University of Iowa doctor using blood test to detect leftover cancer DNA in patients

Published: Jun. 18, 2020 at 12:54 AM CDT
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What if you could detect the presence or absence of leftover cancer DNA in a patient previously diagnosed with cancer?

A test called the

is doing just that, and a doctor with the University of Iowa Health Care explained to TV6 in an exclusive interview how the hospital is part of an expanded access program, allowing some Gastrointestinal (GI) cancer patients access to the testing.

Dr. Pashtoon Kasi, Assistant Professor in the Division of Oncology, said they were one of the first hospitals to be a part of the program and have had nearly 100 patients who have been tested at least one time.

This liquid biopsy is not a treatment, but rather it can detect and calculate how much cancer is left in the body, if any, after a patient has their curative surgery, or whether there is none.

"Liquid biopsies, in general, are something that are revolutionizing cancer care and treatment," said Kasi.

The name is misleading; the test is not a biopsy, but rather a simple blood draw that can even be done in the comfort of a patient’s home, with the vials sent to the lab.

“There are two steps to this cancer testing. One is taking a piece of the person's tumor, seeing what it's made of, and designing a custom-built assay for each patient. Theoretically, it can work for all kinds of cancers,” said Kasi. “The program we're participating in initially was focusing on Colorectal cancer and then it expanded as a means of providing expanded access to patients during this challenging time of all GI cancer patients.”

Dr. Kasi said, “It can detect cancer a year before the scan detects it. That's why right now if somebody is cured after their surgery, we still see them for ‘x’ number of years because we don't have a crystal ball to know who's the one who's cured, who's the one who's not. It's opening doors to questions that we never even had the opportunity of asking because we were often relying on cruel measures and scans that often lag behind in terms of cancer detection and recurrence.”

The test can detect even minimal amounts of disease in a patient. It is the first custom-built tumor-informed blood test and is personalized to each patient, said Kasi.

As Kasi explained, “Because circulating tumor DNA (ctDNA) – tumor from the patient’s cancer in their blood – has a very short half-life (disappears within hours to days) from the time of their curative surgery, a blood sample done a few weeks-operatively should not show any more ‘left-over’ cancer. If it is present, it is ominous. Not the kind of news one would like to deliver; but both from the patient and provider experience, would rather know than not know.”

“The test right now is being used in what we call the minimal residual disease setting which is, simplistically speaking, checking for presence or absence of DNA after somebody has already had their curative surgery,” said Kasi.

“Right now arbitrarily everybody gets some chemo afterwards to mop up simplistically what may have been left behind,” he explained. By doing the testing it is allowing providers to determine next steps of treatment, or spare those from the toxicity of treatments they are undergoing if their test is negative.

Kasi said the testing is relevant to the COVID-19 pandemic, because patients can be tested through an in-home blood draw, which is sent back to the lab. “This is one more tool, again in a noninvasive way, at the comfort of the patients home. A simple blood draw and the turnaround time is within seven to 10 days so it is timely,” said Kasi.

During the pandemic, Kasi said cancer care and detection has taken a significant hit, and that doctors have been tasked with prioritizing risks for cancer patients who are already more vulnerable due to lower immune systems.

"Cancer patients are up to three times more at risk of not only complications of COVID related illness but also at risk of dying from the disease so our goal right now in these challenging times has been to reduce the exposure of as many cancer patients to the cancer center as possible," said Kasi.

With an at-home test such as this liquid biopsy, it minimizes risks for patients and limits how many people are going to the hospital.

To explain how the test works, Dr. Kasi provided a comparison. He said, “A lot of this technology originated in the world of pregnancy and prenatal diagnostics. If you think about it, the cancer, as well, is a foreign object in a person's body. As it's growing it's also shedding its DNA in the blood, which can then be captured with the same technology that was being used for sex detection, now for cancer detection.”

The Signatera liquid biopsy, Kasi said is "empowering us with info we didn't have access to before. Knowing who's potentially cured, who's not cured, who still has cancer DNA in their blood, who doesn't."

One of Dr. Kasi’s patients, Ron Schulte, who lives in the Quad Cities, said “you know, instead of waiting for something to happen, you’re preventative.”

In July of 2019, Ron and his wife Cindy received news that Ron was diagnosed with stage 4 Colon cancer.

As Cindy explained, Ron underwent surgery, where a local doctor removed 22 lymph nodes, 18 of which were cancerous. She said, “they removed his appendix. Part of his ascending colon, part of his mesentery and part of the peritoneum.”

After consulting with a local oncologist, Cindy said, “he basically told Ron he would keep him comfortable."

Ron explained, “You kind of start thinking about a death sentence. That was the initial thoughts that did go through your head. It's like dropping a bomb on you. One minute it's fine and the next minute you have cancer."

The Schulte’s decided to travel out to Iowa City and meet with Dr. Kasi for a second opinion in Ron’s options after his cancer diagnosis.

Two days later, Cindy explained, “he had the scans and he had already ordered the tissue samples from pathology."

Ron began chemotherapy and seven into his eight rounds, his nurse informed him that they had been approved for the test.

"His nurse came down and she's like we have it!! We have the test. It was great," said Cindy.

On Ron’s first blood draw, seven rounds into chemo, the Schultes were informed that Ron had no circulating tumor DNA in his blood. His test showed there was no leftover cancer in his body.

“They actually stopped at seven which was okay by me. Each one seemed to get progressively worse,” said Ron.

Several tests later, Ron has had all clear results. “I feel great. Still a little tired, but you know, I think that was just all the chemo,” he said.

“It’s the best thing we did… making that call to Iowa City,” said Cindy.

Ron said, “We were destined to go find the best and I think we did.”

The Schultes credit Dr. Kasi for helping them with the gift of knowledge, and said they were able to get through the difficult times by keeping a positive outlook.

As for patients who are tested by the liquid biopsy, Kasi said, “Somebody could be liquid biopsied positive and then turn negative on treatment and stay negative and hopefully is cured. Somebody could be negative and turn positive and that person probably already has cancer back and could require more attention.”

The test can be done a number of times because it is non-invasive.

"I see the future of care of cancer patients brighter," said Kasi. "I can use it to prioritize which cancer patients should received further treatment to clear the cancer from their body and who can be spared of the toxicity."