Conner Curran, now 10 years old, can walk more than two miles after gene therapy treatment for his Duchenne's muscular dystrophy.
That the medical world is on the cusp of a successful treatment for a crippling and deadly disease is the culmination of more than 35 years of work by Dr. Jude Samulski, a professor of pharmacology at the University of North Carolina School of Medicine in Chapel Hill. More recently, he's become a leading gene therapy entrepreneur.
But Samulski likens this breakthrough to the frustrations of solving a Rubik's cube. "Just because one side is now all the color yellow does not mean that it is completely aligned," he says.
Although Conner's life and future have dramatically improved, he's not cured. The gene therapy tamed but did not extinguish his disorder: Conner is now suffering from the equivalent of Becker's muscular dystrophy, a milder form of the disease with symptoms that appear later in life and progress more slowly. Moreover, the loss of muscle cells Conner suffered prior to the treatment is permanent.
"It will take more time and more innovations," Samulski says of finding an even more effective gene therapy for muscular dystrophy.
Conner's family is still overjoyed with the results. "Jude's grit and determination gave Conner a chance at a new life, one that was not in his cards before gene therapy," says his mother Jessica Curran. She adds that "Conner is more confident than before and enjoys life, even though he has limitations, if compared to his brothers or peers."
Conner Curran holding a football post gene therapy treatment.
Courtesy of the Curran family
For now, the use of gene therapy as a treatment for diseases and disorders remains relatively isolated. On paper at least, progress appears glacially slow. In 2018, there were four FDA-approved gene therapies (excluding those reliant on bone marrow/stem cell transplants or implants). Today, there are 10. One therapy is solely for the cosmetic purpose of reducing facial lines and folds.
Nevertheless, experts in the space believe gene therapy is poised to expand dramatically.
"Certainly in the next three to five years you will see dozens of gene therapies and cell therapies be approved," says Dr. Pavan Cheruvu, who is CEO of Sio Gene Therapies in New York. The company is developing treatments for Parkinson's disease and Tay-Sachs, among other diseases.
Cheruvu's conclusion is supported by NEWDIGS, a think tank at the Massachusetts Institute of Technology that keeps tabs on gene therapy developments. NEWDIGS predicts there will be at least 60 gene therapies approved for use in the U.S. by the end of the decade. That number could be closer to 100 if Chinese researchers and biotech ventures decide the American market is a good fit for the therapies they develop.
"We are watching something of a conditional evolution, like a dot-com, or cellphones that were sizes of shoeboxes that have now matured to the size of wafers. Our space will follow along very similarly."
Dr. Carsten Brunn, a chemist by training and CEO of Selecta Biosciences outside of Boston, is developing ways to reduce the immune responses in patients who receive gene therapy. He observes that there are more than 300 therapies in development and thousands of clinical trials underway. "It's definitely an exciting time in the field," he says.
That's a far cry from the environment of little more than a decade ago. Research and investment in gene therapy had been brought low for years after the death of teenager Jesse Gelsinger in 1999 while he had been enrolled in a clinical trial to treat a liver disease. Gene therapy was a completely novel concept back then, and his death created existential questions about whether it was a proper pathway to pursue. Cheruvu, a cardiologist, calls the years after Gelsinger's death an "ice age" for gene therapy.
However, those dark years eventually yielded to a thaw. And while there have been some recent stumbles, they are considered part of the trial-and-error that has often accompanied medical research as opposed to an ominous "stop" sign.
The deaths of three patients last year receiving gene therapy for myotubular myopathy – a degenerative disease that causes severe muscle weakness – promptly ended the clinical trial in which they were enrolled. However, the incident caused few ripples beyond that. Researchers linked the deaths to dosage sizes that caused liver toxicity, as opposed to the gene therapy itself being an automatic death sentence; younger patients who received lower doses due to a less advanced disease state experienced improvements.
The gene sequencing and editing that helped create vaccines for COVID-19 in record time also bolstered the argument for more investment in research and development. Cheruvu notes that the field has usually been the domain of investors with significant expertise in the field; these days, more money is flowing in from generalists.
The Challenges Ahead
What will be the next step in gene therapy's evolution? Many of Samulski's earliest innovations came in the laboratory, for example. Then that led to him forming a company called AskBio in collaboration with the Muscular Dystrophy Association. AskBio sold its gene therapy to Pfizer five years ago to assure that enough could be manufactured for stage 3 clinical trials and eventually reach the market.
Cheruvu suggests that many future gene therapy innovations will be the result of what he calls "congruent innovation." That means publicly funded laboratories and privately funded companies might develop treatments separately or in collaboration. Or, university scientists may depend on private ventures to solve one of gene therapy's most vexing issues: producing enough finished material to test and treat on a large scale. "Manufacturing is a real bottleneck right now," Brunn says.
The alternative is referred to in the sector as the "valley of death": a lab has found a promising treatment, but is not far enough along in development to submit an investigational new drug application with the FDA. The promise withers away as a result. But the new abundance of venture capital for gene therapy has made this scenario less of an issue for private firms, some of which have received hundreds of millions of dollars in funding.
There are also numerous clinical challenges. Many gene therapies use what are known as adeno-associated virus vectors (AAVs) to deliver treatments. They are hollowed-out husks of viruses that can cause a variety of mostly mild maladies ranging from colds to pink eye. They are modified to deliver the genetic material used in the therapy. Most of these vectors trigger an antibody reaction that limits treatments to a single does or a handful of smaller ones. That can limit the potential progress for patients – an issue referred to as treatment "durability."
