NorthWest Biotherapeutics Inc (NWBO)

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I’m familiar with the abstract referenced in the above intro section:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5833160/

I’d put that visual up on top as I found it helpful (at the time), pretty much for the same reasons you probably did. However, given that it does group the mesenchymal type under the IDH unmethylated type, the logical question, which you’ve asked, is how can the mesenchymal type do so well, when it’s the pro neural type that’s listed as methylated (as cited by the article and visual cited above in the intro section).

You have a lot of subtext in your question, but I think that this question has bothered you for awhile. I know you’ve asked about it before, and as a result, I wonder about the answer too, so I thought I’d look further into the question to see if I could find something that might help explain this conundrum for me.

I found an article that I’ve linked below that I found quite useful. I’m not sure if it will help you in your quest for an answer, but I do think it might either give you some answers, or take you closer to an answer.
https://www.sciencedirect.com/science/article/pii/S0923753420424287

I’d also like to point out the timing of these two articles, which as I’m sure you know, is important as practitioners garner a better and deeper understanding of the science. The one referenced above in the info section dates was first published in February 2018, so it’s now about 3 years old; and this article is more recent, have just been published in December 2020.

According to this article, IDH-wildtype GBM is often associated with the mesenchymal type and is often methylated. Here is a passage from the article that makes that claim. It’s a bit out of order, and below, I’ll copy and paste some sections (so you can find them more easily in the article and read the context) from the article, and I’ll do them in order (first to last).

DNA methylation is a key factor in defining GBM heterogeneity. Patterns of DNA methylation in tumour cells play a significant role in defining the characteristics inherent to each GBM subgroup.15,20,21 MGMT promoter methylation is a well-known prognostic and predictive factor associated with response to alkylating agents such as temozolomide (TMZ).22 Indeed, integration of DNA methylation with RNA expression profiles in adult gliomas has revealed multiple novel glioma subgroups.4 Recent work has established two methylation clusters in IDH-wt; classic-like and mesenchymal-like (Figure 2).

I’ll be curious to learn what your thoughts after checking out this article. Some of the content may be repetitive and you may already know (such as the neural type having been removed), but I’m posting the passages as I thought might they might be helpful.

The article is entitled, New hints towards a precision medicine strategy for IDH wild-type glioblastoma and published in the “Annals of Oncology” December 2020.

IDH mutation status was incorporated into the revised World Health Organization classification of brain tumours in 2016,6 thereby classifying GBM into two distinct entities: IDH-mutant (IDH-mt) GBM and wild-type (IDH-wt) GBM,6 although further molecular assessment suggests that IDH-mt GBMs align more closely with aggressive anaplastic astrocytomas.

In this review, we will focus on IDH-wt GBM, which is often associated with single copy loss of chromosome 10 and gain in chromosome 7.11 IDH-wt GBM manifests with significant interpatient differences and marked intratumoural heterogeneity.

Initial tumour stratification carried out before identification of IDH status by Phillips et al.13 in 2006 showed that molecular classes with enriched markers for proliferation, angiogenesis and the mesenchyme were predictive of overall survival (OS) and disease progression, with tumours commonly shifting towards the mesenchymal subclass upon recurrence.

That most GBM subtypes shifted to mesenchymal was something many of us have known for awhile.

In 2010, Verhaak et al.14 identified four discrete transcriptomic subtypes of GBM: proneural, neural, mesenchymal and classical (n = 202 patients). Since then, the proneural phenotype was shown to correspond more closely to IDH-mt astrocytomas, younger age and secondary GBM. The initial favourable prognosis observed in the proneural subtype was due to the inclusion of secondary GBM.

So the pro neural subtype usually starts as an astrocytoma. I don't know that any astrocytoma patients (whose tumors might have developed into a stage IV GBM) were put into the trial as I think (but am not sure) that only newly diagnosed GBM patients were enrolled. If someone knows differently, feel free to let me know. It’s something I can find out, I think, though. I would wonder, however, if an astrocytoma begins as a pro neural tumor and becomes a stage IV GBM, does it evolve into a mesenchymal subtype, given that most recurrent GBM does?

Following emergence of the most recent classification of diffuse gliomas, and coupled with new data illustrating the influence of TME on GBM subtyping,17 Wang et al.12 have now further refined GBM IDH-wt molecular subtypes. This subtyping approach is based on tumour-intrinsic transcriptomic signatures which are uniquely expressed by GBM tumour cells and not by tumour-associated host cells. In this context, three distinct subtypes have been shown to correlate with proneural, classical and mesenchymal tumours. The neural subtype was found to be largely comprised of samples with low tumour content and thus removed.18

And that is as you had stated.

DNA methylation is a key factor in defining GBM heterogeneity. Patterns of DNA methylation in tumour cells play a significant role in defining the characteristics inherent to each GBM subgroup.15,20,21 MGMT promoter methylation is a well-known prognostic and predictive factor associated with response to alkylating agents such as temozolomide (TMZ).22 Indeed, integration of DNA methylation with RNA expression profiles in adult gliomas has revealed multiple novel glioma subgroups.4 Recent work has established two methylation clusters in IDH-wt; classic-like and mesenchymal-like (Figure 2).

This study underscores epigenetic profiling as a robust classifier of GBM, which can identify key genetic alterations contributing to the aggressive IDH-wt phenotype. Additional studies to fully identify the evolutionary patterns driving these methylation changes are warranted.

The degree to which macrophages infiltrate the tumour has been shown to correlate with a more aggressive clinical course and reduced OS.29

IDH-wt tumours (specifically within the mesenchymal subtype) have been shown to increase expression of immune checkpoint proteins such as programmed cell death ligand 1 (PD-L1).42 This prevents stimulation of effector T cells, which impairs the adaptive immune response. As these tumours exhibit a diverse immune cell infiltrate and harbour a TME that may be responsive to immunomodulating therapies, it is possible that IDH-wt mesenchymal tumours could be more responsive to combinatorial immune checkpoint inhibitor (ICI) treatment strategies.43

Again, the article shows that the mesenchymal subtype is associated with the IDH-wild type tumor, and I believe that most of the GBM patients in the DCVax-L trial are wild type, as that type is usually associated with the newly diagnosed stage IV GBM tumor.

the mesenchymal subtype has a significantly reduced tumour purity (Figure 2) compared with proneural and classical subtypes, with an increased abundance of macrophages, microglia and neuroglia.

These data suggest that IDH-wt GBM varies according to transcriptional context, and that the immune contexture is partially dependent on IDH status. It therefore seems likely that IDH-wt tumours assigned to the mesenchymal subtype could respond better to immunotherapy due to its increased immune infiltrate, and might therefore be prioritised for future clinical trials with a targeted ICI.47

Anyhow, while this article may not thoroughly answer your question, I thought it at least indicated that mesenchymal tumors are often methylated... unlike what that chart had indicated in the information section above.