Scientists reported positive Phase 1 trial results of their “intratumoral microdevice” in patients with glioma tumors
Here is an example of new microtechnology which has the potential to greatly shorten the time and improve the ability of physicians to determine which anti-cancer drug is most effective for an individual patient’s glioblastoma. As it is further developed, this technology could give anatomic pathologists and clinical laboratories an increased role in assessing the data produced by microdevices and helping physicians determine the most appropriate anti-cancer drug for specific patients.
In a news release, researchers at Brigham and Women’s Hospital (BWH) in Boston said they have developed an implantable “intratumoral microdevice” (IMD) that functions as a “lab in a patient,” capable of gauging the effectiveness of multiple drugs that target brain tumors. In a Phase 1 clinical trial, they tested the IMD on six patients with glioma tumors.
“In order to make the greatest impact on how we treat these tumors, we need to be able to understand, early on, which drug works best for any given patient,” study co-author Pier Paolo Peruzzi, MD, PhD, told the Harvard Gazette. “The problem is that the tools that are currently available to answer this question are just not good enough. So, we came up with the idea of making each patient their own lab, by using a device which can directly interrogate the living tumor and give us the information that we need.”
Peruzzi is Principal Investigator at the Harvey Cushing Neuro-Oncology Laboratories and Assistant Professor of Neurosurgery at Harvard Medical School.
“Our goal is for the placement of these devices to become an integral part of tumor surgery,” said Pier Paolo Peruzzi, MD PhD (above) of Brigham and Women’s Hospital and Harvard Medical School in an article he co-wrote for Healio. “Then, with the data that we have from these microdevices, we can choose the best systemic chemotherapy to give to that patient.” Pathologists and clinical laboratories may soon play a role in helping doctors interpret data gathered by implantable microdevices and choose the best therapies for their patients. (Photo copyright: Dana-Farber Cancer Institute.)
New Perspective on Tumor Treatments
In a news story he co-wrote for Healio, Peruzzi explained that the microdevice—about the size and shape of a grain of rice—contains up to 30 tiny reservoirs that the researchers fill with the drugs they want to test. Surgeons implant the device during a procedure to remove the tumors.
The surgery takes two to three hours to perform, and during that time, the device releases “nanodoses” of the drugs into confined areas of the tumor. Near the end of the procedure, the device is removed along with tissue specimens. The researchers can then analyze the tissue to determine the effectiveness of each drug.
“This is not in the lab, and not in a petri dish,” Peruzzi told Harvard Gazette. “It’s actually in real patients in real time, which gives us a whole new perspective on how these tumors respond to treatment.”
The Healio story notes that gliomas are “among the deadliest brain cancers and are notoriously difficult to treat.” With current approaches, testing different therapies has posed a challenge, Peruzzi wrote.
“Right now, the only way these drugs are tested in patients is through what are called window-of-opportunity studies, where we give one drug to the patient before we resect the tumor and analyze the effect of the drug,” he said. “We can only do this with one drug at a time.”
Determining Safety of Procedure
The primary goal of the Phase 1 trial was to determine the safety of the procedure, Peruzzi noted. “To be in compliance with standard clinical practice and minimize risks to the patients, we needed to integrate the placement and retrieval of the device during an otherwise standard operation.”
The trial consisted of three men and three women ranging from 27 to 86 years old, with a median age of 76. Five were diagnosed with glioblastoma and one with grade 4 astrocytoma.
“None of the six enrolled patients experienced adverse events related to the IMD, and the exposed tissue was usable for downstream analysis for 11 out of 12 retrieved specimens,” the researchers wrote in Science Translational Medicine. They noted that application of the IMD added about 32 minutes to the time required for the surgery, equating to a cost increase of $7,800.
