Titles and Affiliations
Clinical Research Fellow
Conquer Cancer, the ASCO Foundation
Research Area
Investigating how the gut microbiome influences side effects from treatment.
Impact
Abemaciclib (Verzenio®) is an oral medication that has improved survival for many patients with hormone receptor (HR)-positive, HER2-negative breast cancer, but diarrhea is a common and disruptive side effect. It leads to dose reductions, treatment delays, and early discontinuation. Current treatments for this side effect, like additional medications or lowering the drug dose, are not always effective nor ideal for patients. Researchers are learning that the gut microbiome, a community of bacteria living in the gut, may play a role in who develops side effects from certain medications, but this hasn’t been well studied in people taking abemaciclib. The gut microbiome can be changed through simple approaches like diet modification. For her Conquer Cancer research supported by BCRF, Dr. Hennessy is launching a two-stage study to understand how the gut microbiome may affect side effects from abemaciclib.
What’s Next
In the first stage, Dr. Hennessy will follow patients with HR-positive/HER2-negative breast cancer who are starting abemaciclib, using an at-home stool collection system to track changes in their gut bacteria before and during the first month of treatment, when diarrhea most often occurs. The team will look at whether the types and variety of gut bacteria are linked to who develops diarrhea and how severe it is. In the second stage, a smaller pilot study will test whether it’s practical for patients to add more fiber to their diet before starting treatment. This research could lay the groundwork for future studies testing whether diet or other non-medication approaches can prevent diarrhea, helping patients stay on treatment longer with a better quality of life.
Biography
Maeve Hennessy, MBBCh is a medical oncologist and graduate of University College Dublin, Ireland. She completed Higher Specialist Training in Medical Oncology through the Royal College of Physicians of Ireland and began an advanced fellowship in breast oncology at the University of Chicago in 2025. Her research focuses on biomarker development and microbiome-host interactions in breast cancer, aiming to better predict treatment response and reduce therapy-related toxicity. She was the inaugural recipient of the Breakthrough Cancer Research Fellowship, completing a postgraduate thesis exploring the perioperative period as a platform for biomarker discovery. She has also received support from ESMO and the International Cancer Foundation and was awarded the Alavi-Mandell Award from the Society of Nuclear Medicine and Molecular Imaging.
