U Researcher Leads National Study to Optimize Response Assessment with Prostate Cancer Treatments

When Arpit Rao, MBBS, began his oncology rotations during residency, it wasn't the practice that inspired his career in prostate cancer research and treatment—it was the patients.

"Patients with prostate cancer are generally older men with a different perspective on life. I found that they tend to be just grateful for every year of their lives after the diagnosis," Dr. Rao said.

Today, Dr. Rao is an assistant professor in the Department of Medicine at the University of Minnesota Medical School and a member of the Masonic Cancer Center. Last fall, he received the Alliance Scholar Award, a two-year research grant from the Alliance for Clinical Trials in Oncology. The Alliance, which is one of only four national clinical trial networks funded by the National Cancer Institute (NCI), conducts clinical research at hundreds of sites across the country and has nearly 10,000 members.

Dr. Rao will lead a multi-institutional team of Alliance investigators, including those at NYU-Cornell, Memorial Sloan-Kettering Cancer Center and Mayo Clinic, to develop a response-adaptive imaging strategy in metastatic, castration-resistant prostate cancer.

“When patients get put on clinical trials of new treatments, two of the most important things we want to find out are what proportion of patients are responding to the treatment and for how long,” Dr. Rao said.

Response assessment in prostate cancer trials is done by measuring blood prostate-specific antigen (PSA) levels and doing periodic CT and bone scans. However, regular scans come with side effects from radiation and contrast exposure in addition to being expensive and labor-intensive.

“Ideally, to get the exact date of progress, one would need to be scanned every day, but you can’t do that. So, we have to find a way to balance the frequency of scans with the risk of scans,” he said.

Dr. Rao, who is currently leading a few clinical trials nationally, says that clinical trials follow the Prostate Cancer Working Group guidelines, which recommend scanning patients every eight to nine weeks during the first six months and every 12 weeks thereafter. However, this one-size-fits-all approach may not be needed for everyone.

“Let’s say a patient’s PSA level drops from 1,000 at the beginning of treatment to 10 in six months. In those six months, it will be very unlikely that that patient will have cancer progression on scans, so why do them?” Dr. Rao asked.

“We want to figure out a way to optimize the imaging schedule that improves accuracy while reducing excessive imaging,” he added. “We will evaluate patient-level data from a recently completed Alliance clinical trial of 1,200 prostate cancer patients to understand which factors, including clinicopathologic characteristics and treatment-response variables, are predictive of the likelihood of cancer progression within a finite time period.”

Dr. Rao hopes that this predictive model will be validated in upcoming clinical trials, and eventually be incorporated in the guidelines and routine clinical care.

“Ultimately, our goal is to help patients and their doctors. If a doctor can track PSA levels for three, six and 12 months after starting treatment and make individualized decisions on the frequency of scans, that’ll change practice nationally,” Dr. Rao said. “Patients are often worried about too few or too many scans, and our findings will help drive that conversation and give them some comfort.”

Dr. Rao and the team expect to finish the study in February 2022 upon completion of the two-year grant, and then publish their findings a year later.