Glioblastoma Multiforme (GBM)
Glioblastoma multiforme (GBM) is an incredibly aggressive and almost universally fatal disease. Even with the most extensive surgical resections and the most aggressive radiation and chemotherapy regimens, median overall survival is as low as 15- to 19- months (Stupp, NEJM, 2005). This is likely due, in part, to the intrinsic propensity for treatment resistance and, as a result, the essentially unavoidable event of tumor recurrence. The current prognosis for most patients necessitates significant advances in the standard of care to improve both overall survival and patient quality of life.
Cannabidiol (CBD) has been shown to influence many of the key pathways involved in GBM pathogenesis – from tumor stemness and proliferation to angiogenesis and local invasion. The prospect of CBD used in combination with other pharmacologic interventions holds great promise for the treatment of GBM. The development of clinical trials to evaluate the efficacy of CBD combination therapies may represent an important step towards improving the clinical outcomes in a population of patients with few other effective therapeutic options.
MRI of a brain tumor in the right parietal lobe.
About Glioblastoma Multiforme
- Standard of Care
Glioblastoma, alternatively called glioblastoma multiforme, is the most aggressive malignant tumor of the central nervous system. GBM arises from a specific type of glial cell called astrocytes, which support the survival and function of the surrounding neurons. The World Health Organization (WHO) grades gliomas on a scale of I-IV based on the degree of histopathologic atypia observed. GBM receives the most malignant designation, WHO Grade IV, for the presence of many abnormal, actively dividing cells, new vessel growth, and necrosis (Louis, Acta Neuropathol, 2016).
GBM is relatively rare, with a worldwide incidence of less than 10 cases per 100,000 people (Hanif, Asian Pac J Cancer Prev, 2017). Nonetheless, the impact of GBM is profound – they are largely incurable with only 5-10% of patients surviving five years after diagnosis (Chien, Front Public Health, 2016). With such a poor prognosis and relatively few effective interventions, new therapies are desperately needed to improve outcomes and survival.
U.S. Brain and Nervous System Cancer Incidence (NIH SEER)
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The symptoms of GBM are relatively non-specific and often depend on the size and location of the tumor. In general, symptoms can include headache, seizure, and focal neurologic deficits that correlate with tumor location, such as weakness, language deficits, and cognitive impairment (Chang, JAMA, 2005). Ultimately, GBM is usually detected by MRI and officially diagnosed by tissue biopsy, which can occur during surgical removal of the tumor or during a separate procedure (Glioma, Mayo Clinic).
The clinical course of GBM patients depends on several factors intrinsic to the tumor itself. GBM can develop from a pre-existing, lower grade brain tumor called an astrocytoma or can arise de novo. These GBM subsets differ in their underlying pathogenesis and in disease phenotype. Sporadic GBM are the most common subtype, comprising 90% of all GBM. They typically present later in life, develop much more rapidly, and have an overall worse prognosis (Ohgaki & Kleihues, Am J Pathol, 2007; Ohgaki & Kleihues, Clin Cancer Res, 2013).
Several common genetic mutations underlie both primary and secondary GBM, including loss of tumor suppressor function on chromosome 10q and of the TP53 gene, both of which permit dysregulated cell growth and division (Ohgaki & Kleihues, Am J Pathol, 2007; Ohgaki & Kleihues, Clin Cancer Res, 2013; Rasheed, Oncogene, 1995). Additional mutations are involved in the progression from low grade astrocytomas to malignant GBM. Perhaps two of the most well-researched mutations are those occurring in IDH1 and IDH2, which segregate almost exclusively in secondary GBM (Ohgaki & Kleihues, Clin Cancer Res, 2013). IDH1/2 encodes the isocitrate dehydrogenase, which is critical for energy metabolism in the cell. Although the mechanism is not fully understood, it is thought the IDH1/2 mutations result in malignant transformation either through the production of an oncogenic metabolite or through inhibition of wild-type protein function (Bunse, Nat Med, 2018; Zhao, Science, 2009). Interestingly, possession of mutated IDH1/2 is an independent, beneficial prognostic marker, which may account, at least in part, for the differences in outcomes between primary and secondary GBM (Sanson, J Clin oncol, 2009; Weller, J Clin Oncol, 2009).
Another major contributor to the poor prognosis in these patients is the presence of a subpopulation of glioma stem cells (GSCs) within the tumor. GSCs are able to self-renew and produce a host of proteins and growth-factors that support proliferation, angiogenesis, and local tumor invasion (Liebelt, Stem Cells Int, 2016). GSCs are notoriously difficult to eradicate with the traditional therapeutic regimen, and as such, they are thought to account for treatment resistance and the nearly inevitable recurrence of disease (Bao, Nature, 2006).
GBM is typically managed by a combination of surgical resection, radiation, and chemotherapy. When possible, gross total resection with preservation of neurologic function is the preferred intervention, as it confers a more favorable outcome than subtotal resection (Noorbakhsh, J Neurosurg, 2014). After surgical intervention, most patients are treated with adjuvant radiation and chemotherapy, specifically with the alkylating agent temozolomide. Response to temozolomide largely depends on the methylation status of the MGMT gene (Zhao, World J Surg Oncol, 2016). Methylated MGMT prevents DNA repair in response to alkylating agents, allowing the tumor cell to accumulate more damage and be sensitized to chemotherapy. Presence of MGMT methylation improves overall survival by about 50% (Zhao, World J Surg Oncol, 2016).
It is important to keep in mind that GBM has a poor prognosis regardless of tumor subtype and genetic makeup. The survival benefit conferred by any one beneficial prognostic factor is a matter of months. While this can, of course, be meaningful to patients, there is a clear opportunity for improvement upon the current standard of care in order to prolong survival and improve quality of life.Glioblastoma Multiforme (GBM) Introduction Glioblastoma multiforme (GBM) is an incredibly aggressive and almost universally fatal disease. Even with the most extensive surgical resections and
CANNABIDIOL AND GLIOBLASTOMAS
We are all looking for more evidence regarding the efficacy treating cancer with CBD and/or THC. There is a plethora of articles on the issue and particularly a lot of data with regard to treating Glioblastomas – a very challenging Brain Cancer that is most common in children.
I believe there are three points to be taken home with regard to Cannabidiol and Glioblastomas backed by the articles below. Again, there are hundreds of articles and these are not the final answer for certain, but consider the safety of CBD and the probably great efficacy of CBD, it seems reasonable therapy to consider.
So, the three major points:
1. CBD helps aid the Glioblastoma cells in committing apoptosis or “cellular suicide”. It is this property that helps prevent the tumor from becoming tolerant to chemotherapy
2. CBD helps increase the efficacy of chemotherapy
3. CBD helps increase the efficacy of radiation
So, cannabis, at least in my opinion, is an adjuvant form of anti-cancer therapy. It works with Chemo and Radiation therapy and perhaps also has efficacy without them
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