Our Research

Advances in research through focus and expertise.

Our Research

Advances in research through focus and expertise.

Diffuse Intrinsic Pontine Glioma (DIPG)

The Rutka Lab is developing new ways to treat this universally fatal paediatric brain tumour.

Unlike some tumour types, DIPG cannot be surgically removed.

DIPG is inoperable because of its location within the brainstem. The brainstem (outlined in yellow) controls vital functions like breathing, heart rate and blood pressure. The DIPG tumour is highlighted in pink.

Brain MRI (sagittal view) showing DIPG. The brainstem is outlined in yellow, the DIPG tumour is highlighted in pink.

The Rutka Lab is developing new ways to treat this universally fatal paediatric brain tumour.

Unlike some tumour types, DIPG cannot be surgically removed.

DIPG is inoperable because of its location within the brainstem. The brainstem (outlined in yellow) controls vital functions like breathing, heart rate and blood pressure. The DIPG tumour is highlighted in pink.

Brain MRI (sagittal view) showing DIPG. The brainstem is outlined in yellow, the DIPG tumour is highlighted in pink.
3D rendering of the inside of a blood vessel with red blood cells flowing through. A section of the blood vessel is enlarged to show the tight junctions in the walls of the vessel.

The blood-brain barrier presents a unique problem.

Like a security gate, the blood-brain barrier (BBB) protects the brain – stopping toxins, viruses and other harmful compounds from leaving the bloodstream and entering the brain.

In the same way, the BBB prevents helpful chemotherapies from reaching tumour targets.

In fact, there have been hundreds of clinical trials for DIPG using drugs that are predicted to work in patients, but because the BBB blocks these new drugs from reaching the tumour, the clinical trials inevitably fail.

The blood-brain barrier presents a unique problem.

Like a security gate, the blood-brain barrier (BBB) protects the brain – stopping toxins, viruses and other harmful compounds from leaving the bloodstream and entering the brain.

In the same way, the BBB prevents helpful chemotherapies from reaching tumour targets.

In fact, there have been hundreds of clinical trials for DIPG using drugs that are predicted to work in patients, but because the BBB blocks these new drugs from reaching the tumour, the clinical trials inevitably fail.

3D rendering of the inside of a blood vessel with red blood cells flowing through. A section of the blood vessel is enlarged to show the tight junctions in the walls of the vessel.

The blood-brain barrier presents a unique problem.

Like a security gate, the blood-brain barrier (BBB) protects the brain – stopping toxins, viruses and other harmful compounds from leaving the bloodstream and entering the brain.

In the same way, the BBB prevents helpful chemotherapies from reaching tumour targets.

In fact, there have been hundreds of clinical trials for DIPG using drugs that are predicted to work in patients, but because the BBB blocks these new drugs from reaching the tumour, the clinical trials inevitably fail.

3D rendering of the inside of a blood vessel with red blood cells flowing through. A section of the blood vessel is enlarged to show the tight junctions in the walls of the vessel.

To overcome this obstacle, we collaborated with Dr. Kullervo Hynynen and his biophysics lab at Sunnybrook Hospital.

We developed a way to test drug delivery by temporarily opening the BBB using ultrasound waves.

This gives us a four-hour window to administer chemotherapy directly to the tumour. MRI machines are used to focus the ultrasound to ensure none of the surrounding healthy tissue is affected. Photo credit: Sunnybrook Health Sciences Centre.

A photograph of a healthcare team prepping a patient for an MRI.

To overcome this obstacle, we collaborated with Dr. Kullervo Hynynen and his biophysics lab at Sunnybrook Hospital.

We developed a way to test drug delivery by temporarily opening the BBB using ultrasound waves.

This gives us a four-hour window to administer chemotherapy directly to the tumour. MRI machines are used to focus the ultrasound to ensure none of the surrounding healthy tissue is affected. Photo credit: Sunnybrook Health Sciences Centre.

A photograph of a healthcare team prepping a patient for an MRI.

“Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.”

– Marie Curie

How did we get here? Background research was conducted in mouse models.

