<![CDATA[ - Blog]]>Thu, 26 Oct 2017 15:09:26 -0700Weebly<![CDATA[Metabolic Mayhem From Missing PD-1 Makes Mice Moody]]>Thu, 26 Oct 2017 15:41:09 GMThttp://celentyx.com/blog/metabolic-mayhem-from-missing-pd-1-makes-mice-moodyA really exciting breakthrough article has just appeared in Nature Immunology (ref.1) linking T-cell hyper-activation to systemic amino acid depletion then onto reduced serotonin and dopamine in the brain.
 
The Japanese based group led by Sidonia Fagarasan were exploring metabolomic changes arising in mice genetically engineered to be deficient in the immune checkpoint receptor PD-1. In addition to changes in compounds involved in energy production they also spotted decreased levels of a variety of amino acids and especially of the aromatic kind. Comparing PD-1 / CD3e double knockouts with a CD3e alone knockout they were able to focus responsibility for these shifts in amino acids onto T cells.
 
They then went on to show that the responsible T cells were dominant in lymph nodes, highly active, expressed high levels of amino acid transporters, and correspondingly contained higher levels of a.a. as exemplified by the accumulation of tryptophan in the PD-1-ve T cells.
 
So, is this tantalising observation simply a vagary of the highly artificial system employed? It seems the answer is “no”! The same serum a.a. depletion was likewise seen in wild-type mice subjected to a potent acute immune challenge. Some more genetic trickery then allowed them to show that CD4+ and CD8+ T cells were equal culprits in the metabolic shift.
 
Next, the tour-de-force… And where I get particularly excited (see ref.2)! Looking at the brains of the PD-1 k.o. mice, they saw – mirroring serum – reduced concentrations of tyrosine and tryptophan which, in turn, resulted in depleted levels of dopamine and serotonin: Tyr & Trp being precursor molecules to the synthesis of the two neurotransmitters respectively. And, yes, in turn, the disturbed dopamine and serotonin availability impacted the animals’ behaviour, consistent with roles for the neurotransmitters in e.g. anxiety, fear, inquisitiveness.
 
As ever, all well-&-good in mice: but what about people – where we don’t tend to knock out their PD-1 genes?! Well, the authors – again in a mouse model, but one directly pertinent to the current excitement around immuno-oncology & immune checkpoint inhibition – demonstrated the self-same metabolic shift towards reduced a.a. levels in mice inoculated with adenocarcinoma cells then acutely administered anti-PD-1: isotype control-treated mice showed no such perturbation. The authors raise the important and intriguing question as to whether patients undergoing T cell-boosting immunotherapy might possibly develop affective and behavioural disorders akin to those observed in the mice. If these were to be the case, then appropriate intervention might help: either (as shown in their paper) by dietary supplementation with relevant amino acids or pharmacologically through a neurotransmitter-promoting drug (such as fluoxetine [Prozac]).
  1. http://www.nature.com/ni/journal/vaop/ncurrent/full/ni.3867.html
  2. Gordon J, Barnes NM. Lymphocytes transport serotonin & dopamine: agony or ecstasy? Trends Immunol. 24:438-443; 2003
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<![CDATA[​Keeping TABs on Melanoma B Cells: Pivotal Role in Tumour Heterogeneity & Therapy Resistance...]]>Wed, 27 Sep 2017 09:07:25 GMThttp://celentyx.com/blog/keeping-tabs-on-melanoma-b-cells-pivotal-role-in-tumour-heterogeneity-therapy-resistanceJustifiably, there is much excitement and focus in the cancer world on immunotherapies that exploit biologics to 're-awaken' the immune system where T cells - especially - take centre stage. The success of immune checkpoint inhibition in melanoma has rightly hit the headlines. Yet only a third of melanoma patents show durable responses to such therapies. There is still room - and the need - to improve & refine more 'classic' non-biologic treatments.
 
So it really pepped my interest to come across the recent paper in NATURE COMMUNICATIONS from Somasundaram et al* - even more so as a 'B-Cell Man' given how key the 'B'est cell was to the core of this study!
 
