Researchers recently did something that sounds weird: they gave 15 people with bladder cancer a strain of the common cold virus—not to make them cough and sniffle through a cold, but rather to see whether the virus was safe, so that it might one day empower the immune system to attack bladder cancer cells.Read More
The study shared the findings from a (very small) phase I trial, and included a detail that has since garnered a great deal of attention: One of the patients given the virus had a “complete resolution of tumor”—meaning their cancer was undetectable after the cold virus injection.
News outlets have since focused on that detail, publishing stories about the study with headlines such as “Bladder Cancer Destroyed By the Common Cold Virus,” and “This Strain of the Common Cold Kills Cancer Cells.”
“That’s not the message that people should take from this study,” Dr. Jay Shah, a urologic oncologist at Stanford Medicine who treats patients with bladder cancer, told SurvivorNet. “But of course that’s the message everyone is wanting to take from it.”
Phase I Studies Give Us Limited (Albeit Important) Information
The reason Dr. Shah doesn’t think people should jump to these conclusions is that the study was only phase I—which means it was actually only testing out whether it was safe to give the 15 patients with bladder cancer the cold virus (which they put right into the bladder using a catheter). The study wasn’t designed to test how well the virus accomplished the task of “destroying bladder cancer.”
“If you have a new agent that you want to test and you think you’ve made progress in terms of what you know about it in the lab, you have to do a phase I study to make sure it’s safe,” Dr. Shah explained. “That’s all a phase I study is; it’s ‘is it tolerable or not?’ You can’t actually make conclusions about the efficacy of the drug. That’s not at all what a phase I study is for.”
And although the one person in the study (who researchers would call an “exceptional responder“) saw their bladder cancer tumor disappear, Dr. Shah said, “I think it’s very dangerous to take the results from that one person and say, ‘Oh, this is going to be the future.’ Because the truth is, that one patient who had complete regression… maybe it would have gone away without the cold virus. That has been known to happen.”
Ok, The Cold Virus Didn’t Necessarily “Kill Bladder Cancer.” But Could it Someday?
To be sure, treating bladder cancer with the help of the common cold virus is indeed the end goal; the researchers at the University of Surrey in England hope this will eventually be the case. They were only testing for safety in this trial, but they still noted in the published findings that, at the time of their surgeries a week after getting the virus infusions, the majority of the patients in the study showed “virus cell death” in their tumors—which encouraged the researchers, but didn’t definitively indicate that the virus was the cause of said cell death.
“I’m happy that they did this study—and I’m excited by the idea that there could be another option for patients with bladder cancer,” Dr. Shah said. “But it needs to be studied so, so much more rigorously before we can even begin to say if it works for bladder cancer.”
Now that researchers have tested whether injecting the specific strain of the common cold virus (called “Coxsackievirus A21,” or “CVA21”) into patients’ bladders through a catheter is safe and tolerable—and found that it is—they will need to move into phase II and III trials to investigate how well it works. Dr. Shah said that could take years.
And the researchers shared that they plan to test the drug in combination with other exciting new immunotherapy drugs, too, including checkpoint inhibitors.
Wait, Back Up – How, Exactly, Could the Common Cold Virus Help Treat Bladder Cancer?
If the CVA21 virus does ultimately show it’s effective in treating bladder cancer (as the researchers, Dr. Shah, and anyone with bladder cancer that hasn’t responded to available treatments hope it will), it would essentially work by catching the immune system’s attention and encouraging it to come take action in the bladder. The immune system would see the virus and identify it as something it needs to get rid of—and since the virus would have infected the cancer cells, the immune system would, the idea is, get rid of the cancer cells, too.
“Typically, tumors in the bladder do not have immune cells, preventing a patient’s own immune system from eliminating the cancer as it grows,” the study’s authors shared in a press release. “Evidence suggests that treatment with [the cold virus] inflames the tumor, causing immune cells to rush into the cancer environment, targeting and killing the cancer cells.”
Tumors that, like bladder cancer, lack immune cells are known as “cold” areas—and when you add in the virus, they become “heated.” That is to say, the common cold virus “heats up” the area with immune system action.
A couple of additional things to note about the study include the fact that the virus was specifically tested in patients with non-muscle invasive bladder cancer, a type of bladder cancer in which the cancerous cells are infecting the lining of the bladder, but not the bladder muscle itself.
And Dr. Shah also explained that the idea of using the cold virus to help the immune system fight cancer wouldn’t necessarily be an idea that would only work in bladder cancer, but the researchers likely chose bladder cancer because the bladder is a closed, contained environment in the body, making it an ideal location to test the “cold virus kills cancer cells” idea. Plus, patients with bladder cancer could certainly use more treatment options.