The brains of mice and humans are remarkably evolutionarily conserved, which means the cell types making up the brain and its structural architecture are similar. Consequently, mouse models that develop DIPG tumours within the mouse brainstem can be utilized experimentally. We set out to test the effectiveness of targeted chemotherapy when paired with MRI-guided focused ultrasound (MRgFUS) in mouse models of DIPG.

Image of four mouse brains (sagittal sections) with magnified areas of cells showing the expression of four molecular markers (Ki-67, Nestin, p53, H3K27me3).

DIPG mouse models exhibit the same molecular markers as clinical DIPGs. Immunohistochemistry on SU-DIPG-17 xenografts (mice with human tumours) revealed expression patterns for 4 common DIPG molecular markers (Ki-67, Nestin, p53, H3K27me3) that closely resembled those seen in clinical patient samples.

How did we get here? Background research was conducted in mouse models.

The brains of mice and humans are remarkably evolutionarily conserved, which means the cell types making up the brain and its structural architecture are similar. Consequently, mouse models that develop DIPG tumours within the mouse brainstem can be utilized experimentally. We set out to test the effectiveness of targeted chemotherapy when paired with MRI-guided focused ultrasound (MRgFUS) in mouse models of DIPG.

Image of four mouse brains (sagittal sections) with magnified areas of cells showing the expression of four molecular markers (Ki-67, Nestin, p53, H3K27me3).

DIPG mouse models exhibit the same molecular markers as clinical DIPGs. Immunohistochemistry on SU-DIPG-17 xenografts (mice with human tumours) revealed expression patterns for 4 common DIPG molecular markers (Ki-67, Nestin, p53, H3K27me3) that closely resembled those seen in clinical patient samples.

Before and after MRI images of a mouse brain showing enhancement of blood-brain barrier permeability via MRgFUS.

Enhancement of BBB permeability via MRgFUS resulted in increased doxorubicin uptake in SU-DIPG-17 tumours. A) A targeting grid (right) was mapped to cover the entire tumour region prior to ultrasound treatment. B) The tumour area targeted on the T2 weighted image was treated with ultrasound and the contrast agent Gadolinium was observed in the same area in post treatment images (right) suggesting successful BBB permeability and uptake of circulating contrast agent.

Choosing the right chemotherapeutic

Doxorubicin was selected from a drug screen consisting of conventional chemotherapeutics tested on patient-derived cell lines. Doxorubicin was the ideal choice because it not only demonstrated efficacy on DIPG cell lines, but also because it normally doesn’t cross the BBB – shielding the normal brain tissue and limiting potential side effects.

Mice that develop DIPG tumours demonstrated a diffusely infiltrative tumour growth pattern similar to human DIPG. In our study, SU-DIPG-17 xenografts were more representative of human DIPG with an intact BBB.

The importance of choosing the right chemotherapeutic

Doxorubicin was selected from a drug screen consisting of conventional chemotherapeutics tested on patient-derived cell lines. Doxorubicin was the ideal choice because it not only demonstrated efficacy on DIPG cell lines, but also because it normally doesn’t cross the BBB – shielding the normal brain tissue and limiting potential side effects.

Mice that develop DIPG tumours demonstrated a diffusely infiltrative tumour growth pattern similar to human DIPG. In our study, SU-DIPG-17 xenografts were more representative of human DIPG with an intact BBB.

Before and after MRI images of a mouse brain showing enhancement of blood-brain barrier permeability via MRgFUS.

Enhancement of BBB permeability via MRgFUS resulted in increased doxorubicin uptake in SU-DIPG-17 tumours. A) A targeting grid (right) was mapped to cover the entire tumour region prior to ultrasound treatment. B) The tumour area targeted on the T2 weighted image was treated with ultrasound and the contrast agent Gadolinium was observed in the same area in post treatment images (right) suggesting successful BBB permeability and uptake of circulating contrast agent.

Choosing the right chemotherapeutic

Doxorubicin was selected from a drug screen consisting of conventional chemotherapeutics tested on patient-derived cell lines. Doxorubicin was the ideal choice because it not only demonstrated efficacy on DIPG cell lines, but also because it normally doesn’t cross the BBB – shielding the normal brain tissue and limiting potential side effects.

