The closely watched annual meeting of the American Society of Clinical Oncology (ASCO) is about to kick off in Chicago, and if the last few years are any indication, immunotherapy will likely steal the show. Cancer researchers have been perfecting all sorts of ways to stimulate patients’ immune systems to fight cancer, from chimeric antigen receptor T-cells (CARTs) now being tested in blood cancers, to “checkpoint inhibitors” like Bristol-Myers Squibb’s blockbuster melanoma treatment Yervoy (ipilimumab). But this year, an up-and-coming class of immune-boosting drugs could draw attention at ASCO—viruses that are specially engineered so they destroy tumors and then prime patients’ immune systems to continue fighting off their cancer.
Virus-based cancer treatments, sometimes referred to as “virotherapy,” constitute a fast-growing niche within immunotherapy, and one that is generating a tremendous amount of excitement in the oncology world this year. The idea has actually been around since the late 1800s, when physicians first realized that some viruses have a natural ability to kill cancer cells. But these so-called oncolytic viruses didn’t start breaking out until recently, as advances in genetic engineering have made it feasible to manipulate the virus’ genomes—recreating them, if you will, into supercharged cancer-killing machines that attack tumors but leave normal tissues alone.
Turning the dream of virotherapy into reality has not been easy, but this year, the field got a huge boost from the world’s largest biotech company,
Amgen will be presenting data on its virus-based treatment at ASCO, as will several other companies and academic research groups working on a range of oncolytic viruses, from polio to adenovirus to vaccinia (cowpox). Although some of these scientists are testing their viruses as standalone treatments, virtually everyone working in the field of virotherapy believes their greatest potential may be in combination with other types of immunotherapy, such as the checkpoint inhibitors, which work by blocking certain proteins that prevent the immune system from attacking cancer.
The idea of such combinations would be to kill cancer cells directly with the viruses, while also taking the brakes off the immune system with another immunotherapy treatment, to boost the body’s ability to continue fighting the disease. Viruses might even help patients who otherwise don’t respond to checkpoint inhibitors, says John Beadle, CEO of U.K.-based PsiOxus Therapeutics, which will be presenting data on an oncolytic virus at ASCO this year.
“We’re starting to see a reasonable percentage of patients being cured by checkpoint inhibitors or at least having long-term control of their disease,” Beadle says. “But we’re still seeing that more than 70 percent of patients don’t get a long-term benefit. Combination therapies may give more patients that benefit.” PsiOxus is currently planning a trial of its experimental virus-based treatment, enadenotucirev, with a checkpoint inhibitor in colorectal cancer—a tumor type that so far has not been responsive to immunotherapy. On May 19, PsiOxus raised £25 million ($38.2 million) in a Series C funding round to continue its research.
John Beadle is the CEO of PsiOxus, which recently raised new funding to advance its experimental... [+]
Here’s more on the companies and research groups making a splash at this year’s ASCO with their cancer-killing viruses:
Amgen: The biotech will present data from four studies of T-VEC, including one trial in which it is combining the virus with Yervoy in patients with late-stage melanoma. The study shows that two-thirds of the patients on the combination treatment were still alive after 18 months—a result that’s known in oncology circles as a “durable response.” The trial has not yet ended, so the median survival time is still to be determined.
Duke University: A team of scientists at Duke is in the early stages of testing a genetically modified form of polio virus in patients with glioblastoma, one of the deadliest tumor types. The research came to the world’s attention back in March, when the hit
Genelux: This San Diego company is developing a cancer treatment, GL-ONC1, derived from vaccinia, the cowpox virus that's the basis of the smallpox vaccine. Investigators from Memorial Sloan Kettering Cancer Center and UC San Diego Moores Cancer Center will present data from two early-stage trials—one in head and neck cancer and the other in malignant pleural effusion, a condition that causes fluid buildup in the chest. The company is reporting that in 18 patients with head and neck cancer, the drug was safe and indicated a potential overall survival benefit of 75%, though that figure was based on an estimate. Actual survival figures won’t be reported until the company completes later-stage trials.
Oncos Therapeutics: Finland-based Oncos has developed a modified strain of adenovirus, which it tested in 12 patients with various forms of solid tumors. In the study being presented at ASCO, the virus was injected directly into patients’ tumors, after which the presence of “immune markers”—signals that the immune system is, in fact, being activated—was measured. The company is reporting that all but one patient showed an increase in at least some immune markers.
PsiOxus: This biotech has one of the most unorthodox approaches to virotherapy. Instead of modifying an existing virus, the company created its own adenoviruses by infecting cancer cells with different strains of the virus, observing them as they evolved, isolating the strains that showed the most promise, and then arming them with further immune-boosting properties. The company is testing its lead creation, enadenotucirev, in ovarian and colorectal cancer, and at ASCO it will describe its approach to studying the virus in patients with a certain form of treatment-resistant ovarian cancer.
Virttu Biologics: Glasgow-based Virttu is testing oncolytic versions of herpes and adenovirus. At ASCO it will describe its efforts to create a “Trojan horse” system that would use engineered forms of both viruses in tandem to treat multiple myeloma.
Viralytics: Could the common cold cure cancer? That’s the question Viralytics has set out to answer with its specially formulated version of coxsackievirus, better known as the cold virus. At ASCO, the Aussie company will present data from a mid-stage trial in 57 patients with advanced melanoma. The company will report that 21 of the patients reached the primary endpoint of the trial—achieving immune-related progression-free survival at six months. Further clinical studies are underway, the company reports.
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