UW-Madison: Combining low-dose radiotherapy with immunotherapy eradicates metastatic cancer in mice

UW-Madison: Combining low-dose radiotherapy with immunotherapy eradicates metastatic cancer in mice

More doesn’t necessarily mean better — including in cancer treatment.

University of Wisconsin–Madison and University of Pittsburgh School of Medicine scientists report today in the journal Science Translational Medicine that combining targeted radiopharmaceutical therapy with immunotherapy significantly boosts eradication of metastatic cancer in mice, even when the radiation is given in doses too low to destroy the cancer outright.

Ravi Patel

“We’re excited — with such low doses of radiation, we didn’t expect the response to be so positive,” says lead author Ravi Patel, assistant professor at Pitt and radiation oncologist at UPMC Hillman Cancer Center. “In clinical trials, we tend to go with the maximum tolerable dose, the idea being that radiation kills the cancer and the more we give, the better. But in this study our concept is different — we’re not trying to destroy the tumor with radiation, we’re trying to trigger the immune system to kill the cancer.”

Immunotherapy has revolutionized cancer treatment by helping patients’ immune systems fight off cancer. But some patients develop resistance to current immunotherapies and others have cancers characterized by immunologically “cold” tumors, which evade or suppress the patient’s immune response against his or her cancer.

In these cases, oncologists have found that external beam radiotherapy, or EBRT — where a patient is placed in a carefully calibrated machine that aims a beam of radiation directly at their tumor — can help turn “cold” or resistant tumors into “hot” tumors against which the immunotherapy treatments work better.

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