Study finds serious blood-related side effects associated with antibody-drug conjugates

A major real-world study by University of California, Irvine pharmacy researchers has found serious blood-related side effects associated with antibody-drug conjugates, an increasingly important class of targeted cancer therapies. Over the years, many novel ADC therapies have been approved for treating various types of cancers.

The study, published in the journal Cancers, analyzed treatment data from 3,511 patients across six University of California medical centers. It discovered that some ADCs were associated with substantial rates of severe neutropenia – dangerously low levels of infection-fighting white blood cells – and related complications, such as hospitalization, intensive care admissions and febrile neutropenia, a potentially life-threatening condition involving fever and infection risk.

Researchers at the School of Pharmacy & Pharmaceutical Sciences and UCI Health, including corresponding author Alexandre Chan, professor and chair of clinical pharmacy practice, led the effort.

ADCs are designed to deliver chemotherapy directly to cancer cells while minimizing damage to healthy tissue. Although they have improved treatment outcomes for several cancers, including breast and blood cancers, the study found that risks of severe neutropenia and infection-related complications varied widely depending on the specific drug used.

Our findings demonstrate that while antibody-drug conjugates offer tremendous promise for cancer patients, clinicians must remain vigilant about potentially serious hematologic toxicities. Using real-world data allows us to understand better how these therapies affect diverse patient populations outside the controlled environment of clinical trials."

Alexandre Chan, professor and chair of clinical pharmacy practice, University of California, Irvine

Researchers evaluated 10 commonly used FDA-approved ADCs using data collected between 2012 and 2024 through the University of California Health Data Warehouse. The analysis showed that certain therapies were associated with particularly high rates of hematological toxicities, such as febrile neutropenia and severe neutropenia, while underlying conditions such as anemia and immunodeficiency disorders increased patients' risk of complications.

The study also highlighted the importance of large-scale health system data to improve supportive cancer care and to identify patients who may benefit from earlier monitoring or preventive interventions.

"As these targeted therapies become more widely used, understanding and anticipating side effects becomes increasingly important," Chan said. "This work can help inform safer treatment strategies and improve patient outcomes."

The research involved collaboration among investigators from UC Irvine, UCI Health, the University of Washington and the broader University of California health system.