The starting point for the authors was this: that while therapies with inhibitors to oncogenic BRAFV600E are highly effective in melanoma, the responses are all too often transient due to the emergence of drug-resistant tumour subpopulations. What they discovered was that the mechanism for acquired drug resistance emerged from within the tumour microenvironment: and, most notably, this was mediated by TABs - the Tumour-Associated B cells which represented up to a third of all infiltrating immune cells.
 
This is what is happening. (i) The melanoma cells constitutively produce the growth factor FGF-2. (ii) Paracrine signalling then activates tumour-infiltrating B cells to produce IGF-1. (iii) This B-cell-derived IGF-1 is then critical for resistance of the melanoma to BRAF - and MEK - inhibitors due to the emergence of heterogeneous subpopulations plus the activation of FGFR-3.
Consistently, resistance of melanomas to BRAF and/or MEK inhibitors was associated with increased CD20 and IGF-1 transcript levels in the tumours and IGF-1 expression in the tumour-associated B cells.
 
Lovely observations: but of any clinical utility? How, if at all, could this be exploited?! Well, you may have figured it out for yourself... And indeed, the authors report initial data from a pilot trial in therapy-resistant metastatic melanoma patients showing anti-tumour activity through B-cell depletion by anti-CD20 antibody. 
 
Move over T cells, the B-cell boys are back in town!

www.ncbi.nlm.nih.gov/pmc/articles/PMC5605714/
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<![CDATA[​Exhausted? Or Ready for a Spot-the-Difference Competition? Then Checkout CTLA-4 & PD-1 Checkpoint Commonalities & Distinctions…]]>Thu, 17 Aug 2017 12:28:13 GMThttp://celentyx.com/blog/exhausted-or-ready-for-a-spot-the-difference-competition-then-checkout-ctla-4-pd-1-checkpoint-commonalities-distinctionsA landmark paper in CELL*, utilising mass cytometry to deep mine the effects of checkpoint blockade on immune infiltrates, reveals commonalities & differences between anti-CTLA-4 & anti-PD-1 in both human melanoma and murine tumour models. Groups at the MD Anderson Cancer Center, Houston, were wishing to understand the mechanisms underlying anti-CTLA-4- and anti-PD-1-induced tumor rejection. First of all, their analyses found there to be a spectrum of tumor-infiltrating T cell populations  – highly similar between the different tumor models – and that checkpoint blockade targeted only specific subsets of the tumor-infiltrating T cells. They then went on to show that anti-PD-1 predominantly induced the expansion of specific tumor-infiltrating exhausted-like CD8 T cell subsets. In contrast, anti-CTLA-4 induced the expansion of an ICOS+ Th1-like CD4 effector population: in addition to engaging specific subsets of exhausted-like CD8 T cells.
 
The bottom line: anti-CTLA-4 and anti-PD-1 checkpoint-blockade-induced immune responses are driven by distinct cellular mechanisms.
 
Perhaps not too surprising in itself, but better understanding the details of – & rationale for – these differences will likely serve to fine-tune & tailor future immunotherapeutic strategies to expand benefit to even more cancer patients than currently accommodated.
 
*http://www.cell.com/cell/fulltext/S0092-8674(17)30831-0
 
 

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<![CDATA[ PD-1 / PD-L1 Checkpoint Inhibition: It’s a Literal Tug-of-War between Macrophages & T Cells… In Fact, it’s a Total Rip-Off! ]]>Mon, 15 May 2017 08:10:13 GMThttp://celentyx.com/blog/-pd-1-pd-l1-checkpoint-inhibition-its-a-literal-tug-of-war-between-macrophages-t-cells-in-fact-its-a-total-rip-offUsing real-time video imaging, Arlauckas and colleagues (from various labs centred on the Boston area) have revealed in a new Science Translational Medicine* paper that macrophages have a habit of sneaking into regions of ongoing immunotherapy to snatch infused anti-PD-1 from tumour-infiltrating CD8+ T cells thereby reducing the desired benefit of this approach.