Mice that develop DIPG tumours demonstrated a diffusely infiltrative tumour growth pattern similar to human DIPG. In our study, SU-DIPG-17 xenografts were more representative of human DIPG with an intact BBB.

Before and after MRI images of a mouse brain showing enhancement of blood-brain barrier permeability via MRgFUS.

Enhancement of BBB permeability via MRgFUS resulted in increased doxorubicin uptake in SU-DIPG-17 tumours. A) A targeting grid (right) was mapped to cover the entire tumour region prior to ultrasound treatment. B) The tumour area targeted on the T2 weighted image was treated with ultrasound and the contrast agent Gadolinium was observed in the same area in post treatment images (right) suggesting successful BBB permeability and uptake of circulating contrast agent.

Testing the results of our MRgFUS experiment

Following IV administration of doxorubicin, MRgFUS-treated animals exhibited a 4-fold higher concentration of the chemotherapy drug within the SU-DIPG-17 brainstem tumours compared to controls not exposed to ultrasound.

Bar graph showing that mice that received MRgFUS treatment showed significantly higher brainstem/plasma ratio of chemotherapy drug Doxorubicin (Dox).

Liquid chromatography-mass spectrometry (LC-MS)/mass spectrometry (MS) revealed that mice that received MRgFUS treatment showed significantly higher brainstem/plasma ratio of chemotherapy drug Doxorubicin (Dox).

Testing the results of our MRgFUS experiment

Following IV administration of doxorubicin, MRgFUS-treated animals exhibited a 4-fold higher concentration of the chemotherapy drug within the SU-DIPG-17 brainstem tumours compared to controls not exposed to ultrasound.

Bar graph showing that mice that received MRgFUS treatment showed significantly higher brainstem/plasma ratio of chemotherapy drug Doxorubicin (Dox).

Liquid chromatography-mass spectrometry (LC-MS)/mass spectrometry (MS) revealed that mice that received MRgFUS treatment showed significantly higher brainstem/plasma ratio of chemotherapy drug Doxorubicin (Dox).

An exciting next step – applying our research to the patient population

The successes in our studies has directly resulted in the opening of a world-first clinical trial to test enhanced drug delivery using focused ultrasound in patients with DIPG. The trial is now Health Canada approved and the very first patient enrolled in the trial received ultrasound treatment in January 2023! A huge landmark!

Currently, our lab is extending our focus to finding the right chemotherapy drugs for each patient (called targeted therapy) that will work synergistically to shrink and hopefully eliminate the tumour.

An exciting next step – applying our research to the patient population

The successes in our studies has directly resulted in the opening of a world-first clinical trial to test enhanced drug delivery using focused ultrasound in patients with DIPG. The trial is now Health Canada approved and the very first patient enrolled in the trial received ultrasound treatment in January 2023! A huge landmark!

Currently, our lab is extending our focus to finding the right chemotherapy drugs for each patient (called targeted therapy) that will work synergistically to shrink and hopefully eliminate the tumour.

Glioblastoma

Malignant gliomas are highly aggressive cancers.

Despite surgery, chemotherapy, and radiation therapy, survival expectancy is less than 2 years.

Over the past 30 years, limited progress has been made in treating this aggressive cancer despite our increased understanding of the molecular genetics and basic biology of these tumours. New treatment strategies are desperately needed. The cerebrum (outlined in yellow) is responsible for sending and receiving signals to and from the body. A typical tumour is highlighted in pink.

Brain MRI (transverse view) showing a brain tumour. The cerebrum is outlined in yellow, the tumour (glioblastoma) is highlighted in pink.

Malignant gliomas are highly aggressive cancers.

Despite surgery, chemotherapy, and radiation therapy, survival expectancy is less than 2 years.

Over the past 30 years, limited progress has been made in treating this aggressive cancer despite our increased understanding of the molecular genetics and basic biology of these tumours. New treatment strategies are desperately needed. The cerebrum (outlined in yellow) is responsible for sending and receiving signals to and from the body. A typical tumour is highlighted in pink.

