PROVIDENCE, R.I. [Brown University] — The first study to evaluate the clinical characteristics and outcomes of vaccinated (but not boosted) patients with cancer who had breakthrough COVID-19 infections indicates they remained at high risk for hospitalization and death. 

The study, published in Annals of Oncology, showed that vaccinated patients who experienced breakthrough COVID-19 infections had a hospitalization rate of 65%, an ICU or mechanical ventilation rate of 19% and a 13% death rate. Data for the study was collected before booster vaccines were recommendation for patients with cancer by the U.S. Centers for Disease Control and Prevention.

The study was conducted by the COVID-19 and Cancer Consortium, a group of 129 research centers that is tracking the impact of COVID-19 on patients with cancer. The Lifespan Cancer Institute and partner Brown University are among the participating institutions.

“These findings come at a time of concerns that immune escape mutants such as the omicron strain may emerge from chronically infected patients with weakened immune systems, said Dr. Dimitrios Farmakiotis, a senior author of the study. “Thus, the immunosuppressed and their close contacts should be target groups for therapeutic and preventive interventions, including community-level outreach and educational efforts.”

Farmakiotis is an associate professor of medicine at Brown’s Warren Alpert Medical School and director of transplant and oncology infectious diseases at Rhode Island Hospital, the Lifespan Cancer Institute and the Lifespan Cardiovascular Institute.

Similar high COVID-19 mortality rates among fully vaccinated individuals have been reported in other immunocompromised patient populations, such as organ transplant recipients, prior to the utilization of additional vaccine doses, he said.

At the time the study was conducted, patients were considered fully vaccinated after having received two doses of either the Pfizer-BioNTech vaccine or the Moderna vaccine, or one dose of the Johnson & Johnson vaccine, with the last dose long enough before breakthrough COVID-19 to consider them fully vaccinated. The data were collected from November 2020 through May 2021, before booster vaccines were recommended by the CDC.

The consortium identified 1,787 patients with cancer and COVID-19 for the study, the vast majority of which were unvaccinated. The number of fully vaccinated was 54, and 46% of those fully vaccinated had reduced levels of lymphocytes — the T cells and B cells responsible for immunological responses to viruses. Lymphopenia commonly occurs in patients with cancer receiving anti-CD20 monoclonal antibodies or CAR-T-cell treatments for hematologic malignancies, including lymphoma and leukemia.

The study appears to support previous observations that patients with hematologic malignancies are at greater risk for severe outcomes from COVID-19. However, the number of patients in the study is too small to make definitive conclusions about specific types of anticancer therapies that might be associated with breakthrough infections, the researchers noted. Patients on a treatment regimen of corticosteroids also appeared to be more susceptible to hospitalization.

“Because measures of immunity are not routinely collected in clinical care, we don’t know whether these were patients who mounted effective immune responses after vaccination; a lot of emerging data have suggested that patients with cancer, especially blood cancers, don’t mount adequate protective antibody responses,” said Dr. Jeremy Warner, director of the CCC19 Research Coordinating Center, associate professor at Vanderbilt-Ingram Cancer Center and a senior author of the study. “It’s important to note that many of the same factors that we identified prior to the availability of vaccination — age, comorbidities, performance status, and progressing cancer — still seem to drive many of the bad outcomes.”

The study’s lead authors are Andrew Schmidt, Chris Labaki, Ziad Bakouny, all from Dana-Farber Cancer Institute; and Chih-Yuan Hsu of Vanderbilt-University Medical Center. The senior authors are Choueiri of Harvard, Farmakiotis of Brown University, and Warner and Yu Shyr, of Vanderbilt University Medical Center. Other Brown contributors included Orestis Panagiotou.