This ‘cellular tug-of-war’ is shown to depend on the biologic’s Fc domain glycan being grabbed by the macrophage’s Fc-gamma receptor. Neatly, the authors demonstrate how in vivo pre-blocking of the macrophage receptors prolongs biding of the anti-PD-1 to the T cells and, consequently, enhances immunotherapy-induced tumour regression. While these studies have been performed in mice, there are clear lessons here for such immunotherapeutic strategies in patients. 
*http://stm.sciencemag.org/content/9/389/eaal3604    
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<![CDATA[George Klein (1925-2016): Father of Tumour Biology, Viral Oncology, Oncogenes, &… a Truly Exceptional Human Being]]>Thu, 16 Feb 2017 16:46:36 GMThttp://celentyx.com/blog/george-klein-1925-2016-father-of-tumour-biology-viral-oncology-oncogenes-a-truly-exceptional-human-beingAs reported in today’s Nature1 – and known to us who have had the privilege of being able to call him “Mentor, an Inspiration, Colleague, and Friend” since before Christmas – George Klein passed away on 10th December 2016, at the age of 91 in his adopted city of Stockholm.

As a précis of the momentous contributions to Science that George has bequeathed us all, the AACR (of which George was a Fellow) writes2: “Klein, who collaborated with his wife, Eva Klein, MD, PhD, FAACR, for most of his long and notable career, was at the forefront of advances in tumor biology and immunology. Among Klein’s many accomplishments was the discovery that neoplasms including Burkitt’s lymphoma and nasopharyngeal carcinoma have a common origin in the Epstein-Barr virus. Another landmark discovery was the role of chromosomal translocations in the activation of proto-oncogenes”.

On his life: “Born July 28, 1925, Klein spent most of his childhood in Budapest, Hungary. During the Holocaust, many of his relatives and friends were sent to Auschwitz under the guise of ‘resettlement’. He had read a report about the atrocities, and although he was slated to be sent to the concentration camp in 1944, he fled. In 1947, Klein settled in Sweden, where he completed his medical degree and PhD. He received a personal professorship in tumor biology at the Karolinska Institutet, launching a lifetime of service to science. From his retirement in 1993 until his death, he was a research team leader at the Department of Microbiology, Tumour and Cell Biology, MTC, at Karolinska Institutet”.

In the summer of 1981, with a Southampton postdoctoral position under my belt, I wrote to George (admired from afar through his numerous papers and reviews, each inspirational and trailblazing) enquiring whether there was any possibility of my coming to work with him. His response was immediate, positive, and full of suggestions how this might be facilitated. George felt an EMBO Fellowship might be a good first bet: and he was right (his full support of my application boosting its success by around 100%). During one of the coldest Swedish winters in decades, with a young family in tow, we arrived in Stockholm February 1982 greeted by 6ft walls of snow and daytime temperatures of -20oC. Three days later, I trekked to the central KI campus for my initiation into the chaos that was ‘Tumorbiologen’: George’s domain at the time. But what beautiful and creative chaos!

Students, postdocs, technicians, and scientists, three or more to a (very) small desk, spilling out into the corridors where makeshift areas became overflow ‘labs’ all to the cacophony of ‘Swinglish’ and as many languages as accommodated in the Tower of Babel. And at its helm – orchestrating, inspiring, exciting, enthusing, enabling – sat George who, while so in demand, so busy, so constantly on the move, found time for ‘you’. Every week: ‘the famous Friday Letter’. Where each and every one of the 200+ Department members would distill their results, observations, thoughts, musings, questions – and unwaveringly (and individually!) receive by the following week a reply from George, one which was guaranteed to be at least as twice as long as the one sent. And – in the nicest possible way – those replies would be insightful, challenging, questioning, probing, and facilitating: for example, by cc-ing in a Nobel Laureate buddy of his such that you would subsequently be in direct contact with The World Leading Expert on whatever the subject happened to be.

Though in this multinational, multicultural, multidisciplinary melting pot for only 15 months, that period with George has and will provide a lifetime of inspiration (that word again!). And through the 30 or so years since, a not-so-frequent ‘Friday Letter’ to George continued to be greeted and welcomed with openness and the generosity that marked the man: even towards the end, the response still being twice as long as sent and full of the same razor intellect, insight, and curiosity tempered by a warmth, humanity, and kindness rarely met.

R.I.P. George.   