Brain MRI (transverse view) showing a brain tumour. The cerebrum is outlined in yellow, the tumour (glioblastoma) is highlighted in pink.
Illustration of a brain with a glioma (transverse section). The tumour center is labelled as necrosis, the area around the center is labelled as the glioma core, and a more diffuse area of cells outside of the core is labelled as the zone of infiltration.

Malignant gliomas are comprised of two zones/types of cells.

There is a central core of cancer cells which is rapidly dividing to increase tumour mass. Cells within the core have evolved ways to resist chemotherapy and radiation, threatening their effectiveness.

There are also highly invasive cells which are not rapidly dividing and can migrate a considerable distance away from the central core. These cells tend to reside in the periphery of the tumour, and are what we refer to as the “zone of infiltration” (ZOI). These invading glioma cells are somewhat protected by an intact blood brain barrier which prevents chemotherapy from effectively reaching them.

Malignant gliomas are comprised of two zones/types of cells.

There is a central core of cancer cells which is rapidly dividing to increase tumour mass. Cells within the core have evolved ways to resist chemotherapy and radiation, threatening their effectiveness.

There are also highly invasive cells which are not rapidly dividing and can migrate a considerable distance away from the central core. These cells tend to reside in the periphery of the tumour, and are what we refer to as the “zone of infiltration” (ZOI). These invading glioma cells are somewhat protected by an intact blood brain barrier which prevents chemotherapy from effectively reaching them.

Illustration of a brain with a glioma (transverse section). The tumour center is labelled as necrosis, the area around the center is labelled as the glioma core, and a more diffuse area of cells outside of the core is labelled as the zone of infiltration.

Malignant gliomas are comprised of two zones/types of cells.

There is a central core of cancer cells which is rapidly dividing to increase tumour mass. Cells within the core have evolved ways to resist chemotherapy and radiation, threatening their effectiveness.

There are also highly invasive cells which are not rapidly dividing and can migrate a considerable distance away from the central core. These cells tend to reside in the periphery of the tumour, and are what we refer to as the “zone of infiltration” (ZOI). These invading glioma cells are somewhat protected by an intact blood brain barrier which prevents chemotherapy from effectively reaching them.

Illustration of a brain with a glioma (transverse section). The tumour center is labelled as necrosis, the area around the center is labelled as the glioma core, and a more diffuse area of cells outside of the core is labelled as the zone of infiltration.

Our lab is developing novel therapies to treat the rapidly dividing cells in the glioma core.

One approach is to focus on metabolically reprogramming the core cells.

This reprogramming acts to reduce their proliferation, and to inhibit glioma cells from following pro-survival pathways in response to cellular stresses such as low oxygen levels, chemotherapy, and radiation therapy.

3D Rendering of an isolated tumor microenvironment. The tumour core is made of vascularized, closely packed, dark blue and purple cells. Single cells extend out into the surrounding environment.

Our lab is developing novel therapies to treat the rapidly dividing cells in the glioma core.

One approach is to focus on metabolically reprogramming the core cells.

This reprogramming acts to reduce their proliferation, and to inhibit glioma cells from following pro-survival pathways in response to cellular stresses such as low oxygen levels, chemotherapy, and radiation therapy.

3D Rendering of an isolated tumor microenvironment. The tumour core is made of vascularized, closely packed, dark blue and purple cells. Single cells extend out into the surrounding environment.
3D rendering of a migrating cancer cell. The cell is pink with a dark purple nucleus and orange filaments extending outward. The background is a dark grey gradient.

Targeting invading glioma cells is just as important.

How do we do it?

We target invading glioma cells using novel inhibitors of cell invasion, and MRI-guided focused ultrasound to break down the BBB around the tumour core and facilitate contact of inhibitors with the invading cells.

We anticipate that our approach of simultaneous precision targeting of the glioma core and zone of infiltration with potent drugs and advanced delivery strategies will provide therapeutic and survival benefit to patients suffering from this lethal cancer.

Targeting invading glioma cells is just as important.

How do we do it?