One drug they tested was temozolomide (TMZ), “the most widely used agent in this patient population,” they wrote. “Several patients in our trial received it systemically, either before or after IMD insertion, as part of the standard of care. Thus, although our trial was not designed to choose chemotherapy agents based on IMD data, we still could compare the observed clinical-radiological response to systemic TMZ with the patient-specific response to TMZ in the IMD-exposed tissue.”
One patient, the researchers noted, had not benefited from the drug “in concordance with the poor tissue response observed in the IMD analysis.” But in another patient, a 72-year-old woman, “IMD analysis showed a marked response to TMZ,” and she survived for 20 months after receiving the treatment “with radiological evidence of tumor response. This was despite having a subtotal tumor resection, in itself an unfavorable prognostic factor. The patient expired because of an unrelated cardiovascular event, although she had remained neurologically stable.”
Drug Duration Limitation
One limitation of the study was that testing the device during the tumor removal procedure limited the duration of the drug treatments, Peruzzi said. The Harvard Gazette noted that following their initial study, the researchers were testing a variation of the procedure in which the device is implanted three days before the main surgery in a minimally invasive technique. This gives the drugs more time to work.
Cancer researchers have theorized that common treatments for tumors can impair the immune system, Peruzzi wrote in Healio. “One thing we want to look at is which drugs can kill the tumor without killing the immune system as well,” he noted.
Future studies will determine the effectiveness of implanting microdevices into tumors to test therapies in vivo. Should they become viable, clinical laboratories and anatomic pathologists will likely be involved in receiving, interpreting, storing, and transmitting the data gathered by these devices to the patient’s doctors.
Ten year collaboration between Google and Harvard may lead to a deeper understanding of the brain and new clinical laboratory diagnostics
With all our anatomic pathology and clinical laboratory science, we still do not know that much about the structure of the brain. But now, scientists at Harvard University and Google Research studying the emerging field of connectomics have published a highly detailed 3D reconstruction of human brain tissue that allows visualization of neurons and their connections at unprecedented nanoscale resolutions.
Further investigation of the nano-connections within the human brain could lead to novel insights about the role specific proteins and molecules play in the function of the brain. Though it will likely be years down the road, data derived from this study could be used to develop new clinical laboratory diagnostic tests.
The data to generate the model came from Google’s use of artificial intelligence (AI) algorithms to color-code Harvard’s electron microscope imaging of a cubic millimeter of neural tissue—equivalent to a half-grain of rice—that was surgically removed from an epilepsy patient.
“That tiny square contains 57,000 cells, 230 millimeters of blood vessels, and 150 million synapses, all amounting to 1,400 terabytes of data,” according to the Harvard Gazette, which described the project as “the largest-ever dataset of human neural connections.”
“A terabyte is, for most people, gigantic, yet a fragment of a human brain—just a minuscule, teeny-weeny little bit of human brain—is still thousands of terabytes,” said neuroscientist Jeff W. Lichtman, MD, PhD, Jeremy R. Knowles Professor of Molecular and Cellular Biology, whose Lichtman Lab at Harvard University collaborated on the project with researchers from Google. The two labs have been working together for nearly 10 years on this project, the Harvard Gazette reported.
Lichtman’s lab focuses on the emerging field of connectomics, defined “as understanding how individual neurons are connected to one another to form functional networks,” said neurobiologist Wei-Chung Allen Lee, PhD, Assistant Professor of Neurology, Harvard Medical School, in an interview with Harvard Medical News. “The goal is to create connectomes—or detailed structural maps of connectivity—where we can see every neuron and every connection.” Lee was not involved with the Harvard/Google Research study.
“The human brain uses no more power than a dim incandescent light bulb, yet it can accomplish feats still not possible with the largest artificial computing systems,” wrote Google Research scientist Viren Jain, PhD (above), in a blog post. “To understand how requires a level of understanding more profound than knowing what part of the brain is responsible for what function. The field of connectomics aims to achieve this by precisely mapping how each cell is connected to others.” Google’s 10-year collaboration with Harvard University may lead to new clinical laboratory diagnostics. (Photo copyright: Google Research.)