1http://www.nature.com/nature/journal/v542/n7641/full/542296a.html
2http://www.aacr.org/Membership/Pages/klein-george-obituary.aspx#.WKWxQRRS1lk

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<![CDATA[Eradicating the Eradicators: Engineering CD19-directed CAR T cells for Subsequent Elimination with Monoclonal Antibody…]]>Tue, 18 Oct 2016 19:07:46 GMThttp://celentyx.com/blog/eradicating-the-eradicators-engineering-cd19-directed-car-t-cells-for-subsequent-elimination-with-monoclonal-antibodySome pretty efficient CAR T cells are being developed against B-cell malignancy. Only problem is: they’re too damned efficient! Getting rid of those CD19-carrying malignant B cells by highly effective long-lasting CAR Ts is undoubtedly A Very Good Thing. Simultaneously taking out all the normal CD19+ B cells – Not So Good!

A team led by Dirk Busch had a cunning plan to curtail the accompanying unwanted hypogammaglobulinemia associated with CD19-based CAR T cell therapy: the results of which are reported this week online in the Journal of Clinical Investigation*.

First, they developed a truncated version of the epidermal growth factor receptor (EGFRt) which they co-expressed with the CD19-CAR on the T cell surface. Then, they targeted the EGFRt with the IgG1 monoclonal antibody cetuximab thereby eliminating CD19 CAR T cells both early and late after adoptive transfer in mice. The exciting finding was a complete and permanent recovery of normally functioning B cells – without tumor relapse!

The authors discuss how EGFRt can be incorporated into many clinical applications in order to knock out gene-engineered cells exactly when needed. All this heralds a promising new approach to improve the safety of increasingly popular and exciting cell-based therapies.

*http://www.jci.org/articles/view/84813
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<![CDATA[Who Needs Antigen? IgE Does It All By Itself…]]>Thu, 04 Aug 2016 12:22:16 GMThttp://celentyx.com/blog/who-needs-antigen-ige-does-it-all-by-itselfKitamura & colleagues from Tokyo University report a fascinating - & surprising  - finding about membrane IgE+ B cells in Nature Immunology, now online*.

We’ve known for a while that rare mIgE+ B cells participate only transiently in the germinal centre: consequently, they infrequently generate IgE memory or long-lived IgE plasma cells. It seems mIgE autonomously triggers rapid plasma-cell differentiation and apoptosis: without any need for antigen and independently of cellular context. Apparently, this mainly happens through the mutually independent CD19-PI3K-Akt-IRF4 and BLNK-Jnk/p38 pathways. Correspondingly, CD19- and BLNK-deficient mice show deregulated germinal centre IgE+ B cell proliferation and prolonged IgE production: together with exaggerated anaphylaxis!

As the authors state, “these findings provide insights into the molecular pathogenesis of allergic diseases”. Much needed insights given the increasing prevalence of atopy and our current inability to reverse or control it effectively.

[Information on Celentyx’s UNIQUE ALLERGY / IgE DIFFERENTIATION PLATFORM for screening potential anti-allergy compounds can be found at: http://www.celentyx.com/b-cells.html]

*http://www.nature.com/ni/journal/vaop/ncurrent/full/ni.3508.html
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<![CDATA[It may be May but APRIL, & BCMA, are now prime suspects in multiple myeloma progression...]]>Sun, 01 May 2016 20:48:31 GMThttp://celentyx.com/blog/it-may-be-may-but-april-bcma-are-now-prime-suspects-in-multiple-myeloma-progressionA new online Blood paper from Kenneth Anderson’s group shows that over-expression, or activation, of BCMA (B Cell Maturation Antigen) by its ligand APRIL (A PRoliferation-Inducing Ligand) promotes the progression of MM (Multiple Myeloma) in vivo*.

BCMA down-regulation decreased both MM cell viability and colony formation: strongly! On the other hand, BCMA over-expression augmented MM cell growth and survival and was shown to do so by engaging AKT, MAPK, and NFκB signaling cascades.

BCMA-over-expressing tumors exhibited increased CD31/microvessel density and VEGF. Moreover, they showed increased transcripts crucial for osteoclast activation, adhesion, and angiogenesis/metastasis. Notably, genes mediating immune inhibition – including PD-L1, TGFβ, and IL-10 – were also increased.

