LA JOLLA, CA—Cancer treatments take a toll on the immune system. Chemotherapies and cancer immunotherapies are notorious for weakening the immune system and leaving patients vulnerable to life-threatening infections.
For pediatric patients, the fact that their young immune systems are still undergoing development means cancer treatments may have additional, unexpected side effects. These patients haven’t had a chance yet to build up strong immunity against pathogens.
“The leading cause of mortality in our patients, outside of cancer relapse, is infectious disease,” says L. Benjamin Hills, M.D., Ph.D., a member of the Crotty Lab at La Jolla Institute for Immunology (LJI) and a pediatric oncology fellow at UC San Diego School of Medicine.
Hills, who treats patients at Rady Children’s Hospital, is dedicated to reducing that risk. He was recently awarded the Cancer Research Institute’s prestigious Irvington Postdoctoral Fellowship to support his novel research idea.
With this three-year, $243,000 fellowship, Hills will investigate how the immune system changes over the course of cancer treatment—and how doctors can keep their patients as healthy as possible along the way.
Hills will work with a group of pediatric oncology patients receiving care at Rady Children’s. To study their immune cells, Hills will use a nasal swabbing technique originally developed in the Crotty Lab at LJI. This nasal swabbing technique made headlines in 2024, when LJI researchers showed that they could use nasal swabs to capture large numbers of immune cells that reside in—and defend—a person’s upper airway.
“With this nasal swabbing technique, we were able to capture populations of T cells and B cells that you really don’t find in the blood and are critical for protective immunity,” says Hills. “Part of the power of the nasal swabs is that the cells we capture may reflect analogous cells in other secondary lymphoid organs (such as lymph nodes) and barrier tissues that are typically inaccessible in human studies.”
Hills plans to swab pediatric cancer patients at the time of diagnosis, during cancer treatment, and after treatment has ended. From these swabs, Hills will isolate immune cells and study how they might change over the course of each patient’s treatment.
Hills hopes his work can help guide clinical care. For example, many of his patients are at an age when they should be receiving their routine childhood vaccinations. Unfortunately, their vaccination schedules are often interrupted by cancer treatment.
Hills wants to know if his cancer patients have enough immune cells—and of the right types—to even build protective responses to a vaccine.
When it comes to vaccine schedules for young cancer patients, current guidelines are limited by a lack of high-quality evidence. Vaccine schedules are also based entirely on observations from blood, which reflects a minority of total body immune cells, says Hills.
“We need the best evidence possible to support vaccine timing recommendations for these patients,” says Hills. “When might these patients actually be able to mount immune responses to vaccines, and when are they going to be most susceptible to infections?”
With his new support from the Cancer Research Institute, Hills can track immune cell responses to vaccines and get a clearer picture of patient health. “That insight would help us provide better supportive care, including evidence for when to offer prophylactic antimicrobials,” says Hills.
Hills credits his mentor, LJI Professor and Chief Scientific Officer Shane Crotty, Ph.D., for encouraging him to pursue a project where he can answer questions about fundamental immunology and clinical care at the same time. He also thanks the UC San Diego Pediatric Physician Scientist Training Program for ongoing support throughout his training. He says receiving the new fellowship reinforces his hope that better immune cell tracking can lead to better pediatric oncology care.
“This is validation that we’re on the right track,” says Hills.
