McMaster researchers pinpoint cell that causes cancer to return
Now they’re looking for a way to ‘take it down’ so patients in remission can stay that way
A potential key to stopping cancers from returning has been discovered by Hamilton researchers.
A previously unknown cell has been found to be responsible when acute myeloid leukemia patients in remission relapse, concludes groundbreaking work by the Stem Cell and Cancer Research Institute (SCCRI) at McMaster University.
The results from the study published Monday in the journal Cancer Cell are believed to be true for other cancers as well and work has already begun to find this comeback cell in brain tumours and colon cancer.
“We have a new enemy,” said Mick Bhatia, lead author of the study and director of SCCRI. “It has a bunch of Achilles heels and we’re going to test and see if we can take it down.”
It’s significant because the same treatment often doesn’t work the second time around, making relapse a particularly deadly puzzle that cancer researchers have been struggling to solve.
“We now have analytical evidence that cancers largely come back and the problem is when they come back, you can’t just repeat the treatment,”
said Bhatia. “When it comes back, it comes back with a vengeance.”
Up until now there have been questions of how the disease returns after tests show chemotherapy has killed off all the cancer cells.
“How is that possible?” says Bhatia. “We’ve been on this issue for a while of why cancers come back after chemotherapy. Obviously, chemotherapy is very effective. It puts people in remission to a point where you are not detectible (as having cancer).”
In what Bhatia compares to a police stakeout, McMaster researchers put seemingly noncancerous cells under surveillance after leukemia patients and mice went into remission.
One of those cells eventually revealed itself to be cancer in disguise in the study funded by the Canadian Cancer Society, the Canadian Institutes of Health Research and the Ontario Institute for Cancer Research.
“That was the surprise,” said Bhatia. “They are responsible for the regeneration of the disease …We think the chemotherapy is doing two things. It’s killing the bulk of the cells and, in addition to that, it’s teaching a subset of cells to hide and masquerade into something else so we can’t find them … They change themselves in a way so we can’t detect them by measuring things in the blood or imaging.”
Bhatia compares it to a robber who goes into the bank as a woman wearing a blue hat but takes off the hat and puts on a moustache in the getaway car to no longer resemble the suspect.
“We found there were these really small numbers of cells — five, 10 or 15 cells even — that were left over and those cells did not look like cells we’ve ever seen before,” said Bhatia. “They expressed different proteins, they expressed different genes and things you never would have ever thought were the original cancer.”
The discovery is like finding out you’re missing a key ingredient in a recipe. It gives researchers a new path to go down to try and prevent cancer from returning.
“Now we know what we’re trying to kill,” said Bhatia. “We’re just missing that second ingredient in the treatment.”
These masquerading cells need to be targeted differently than typical cancer cells with new weapons.
“It means chemotherapy needs something else,” said Bhatia “Our ongoing idea, based on our findings, is if we take the chemotherapy that works quite effectively and add something that kills these comeback cells, then you’ve gotten rid of the cancer for good.”
SCCRI has already launched several projects to find the drug that will kill comeback cells in leukemia, which is a cancer that starts in blood stem cells.
“We just created an entire campaign of research,” said Bhatia. “We’re excited because we think if people who are studying other tumours do the same thing, they will get other masquerading cells.”
Bhatia expects the work will move forward quickly because a handful of drugs have already been identified as contenders.
“Surprisingly there are not a lot of new procedures to deal with relapse right now. Most new drugs from private sector are all being tested in early diagnosis of acute myeloid leukemia,” said Bhatia.
“We think the drug we’re testing now, once we have enough evidence, will probably move ahead fairly rapidly because there aren’t a lot of options out there for patients.”
‘‘ We think the chemotherapy is doing two things. It’s killing the bulk of the cells and, in addition to that, it’s teaching a subset of cells to hide.
MICK BHATIA