The same target genes were found to be induced by paracrine APRIL binding to BCMA on the MM cells. This was blocked in the presence of an antagonistic anti-APRIL monoclonal antibody which was shown to be cytotoxic against MM cells: even in the presence of protective bone marrow (BM) myeloid cells including osteoclasts, macrophages, and plasmacytoid dendritic cells. Moreover, the antagonistic anti-APRIL prevented in vivo MM cell growth within implanted human bone chips in SCID mice. Its effect on MM cell viability was enhanced by lenalidomide and bortezomib.

It seems that APRIL, along with its receptor BCMA, may well be offering new therapeutic opportunities for multiple myeloma in the coming months, and beyond… 

* http://www.bloodjournal.org/content/early/2016/04/27/blood-2016-01-691162
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<![CDATA[IL-4 enhances expression and function of surface IgM in CLL cells…]]>Thu, 31 Mar 2016 12:29:43 GMThttp://celentyx.com/blog/il-4-enhances-expression-and-function-of-surface-igm-in-cll-cellsA really neat paper from my old Alma Mater on a subject dear to my heart has just appeared in BLOOD online*. The Southampton group led by Andrew Steele demonstrates a pleiotropic action of interleukin-4 that could contribute to the pathogenesis of chronic lymphocytic leukaemia on several fronts. As always, when ever there’s a new-kid-on-the-block regards disease activity, there’s a new opportunity for therapeutic management of said disease.    

There was already the backdrop of IL-4 protecting some normal and malignant B cells from apoptosis; and for increasing the surface expression of IgM on murine splenic B cells. This new study from Aguilar-Hernandez et al now shows IL-4 likewise increasing IgM expression on human B cells including malignant counterparts contained within the monoclonal populations of CLL: and especially where the disease is of the more progressive U-CLL subtype i.e. with unmutated V-genes populating the clonal immunoglobulin. IL-4-induced surface IgM expression was associated with increased receptor signalling activity, measured by anti-IgM-induced calcium mobilisation, and with increased expression of CD79B mRNA and protein, and the mature glycoform of sIgM.

Moreover, and in striking contrast to the up-regulation of surface IgM observed, IL-4 decreased CXCR4 and CXCR5 expression. They also add into the mix that in CLL, IL-4 target genes are overexpressed in cells purified from the lymph nodes of patients compared to cells derived from matched blood and bone marrow samples. All together, their findings point to CLL cells, particularly within the progressive U-CLL subset, harnessing the ability of IL-4 to promote BCR signalling and B-cell retention within lymph nodes. The multiple effects of IL-4 were mediated via JAK3/STAT6 leading the authors to propose a potential use for JAK inhibitors – in combination with BCR-kinase inhibitors – for the treatment of CLL. Pretty exciting stuff!


*http://www.bloodjournal.org/content/early/2016/03/21/blood-2015-11-682906.long
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<![CDATA[IgE – much more than, parasites, dust mites, and atopy: a whole new role in SLE…]]>Fri, 08 Jan 2016 17:05:45 GMThttp://celentyx.com/blog/ige-much-more-than-parasites-dust-mites-and-atopy-a-whole-new-role-in-sleFor such a low abundance immunoglobulin, IgE – for all its good in clearing parasites – also causes us a lot of bother. Bothersome Hay Fever is certainly no fun while life-threatening anaphylaxis, well, is just that: potentially fatal… Now a group of MedImmune scientists publishing online in Nature Immunology* puts IgE in the frame for damaging aspects of lupus. 

Henault et al found IgE antibodies specific for double-stranded DNA circulating in lupus patients and that such autoantibody activated plasmacytoid dendritic cells to secrete substantial amounts of interferon-a. The high affinity IgE receptor was instrumental in allowing IgE-dsDNA complexes to internalize resulting in TLR9 activation leading to greatly potentiated pDC function. In keeping with this, serum levels of self-reactive IgE correlated with disease severity. The good news is, that fingering this new kid on the lupus block opens novel avenues for therapeutic intervention in debilitating SLE.

‘Self-reactive IgE exacerbates interferon responses associated with autoimmunity’ *http://www.nature.com/ni/journal/vaop/ncurrent/full/ni.3326.html

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