The Question Most Families Ask Too Late
When a glioblastoma diagnosis arrives, attention immediately turns to surgery, radiation, and temozolomide chemotherapy. Since 2005, this sequence—called the Stupp protocol—has been the standard approach. For many patients, it is the right starting point. Yet another important question often goes unasked in the weeks that follow: Are there other approved drugs for other conditions that might work against this specific tumor?
This question drives drug repurposing and drug sensitivity analysis for glioblastoma. Precision oncology tackles it one tumor at a time, tailoring solutions to each patient's tumor biology.
Why Standard Chemotherapy Has Limits
Temozolomide remains the main chemotherapy for newly diagnosed glioblastoma. It works best in patients whose tumors have a methylated MGMT promoter—a sign that the tumor's DNA repair system is weaker and more vulnerable to the drug. But glioblastoma evolves. Cells that survive initial treatment can develop resistance. Over time, new tumor cell populations emerge, each with different biological weaknesses and survival strategies.
For recurring glioblastoma, standard treatment options narrow. Bevacizumab and lomustine are common second-line choices, but they help only some patients. Patients and caregivers researching beyond standard care often find evidence for a different approach: medications already used for other diseases that may work against glioblastoma.
What Drug Repurposing Means for Glioblastoma
Drug repurposing means using an existing, approved medication for another disease to treat a new condition. These drugs have known safety profiles, established dosing information, and cost far less than newly developed cancer drugs. For glioblastoma, this approach has drawn serious scientific interest.
A systematic review published in the journal Cancers identified repurposed drug candidates across multiple categories. These include antidiabetic drugs, antimalarials, antifungals, antiparasitic compounds, antibiotics, antidepressants, and statins for cholesterol—each studied for anti-tumor activity in glioblastoma models.
Some of the most researched candidates include:
- Metformin—a diabetes medication tested for its ability to disrupt tumor cell metabolism and inhibit the mTOR signaling pathway. Research has explored its role as an anti-angiogenic addition to GBM treatment.
- Chloroquine and hydroxychloroquine—antimalarial drugs tested to block autophagy, a survival mechanism tumors use during stress, and to help chemotherapy and radiation work better on GBM cells.
- Disulfiram—approved for alcohol dependence and tested for anti-tumor activity in GBM, especially in tumors where temozolomide alone is less effective.
- Statins—including pitavastatin, being tested to see if they reach effective levels in glioblastoma tissue and block lipid-dependent tumor signaling.
- Sertraline, itraconazole, celecoxib, and ritonavir—repurposed from depression, fungal infection, inflammation, and HIV treatment, each targeting different survival pathways in GBM.
These candidates are investigational for glioblastoma. Research shows potential, but large clinical trials for most of them are still in progress. The key point is this: understanding a tumor's biology is the first step toward knowing which options may help a specific patient.
The Multi-Drug Strategy: What CUSP9 Reveals About Tumor Heterogeneity
One of the most discussed multi-drug repurposing frameworks is CUSP9—the Coordinated Undermining of Survival Paths. It combines nine repurposed drugs with low-dose temozolomide. The nine drugs are aprepitant, auranofin, captopril, celecoxib, disulfiram, itraconazole, minocycline, ritonavir, and sertraline.
The scientific reasoning reflects a core problem in glioblastoma: the tumor does not depend on a single pathway to survive. Blocking one route often causes tumor cells to activate other survival paths. CUSP9 attempts to close multiple routes at once, using non-cancer drugs that individually have manageable side effects.
The Anticancer Fund has tracked clinical investigation into this approach for recurring glioblastoma. Early research in compassionate-use settings showed the protocol was generally well-tolerated and slowed tumor cell growth in glioblastoma models. Large clinical trials are still developing. CUSP9 is not a standard recommendation, but it shows why knowing which survival pathways are active in an individual tumor is important for any discussion of off-label or trial-based treatment.
