARs against a multitude of different antigens are being developed and tested (pre)clinically, there is still a need for optimization. The use of single-chain variable fragments (scFvs) as targeting moieties hampers the quick generation of functional CARs and could potentially limit the efficacy. Instead, nanobodies may largely circumvent these difficulties. We used an available nanobody library generated after immunization of llamas against Cluster of Differentiation (CD) 20 through DNA vaccination or against the ectodomain of CD33 using soluble protein. The nanobody specific sequences were amplified by PCR and cloned by Gibson Assembly into a retroviral vector containing two different second-generation CAR constructs. After transduction in T cells, we observed high cell membrane nanoCAR expression in all cases. Following stimulation of nanoCAR-expressing T cells with antigen-positive cell lines, robust T cell activation, cytokine production and tumor cell lysis both in vitro and in vivo was observed. The use of nanobody technology in combination with PCR and Gibson Assembly allows for the rapid and effective generation of compact CARs.

Few studies thus far have compared head-to-head different non-myelooablative conditioning regimens for allogeneic hematopoietic cell transplantation (allo-HCT). Here, we report the results of a phase II multicenter randomized study comparing non-myeloablative allo-HCT from HLA-identical siblings (n = 54) or from 10/10 HLA-matched unrelated donors (n = 40) with either fludarabine plus 2 Gy total body irradiation (Flu-TBI arm; n = 49) or 8 Gy TLI + anti-thymocyte globulin (TLI-ATG arm; n = 45) conditioning. The 180-day cumulative incidences of grade II-IV acute GVHD (primary endpoint) were 12.2% versus 8.9% in Flu-TBI and TLI-ATG patients, respectively (P = 0.5). Two-year cumulative incidences of moderate/severe chronic GVHD were 40.8% versus 17.8% in Flu-TBI and TLI-ATG patients, respectively (P = 0.017). Five Flu-TBI patients and 10 TLI-ATG patients received pre-emptive DLI for low donor chimerism levels, while 1 Flu-TBI patient and 5 TLI-ATG patients (including 2 patients given prior pre-emptive DLIs) received a second HCT for poor graft function, graft rejection, or disease progression. Four-year cumulative incidences of relapse/progression were 22% and 50% in Flu-TBI and TLI-ATG patients, respectively (P = 0.017). Four-year cumulative incidences of nonrelapse mortality were 24% and 13% in Flu-TBI and TLI-ATG patients, respectively (P = 0.5). Finally, 4-year overall (OS) and progression-free survivals (PFS) were 53% and 54%, respectively, in the Flu-TBI arm, versus 54% (P = 0.9) and 37% (P = 0.12), respectively, in the TLI-ATG arm. In comparison to patients included in the Flu-TBI arm, patients included in the TLI-ATG arm had lower incidence of chronic GVHD, higher incidence of relapse and similar OS. The study was registered on ClinicalTrial.gov ( NCT00603954 ) and EUDRACT (2010-024297-19) .

Objectives: To summarize important findings from research on chimeric antigen receptor (CAR) T-cell immunotherapy in cancer. We discuss CAR design, cell products, toxicity management, heterogenous solid tumors and allogeneic transfer. Methods: A review of literature was conducted. The available literature was selected on original research, state-of-the art design, relevance to the objective and journal impact factor. Results: First-generation CARs provide patient T cells with tumor-specific antigen recognition. Second- and third-generation CARs incorporate costimulatory domains for enhanced T-cell persistence and antitumor activity. Fourth-generation CAR T cells (TRUCKs) include a cytokine production cassette, and hold promise in the treatment of heterogenous solid tumors. Transduced cell phenotype and subset composition are important factors. Suicide genes and safety switches are designed to decrease potential toxicity. Multi-specific CAR T cells can address heterogenous tumors. Allogeneic, off-the-shelf CAR T cells might reduce the production delay. Conclusion: CAR T cells have revolutionized the immunotherapeutic treatment of cancer: exciting results in refractory and relapsed B-cell malignancies have been published. Neurologic complications, solid tumor management and allogeneic constructs require further research. In conclusion, further design adjustments will enable CAR T cells to decisively reshape the field of cancer immunotherapy.

Accumulating evidence supports the role of leukemic stem cells (LSCs) in the high relapse rate of acute myeloid leukemia (AML) patients. The clinical relevance of LSCs, which were originally charac...