Generation of a poor prognostic chronic lymphocytic leukemia-like disease model: PKC subversion induces up-regulation of PKC II expression in B lymphocytes

Overwhelming evidence identifies the microenvironment as a critical factor in the development and progression of chronic lymphocytic leukemia, underlining the importance of developing suitable translational models to study the pathogenesis of the disease. We previously established that stable expression of kinase dead protein kinase C alpha in hematopoietic progenitor cells resulted in the development of a chronic lymphocytic leukemia-like disease in mice. Here we demonstrate that this chronic lymphocytic leukemia model resembles the more aggressive subset of chronic lymphocytic leukemia, expressing predominantly unmutated immunoglobulin heavy chain genes, with upregulated tyrosine kinase ZAP-70 expression and elevated ERK-MAPK-mTor signaling, resulting in enhanced proliferation and increased tumor load in lymphoid organs. Reduced function of PKCα leads to an up-regulation of PKCβII expression, which is also associated with a poor prognostic subset of human chronic lymphocytic leukemia samples. Treatment of chronic lymphocytic leukemia-like cells with the selective PKCβ inhibitor enzastaurin caused cell cycle arrest and apoptosis both in vitro and in vivo, and a reduction in the leukemic burden in vivo. These results demonstrate the importance of PKCβII in chronic lymphocytic leukemia-like disease progression and suggest a role for PKCα subversion in creating permissive conditions for leukemogenesis

A declining CD4 count and diagnosis of HIV-associated Hodgkin lymphoma: do prior clinical symptoms and laboratory abnormalities aid diagnosis?

BACKGROUND: The incidence of Hodgkin lymphoma (HL) among HIV-infected individuals remains unchanged since the introduction of combination antiretroviral therapy (cART). Recent epidemiological data suggest that CD4 count decline over a year is associated with subsequent diagnosis of HL. In an era of economic austerity monitoring the efficacy of cART by CD4 counts may no longer be required where CD4 count>350 cells/µl and viral load is suppressed (350 may not have delayed diagnosis

Ibrutinib-based therapy reinvigorates CD8 T cells compared to chemoimmunotherapy: immune-monitoring from the E1912 trial

Bruton's tyrosine kinase Inhibitors (BTKis) that target B cell receptor signaling have led to a paradigm shift in CLL treatment. BTKis have been shown to reduce abnormally high CLL-associated T cell counts and the expression of immune checkpoint receptors concomitantly with tumor reduction. However, the impact of BTKi therapy on T cell function has not been fully characterized. Here, we performed longitudinal immunophenotypic and functional analysis of pre- and on-treatment (6- and 12-months) peripheral blood samples from patients in the phase 3 E1912 trial comparing ibrutinib-rituximab to fludarabine, cyclophosphamide and rituximab (FCR). Intriguingly, we report that despite reduced overall T cell counts, higher numbers of T cells including effector CD8+ subsets at baseline and at the 6-month time-point associated with no infections and favorable progression-free survival (PFS) in the ibrutinib-rituximab arm. Assays demonstrated enhanced anti-CLL T cell killing function during ibrutinib-rituximab, including a switch from predominantly CD4+ T-cell:CLL immune synapses at baseline to increased CD8+ lytic synapses on-therapy. Conversely, in the FCR arm, higher T cell numbers correlated with adverse clinical responses and showed no functional improvement. We further demonstrate the potential of exploiting rejuvenated T cell cytotoxicity during ibrutinib-rituximab using the bispecific antibody glofitamab - supporting combination immunotherapy approaches

Phenotype and immune function of lymph node and peripheral blood CLL cells are linked to transendothelial migration