Although vectors from animals such as horses trigger far less of an antibody reaction in patients -- and there has been significant work done on using artificial vectors -- both are likely years away from being used on a large scale. "For the foreseeable future, AAV is the delivery system of choice," Brunn says.
Also, there will likely be demand for concurrent gene therapies that can lead to a complete cure – not only halting the progress of Duchenne's in kids like Conner Curran, but regenerating their lost muscle cells, perhaps through some form of stem cell therapy or another treatment that has yet to be devised.
Nevertheless, Samulski believes demand for imperfect treatments will be high – particularly with a disease such as muscular dystrophy, where many patients are mere months from spending the remainder of their lives in wheelchairs. But Samulski believes those therapies will also inevitably evolve into something far more effective.
"We are watching something of a conditional evolution, like a dot-com, or cellphones that were sizes of shoeboxes that have now matured to the size of wafers," he says. "Our space will follow along very similarly."
Jessica Curran will remain forever grateful for what her son has received: "Jude gave us new hope. He gave us something that is priceless – a chance to watch Conner grow up and live out his own dreams."
How It Works
“The whole idea originally came from a conversation I had with General Norman Schwarzkopf, a supposedly brilliant military strategist,” says Dr David Baskin, professor of neurosurgery and leader of the effort at Houston Methodist. “I asked him what is the secret to your success and he said, ‘Energy. Take out the power grid and the enemy can't communicate.’ So I thought about what supplies [energy to] cancer, especially brain cancer.”
Baskin came up with the idea of targeting the mitochondria, which process and produce energy for cancer cells.
This is the most exciting thing in glioblastoma treatment I've seen since I've been a neurosurgeon but it is very preliminary.”
The magnetic helmet creates a powerful oscillating magnetic field. At a set range of frequencies and timings, it disrupts the flow of electrons in the mitochondria of cancer cells. This leads to a release of certain chemicals called ROS (Reactive Oxygen Species). In normal cells, this excess ROS is much lower, and is neutralized by other chemicals called antioxidants.
However, cancer cells already have more ROS: they grow rapidly and uncontrollably so their mitochondria need to produce more energy which in turn generates more ROS. By using the powerful magnetic field, levels of ROS get so high that the malignant cells are torn apart.
The biggest challenge was working out the specific range of frequencies and timing parameters they needed to use to kill cancer cells. It took skill, intuition, luck and lots of experiments. The helmet could theoretically be used to treat all types of glioblastoma.
Developing the magnetic helmet was a collaborative process. Dr Santosh Helekar is a neuroscientist at Houston Methodist Research Institute and the director of oncomagnetics (magnetic cancer therapies) at the Peak Center in Houston Methodist Hospital. His previous invention with colleagues gave the team a starting point to build on. “About 7 years back I developed a portable brain magnetic stimulation device to conduct brain research,” Helekar says. “We [then] conducted a pilot clinical trial in stroke patients. The results were promising.”
Helekar presented his findings to neurosurgeons including Baskin. They decided to collaborate. With a team of scientists behind them, they modified the device to kill cancer cells.
The magnetic helmet studied for treatment of glioblastoma
Dr. David Baskin
Initial Results
After success in the lab, the team got FDA approval to conduct a compassionate trial in a 53-year-old man with end-stage glioblastoma. He had tried every other treatment available. But within 30 days of using the magnetic helmet his tumor shrank by 31%.
Sadly, 36 days into the treatment, the patient had an unrelated head injury due to a fall. The treatment was paused and he later died of the injury. Autopsy results of his brain highlighted the dramatic reduction in tumor cells.
Baskin says, “This is the most exciting thing in glioblastoma treatment I've seen since I've been a neurosurgeon but it is very preliminary.”
The helmet is part of a growing number of non-invasive cancer treatments. One device that is currently being used by glioblastoma patients is Optune. It uses electric fields called tumor treating fields to slow down cell division and has been through a successful phase 3 clinical trial.
The magnetic helmet has the promise to be another useful non-invasive treatment according to Professor Gabriel Zada, a neurosurgeon and director of the USC Brain Tumor Center. “We're learning that various electromagnetic fields and tumor treating fields appear to play a role in glioblastoma. So there is some precedent for this though the tumor treating fields work a little differently. I think there is major potential for it to be effective but of course it will require some trials.”
Professor Jonathan Sherman, a neurosurgeon and director of neuro-oncology at West Virginia University, reiterates the need for further testing. “It sounds interesting but it’s too early to tell what kind of long-term efficacy you get. We do not have enough data. Also if you’re disrupting [the magnetic field] you could negatively impact a patient. You could be affecting the normal conduction of electromagnetic activity in the brain.”
The team is currently extending their research. They are now testing the treatment in two other patients with end-stage glioblastoma. The immediate challenge is getting FDA approval for those at an earlier stage of the disease who are more likely to benefit.
The Future
Baskin and the team are designing a clinical trial in the U.S., .U.K. and Germany. After positive results in cell cultures, they’re in negotiations to collaborate with other researchers in using the technology for lung and breast cancer. With breast cancer, the soft tissue is easier to access so a magnetic device could be worn over the breast.
“My hope is to develop a treatment to treat and hopefully cure glioblastoma without radiation or chemotherapy,” Baskin says. “We're onto a strategy that could make a huge difference for patients with this disease and probably for patients with many other forms of cancer.”