Study Data and Tools Freely Available
Along with the Science paper, the researchers publicly released the data along with analytic and visualization tools. The study noted that the dataset “is large and incompletely scrutinized,” so the scientists are inviting other researchers to assist in improving the model.
“The ability for other researchers to proofread and refine this human brain connectome is one of many ways that we see the release of this paper and the associated tools as not only the culmination of 10 years of work, but the beginning of something new,” wrote Google Research scientist Viren Jain, PhD, in a blog post that included links to the online resources.
One of those tools—Neuroglancer—allows any user with a web browser to view 3D models of neurons, axons, synapses, dendrites, blood vessels, and other objects. Users can rotate the models in xyz dimensions.
Users with the requisite knowledge and skills can proofread and correct the models by signing up for a CAVE (Connectome Annotation Versioning Engine) account.
Researchers Found Several Surprises
To perform their study, Lichtman’s team cut the neural tissue into 5,000 slices, each approximately 30 nanometers thick, Jain explained in the blog post. They then used a multibeam scanning electron microscope to capture high-resolution images, a process that took 326 days.
Jain’s team at Google used AI tools to build the model. They “stitched and aligned the image data, reconstructed the three dimensional structure of each cell, including its axons and dendrites, identified synaptic connections, and classified cell types,” he explained.
Jain pointed to “several surprises” that the reconstruction revealed. For example, he noted that “96.5% of contacts between axons and their target cells have just one synapse.” However, he added, “we found a class of rare but extremely powerful synaptic connections in which a pair of neurons may be connected by more than 50 individual synapses.”
In their Science paper, the researchers suggest that “these powerful connections are not the result of chance, but rather that these pairs had a reason to be more strongly connected than is typical,” Jain wrote in the blog post. “Further study of these connections could reveal their functional role in the brain.”
Mysterious Structures
Another anomaly was the presence of “axon whorls,” as Jain described them, “beautiful but mysterious structures in which an axon wraps itself into complicated knots.”
Because the sample came from an epilepsy patient, Jain noted that the whorls could be connected to the disease or therapies or could be found in all brains.
“Given the scale and complexity of the dataset, we expect that there are many other novel structures and characteristics yet to be discovered,” he wrote. “These findings are the tip of the iceberg of what we expect connectomics will tell us about human brains.”
The researchers have a larger goal to create a comprehensive high-resolution map of a mouse’s brain, Harvard Medical News noted. This would contain approximately 1,000 times the data found in the 1-cubic-millimeter human sample.
Dark Daily has been tracking the different fields of “omics” for years, as research teams announce new findings and coin new areas of science and medicine to which “omics” is appended. Connectomics fits that description.
Though the Harvard/Google research is not likely to lead to diagnostic assays or clinical laboratory tests any time soon, it is an example of how advances in technologies are enabling researchers to investigate smaller and smaller elements within the human body.
‘Prime editing’ is what researchers are calling the proof-of-concept research that promises improved diagnostics and more effective treatments for patients with genetic defects
Known as Prime Editing, the scientists developed this technique as a more accurate way to edit Deoxyribonucleic acid (DNA). In a paper published in Nature, the authors claim prime editing has the potential to correct up to 89% of disease-causing genetic variations. They also claim prime editing is more powerful, precise, and flexible than CRISPR.
The research paper describes prime editing as a “versatile and precise genome editing method that directly writes new genetic information into a specified DNA site using a catalytically impaired Cas9endonuclease fused to an engineered reverse transcriptase, programmed with a prime editing guide RNA (pegRNA) that both specifies the target site and encodes the desired edit.”
And a Harvard Gazette article states, “Prime editing differs from previous genome-editing systems in that it uses RNA to direct the insertion of new DNA sequences in human cells.”
Assuming further research and clinical studies confirm the
viability of this technology, clinical laboratories would have a new diagnostic
service line that could become a significant proportion of a lab’s specimen
volume and test mix.