everal lines of evidence suggest that homing of tumor cells to lymphoid tissue contributes to disease progression in chronic lymphocytic leukemia (CLL). Here, we demonstrate that lymph node (LN)-derived CLL cells possess a distinct phenotype, and exhibit enhanced capacity for T-cell activation and superior immune synapse formation when compared with paired peripheral blood (PB) samples. LN-derived CLL cells manifest a proliferative, CXCR4(dim)CD5(bright) phenotype compared with those in the PB and higher expression of T-cell activation molecules including CD80, CD86, and HLA-D-related (DR). In addition, LN-CLL cells have higher expression of α4β1 (CD49d) which, as well as being a co-stimulatory molecule, is required for CLL cells to undergo transendothelial migration (TEM) and enter the proliferation centers of the LNs. Using an in vitro system that models circulation and TEM, we showed that the small population of CLL cells that migrate are CXCR4(dim)CD5(bright) with higher CD49d, CD80, CD86, and HLA-DR compared with those that remain circulating; a phenotype strikingly similar to LN-derived CLL cells. Furthermore, sorted CD49d(hi) CLL cells showed an enhanced capacity to activate T cells compared with CD49d(lo) subpopulations from the same patient. Thus, although PB-CLL cells have a reduced capacity to form immune synapses and activate CD4(+) T cells, this was not the case for LN-CLL cells or those with the propensity to undergo TEM. Taken together, our study suggests that CLL cell immunologic function is not only modulated by microenvironmental interactions but is also a feature of a subpopulation of PB-CLL cells that are primed for lymphoid tissue homing and interaction with T cells

Corrigendum: POPIA Code of Conduct for Research

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Investigator choice of standard therapy versus sequential novel therapy arms in the treatment of relapsed follicular lymphoma (REFRACT): study protocol for a multi-centre, open-label, randomised, phase II platform trial

BackgroundRelapsed or refractory follicular lymphoma (rrFL) is an incurable disease associated with shorter remissions and survival after each line of standard therapy. Many promising novel, chemotherapy-free therapies are in development, but few are licensed as their role in current treatment pathways is poorly defined. MethodsThe REFRACT trial is an investigator-initiated, UK National Cancer Research Institute, open-label, multi-centre, randomised phase II platform trial aimed at accelerating clinical development of novel therapies by addressing evidence gaps. The first of the three sequential novel therapy arms is epcoritamab plus lenalidomide, to be compared with investigator choice standard therapy (ICT). Patients aged 18 years or older with biopsy proven relapsed or refractory CD20 positive, grade 1-3a follicular lymphoma and assessable disease by PET-CT are eligible. The primary outcome is complete metabolic response by PET-CT at 24 weeks using the Deauville 5-point scale and Lugano 2014 criteria. Secondary outcomes include overall metabolic response, progression-free survival, overall survival, duration of response, and quality of life assessed by EQ-5D-5 L and FACT-Lym. The trial employs an innovative Bayesian design with a target sample size of 284 patients: 95 in the ICT arm and 189 in the novel therapy arms. Discussion:Whilst there are many promising novel drugs in early clinical development for rrFL, understanding the relative efficacy and safety of these agents, and their place in modern treatment pathways, is limited by a lack of randomised trials and dearth of published outcomes for standard regimens to act as historic controls. Therefore, the aim of REFRACT is to provide an efficient platform to evaluate novel agents against standard therapies for rrFL. The adaptive Bayesian power prior methodology design will minimise patient numbers and accelerate trial delivery. Trial registration: ClinicalTrials.gov: NCT05848765; 08-May-2023. EudraCT: 2022-000677-75; 10-Feb-2022

Natural Allelic Variation Defines a Role for ATMYC1: Trichome Cell Fate Determination

The molecular nature of biological variation is not well understood. Indeed, many questions persist regarding the types of molecular changes and the classes of genes that underlie morphological variation within and among species. Here we have taken a candidate gene approach based on previous mapping results to identify the gene and ultimately a polymorphism that underlies a trichome density QTL in Arabidopsis thaliana. Our results show that natural allelic variation in the transcription factor ATMYC1 alters trichome density in A. thaliana; this is the first reported function for ATMYC1. Using site-directed mutagenesis and yeast two-hybrid experiments, we demonstrate that a single amino acid replacement in ATMYC1, discovered in four ecotypes, eliminates known protein–protein interactions in the trichome initiation pathway. Additionally, in a broad screen for molecular variation at ATMYC1, including 72 A. thaliana ecotypes, a high-frequency block of variation was detected that results in >10% amino acid replacement within one of the eight exons of the gene. This sequence variation harbors a strong signal of divergent selection but has no measurable effect on trichome density. Homologs of ATMYC1 are pleiotropic, however, so this block of variation may be the result of natural selection having acted on another trait, while maintaining the trichome density role of the gene. These results show that ATMYC1 is an important source of variation for epidermal traits in A. thaliana and indicate that the transcription factors that make up the TTG1 genetic pathway generally may be important sources of epidermal variation in plants