The molecular ontogeny of follicular lymphoma: gene mutations succeeding the BCL2 translocation define common precursor cells

Relapsed follicular lymphoma (FL) can arise from common progenitor cells (CPCs). Conceptually, CPC-defining mutations are somatic alterations shared by the initial and relapsed tumours, mostly B-cell leukaemia/lymphoma 2 (BCL2)/immunoglobulin heavy locus (IGH) translocations and other recurrent gene mutations. Through complementary approaches for highly sensitive mutation detection, we do not find CPC-defining mutations in highly purified BCL2/IGH-negative haematopoietic progenitor cells in clinical remission samples from three patients with relapsed FL. Instead, we find cells harbouring the same BCL2/IGH translocation but lacking CREB binding protein (CREBBP), lysine methyltransferase 2D (KMT2D) and other recurrent gene mutations. Thus, (i) the BCL2/IGH translocation can precede CPC-defining mutations in human FL, and (ii) BCL2/IGH-translocated cells can persist in clinical remission.

Gene editing enables T-cell engineering to redirect antigen specificity for potent tumor rejection

Targeted integration of a tumor-reactive T-cell receptor into the TRAC locus using CRISPR-Cas9 and AAV6 redirects primary human T cells against tumor cells in vitro and in vivo.

Adoptive transfer of TCR transgenic T cells holds great promise for treating various cancers. So far, mainly semi-randomly integrating vectors have been used to genetically modify T cells. These carry the risk of insertional mutagenesis, and the sole addition of an exogenous TCR potentially results in the mispairing of TCR chains with endogenous ones. Established approaches using nonviral vectors, such as transposons, already reduce the risk of insertional mutagenesis but have not accomplished site-specific integration. Here, we used CRISPR-Cas9 RNPs and adeno-associated virus 6 for gene targeting to deliver an engineered TCR gene specifically to the TCR alpha constant locus, thus placing it under endogenous transcriptional control. Our data demonstrate that this approach replaces the endogenous TCR, functionally redirects the edited T cells’ specificity in vitro, and facilitates potent tumor rejection in an in vivo xenograft model.

AR-V7 in Peripheral Whole Blood of Patients with Castration-resistant Prostate Cancer: Association with Treatment-specific Outcome Under Abiraterone and Enzalutamide

BACKGROUND

It has been demonstrated that androgen receptor splice variant 7 (AR-V7) expression in circulating tumor cells (CTCs) predicts poor treatment response in metastatic castration-resistant prostate cancer (mCRPC) patients treated with abiraterone or enzalutamide.

OBJECTIVE

To develop a practical and robust liquid profiling approach for direct quantification of AR-V7 in peripheral whole blood without the need for CTC capture and to determine its potential for predicting treatment response in mCRPC patients.

DESIGN, SETTING, AND PARTICIPANTS

Whole blood samples from a prospective biorepository of 85 mCRPC patients before treatment initiation with abiraterone (n=56) or enzalutamide (n=29) were analyzed via droplet digital polymerase chain reaction.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The association of AR-V7 status with prostate-specific antigen (PSA) response defined by PSA decline ≥50% and with PSA-progression-free survival (PSA-PFS), clinical PFS, and overall survival (OS) was assessed.

RESULTS AND LIMITATIONS

High AR-V7 expression levels in whole blood were detectable in 18% (15/85) of patients. No patient with high AR-V7 expression achieved a PSA response, and AR-V7 status was an independent predictor of PSA response in multivariable logistic regression analysis (p=0.03). High AR-V7 expression was associated with shorter PSA-PFS (median 2.4 vs 3.7 mo; p<0.001), shorter clinical PFS (median 2.7 vs 5.5 mo; p<0.001), and shorter OS (median 4.0 vs. 13.9 mo; p<0.001). On multivariable Cox regression analysis, high AR-V7 expression remained an independent predictor of shorter PSA-PFS (hazard ratio [HR] 7.0, 95% confidence interval [CI] 2.3-20.7; p<0.001), shorter clinical PFS (HR 2.3, 95% CI 1.1-4.9; p=0.02), and shorter OS (HR 3.0, 95% CI 1.4-6.3; p=0.005).

CONCLUSIONS

Testing of AR-V7 mRNA levels in whole blood is a simple and promising approach to predict poor treatment outcome in mCRPC patients receiving abiraterone or enzalutamide.

PATIENT SUMMARY

We established a method for determining AR-V7 status in whole blood. This test predicted treatment resistance in patients with metastatic castration-resistant prostate cancer undergoing treatment with abiraterone or enzalutamide. Prospective validation is needed before application to clinical practice.

Overexpression of CDX2 perturbs HOX gene expression in murine progenitors depending on its N-terminal domain and is closely correlated with deregulated HOX gene expression in human acute myeloid leukemia

The mechanisms underlying deregulation of HOX gene expression in AML are poorly understood. The ParaHox gene CDX2 was shown to act as positive upstream regulator of several HOX genes. In this study, constitutive expression of Cdx2 caused perturbation of leukemogenic Hox genes such as Hoxa10 and Hoxb8 in murine hematopoietic progenitors. Deletion of the N-terminal domain of Cdx2 abrogated its ability to perturb Hox gene expression and to cause acute myeloid leukemia (AML) in mice. In contrast inactivation of the putative Pbx interacting site of Cdx2 did not change the leukemogenic potential of the gene. In an analysis of 115 patients with AML, expression levels of CDX2 were closely correlated with deregulated HOX gene expression. Patients with normal karyotype showed a 14-fold higher expression of CDX2 and deregulated HOX gene expression compared with patients with chromosomal translocations such as t(8:21) or t(15;17). All patients with AML with normal karyotype tested were negative for CDX1 and CDX4 expression. These data link the leukemogenic potential of Cdx2 to its ability to dysregulate Hox genes. They furthermore correlate the level of CDX2 expression with HOX gene expression in human AML and support a potential role of CDX2 in the development of human AML with aberrant Hox gene expression.

Hyaluronan in the bovine oviduct--modulation of synthases and receptors during the estrous cycle

The extracellular matrix (ECM) component hyaluronan (HA) is considered to contribute to the optimal development of the gametes and the embryo. In this study, the regulation and localization of HA, its synthases (HAS 1-3) and the receptors CD44, RHAMM, and putative HARE were investigated in bovine oviducts during the estrous cycle. HA could be demonstrated in the entire lamina propria of the oviduct. Immunoreactive CD44 was found in the muscle layer additionally to the lamina propria. As for HA the luminal epithelium was devoid of CD44. Introducing quantitative real-time RT-PCR, a remarkable cyclic change of CD44 occurred. In addition, CD44 expression was much higher in the isthmus than in the ampulla. RHAMM transcripts were elevated particularly in the ampulla during estrus. A major part of the bovine putative HARE coding sequence was characterized. An analysis of the tissue distribution revealed transcripts not restricted to liver, spleen, and lymph node, providing evidence for a local putative HARE-mediated turnover of HA. These results suggest that in the bovine oviduct the cell surface receptor CD44 in particular might inversely regulate HA during the estrous cycle. The local turnover of HA through synthases and receptors may indicate its participation in the bovine oviduct supporting gamete maturation and early embryonic development.