We target invading glioma cells using novel inhibitors of cell invasion, and MRI-guided focused ultrasound to break down the BBB around the tumour core and facilitate contact of inhibitors with the invading cells.

We anticipate that our approach of simultaneous precision targeting of the glioma core and zone of infiltration with potent drugs and advanced delivery strategies will provide therapeutic and survival benefit to patients suffering from this lethal cancer.

3D rendering of a migrating cancer cell. The cell is pink with a dark purple nucleus and orange filaments extending outward. The background is a dark grey gradient.

Targeting invading glioma cells is just as important.

How do we do it?

We target invading glioma cells using novel inhibitors of cell invasion, and MRI-guided focused ultrasound to break down the BBB around the tumour core and facilitate contact of inhibitors with the invading cells.

We anticipate that our approach of simultaneous precision targeting of the glioma core and zone of infiltration with potent drugs and advanced delivery strategies will provide therapeutic and survival benefit to patients suffering from this lethal cancer.

3D rendering of a migrating cancer cell. The cell is pink with a dark purple nucleus and orange filaments extending outward. The background is a dark grey gradient.

Additional Strategies

3D rendering of layers of spaced out, blue-green mitochondria floating on top of one another. The top layer is in focus, the bottom layers are out of focus.

Mitochondria: A new mechanism underlying chemotherapy resistance?

Part of the reason glioblastoma is so difficult to treat is due to its rapid ability to adapt and overcome the effects of chemotherapy and radiation, often within months. We now know that mitochondria, the energy machinery of the cell, plays a role in how glioblastoma responds to chemotherapy and helps these tumours recur after treatment. We have discovered a new mechanism of chemotherapy resistance within the mitochondria that has the potential to be exploited to make cancer cells more sensitive to existing therapies.

Mitochondria: A new mechanism underlying chemotherapy resistance?

Part of the reason glioblastoma is so difficult to treat is due to its rapid ability to adapt and overcome the effects of chemotherapy and radiation, often within months. We now know that mitochondria, the energy machinery of the cell, plays a role in how glioblastoma responds to chemotherapy and helps these tumours recur after treatment. We have discovered a new mechanism of chemotherapy resistance within the mitochondria that has the potential to be exploited to make cancer cells more sensitive to existing therapies.

3D rendering of layers of spaced out, blue-green mitochondria floating on top of one another. The top layer is in focus, the bottom layers are out of focus.

Mitochondria: A new mechanism underlying chemotherapy resistance?

Part of the reason glioblastoma is so difficult to treat is due to its rapid ability to adapt and overcome the effects of chemotherapy and radiation, often within months. We now know that mitochondria, the energy machinery of the cell, plays a role in how glioblastoma responds to chemotherapy and helps these tumours recur after treatment. We have discovered a new mechanism of chemotherapy resistance within the mitochondria that has the potential to be exploited to make cancer cells more sensitive to existing therapies.

3D rendering of layers of spaced out, blue-green mitochondria floating on top of one another. The top layer is in focus, the bottom layers are out of focus.

Outsmarting the blood-brain barrier: A novel strategy for brain tumour treatment

Using gold nanoparticles, microbubbles and focused ultrasound we can localize chemotherapeutics to tumours in high concentrations. Tumour targeting antibodies attached to the gold nanoparticle allow glioma cells to internalize them, releasing their attached drugs within the tumour cell, resulting in cell death. Watch our animation demonstrating this process below.

Text on screen: Outsmarting the Blood-Brain Barrier: A Novel Strategy for Brain Tumour Treatment. A Master’s Research Project submitted in conformity with the requirements for the degree of Master of Science in Biomedical Communications (MScBMC). Offered through the Institute of Medical Science, Faculty of Medicine, University of Toronto in collaboration with Biomedical Communications, Department of Biology, University of Toronto Mississauga. Copyright 2015.

