Key Points Genomic disruption of CD7 prior to CAR transduction allows generation of CD7 CAR T cells without extensive self-antigen-driven fratricide. CD7 CAR T cells have robust activity against T-cell malignancies in vitro and in vivo.

Circulating tumor cells (CTCs) are a major contributor of cancer metastases and hold a promising prognostic significance in cancer detection. Performing functional and molecular characterization of CTCs provides an in-depth knowledge about this lethal disease. Researchers are making efforts to design devices and develop assays for enumeration of CTCs with a high capture and detection efficiency from whole blood of cancer patients. The existing and on-going research on CTC isolation methods has revealed cell characteristics which are helpful in cancer monitoring and designing of targeted cancer treatments. In this review paper, a brief summary of existing CTC isolation methods is presented. We also discuss methods of detaching CTC from functionalized surfaces (functional assays/devices) and their further use for ex-vivo culturing that aid in studies regarding molecular properties that encourage metastatic seeding. In the clinical applications section, we discuss a number of cases that CTCs can play a key role for monitoring metastases, drug treatment response, and heterogeneity profiling regarding biomarkers and gene expression studies that bring treatment design further towards personalized medicine.

The prognosis of patients with acute myeloid leukemia (AML) remains dismal highlighting the need for novel innovative treatment strategies. The application of chimeric antigen receptor (CAR) T-cell therapy to AML patients has been limited in particular by the lack of a tumor-specific target antigen. CD70 is a promising antigen to target AML as it is expressed on the majority of leukemic blasts, whereas little or no expression is detectable in normal bone marrow samples. To target CD70 on AML cells, we generated a panel of CD70-CARs that contained a common single chain variable fragment (scFv) for antigen detection but differed in size and flexibility of the extracellular spacer, and in the transmembrane and the co-stimulatory domains. These CD70scFv CARs were compared with a CAR construct that contained the human CD27, the ligand of CD70 fused to the CD3z chain (CD27z). The structural composition of the CAR strongly influenced expression levels, viability, expansion and cytotoxic capacities of CD70scFv CAR T-cells, but the CD27z-CAR T-cells demonstrated superior proliferation and anti-tumor activity in vitro and in vivo, compared to all CD70scFv-CARs. While CD70-CAR T-cells recognized activated virus-specific T-cells (VSTs) that expressed CD70, they did not prevent colony formation by normal hematopoietic stem cells (HSCs). Thus, CD70-targeted immunotherapy is a promising new treatment strategy for patients with CD70-positive AML that does not affect normal hematopoiesis but will require monitoring of virus-specific T-cell responses.