Tumors grown in a petri dish may help physicians find more effective treatment for cancer patients.

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Experts are learning how lab-grown tumors can help patients. Getty Images

Scientists have developed a way to quickly test hundreds of cancer drugs in order to find the best treatment: using mini-tumors grown from a patient’s own cancer cells.

These tumor organoids, as they’re called, represent another step forward for precision medicine, where treatments are tailored to a person’s particular cancer.

Recent advances in gene sequencing have made it easier for scientists to know a tumor’s exact DNA makeup. This could potentially allow them to choose the best drug to treat that specific subtype of cancer.

But right now there’s limited information on which drugs work for which cancer mutations.

“We have lots of drugs available, but we have a hard time knowing who’s going to respond to which drug or to which drug combination,” said Alice Soragni, PhD, the senior author of a new study and scientist at the UCLA Jonsson Comprehensive Cancer Center.

To work around this limitation, Soragni and her colleagues grew mini-tumors in the lab using cancer cells collected from patients during surgery.

First they processed the tumor tissue to break it apart. Then they placed isolated cancer cells in hundreds of tiny wells on multiple test plates.

Within two to three days, the cells had grown into three-dimensional mini-tumors. Over the next two days, the researchers tested different drugs and drug concentrations on the mini-tumors.

The tumors are thin enough that many types of drugs — both small molecules and larger compounds — easily penetrate the cancer cells.

Using this method, the researchers were able to determine which drugs the cancers were most sensitive to.

“We now have a way to take cancer cells directly from a patient and grow these miniature tumors in a dish that are basically avatars of the patient’s tumor,” Soragni said.

The researchers used ovarian and peritoneal cancer cells, but other studies have already created mini-tumors — using different methods — for other types of cancers, including bladder, bowel and gastrointestinal cancers.

Using mini-tumors, though, won’t work for every type of cancer treatment.

“Right now we can only test drugs which directly target the tumor,” Soragni said. “For example, we cannot test immunotherapies or types of drugs that require some other components besides the tumor itself.”

The researchers described their technique Feb. 25 in Communications Biology.

Much of this process can be automated, which speeds things up and reduces the potential for human error.

“We get the tumor, we process it, we seed the cells in the wells, and then we never touch the cells again,” Soragni said. “Everything else is done automatically.”

From tissue collection to screening hundreds of drugs takes only about two weeks, says Soragni.

“The results of the screening could potentially be available to the oncologist by the time the patient is recovered from surgery and ready to move forward with drug therapy,” she said.

Dr. Ron Bose, a medical oncologist at Siteman Cancer Center at Washington University School of Medicine, who wasn’t involved in the study, said, “Being able to provide drug testing results on cancer samples within one week of surgery offers tremendous possibilities.”

Still, he said, “More information is needed before we can say whether this will hold up clinically for patients and their care.”

A 2018 study in Science found that mini-tumors were highly accurate in predicting how patients would respond to drug therapy.

Bose says the new mini-tumor method would still need to be tested in clinical trials with large numbers of participants.

These trials would show whether the method was accurate enough to improve patient care. They may also indicate whether only two days of drug testing on the mini-tumors is sufficient.

“While this was likely done for speed of testing,” Bose said, “it has the potential of increasing false negatives, as some drugs may require more time for their effects to become measurable.”

The researchers, and other groups, will need to address these questions over the next several years before this method will be ready for the clinic.

But many see the research as promising.

“I am excited and encouraged about this study,” Bose said, “and I look forward to seeing more data on this in the future.”