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Text on screen: SLK ART presents, in association with The Arthur and Sonia Labatt Brain Tumour Research Centre, Outsmarting the Blood-Brain Barrier: A Novel Strategy for Brain Tumour Treatment

A voice off screen: Every day, 27 Canadians are diagnosed with a brain tumour. The most common type of primary malignant brain tumour is glioblastoma multiforme. Average survival, even with aggressive treatment, is less than one year. One of the main obstacles in the treatment of brain tumours is the effective delivery of therapeutics across the blood-brain barrier. This barrier serves to protect the brain from harmful toxins and chemicals, by allowing only certain molecules to leave the blood and enter the brain tissue. So how do we get anti-cancer therapeutics pass the blood-brain barrier? One approach is to use gold nanoparticles as carriers. These nanoparticles are able to cross the blood-brain barrier due to their minute size. Once in the brain tissue, tumour specific antibodies help to specifically target cancer cells. But how do we focus the nanoparticles to the area of the brain that has the tumour? The Peter Gilligan Center for Research and Learning is home to the Arthur and Sonia Labatt Brain Tumour Research Centre. Researchers here have found a way to use MRI-guided focus ultrasound to outsmart the blood-brain barrier. This technique is being developed using mouse models of brain tumours. The mouse shown here has a growing brain tumour and can be used to evaluate the delivery of therapeutic-laden gold nanoparticles to tumour tissue. Via the tail vein, the mouse is intravenously administered ultrasound responsive micro bubbles. As the micro bubbles reach the brain and the tumour capillary bed, magnetic resonance imaging is used to focus ultrasound waves on the specific area of the brain where the tumour is located. The ultrasound waves trigger a transient size enhancement in the micro bubbles. The swelling of the micro bubbles within the ultrasound field causes microscopic physical disruptions of the capillary lining and results in a localized, temporary breach of the blood-brain barrier. The mouse is then injected with the therapeutic-laden, antibody-coated gold nanoparticles. The nanoparticles travel in the blood, reaching the area of the brain tumour. The holes in the capillary lining, temporarily created by the micro bubbles, allow the nanoparticles to escape the blood-brain barrier and enter into the extracellular space of the tumour tissue. This results in a concentration of gold nanoparticles in the region of the tumour. Tumour cells have receptors expressed on their surface. The antibodies on the surface of the nanoparticles allow them to bind to certain receptors that are enriched on the surface of tumour cells. Binding to the cell surface receptor triggers internalization of the nanoparticle. The internalized nanoparticles release their anti-cancer drugs within the tumour cell, triggering the cell to die. This process occurs simultaneously throughout the tumour, resulting in widespread tumour cell death. This not only significantly reduces the size of the brain tumour, but importantly, eliminates aggressive, invasive cells along the tumour border. With success of this tumour targeting strategy in mouse models, it is our hope to apply this technology to the treatment and elimination of various types of human brain tumours.

Text on screen: Committee Members. Faculty Advisor. Shelley Wall, AOCAD, MScBMC, PhD. Assistant Professor. Biomedical Communications Program. Institute of Medical Science, Faculty of Medicine, University of Toronto. Department of Biology, University of Toronto at Mississauga. Content Advisors. James T. Rutka, MD, PhD, FRCSC, FACS, FAAP. R.S. McLaughlin Professor and Chair. Department of Surgery, University of Toronto. Christian Smith, PhD. Operations Manager. Labatt Brain Tumour Research Centre, Hospital for Sick Children. Any material contained in this video must not be manipulated, reproduced, or distributed without permission. Copyright 2015.

A very special thank you to: The Class of 1T5 – Natalie Cormier, Kateryna Procunier, Derek Ng, Cassandra Cetlin, Robert Lancefield, Jerry Won, Priya Panchal, Chi-Chun Liu, Sara Vukson, Naveen Devasagayam, Christy Groves, Lauren DiVito, Kristen Browne, Ashley Hui, Vijay Shahani, Qingyang Chen. My Family & Friends – Brandon Town, Erica Banihashemi, Stephanie Porter. The BMC Program & Faculty – Maeve Doyle, Marc Dryer, Stuart Jantzen, Nick Woolridge, Jodie Jenkinson, Michael Corrin, Dave Mazierski, Leila Lax, Andrea Gauthier, Linda Wilson-Pauwels.

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