What Standard Pathology Reports Often Cannot Reveal
Most glioblastoma patients receive a pathology report confirming the diagnosis and including MGMT methylation status, IDH mutation status, and EGFR amplification. These results are standard and essential. But they do not answer every clinically important question about the tumor's biology.
Standard histopathology cannot tell you which signaling pathways are most active now, which repurposed or off-label drugs the tumor may be vulnerable to, whether resistant cell populations have emerged since the original surgery, or how the tumor's gene expression compares to published drug response data.
This is the gap that advanced tumor intelligence addresses. Whole exome sequencing, RNA sequencing, and ex vivo drug sensitivity analysis go beyond the standard panel to examine the tumor at a deeper level. A pilot study on personalizing glioblastoma treatment using whole exome sequencing found that personalized drug combinations worked better against tumor cells than single drugs alone—combinations that standard pathology alone would not have identified.
How Drug Sensitivity Analysis Works
Drug sensitivity analysis takes tumor cells from a surgical specimen or stem cell cultures and tests how those cells respond to different drugs in a laboratory setting. High-throughput methods allow many drug and dose combinations to be tested at once.
A feasibility study using high-throughput drug sensitivity testing in recurring glioblastoma stem cell cultures showed that this approach could identify patient-specific drug vulnerabilities quickly enough to guide treatment decisions. The study found it was possible to isolate tumor cells, screen them against multiple drugs, and provide results before critical treatment decisions needed to be made.
Drug sensitivity results are not guarantees. The tumor's environment inside the brain—including the blood-brain barrier, immune cell activity, and metabolic factors—affects how drugs perform in ways laboratory models cannot fully capture. But this information can guide conversations about which options may be worth exploring, which drugs make biological sense for a given tumor, and whether any active clinical trials might apply.
To understand how drug sensitivity analysis guides treatment decisions at recurrence, this resource on salvage treatment options for recurring GBM explains how these results are used in that situation.
Connecting Molecular Profiling to Repurposed Drug Selection
Whole exome sequencing and RNA sequencing identify the specific mutations, amplifications, pathway activations, and gene expression changes in an individual tumor. These findings guide repurposed drug selection in two important ways.
First, profiling shows whether a tumor has a biological target that a specific repurposed drug acts on. If mTOR pathway overactivation is found, drugs that influence this pathway become biologically plausible to explore. If c-Met amplification is identified, drugs with c-Met inhibitory properties warrant discussion with the treating team. The molecular profile shows which drug-pathway interactions are most relevant for this specific tumor.
Second, molecular data is frequently required for clinical trial eligibility. Many trials recruiting patients for repurposed drug studies require specific molecular criteria that a standard pathology report may not show. Without broader sequencing, patients may not know they qualify for trials designed around their tumor's genetic characteristics.
A trial registered at ClinicalTrials.gov (NCT02060890) has examined molecular profiling as a guide to individualized treatment planning in adults with recurring or progressive glioblastoma, showing how this approach is being incorporated into research protocols.
For families trying to understand existing molecular results, this patient guide to interpreting glioblastoma molecular reports explains what key mutations, pathways, and markers mean for treatment options and drug selection.
What Reports Should You Gather Before Seeking an Expert Review?
Before requesting a tumor intelligence review or precision oncology consultation, collect the right documents so a specialist team can conduct a thorough assessment. Gather these documents:
- Pathology Report—the primary diagnostic document including tumor grade and WHO classification
- Histopathology Report—detailed cellular analysis from the surgical specimen
- MRI Brain Reports—including pre-operative, post-operative, and all follow-up imaging
- Surgical Notes—documenting the extent of resection and operative findings
- Molecular Testing Results—MGMT methylation status, IDH mutation status, EGFR amplification, TERT promoter status, and any panel sequencing performed
- Current Treatment Plan—including radiation protocol, chemotherapy regimen, and any additional treatments
- Previous Treatment History—especially important at recurrence to understand prior drug exposures and potential resistance
For a complete preparation checklist, this guide to preparing for a tumor intelligence review covers everything an expert team needs to assess a case.