In that e-briefing we wrote that Liu “has led a team of scientists in the development of a gene-editing protein delivery system that uses cationic lipids and works on animal and human cells. The new delivery method is as effective as protein delivery via DNA and has significantly higher specificity. If developed, this technology could open the door to routine use of genome analysis, worked up by the clinical laboratory, as one element in therapeutic decision-making.”
Now, Liu has taken that development even further.
“A major aspiration in the molecular life sciences is the ability to precisely make any change to the genome in any location. We think prime editing brings us closer to that goal,” David Liu, PhD (above), Director of the Merkin Institute of Transformative Technologies in Healthcare at the Broad Institute, told The Harvard Gazette. “We’re not aware of another editing technology in mammalian cells that offers this level of versatility and precision with so few byproducts.” (Photo copyright: Broad Institute.)
Cell Division Not Necessary
CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. It is considered the most advanced gene editing technology available. However, it has one drawback not found in Prime Editing—CRISPR relies on a cell’s ability to divide to generate desired alterations in DNA—prime editing does not.
This means prime editing could be used to repair genetic mutations in cells that do not always divide, such as cells in the human nervous system. Another advantage of prime editing is that it does not cut both strands of the DNA double helix. This lowers the risk of making unintended, potentially dangerous changes to a patient’s DNA.
The researchers claim prime editing can eradicate long lengths of disease-causing DNA and insert curative DNA to repair dangerous mutations. These feats, they say, can be accomplished without triggering genome responses introduced by other forms of CRISPR that may be potentially harmful.
“Prime editors are more like word processors capable of
searching for targeted DNA sequences and precisely replacing them with edited
DNA strands,” Liu told NPR.
The scientists involved in the study have used prime editing to perform over 175 edits in human cells. In the test lab, they have succeeded in repairing genetic mutations that cause both Sickle Cell Anemia (SCA) and Tay-Sachs disease, NPR reported.
“Prime editing is really a step—and potentially a significant step—towards this long-term aspiration of the field in which we are trying to be able to make just about any kind of DNA change that anyone wants at just about any site in the human genome,” Liu told News Medical.
Additional Research Required, but Results are Promising
Prime editing is very new and warrants further
investigation. The researchers plan to continue their work on the technology by
performing additional testing and exploring delivery mechanisms that could lead
to human therapeutic applications.
“Prime editing should be tested and optimized in as many cell types as researchers are interested in editing. Our initial study showed prime editing in four human cancer cell lines, as well as in post-mitotic primary mouse cortical neurons,” Liu told STAT. “The efficiency of prime editing varied quite a bit across these cell types, so illuminating the cell-type and cell-state determinants of prime editing outcomes is one focus of our current efforts.”
Although further research and clinical studies are needed to
confirm the viability of prime editing, clinical laboratories could benefit
from this technology. It’s worth watching.
This technology has potential to create a demand for pathologists to do genetic analysis as a companion diagnostic in support of physicians treating patients with gene-editing proteins
Researchers at Harvard University have demonstrated a new method to deliver gene-editing proteins into cells. This breakthrough could eventually trigger a demand for pathologists to do genetic analysis as the companion diagnostic needed to help clinicians select appropriate gene-editing therapies for their patients.
Of course, it will be several years before such a scenario is feasible. The related example are the companion diagnostic tests that clinical laboratories perform to guide a physician’s decision on an appropriate therapeutic drug. Continued development of gene-editing therapies has the potential to increase the need for pathologists and medical laboratory scientists to do genetic analysis as a companion diagnostic for patients who would benefit from a gene-editing therapy.
The Harvard University researchers used commercially available cationic lipids to deliver genome-editing proteins into cells. The system works on living animals and humans, and the technology enables scientists to precisely and easily change DNA sequences at exact locations. The full study was outlined in an October Nature Biotechnology article. (more…)
