Using Aspirin to Prevent Breast Cancer Recurrence and Targeted Therapy for Treating Advanced Pancreatic Cancer: The ASCO Plenary Series

The pace of progress in cancer research keeps getting faster and faster. However, the results of this research can take time to reach the medical community. The ASCO Plenary Series is a program developed by the American Society of Clinical Oncology (ASCO) to help speed the delivery of high-impact cancer research. In this series, cancer care providers gather online to learn about new, carefully selected research and discuss the study results with their colleagues.

The February 2022 session in the ASCO Plenary Series features 2 studies:

Follow the discussion about research from the ASCO Plenary Series by using the #ASCOPlenarySeries hashtag on Twitter.

Who does this study affect: People treated for HER2-negative breast cancer with a high risk of recurrence.

What did this study find: Several studies have suggested that taking aspirin daily can reduce the risk of breast cancer. However, a phase III randomized, controlled clinical trial has shown that taking aspirin daily does not help prevent recurrence in people diagnosed with HER2-negative breast cancer.

This study included 3,021 people who had invasive HER2-negative breast cancer (both triple negative breast cancer and hormone receptor-positive breast cancer) and were between 18 and 70 years old. To join this clinical trial, participants needed to have a higher risk of recurrence. Among those with HR-positive cancer, the cancer had to also be node-positive, meaning it had spread to lymph nodes, and diagnosed in the past 10 years. Among those with HR-negative cancer, the cancer could be either node-positive or the tumor was larger than 2 centimeters, and it had to have been diagnosed in the past 18 months (about 1 and a half years). The participants were evenly divided into 2 groups. The first group received 300 milligrams of aspirin daily for 5 years. The control group received a placebo pill daily for 5 years. Neither the study participants nor the researchers involved in this study knew whether the participants were receiving the aspirin or the placebo. This kind of study is called a double-blind, placebo-controlled study, and it is a very reliable way to figure out if a treatment is effective without introducing bias.

The researchers were trying to determine how effective aspirin was at preventing recurrence by measuring invasive disease-free survival (iDFS). iDFS is a measurement of the amount of time between the initial treatment for cancer and the time until cancer returns. The participants were observed for a median of 20 months, which means half were observed for more than 20 months and the other half were observed for less than 20 months. Among those taking aspirin, 107 patients had their cancer come back, and among those in the control group, 84 had their cancer come back. At that point, it was calculated that people in the aspirin group did not have a lower rate of cancer recurrence, and it was unlikely that aspirin would be helpful in preventing breast cancer recurrence. The group of experts responsible for judging the safety of the clinical trial (called a Data and Safety Monitoring Board) recommended that participants be notified which treatment group they were in. This ended the clinical trial.

What does this mean for patients: Aspirin did not help prevent recurrence among people diagnosed with HER2-negative breast cancer and a high risk of recurrence.

Read this abstract and authors’ disclosures on ASCO.org.

“Although inflammation may still play a role in cancer progression, aspirin is not recommended for prevention of breast cancer recurrence.”

—   lead study author Wendy Y. Chen, MD, MPH
Dana-Farber Cancer Institute
Boston, Massachusetts

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Who does this study affect: People with advanced pancreatic cancer with a KRAS G12C mutation.

What did this study find: A report from an ongoing clinical trial, called CodeBreaK 100, has shown that a medication called sotorasib might be an effective treatment for advanced pancreatic cancer with a specific genetic mutation. Sotorasib is a targeted therapy that targets a genetic change called a KRAS G12C mutation. CodeBreaK 100 is a phase I/II clinical trial testing whether such tumors respond to sotorasib and the treatment is safe for patients.

In pancreatic cancer, the KRAS mutation is found in about 90% of cases. Between 1% and 2% of metastatic pancreatic cancers will have a specific type of change in the KRAS gene, called G12C. The standard treatment for this diagnosis uses combinations of chemotherapy. If the cancer is not stopped by 2 different lines of chemotherapy, there are no treatments proven to help patients live longer.

This study included 38 people with pancreatic cancer. The average age of the participants was 65 years, and 3 of every 4 were men. By the time the study began, all participants had stage IV cancer, and about 4 of every 5 had received 2 or more lines of treatment.

The participants were observed for a median of nearly 17 months, meaning half were followed for more than 17 months and the other half were followed for fewer than 17 months. In that time, 8 of the participants (21%) had a partial response, meaning the treatment caused the cancer to shrink but not go away completely. For 32 of the participants (84%), the cancer was stable or shrunk. This treatment effect lasted for a median of 5.7 months, and it stopped or slowed the cancer for a median of nearly 4 months. Sotorasib did cause side effects in 16 participants. Serious side effects occurred in 6 people, including diarrhea and fatigue, but these did not lead anyone to stop taking the treatment.

What does this mean for patients: This phase I/II clinical trial showed that advanced pancreatic cancer with the KRAS G12C genetic change responded to sotorasib and that treatment side effects are manageable for patients.

Read this abstract and authors’ disclosures on ASCO.org.

These data are promising for pancreatic cancer patients with high unmet medical need who have limited treatment options.

—   lead study author John H. Strickler, MD
Duke University Medical Center
Durham, North Carolina

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