Central nervous system cancer metastases – the evolution of diagnostics and treatment
Ella Day | August 4, 2025 | Feature | | CERo therapeutics, Cancer, T cell, immunotherapy
Pharmafile talks to Russell Bradley, President and General Manager of CNSide Diagnostics, a subsidiary of Plus Therapeutics, about central nervous system cancer metastases1 and how they’re being diagnosed and treated.
Pharmafile: Can you explain in broad terms how central nervous system cancer metastases develop?
Russell Bradley (RB): When cancer cells originate and mature, they can sometimes infiltrate the blood system, and then circulate around the peripheral vascular system. If they grow as a secondary site, that is what is known as metastases. When cancer cells penetrate the blood brain barrier, and then grow around the brain or down the spinal column, that is known as a central nervous system (CNS) metastases. Our company, CNSide, is focused on diagnosing and providing data for doctors to manage patients who are at that stage.
Pharmafile: How are CNS metastases usually diagnosed?
RB: The diagnostic approach for metastases in the CNS hasn’t really changed very much over the last few decades. It’s a combination of a few methods. The doctor’s examination and clinical notes identify the patient’s symptoms. Imaging, including MRI or CT scans, is then used to look for evidence that the cancer cells have infiltrated the CNS.
A sample of the patient’s cerebral spinal fluid is taken by a doctor via a lumbar puncture. The sample is treated and using cytology – which involves examining cells, usually under a microscope, to identify abnormalities or diseases, including cancer – these cells are then identified. These methods have been the standard of care for a very long time. There have been some innovations, but this is how it is diagnosed currently.
Pharmafile: What are the main drawbacks of the current standard of care methods?
RB: The current standard of care, used in the majority of cases, does not have a very sensitive approach. It is useful when the tumour is very obvious, but that lack of sensitivity is definitely a drawback, particularly in cytology, when a sample taken from the spinal fluid is examined under a microscope.
Pharmafile: What are the newer innovations in standard of care?
RB: A combination of new technologies and techniques has allowed us to view genomic DNA in a very precise way. Up until now, cytology, which was the standard of care, wasn’t very sensitive, so it was difficult to pinpoint cancer cells until the number of cancer cells had increased to the extent that they became easier to identify. CNSide uses precise and sensitive technology that allows us to identify early evidence of infiltration, to the extent to which we can look at one cancer cell at a time. The other innovations are in the genomic DNA, where researchers can now look for the DNA signature of a particular cancer cell, which is a very sensitive technique as well. By taking that sample they can identify abnormal DNA – tumour cell DNA – which is another way of looking for evidence of infiltration into the CNS.
Pharmafile: How do you see the diagnosis of CNS cancer metastases evolving in the next five years?
RB: With more sensitive techniques, we’ll hopefully be able to detect the infiltration of cancer cells into the CNS earlier, giving patients and doctors more options. As, once the primary tumour infiltrates into the central nervous system, it’s a devastating prognosis. In a lot of cases, the data I’ve seen shows that most patients can’t be treated after a tumour is discovered in the CNS and they’re often put into hospice or on palliative care.
Pharmafile: What are the treatments that are available currently?
RB: From what I understand, there aren’t a lot of specific therapies for CNS metastases once they’re diagnosed. There is off-label use, so some of the therapies being used aren’t really designed for that use. Since these patients have so few options, these may be the only options for doctors to use to treat them. The thing about the CNS is that it’s surrounded by a membrane, called the blood brain barrier, and this protects the CNS from a lot of toxins and infections. However, it also makes it very hard to treat these types of tumours; once the cancer cells get into the CNS, many therapeutics can’t cross that barrier, which limits the options. There’s also the option of radiation, which can be effective, but it can be very damaging to surrounding tissue.
Pharamfile: How is current research working to expand the limits of conventional therapies?
Plus Therapeutics, of which CNSide is a subsidiary, is currently conducting clinical trials for a therapy that is similar to a conventional therapeutic, but it is applied directly into the CNS, which enables it to directly treat the cancer cells in that area. So far, the response to the therapy has been quite good. I think there’s hope on the horizon, with the combination of a very sensitive diagnostic method and therapeutics that together can provide these patients with better options.
Pharamfile: How do you see treatments developing alongside diagnostics?
I think there’s a very symbiotic relationship between therapies and diagnosis and it’s getting closer and closer. I feel like I’ve had a ringside seat on this evolution of therapeutics and diagnostics – some people call it ‘theranostics’ –where the study of the two has merged as therapies have become more targeted. Over the last few decades, as we began to understand cell biology and the biology of cancer, the therapies have evolved to become very specific and very targeted to different types of cancer.
Back in the 1970s and 1980s, there was almost a ‘one size fits all’ approach to cancer, and some very toxic agents were used to try to differentially kill the cancer while keeping the patient alive, but that chemotherapy was a very tough therapeutic approach.
The idea of using a therapy to target a specific type of cancer presumes that there’s a way to characterise it precisely – leading to an evolution of those two streams, with the therapeutics approach targeting specific types of cancers and the diagnostic information helping to enable that targeting. Also, with the wider availability of genetic technologies, we’re able to do really fine ‘fingerprinting’ of the different cancer types, which has led to the development of personalised medicine – very specific therapeutic approaches tailored to specific patients – and I can see that continuing. That’s what we are focusing on, providing a really sensitive and precise diagnostic with all the information that we can to the doctors to help them to target each particular patient’s tumour.
Pharmafile: Was there anything you wanted to add to any of the points we’ve discussed?
Going back to my last point, it’s very exciting to be involved at a time when there is increasing effectiveness in the combination of diagnosis and therapy – we’re helping the patients to live longer and better lives. One of the reasons we’re seeing more CNS cancer metastases cases is both ironic and logical. As we’ve gotten better at managing primary cancer when it’s diagnosed, these patients are living longer lives, and as they do and their cancer is managed, there’s a higher likelihood that eventually it might infiltrate into the CNS. So we’re seeing a substantial growth in patients with this condition, and it’s a consequence of actually being very effective at treating the primary tumour. Since it’s so devastating, we want to see more patients have more opportunities and treatment options, and it’s extremely rewarding to be part of this process.
References
1. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/metastasis
2. https://cnside-dx.com/cnside-csf-assay/#overview
Russell Bradley is the President and General Manager of CNSide2, which uses its Cerebrospinal Fluid Assay Platform to diagnose those suspected of having central nervous system cancer metastases (CNS Met). The platform seeks to sensitively diagnosis, monitor and guide treatment, and ultimately improve CNS Met patient outcomes – of which are historically poor.
This article featured in: August 2025 – The Pharmafile Brief
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