What International Patients Need to Know
Patients and caregivers in London, Manchester, New York, Sydney, Toronto, and other cities are increasingly seeking precision oncology input beyond what local care offers. This is not criticism of local oncologists—most deliver appropriate standard treatment. It reflects the fact that interpreting advanced drug sensitivity findings and evaluating repurposed drug candidates against a specific tumor's molecular biology requires specialist expertise outside the routine scope of most neuro-oncology services.
Geography does not limit access to this assessment. Molecular reports can be reviewed remotely. MRI scans can be assessed digitally. Pathology findings and surgical notes can be evaluated without the patient leaving their home country. Initial consultations happen online. Many families start with a virtual case review—a practical first step that clarifies the current molecular picture, identifies which repurposed drug candidates are relevant to this tumor, and shows whether any active clinical trials match the patient's profile.
Expertise matters more than location. Understanding your tumor's biology adds precision to every treatment conversation that follows, regardless of where that conversation takes place.
Common Mistakes Families Make When Researching Off-Label Options
- Pursuing repurposed drugs without molecular context. The usefulness of any repurposed drug depends on whether the tumor has the biological target that drug acts on. Using a drug without first understanding the tumor's pathway activity wastes time and introduces unnecessary risk.
- Relying solely on anecdotal reports. Individual patient stories spread widely in online GBM communities. They can signal important findings but are not clinical evidence. Glioblastoma biology varies greatly between patients. What appeared to help one tumor may be irrelevant or harmful to another.
- Waiting until recurrence to investigate. Molecular profiling and drug sensitivity analysis are most valuable when completed early. Identifying repurposed drug candidates and clinical trial eligibility before recurrence allows options to be understood and ready before the treatment window narrows.
- Assuming the standard molecular panel is complete. MGMT and IDH status are important but show only a narrow slice of tumor biology. Broader sequencing may reveal additional vulnerabilities not visible in the standard diagnostic report.
Questions to Ask Your Oncology Team
- Has my tumor been profiled beyond MGMT methylation and IDH mutation status? Would broader sequencing help?
- Are there active clinical trials for repurposed drugs that my tumor's molecular profile might qualify for?
- Would whole exome sequencing or RNA sequencing reveal additional information relevant to current or future treatment decisions?
- If my tumor recurs, what would guide the choice among salvage treatment options—and how would my tumor's molecular biology factor into that decision?
- Does this center have a multidisciplinary tumor board that considers off-label or investigational strategies for GBM?
Taking the Next Step
Every glioblastoma is biologically unique. The pathways driving one patient's tumor may be inactive in another's. Understanding those biological differences makes it possible to have a genuinely informed conversation about repurposed drugs, drug sensitivity findings, and trial eligibility—conversations that go beyond what a standard diagnostic workup alone can support.
If you or a loved one has been diagnosed with glioblastoma or is facing recurrence, gather your pathology reports, MRI scans, surgical notes, and molecular testing results. A precision oncology team can review these materials, identify biological insights relevant to your tumor's profile, and help clarify which questions are worth raising with your treating physicians.
Many families begin with a remote consultation and report review—a practical step that does not replace local care but adds molecular intelligence to the decisions ahead.
When to Talk to Your Doctor
If you are researching repurposed drugs or drug sensitivity analysis for yourself or a family member, discuss these findings with your treating neuro-oncologist before making any changes to an existing treatment plan. Off-label drugs—even those with well-established safety profiles in other clinical settings—can interact with chemotherapy drugs, affect the metabolism of anti-seizure medications, or alter radiation response. These decisions require guidance from a qualified medical professional who knows your full clinical picture.
This article is for general information and is not a substitute for medical advice. Always consult your oncologist or care team about your specific situation.